Subdivisions of Biology

Notes
• The word ‘Science’comes from the Latin word ‘scientia’,
meaning ‘knowledge’.
• Science is the systematic knowledge of the physical
or material world gained through observation and
experimentation.
• Science has been classified into - (1) Natural Science and
(2) Social Science.
• Natural Science has further classified into - (i) Physical
Science and (ii) biological Science which has been
further divided into many branches and sub-branches.
• Lamarck and Treviranus introduced the term ‘biology’
independently in modern sense in 1802.
Branches and Subbranches of Biology
Zoology - Detailed study of different living and extinct animals.
Botany - Detailed study of plants and their life.
Palaeontology -The study of history of life on Earth as based on
fossils. Fossils are the remains of plants, animals, fungi, bacteria
and single celled living things that have been found in layers of
rock materials or impressions of organisms preserved in rocks.
Palaeobotany - Study of plant fossils.
Ecology - The branch of biology that deals with the relation of
organisms to one another and to their physical surroundings.
Genetics- The study of heredity or how the characteristics of
living things are transmitted from one generation to the next.
Every living thing contains the genetic material that makes
up DNA molecule. This material is passed on when organism
reproduces. The basic unit of heredity is ‘Gene’.
Physiology - Study of normal functions of living creatures
and their parts.
Pedology - It is the study of soils in their natural environment. It
deals with pedogenesis, soil morphology and soil classification.
Edaphology - It concerns with the influence of soils on living
things, particularly plants.
Gerontology - Study of the social, cultural, physiological,
cognitive, and biological aspects of ageing, or the scientifi c
study of old age, the process of ageing and the particular
problems of old people.
Ethology - It is the scientific and objective study of non-human
animal behaviour usually with a focus on behaviour under
natural conditions, and viewing behaviour as an evolutionary
adaptive trait.
Bionics - It is the study of mechanical systems that function
like living organisms or parts of living organisms. Bionics is
the application of biological methods and systems found in
nature to the study and design of engineering systems and
modern technology. The word ‘bionic’ was coined by Jack E.
Steele in 1958.
Bionomics - The study of the mode of life of organisms in
their natural habitat and their adaptations to their surroundings.
Bionomics is the comprehensive study of an organism and its
relation to its environment. It is also referred as ‘ecology’.
Bionomy - Branch of biology concerned with the laws of life.
Biometry - It is also known as biostatistics. It is the
development and application of statistical and mathematical
methods to analyse the data results from biological observations
and phenomenon.
Phrenology - The detailed study of the shape and size of
the cranium as a supposed indication of character and mental
abilities.
Anthology - Study of flowers.
Agrostology - It deals with the scientific study of true grasses.
It is also called Graminology - Scientific study of grasses (the
family Poaceae or Gramineae).
Palynology - The study of pollen grains and other spores
especially as found in archaeological or geological deposits.
Pollen extracted from such deposits may be used for radiocarbon
dating and for studying post climates and environments by
identifying plants then growing.
Oncology -Abranch of biology that deals with the prevention,
diagnosis and treatment of tumours/cancer.
Teratology - The scientific study of congenital abnormalities
and abnormal formations.
Osteology - It is the scientific and detailed study of the structure
of bones, skeletal elements, teeth, microbone, morphology etc.
Chondriology -Abranch of anatomy that deals with cartilage.
Serology - The scientific study or diagnostic examination of
blood serum, especially with regard to the response of the
immune system to pathogens or introduced substances.
Pathology - The science of the causes and effects of diseases,
especially the branch of medicine that deals with the laboratory
examination of samples of body tissue for diagnostic or forensic
purposes.
Parasitology - Parasitology is the study of parasites (viruses,
bacteria, fungus, worms, insects), their hosts and the relationship
between them. Parasites are organisms that use other species of
plants and animals as a host. The hosts provide the environment
in which the parasite lives.
Virology - Virology is the study of viruses - submicroscopic,
parasitic particles of genetic material contained in a protein
coat and virus - like agents.
Bacteriology - Study of the morphology, ecology, genetics
and biochemistry of bacteria as well as many other aspects
related to them.
Entomology - A branch of zoology that deals with insects.
Malacology - Malacology is the branch of invertebrate zoology
that deals with the study of the Mollusca, the second -largest
phylum of animals in terms of described species after the
arthropods. Molluscs include snails and slugs, clams, octopus,
and squid (largest invertebrate) and numerous other kinds, many
of which have shells made of calcium carbonate.
Ichthyology - Ichthyology, also known as fish science, is the
branch of zoology that deals with fishes.
Serpentology - A branch of zoology that studies snakes.
Herpetology - Herpetology is the branch of zoology which
deals with the study of reptiles and amphibians such as snakes,
turtles, lizards, tortoises, crocodilians etc. It deals with their
behaviour, geographic ranges, physiologies, development,
genetics etc.
Ornithology - Ornithology is a branch of zoology that deals
with the study of birds.
Dermatology - A branch of medicine concerned with the
diagnosis and treatment of skin, nails and hair diseases.
Trophology - Study of nutrition. A nutritional approach that
advocates specific combinations of foods as central to good
health and weight loss.
Cell biology - Cell biology is a branch of biology that studies
the structure and function of the cell, which is the basic unit
of life.
Histology - The branch of biology dealing with the study of
the microscopic structure of tissues.
Embryology - A branch of biology concerned with the study
of embryos and their development.
Phycology orAlgology -Abranch of biology which deals with
the scientific study of seaweeds and other algae.
Mycology -Abranch of biology which deals with the scientifi c
study of fungi.
Lichenology - It is the study of lichens, symbiotic organisms
made up of an intimate symbiotic association of a microscopic
alga (or a cyanobacterium) with a filamentous fungus
(mycobiont).
Main Terminologies and related by-products
Apiculture -The raising and care of bees for commercial (honey
production) and agricultural purposes (cross pollination).
Aviculture - The breeding and rearing of birds.
Aquaculture - The rearing of aquatic animals or the cultivation
of aquatic plants for food.
Algaculture - Algaculture is a form of aquaculture involving
the farming of species of algae. Algae are used in wastewater
treatment facilities, reducing the need for greater amounts of
toxic chemicals. Algae can be used to capture fertilizers in run
off from farms, when subsequently harvested, the enriched
algae itself can be used as fertilizer. Microalgae are called
phytoplanktons.
Pisciculture - The controlled breeding and rearing of fishes.
Agriculture - The science or practice of farming, including
cultivation of the soil for the growing of crops and the rearing
of animals to provide food, wool and other products.
Sericulture - The production of silk and the rearing of
silkworms for this purpose.
Silviculture - Silviculture is the practice of controlling the
growth, composition, health and quality of forests to meet
diverse needs and values.
Spongiculture - The cultivation and growing of sponges.
Horticulture - Horticulture is the science and art of growing
fruits, vegetables, flowers and crops like spices, condiments
and other plantation crops.
Floriculture - Floriculture or flower farming, is a discipline
of horticulture concerned with the cultivation of flowering and
ornamental plants for gardens and for floristry, comprising the
floral industry.
Olericulture - Olericulture is the science of vegetables
growing, dealing with the culture of non-woody (herbaeous)
plants for food.
Arboriculture - Cultivation of trees and shrubs.
Pomology - The science that deals with fruit and fruit growing.
Agronomy - A branch of agriculture dealing with crop
production and soil management.
Vermiculture - The cultivation of earthworms, especially in
order to use them to convert organic waste into fertilizer.
Ostriculture - The breeding of oysters for food and pearls.
Heliculture - It is also known as snail farming. It is the process
of raising land snails especially for human use, either to use
their flesh to eat or to obtain snail slime for use in cosmetics
and snail eggs for human consumption as a type of caviar.
Viticulture - Cultivation and harvesting of grapes.
Mariculture - Mariculture is a specialized branch of
aquaculture involving the cultivation of marine organisms
(animal and plant) for food and other products.
Moriculture - Moriculture is the science of mulberry
cultivation for silk production because silk worm (Bombyx
mori) reared on it.
Citriculture - Cultivation of citrus fruit trees.
Vegeculture - The cultivation of vegetables, also the cultivation
of plants, especially root crops, propagated by vegetative means.
Aeroponics - A plant-cultivation technique without soil, in
which the roots hang suspended in the air while nutrient solution
is delivered to them in the form of a fine mist.
Aeroculture - A method of growing plants without soil by
suspending them above sprays that constantly moisten the roots
with water and nutrients.
Hydroponics - It is a method of growing plants without soil by
instead of using mineral nutrient solutions in a water solvent

Evolution of Life
Notes
• Earth formed around 4.54 billion years ago, approximately
at one-third of the age of universe by accretion from the
solar nebula.
• Several theories/postulations have been propounded in
reference to the origin of life on Earth, but most accepted
theory among them is the ‘Oparin-Haldane Theory’.
Oparin-Haldane Theory of Origin of Life :
• According to this theory life originated on early Earth
through physico-chemical processes of atoms combining
to form molecules, which in turn reacting to produce
inorganic and organic compounds. Organic compounds
interacted to produce all types of macromolecules which
organized to form the first living system or cells.
• Thus, according to this theory ‘life’ originated upon
our Earth spontaneously from non-living matter. First
inorganic compounds and then organic compounds were
formed in accordance with ever-changing environmental
conditions. This is called chemical evolution which cannot
occur under present environmental conditions upon Earth.
Conditions suitable for origin of life existed only upon
primitive Earth.
Hypothesis given by Oparin about origin of life is also
known as Materialistic Theory which was published in
his book 'Origin of Life'.
• Modern views regarding the origin of life include both
chemical evolution and biological or organic evolution.
A. Chemical Evolution (Chemogeny) :
1. The Atomic Phase :
• Early Earth had innumerable atoms of all those elements
(e.g. hydrogen, oxygen, carbon, nitrogen, sulphur,
phosphorus) which are essential for the formation of
protoplasm. Atoms were segregated in three concentric
masses according to their weight -
(a) The heaviest atoms of iron, nickel, copper, etc. were
collected in the centre of the Earth.
(b) Medium weight atoms of sodium, potassium, silicon,
magnesium, aluminium, phosphorus, chlorine, fluorine,
sulphur etc. were collected in the core of the Earth.
(c) The lighter atoms of nitrogen, hydrogen, oxygen, carbon
etc. formed the primitive atmosphere.
2. Formation of Inorganic Molecules :
• Free atoms combined to form inorganic molecules such
as H2 (hydrogen), N2 (nitrogen), H2
O (water vapour), CH4
(methane), NH3 (ammonia), CO2 (carbon dioxide), etc.
Hydrogen atoms were most numerous and most reactive
in primitive atmosphere.
• Hydrogen atoms also combined with nitrogen forming
ammonia (NH3
). So the water and ammonia were probably
the first inorganic molecules of primitive Earth.
3. Formation of Simple Organic Molecules (Monomers) :
• The early inorganic molecules interacted and produced
simple organic molecules such as simple sugars (e.g. ribose,
deoxyribose, glucose etc.), nitrogenous bases (e.g. purines,
pyrimidines), amino acids, glycerol, fatty acids etc.
• Terrestrial rains must have fallen. As the water rushed
down, it must have dissolved away and carried with it
salts and minerals, and ultimately accumulated in the form
of oceans. Thus ancient oceanic water contained large
amounts of dissolved NH3
, CH4
, HCN, nitrides, carbides
as well as various gases and elements.
• Some external sources must have been acting on the
mixture for reactions. These external sources might be
(i) solar radiations such as ultraviolet rays (UV rays),
X-rays etc., (ii) energy from electrical discharges like
lightning, (iii) high energy radiations are other sources of
energies (probably unstable isotopes on primitive Earth).
There was no Ozone layer at that time in the atmosphere.
• A soup like broth of chemicals formed in oceans of the
early Earth, from which living cells are believed to have
appeared, was termed by Haldane as prebiotic soup,
also called hot dilute soup. Thus the stage was set for
combination of various chemical elements. Once formed,
the organic molecules accumulated in water, because their
degradation was extremely slow in absence of any life or
enzyme catalysts.
• The formed molecules accumulated in ocean bounded by
a covering forming coacervetes which have the capacity
to self-replication.
Experimental evidence forAbiogenetic MolecularEvolution
of Life :
• Stanley Miller in 1953, who was then a graduate student of
Harold Urey at the University of Chicago, demonstrated
it clearly that ultraviolet radiation or electrical discharges
or heat or combination of these can produce complex
organic compounds from a mixture of methane, ammonia,
water and hydrogen. The ratio of methane, ammonia and
hydrogen in Miller’s experiment was 2 : 1 : 2.
• Miller circulated four gases : methane, ammonia, hydrogen
and water vapour in an airtight apparatus and passed
electrical discharges in it from electrodes at 800o
C. Then
he passed the mixture through a condenser.
• He circulated the gases continuously in this way for one
week and then analysed the chemical composition of the
liquid inside the apparatus. He found a large number of
simple organic compounds including some amino acids
such as alanine, glycine and aspartic acid.
• Miller conducted the experiment to test the idea that
organic molecules could be synthesized in a reducing
environment.
• It is considered that the essential building blocks such as
nucleotides, amino acids etc. of living organisms could
thus have formed on the primitive Earth.
• Early life on Earth formed around 4.0 billion years ago.
• Membrane bound prokaryotes originated around 3.8
billion years ago, which were previously heterotrophs
and later on became autotrophs. Autotrophs were just
like the blue-green algae of modern period.
• Approximately 2.0 billion years ago eukaryotic cells were
formed, from which all the organisms (except bacteria) of
our planet evolved.
B. Biological or Organic Evolution :
Fundamental presumptions and principle of organic
Evolution :
• The fundamental presumption of organic evolution is –
‘the modification of living organisms during their descent,
generation by generation from common ancestors’.
• According to the concept of organic evolution, the present
day animals and plants have been evolved by a process of
gradual change in the earlier simple forms of life, which
took place in millions of years.
• The theories of organic evolution explains convincingly
the origin of life. It also explains how the wide variety of
plants and animals came into existence in the world.
• In organic evolution, there are different theories of
evolution, but following theories are accepted universally.
They are :
(i) Theory of Inheritance of Acquired Character
(Lamarckism)
(ii) Theory of Natural Selection (Darwinism)
(iii) Mutation Theory (Hugo de Vries)
I. Theory of Inheritance of Acquired Character
(Lamarckism) :
• Lamarckism is the first theory of organic evolution,
named after Jean-Baptiste Lamarck (1744-1829), a French
biologist.
• Lamarck's famous book is ‘Philosophie Zoologique’
(1809).
• He announced in 1801, a theory of organic evolution which
has been known as ‘Theory of Inheritance of Acquired
Character’.
• His evolutionary ideas are—
• Internal forces of life tend to increase the size of
the organism and because of an ‘inner want’ new
structures appear.
• The direct environmental effect over living organisms.
• Use or disuse of organs.
• Inheritance of acquired character.
Examples -
• Long neck of giraffe due to lack of surface vegetation
gradually.
• Aquatic birds - they had to go to water due to lack of food
etc. Some structures ‘web’ between their toes developed
and wings for fly gradually reduced.
• Flat fishes (deep sea fishes).
• Whales lost their hind limbs.
• The wading birds (e.g. Jacana) developed its long legs
through generation of sustained stretching to keep the
body above the water level.
II. The Theory of Natural Selection (Darwinism) :
• Charles Darwin explained natural selection in his book
‘On the Origin of Species’ (1859 ; Full Title - On the
Origin of Species by Means of Natural Selection, or
the Preservation of Favoured Races in the Struggle
for Life). It is considered to be the foundation of
evolutionary biology.
• It includes the following elements -
• The universal occurrence of variation
• Over production (rapid multiplication)
• The struggle for existence : Intra-specific struggle
between same species. Inter-specific struggle
between different species. Environmental struggle
due to earthquake, tidal waves, the burning of
valcanoes are all causes for killing large populations.
• Survival of the fittest (Natural Selection):
Organisms struggle for existence and organisms
with advantageous characters survive, while those
which lack such variations perish. Thus, individuals
having favorable variations have better chances of
living long enough to reproduce.
• Inheritance of useful variations : The organisms
after getting fitted to the surroundings transmit their
useful variations to the next generation, while non-
useful variations are eliminated.
• Neo-Darwinism : Neo-Darwinism is a modified form
of Darwinism. Neo-Darwinism term generally used
for describing any integration of Darwin’s theory of
evolution by natural selection with Gregor Mendel’s
theory of genetics. George Romanes first used this word
in 1895.
• Modern synthetic theory is the result of work of a number
of scientists namely T-Dobzhansky, R.A. Fisher, J.B.S.
Haldan, Small Wright, Ernst Mayr and G.I. Stebbins.
Stebbins in his book ‘Process of organic evolution’
discussed the ‘synthetic theory’. This is one of the proven
theories of organic evolution. It includes the following
factors–
1. Mutation
2. Variation or Recombination
3. Heredity
4. Natural Selection
5. Isolation
III. Mutation Theory :
• Dutch botanist Hugo de Vries, in his book ‘The Mutation
Theory’ (1901) proposed this theory.
• He observed on ‘Evening Primrose’, Oenothera
lamarckiana. He studied this plant in wild forms for many
years continuously and observed certain spontaneous
changes in some of these wild plants.
• Mutation Theory states that evolution is a jerky process
where new varieties and species are formed by mutations
(discontinuous variations) that function as raw material of
evolution.
Salient features of mutation theory are :
• Mutation appear all of a sudden. They become operational
immediately.
• The same type of mutation can appear in a number of
individuals of a species.
• All mutations are inheritable.
• Useful mutations are selected by nature. Lethal mutations
are eliminated. However, useless and less harmful ones
can persist in the progeny.
• Accumulation of variations produce new species,
sometimes a new species is produced from a single
mutation.
Important Facts :
• Archaeopterix : It looks like a bird. It has wings and
beak like birds. However its teeth and tail are like those
of reptiles.
• Archaeopterix is, therefore, considered as a connecting
link between reptiles and birds, thereby suggesting that
birds have evolved from reptiles.
• The fossils of Archaeopterix was first discovered from
limestone deposits near Solnhafen, Germany.
• Archaeopterix lived in the late jurassic period of Mesozoic
era around 150 millions years ago.
• Dinosaurs : During the Mesozoic or ‘Middle Life Era’,
life diversified rapidly and giant reptiles dinosaurs and
monstrous beasts roamed the earth. The period, which
spans from 252 million years ago to about 66 millions
years ago was also known as the age of reptiles or the age
of dinosaurs.
• Mesozoic era has been divided into three periods viz– the
Triassic (251-199.6 millions years ago), the Jurassic (199.6
to 145.5 million years ago) and the Cretaceous (145.5 to
65.5 millions years ago).
• Cro-Magnon : The earliest known Cro-Magnon remains
are between 35000 and 45000 years old based on
radiometric dating.
• Cro-Magnon had powerful bodies, which were usually
heavy and solid with strong muscles with height about
180 cm.
• The Cro-Magnon had straight forehead like modern
humans. Their faces were short and wide with a large chin.
Their brains were slightly larger than the average human’s
of today. The brain capacity of Cro-Magnon was 1600 cc.
• The name ‘Cro-Magnon’was coined by Louis Lartet, who
discovered the first Cro-Magnon skull in Southwestern
France in 1868.
• The Cro-Magnon are considered the last direct ancestor of
modern man and it was a sub-species of modern human
named Homo sapiens.

Taxonomy
• Taxonomy is a system for naming and organizing things
especially plants and animals, into groups that share
similar qualities.
• Carl (Carolus) Linnaeus (1707-1778) was a Swedish
botanist, physician and zoologist who formalized binomial
nomenclature-the modern system of naming organism.
He is known as the ‘father of modern taxonomy’.
• Several scientists have classified the living organisms into
different groups but at modern time the classification given
by Whittaker (1969) is widely adopted in the world. He
classified the organisms into five kingdoms viz—Monera,
Protista, Fungi, Plantae and Animalia.
Kingdom Monera :
• Kingdom Monera includes organisms that are single
celled. The microorganisms are considered as the most
ancient living forms on the earth. All the organisms
of this kingdom are prokaryotes. These cells do not
have nuclear membrane. The kingdom Monera includes
bacteria, cyanobacteria and mycoplasma. They do not
have specific mode of nutrition. They can be either
aerobic or anaerobic. These organisms have rigid cell
wall which is made up of peptidoglycan. Cell organelles
like endoplasmic reticulum, mitochondria are absent.
Reproduction is by spore formation or binary fission.
• Mycoplasma are known to be the smallest living cells.
They completely lack cell wall. This characteristic makes
them naturally resistant to many common antibiotics such
as peniciline or other beta-lactum antibiotics that target cell
wall synthesis. They can survive without oxygen. Most of
the mycoplasma are pathogenic in animal and plants e.g.
M. pnuemoniae causes atypical pneumonia in humans.
• Cyanobacteria are photosynthetic, that is, they can
synthesize their own food. They are the photosynthetic
prokaryotes able to produce oxygen. Cyanobacteria are
also called ‘blue-green algae’, though the term algae
in modern usage is restricted to eukaryotes. They can
be found in almost every terrestrial and aquatic habitat.
Cynobacteria such as Anabaena (a symbiont of the aquatic
fern Azolla) can provide rice plantation with biofertilizer.
• Bacteria are microscopic, single celled primitive
organisms. Generally these are about 2 to 4 micron in
length. They can live within soil, in the ocean and inside
the human gut. Human relationship with bacteria is
complex. Sometimes they lend a helping hand by curding
milk into yogurt or helping with our digestion. At other
times they are destructive, causing diseases like cholera,
syphilis, leprosy, tuberculosis and MRSA (Methicillin-
resistant Staphylococcus aureus - a type of staph
bacterial infection that is hard to treat because it cannot
be killed by many common antibiotics).
• On the basis of their nutrition, bacteria have been classifi ed
into heterotrophic and autotrophic bacteria.
• Autotrophic bacteria are of two types —
(i) Photosynthetic and (ii) Chemosynthetic.
• Archaebacteria belong to the domain Archaea and
are single celled organisms that tend to live in extreme
environments, like hot springs or high salt regions. In
fact, these organisms boldly grow there, where others
can not. They have been called Extremophiles, which
means lover of extremes. Example- Methanogens are
microorganisms that produce methane as a metabolic
by product in hypoxic condition. They are common in
wetland, where they are responsible for marsh gas and
in the digestive tract of animals such as ruminants and
human, where they are responsible for the methane content
of belching (emit wind noisily from the stomach through
the mouth) in ruminants and flatulence accumulation of
gas in alimentary canal in humans. These microorganisms
are similar to bacteria in size and simplicity of structure
but radically different in molecular organization. They are
now believed to constitute an ancient intermediate group
between the bacteria and eukaryotes. They are also called
archaea.
• Rhizobia are diazotrophic bacteria that fix nitrogen after
becoming established inside the root nodules of legumes.
Rhizobia are unique in that they are the only nitrogen
fixing bacteria living in a symbiotic relationship with
legumes.
• Unicellular organisms reproduce generally by asexual
means. Asexual modes of reproduction includes binary
fission, multiple fission, fragmentation, budding etc.
Kingdom Protista :
• All single celled eukaryotes are placed under Protista.
They are organisms which are unicellular or unicellular
- colonial and which form no tissues. Protista kingdom
includes chrysophytes (diatoms and golden algae),
dinoflagellates, euglenox, slime moulds and protozoas
such as amoeba, paramecium, flagellata, ciliophora etc.
Some protists reproduce sexually using gametes, while
others reproduce asexually by binary fission.
• Protists live in water, in moist terrestrial habitats, and as
parasites and other symbionts in the bodies of multicellular
eukaryotes. Protists are almost certainly polyphyletic and
they do not have an exclusive common ancestor.
• Some protists are significant parasite pathogens of animals
(e.g. Plasmodium causes malaria in humans) and plants
(e.g. Phytophthora infestans causes late blight in potatoes).
Protist pathogens share many metabolic pathways with
their eukaryotic hosts, which makes therapeutic target
development extremely difficult - a drug that harms a
protist parasite is also likely to harm its host.
Kingdom Fungi :
• Fungi is the plural word for fungus. Fungi are eukaryotic
organisms. The study of fungi is called Mycology.
Fungi lack chlorophyll and vascular bundle. Fungi are
heterotrophs; they aquire food by absorbing dissolved
molecules, typically by secreting digestive enzymes into
their environment. Fungi reproduce both sexually and
asexually.
• Yeasts, molds, mushrooms are the example of fungi.
• Yeast belongs to the division Ascomycetes of the kingdom
Fungi. Most yeasts reproduce asexually by mitosis, and
many do so by the asymmetric division process known as
budding.
• Mold or mould grows in the form of multicellular filament
called hyphae. In contrast, yeasts adopt a single-cell
growth habit. Molds cause biodegradation of natural
materials, which can be unwanted when it becomes food
spoilage or damage to furniture etc.
• Mushrooms belongs to the division Basidiomycetes of
the kingdom fungi. They are fleshy, spore-bearing fruiting
body of a fungus, typically produced above ground on soil
or on its food source. Mushrooms are used extensively in
cooking, however, many mushroom species (e.g. Amanita
phalloides which is called death mushroom) can be toxic.
• Dimorphic fungi are fungi that can exist in the form of
both mold and yeast (e.g. Penicillium marneffei, a human
pathogen that grows as a mold at room temperature and
as a yeast at human body temperature).
• Amycorrhiza is a symbiotic association between a fungus
and a plant.
• Alichen is a composite organism that arises from the algae
or cyanobacteria living among filaments of multiple fungi
species in a mutualistic relationship.
Kingdom Plantae :
• These living organisms are made of eukaryotic cells and
are multicellular. The cells have a cell wall which is made
of cellulose. These are autotrophic and synthesize food by
photosynthesis due to the presence of chloroplasts. They
are divided into following divisions - Algae, Bryophyta,
Pteridophyta, Gymnosperm and Angiosperm.
• Pitcher Plant (Nepenthes) : This plant is able to
synthesise its own food. This plant is insectivorous.
Pitcher plant grows in soil which lacks in nitrogen. To
meet the deficiency of nitrogen, pitcher plant traps the
insects.
• Xerophytic plants : A xerophyte is a species of plant
that has adaptations to survive in an environment with
little liquid water, such as desert or an ice or snow
covered region. Popular examples of xerophytes are
cacti, calotropis, aloe, pineapple and some gymnosperm
plants.
• Adaptations of xerophytes include reduced permeability
of the epidermal layer, stomata and cuticle to maintain
optimal amount of water in the tissues by reducing
transpiration, adaptations of the root system to acquire
water from deep underground sources or directly from
humid atmosphere and succulence, or storage of water
in swollen stems, leaves or root tissues. Their leaves are
modified into spines.
• Phreatophyte is a deep rooted plant that obtains
significant portion of water that it needs from phreatic
zone (zone of saturation) or the capillary fringe above the
phreatic zone. The roots of such plants are approximately
25 to 30 meters reaching to underground water.
• Hydrophytes : Hydrophytes are also referred as aquatic
plants or macrophytes. These plants require special
adaptations for living submerged in water or at the water’s
surface. The most common adaptation is aerenchyma.
• Halophytes :Ahalophyte is a salt-tolerant plant that grows
in waters and soils of high salinity, coming into contact
with saline water through its roots or by salt spray, such
as in saline semi-deserts, mangroove swamps, marshes
and sloughs and seashores.
• Epiphytes : Epiphyte is a plant that grows on the surface
of a plant and derives its moisture and nutrients from the
air, rain, water (in marine environments) or from debris
accumulating around it (Example - Orchids).
• A flower sometimes known as a bloom or blossom, is
the reproductive organ found in flowering plants. The
biological function of flower is to effect reproduction,
usually by providing a mechanism for the union of male
gamete with female gamete. Flowers may facilitate
outcrossing or allow selfing.
• Ginger, potato, Garlic and Suran (jimikand) are the
examples of rhizome, tuber, bulb and corm respectively.
• Shakarkand (Sweet-potato) belongs to the family
Convolvulaceae. Its edible part is root.
• Sugarcane, potato and ginger are the modified stems. It
means their food storage organ are stem.
• In shaljam (Turnip), carrot and sweet potato, storage organ
are the modified roots.
• Pea is a dicotyledonous annual herbaceous plant. Tendril
is present to support the plant. It belongs to Leguminosae
family.
• Sugarcane (Saccharum officinarum) belongs to the
family Graminae or Poaceae. Generally stem cutting
is used for its vegetative propagation. It has nodes and
internodes.
• Cloves are the aromatic flower buds of a tree in the family
Myrtaceae Syzygium aromaticum, native of Indonesia
and commonly used as spice.
• Cloves health benefits include improving digestion,
fighting bacteria, protecting the liver, fighting lung cancer,
regulating blood sugar and relieving tooth pain.
• Saffron : Saffron is a spice derived from the flower of
Crocus sativus (family - Iridaceae). The vivid crimson
stigmata and styles, called threads, are collected and dried to
be used mainly as a seasoning and colouring agent in food.
It has long been the world’s most costly spice by weight.
In saffron safranol and picocrocin chemicals are found.
• Okra (Ladies’finger) : It is a flowering plant. It is valued
for its edible green seed pods. Its pod is known as capsule.
Its botanical name is Abelmoschus esculentus.
Turmeric (Curcuma longa) is a flowering plant of
ginger family-Zingiberaceae. The modified shoot
(stem) rhizome is edible part of it. Turmeric contains
curcumin, a substance with powerful anti-inflammatory
and antioxidant properties.
• Sorosis : This type of fruit is found in Mulberry, Pineapple
and Jack fruit. These fruits are derived from catkin, spike
and spadix type of inflorescence.
• Nut : A nut is a fruit composed of an inedible hard shell
and a seed, which is generally edible. The fruits of Cashew
nut and Trapa (Singhara) are examples of nut. The edible
part of Singhara is seed.
• Lychee : It is the sole member of the genus Litchi in the
soapberry family, Sapindaceae. Fleshy aril of lychee is
the edible part. It is a drupe (like a plum, a cherry or a
mango), externally covered by a pink-red rough textured
rind, easily removable.
• Pome : A fruit consisting of a fleshy enlarged receptacle
and a tough core containing the seeds, e.g. an apple or pear.
• Pepo : Fruits having a fleshy, many-seeded interior
and a hard or firm rind. The fruits of melon, squash and
cucumber are called pepo.
• Retting is a process, employing the action of micro-
organisms, and moisture on plants to dissolve or rot away
much of the cellular tissues and pectins surrounding bast-
fibre bundles, and so facilitating separation of fibre from
the stem of sunn, hemp and jute.
• The botanical name of papaya is Carica papaya (family-
Caricaceae). Enzyme papain found in papaya which helps
in digestion of protein. Papaya are yellow due to presence
of xanthophyll pigments i.e. caricaxanthin present in the
plastid of the fruit pulp.
• Red apples get their colour from anthocyanin pigment.
• The pigments found in some other edible parts of plants
are - carotene in carrot, lycopene in tomato, xanthophyll
in turmeric and betanin in Beta vulgaris (chukandar).
• The distinctive smell of garlic and onion is due to the
presence of sulphur containing chemicals.
• Some compounds in onions, garlic or both, can be responsible
for bad breath and even body odour. These include-
• Allicin- When the insides of a garlic bulb are exposed to
air, a substance called alliin turns into allicin, which then
changes into several sulphur containing compounds that
gives garlic its smell.
• Allyl methyl sulphide- This compound is released from
both garlic and onion, when they are cut. Once eaten,
the substance is absorbed into blood stream, and emitted
through the lungs and skin pores.
Cysteine sulfoxide- This sulphuric compound in garlic
and onions causes an unpleasant odour on the breath
almost immediately after the vegetables are eaten.
• Garlic and onions add flavour to meals and can provide
health benefits. Unfortunately, both can also cause bad
breath, known as halitosis, especially when eaten raw.
• Sulfenic Acid found in onion irritates lacrymal glands and
produces tears in eyes.
• Capsaicin is responsible for sharp taste in chili peppers.
Its chemical formula is C18H27NO3
. When it comes in
contact with skin or mucous membranes it produces a
burning sensation. The amount of capsaicin in a specifi c
species of peppers is measured using the Scoville scale.
• In botany, a bud is an undeveloped or embryonic shoot
normally occurs in the axil of a leaf and stem or at the tip
of stem. Once formed, a bud may remain for sometime
in dormant condition or it may form shoot immediately.
The term bud is also used in Zoology, where it refers to
an outgrowth from the body which can develop into a new
individual.
• Cork is obtained from the bark of oak which botanical
name is Quercus suber. Its native land is mediterranean
region.
Kingdom Animalia :
• Animalia kingdom includes all invertebrates and
vertebrates animals. They are multicellular eukaryotic
organisms.
• With few exceptions, animals consume organic material,
breathe oxgyen, are able to move and can reproduce
sexually.
• Over 1.5 million living animal species have been described
- of which more then1 million are insects - but it has been
estimated there are over 7 million animal species in total.
Arthropoda is the largest phylum in animal kingdom. It
includes species in all habitats which constitute 60% of
all known species of animals.
• Crabs belong to the class Malacostraca (Phylum-
Arthropoda).
• Class Arachnida (Phylum-Arthropoda) are characterized
by having two body regions, a cephalothorox and an
abdomen. They also have 6 pairs of appendages : 4 pairs
of legs and 2 pairs of mouth part appendages, the first pair
of mouth part appendages is called chelecerae and second
pair is called pedipalps. Examples : Scorpions, Spiders.
• The ticks and mites belong to the order Araneae of
class Arachnida. Their appendages are jointed, body is
bisymmetrical and triploblastic.
• Class Insecta (Phylum-Arthropoda) encompasses all
insects. Insects have three main body segments, the head,
thorax and abdomen. They have 3 pairs of legs.
• The glowworm Arachnocampa luminosa (insect) is
famous for having blue-green light on the end of its
tail. Both adult and larva produce it in a process called
bioluminescence. The glow is due to presence of an
enzyme luciferase.
• In female mosquitoes, all mouth parts are elongated. The
labium encloses all other mouth parts like a sheath. The
labrum forms the main feeding tube, through which blood
is sucked. Paired mandibles and maxillae are present,
together forming the stylet, which is used to pierce an
animal’s skin. Thus the female mouth parts are adopted
to suck and pierce.
• Male mosquitoes mouth is adopted to suck the nectar of
flowers.
• The trachea is the respiratory organs and the malpighian
tubules are excretory and osmoregulatory organs of the
insects.
• Echinoderm is the common name given to any member of
the phylum Echinodermata (hard, spiny covering or skin)
of marine animals. The adults are recognisable by their
(usually five points) radial symmetry and include such well
known animals as starfish, sea urchins, sand dollars,
sea cucumbers, sea lilies etc. Echinoderms are second-
largest grouping of deuterostomes (a superphylum) after
the chordates.
• Echinoderms are generally oviparous but some of them
are viviparous.
• Octopus is a soft bodied, eight armed mollusc of the
Phylum Mollusca class Cephalopoda. It is also known
as Devilfi sh.
• Giant squids (Architeuthis dux) and colossal squid
(Mesonychoteuthis hamiltoni) are the largest
invertebrates. The length of colossal squids is less but
weight is more than giant squids.
• Homeothermic or warm blooded animal species maintain
a stable body temperature by regulating metabolic
processes. The only known living homeotherms are birds
and mammals (Their body temperature remains the same
when it’s cold or hot outside).
• Heterothermic or cold blooded animals, like reptiles,
amphibians and fish become hotter and cooler, depending
on the temperature outside (Their body temperature
depends on whether it’s cold or hot outside).
• Nocturnal animals can hunt, mate or generally active after
dark. They have highly developed sense of hearing, smell
and specially adapted eyesight. Examples of nocturnal
animals are mosquito, bat, owl and kiwi. The aye-aye
(Daubentonia medagascariensis), a type of lemur, is the
world’s largest nocturnal primate. It uses echolocation to
find its prey–the only primate known to do so.
• Some animals name resemble with fish but they are
actually not fishes e.g. Jellyfish (Cnidaria); Starfi sh
(Echinodermeta); Silverfish (Insecta) Cuttlefish
(Mollusca); Hagfi sh (Cyclostomata); Devilfish (Mollusca)
and Crayfish (Arthropoda) etc.
• The some true fishes are flying fish, catfish, pipe fish,
paddle fish, gold fish, globe fish, dogfish etc.
• Scoliodon is also known as dogfi sh. It is a cartilaginous
fish.
• Seahorse (Hippocampus) is a bony fish.
• Most fish exchange gases like oxygen and carbon dioxide
using gills that are protected under the gill covers on both
sides of the pharynx (throat). Gills are tissues that are like
short threads, protein structures called filaments.
• During winter ice forms on top of the water. Beneath the
layer of ice there are layers of water where the temperature
is more than 0o
C. This is why the fishes live.
• Amphibians (class-Amphibia) are any member of the
group of vertebrate animals characterized by their ability
to exploid both aquatic and terrestrial habitats. The
name amphibian, derived from the ancient Greek term
'amphibios' which means ‘both kinds of life’.
• Reptiles are tetrapod animals in the class Reptilia,
comprising today’s turtles, crocodiles, snakes,
amphisbaenians, lizards and their extinct relatives.
The king cobra (Ophiophagus hannah) is a venomous
snake species in the family Elapidae, endemic to forests
from India through South-East Asia. It is threatened by
habitat destruction and has been listed Vulnerable on the
IUCN Red List since 2010. It is the world longest venomous
snake. Adult king cobras are about 3.18 to 4 metres long.
The female king cobra lays eggs (20 to 50 eggs) in the nest
(Oviparous). Parental care is found in this snake i.e. guards
its own nest till the emerging of offsprings from the eggs.
Non-poisonous and poisonous snakes
• Most snakes are non-poisonous but some snakes as krait,
cobra and viper are poisonous snake.
• Fangs are sharp, long, hollow or grooved teeth that are
connected to a small sac in the snake’s head behind
its eyes. These sacs produce a poisonous liquid called
venom. For some snakes with really long fangs, the
fangs will fold back into the mouth so they do not bite
themselves.
• Snake venom may contain twenty or more toxins.
• The cobra and krait venoms are neurotoxic and
cardiotoxic while the venom of viper is vasculotoxic and
haemotoxic.
• The poison gland of snakes are homologous to the
salivary glands of vertebrates.
• Bats are mammals of the order Chiroptera, with their
forelimbs adopted as wings, they are the only mammals
naturally capable of true and sustained flight. Bats are
more manoeuvrable than birds, flying with their very
long spread-out digits covered with a thin membrane or
patagium.
• The smallest bat (arguably the smallest extant mammal)
is Kitti’s hog-nosed bat (bumblebee bat), which is about
29-34 mm in length and 15 cm across the wings. The
largest bats are the flying foxes (fruit bat) and the giant
golden-crowned flying fox, which have a wingspan of
about1.7 metre.
• The blue whale (Balaenoptera musculus) is a marine
mammal measuring upto 33 metre in length and with
a maximum recorded weight of more than 180 metric
tonnes. It is the largest animal known to have ever existed.
Its lifespan is 80-90 years.
• Sperm Whale (Physeter macrocephalus) is the largest of
the toothed whales measuring about 55 feet and weight
about 35 to 45 tonnes. It is carnivorous.
• Sea Lion, Seal, Phoca, Walrus and Dolphins are aquatic
mammals. Dolphin belongs to the order Cetacea while
other belong to the order Carnivora.
• Dolphin is very intelligent animal.
• River Ganga Dolphin is the National Aquatic Animal of
India. Its scientific name is Platanista gangetica.
• Sea cow is a giant herbivorous aquatic mammal.
• Echdina and Platypuss are egg-laying mammals.
• Nilgai (Boselaphus tragocamelus) is the largest Asian
antelope (It is not a cow). It is one of the most commonly
seen wild animals of central and northern India, often seen
in farmlands or scrub forests.
• Apes (super family-Hominoidea) are tailless primate of
families Hylobatidae (gibbons-small ape) and Hominidae
(chimpanzees, bonobos, orangutans, gorillas and human
beings - great apes).
• Human beings are categorized zoologically as member of
broader ape superfamily, they are usually placed within
their own subcategories on account of their larger brain
size, more advanced cognitive abilities (particularly the
ability to speak) and striding two legged gait.
• The capacity of an adult human cranial cavity is 1200 -
1700 cm3

Cell
Notes
• The cell (from Latin-Cella- meaning small room) is the
basic structural, functional and biological unit of all known
living organisms.
• Acell is the smallest unit of life. Cells are often called the
‘building blocks’ of life.
• The study of cells is called cell biology or cellular biology.
• The cell consists cytoplasm enclosed within a membrane,
which contains many biomolecules such as proteins and
nucleic acid.
• The number of cells in plants and animals varies from
species to species. Human contain around 40 trillion (4 ×
1013) cells.
• Most plant and animal cells are visible only under
a microscope, with dimensions between 1 to 100
micrometres.
• Cells were discovered by Robert Hooke in 1665 (detailed
description in a book written by him-Micrographia).
• Cell theory, first developed in 1839, by Schleiden and
Schwann. According to his theory, all organisms are made
of one or more cell and all cells originate from pre-existing
cells.
• Cells emerged on Earth at least 3.5 billion years ago.
• On the basis of absence or presence of a nucleus, the cells
have been divided into two groups-
I . Prokaryotic cells :
• Prokaryotic cells are cells that do not have a true nucleus
or most cell organelles. Organisms that have prokaryotic
cells are unicellular and called prokaryotes.
• Prokaryotic cells do not have a true nucleus that contains
their genetic material as eukaryotic cells do. Instead,
prokaryotic cells have a nucleoid region, which is an
irregularly shaped region that contains the DNA and is
not surrounded by the membrane. The cell wall is present
in prokaryotes.
• The ribosome is found in cytoplasm.
• Histone protein is not annexed with the nucleic acid.
• Such type of cells is found in bacteria and blue green algae.
Prokaryotes include bacteria and archaea, two of the three
domains of life. There cells were the first form of life on
Earth.
II . Eukaryotic cells :
• Eukaryotic cells are cells that contain a nucleus and
organelles, which are enclosed by a plasma membrane.
• Organisms that have eukaryotic cells include protozoa,
algae, slime moulds, fungi, plants and animals. These
organisms are grouped into the biological domain
Eukaryota.
• Eukaryotic cells are large and more complex than
prokaryotic cells. These cells are about fifteen times wider
than a typical prokaryote and can be as much as a thousand
times greater in volume.
• Eukaryotic cells contain a variety of structures called
organelles, which perform various functions within the
cell which are as follows -
(a) Cell wall :
• Cell wall is found in the cells of plants and algae, fungi
and most chromalveolates, which is a layer outside the
cell membrance, providing the cell with structural support,
protection, and a filtering mechanism.
• Plants cell wall are made up of cellulose, hemicellulose
and pectin. The fungi cell wall is made up of chitin.
• Animal cells lack a cell wall.
(b) Plasma membrane/Cell membrane :
• The plasma membrane is a biological membrane that
separates the interior of all cells from the outside
environment, which protects the cell from its environment,
consisting of lipid bilayer with embedded protein.
• The cell membrane is a semipermeable or selectively
permeable membrane which controls the movements
of ions and organic molecules.
(c) Endoplasmic Reticulum (ER) :
• ER is a cellular organelle. It is the transport network for
molecules going to specific places.
• ER is of two types-
(i) Rough Endoplasmic Reticulum (RER) - The ribosomes
are found on its surface (which gives it a rough appearance)
so it acts as a site for protein synthesis.
(ii) Smooth Endoplasmic Reticulum (SER) - It is without
ribosome. It synthesizes lipids, phospholipids and steroids.
Similar to the SER, Sarcoplasmic Reticulum (SR) is
found only in muscle cells (myocytes). The SR stores and
pumps calcium ions.
(d) Ribosome :
• The ribosome is a cell organelle. Ribosomes are found free
in the cytoplasm or bound to the endoplasmic reticulum to
form rough ER. It functions as a micromachine for making
proteins.
(e) Mitochondria :
• Mitochondria are surrounded by two membranes and have
their own genome.
• Mitochondria acts as the power plants, it means that the
maximum energy in form of ATP is produced within the
mitochondria, hence it is also known as Power House of
the cells.
• During cellular respiration, the initial process takes place
in cytoplasm and then in mitochondria.
• The most prominent roles of mitochondria are to
produce the energy currency of the cell, ATP (adinosine
triphosphate), through respiration, and to regulate cellular
metabolism. During cellular respiration most ATP is
formed in Kreb’s cycle (Citric acid cycle).
(f) Golgi body :
• Golgi body is also known as Golgi complex or Golgi
apparatus. It was identified in 1897 by Camillo Golgi.
• The Golgi complex is responsible for manufacturing,
warehousing and shipping certain cellular products such
as proteins and lipids that are synthesized by the cell. Its
functional unit is called cisternae.
(g) Lysosomes :
• Lysosomes are also known as the suicidal bag of cells.
• These are membrane-enclosed organelles that contain an
array of enzymes capable of breaking down all types of
biological polymers-proteins, nucleic acids, carbohydrates
and lipids. It functions on the digestive system of the cell
serving both to degrade material taken up from outside the
cell and to digest absolute components of the cell itself.
• Lysosomes also take part in killing the viruses and bacteria
which have entered within the cell.
• The hydrolyzing enzymes act in acidic medium.
• After the rupturing of membrane of lysosome, the enzyme
came out, which hydrolizes all components of cell wall
by the process hydrolysis.
(h) Centrosome :
• It is the cytoskeleton organiser of the cell. It produces
the microtubules of a cell - a key component of the
cytoskeleton.
• A single centrosome is present in the animal cells. Plants
and most fungi lacks centrosome.
(i) Vacuoles
• Vacuoles sequester waste products and in plant cells store
water.
• The vacuoles of plant cells and fungal cells are usually
larger than those of animal cells.
Note : By scientific convention, the term lysosome is applied
to these vesicular organelles only in animals and the term
vacuole is applied to those in plant, fungi and algae (some
animal cells also have vacuoles). However, some botanists
argued that these vacuoles are lysosomes.
(j) Nucleus :
• Nucleus was discovered by Robert Brown in 1831.
• The nucleus is a membrane-bound organelle found in
eukaryotic cells. Eukaryotes usually have a single nucleus
but a few cell types, such as mammalian R.B.C. have no
nuclei and few others as Vaucheria and Cladophora has
many nuclei.
• It is the controlling and coordinating organ of the nucleus
due to the presence of DNA in it. It houses the cell’s
chromosomes, and is the place where almost all DNA
replication and RNA synthesis occur.
• The nucleus is spherical and seperated from the cytoplasm
by a double membrane called the nuclear envelope.
• DNAis also found in mitochondria and chloroplast (found
only in plant cells).
Programmed Cell Death (PCD) :
• Programmed cell death is the death of a cell in any form,
mediated by an intracellular program, and is also referred
to as cellular suicide.
• PCD is carried out in a biological process, which usually
confers advantage during an organism’s life cycle. For
example, the differentiation of fingers and toes in a
developing human embryo occurs because cell between
the fingers apoptose ; the result is that the digits are
separate.
• PCD serves fundamental functions during both plant and
animal tissue development.
• Apoptosis and autophagy, both are the forms of
programmed cell death.

Heredity
Notes
• Heredity is the process of passing the traits and
characteristics from parents to their offsprings.
• The offspring cells get their features, characteristics and
genetic information from their mother and father.
• Heredity and genetics are the reason organisms look so
much like their parents.
• Genetics is a branch of biology that studies the genes,
genetic variation and heredity in living organisms.
• During the sexual reproduction process, genetic variation
occurs due to some error in DNA Copying. Variation is
important because it contributes to evolution and forms
the basis of heredity.
• Variation is caused due to positive gene mutations, the
interaction of genes with the environment and various
combinations of genetic material.
• Variation can occur through asexual reproduction process
too, but these variations are not very noticeable.
Gregor Johann Mendel (The Father of Genetics) :
• Acquiring characteristics or traits from one generation to
the other is nothing but inheritance.
• Here, both parents contribute equally to the inheritance
of traits.
• It was Gregor Johann Mendel, known as the Father of
Genetics, who conducted immense research on garden
pea-Pisum sativum and studied this inheritance of traits.
• Mendel was a priest in the Church of Brunn city (Austria).
• It was his research on plant breeding and hybridization
that he came up with the laws of inheritance in living
organisms.
• Mendel observed the pattern of inheritance from one
generation to the other in pea plants which can be
summarized under the following headings-
• Law of Dominance
• Law of Segregation
• Law of Independent Assortment
Genome :
• A genome is an organism’s complete set of DNA,
including all of its genes. Each genome contains all of the
information needed to build and maintain that organism.
In humans, a copy of the entire genome - more than 3
billion DNA base pairs - is contained in all cells that have
a nucleus
Gene Mapping : Gene Mapping describes the methods
used to identify the locus of a gene and the distance
between genes. The essence of all genome mapping is
to place a collection of molecular markers onto their
respective positions on the genome.
Transposable Elements (TEs) :
• Transposable elements or transposon, also known as
jumping genes, are DNA sequences that move from one
location on the genome to others. Sometimes TEs create
or reverse mutations and alter the cell's genetic identity
and genome size. These elements were first identified by
geneticist Barbara McClintok and for this discovery, she
was awarded Nobel Prize in 1983.
• The production of spotted seeds in maize is due to the
jumping genes.
• Almost half of our DNA sequences are made of jumping
genes. They jump around the genome in developing sperm
and egg cells and are important to evolution. But their
mobilization can also cause new mutations that lead to
diseases such as haemophilia and cancer.
Nucleic Acid :
• The term nucleic acid is the overall name for DNA
(deoxyribonucleic acid) and RNA(ribonucleic acid). They
are composed of nucleotides which are the monomers
made of three components : a 5-carbon sugar, a phosphate
group and a nitrogenous base.
• Nitrogenous bases are of two types-
(i) Purine (ii) Pyrimidine.
• Purine bases are adenine and guanine, which are found
in both DNA and RNA. Pyrimidine bases are cytosine,
thymine and uracil. Cytosine is found in DNA and RNA
both, thymine is present in DNA and uracil is present in
RNA.
• The pentose sugar found in DNAis deoxyribose sugar and
pentose sugar found in RNA is ribose sugar.
• Copying of DNA into RNA is called transcription.
Reverse transcription is the process when the DNA
copy is formed from the RNA. In reverse transcription, a
reverse transciyptase (RT) enzyme takes part.
• It is noteworthy that DNA is the hereditary material in
humans and almost all other organisms.
• DNA was first identified and isolated by Friedrich
Miescher in 1869.
• Its ‘Double Helix Model’ was propounded by Watson
and Crick in 1953.
• DNA carries genetic instructions for the development,
functioning, growth and reproduction of all known
organisms and many viruses.
• It carries hereditary information from parents to offsprings.
Human Chromosomes :
• Human is unisexual animal. In human, each cell normally
contains 23 pairs of chromosomes, for a total of 46.
Twenty-two of these pairs called autosomes in males and
females alike. The 23rd pair, the sex chromosomes, differ
between males and females.
• In males, the chromosomes are 44 + XY and in females,
chromosomes are 44 + XX.
• The offspring which get XY chromosome from parents
is male and offspring which get XX chromosome from
parents is female.
Some terms about heredity
• Gene : It is the basic unit of inheritance. It consists of a
sequence of DNAwhich is the genetic material. The genes
can mutate and can take two or more alternative forms.
• Chromosomes : These are thread-like structures of
nucleic acids and protein that are found in the nucleus
of most living cells. They carry the heredity or genetic
information in the form of genes. These are made up of
nucleoprotein. German anatomist Waldeyer is known for
naming the chromosome. The number of chromosomes
varies from species to species but it remains constant for a
particular species. In most animals, however, any change
from the typical chromosome number for a species may
be due to genetic disorders.
• Genotype : It is the complete heritable genetic identity
of an organism. It is the actual set up of alleles that are
carried by the organisms.
• Phenotype : It is the description of the actual physical
characteristics of an organism, the way the genotype is
expressed.
• Alleles : The alternative forms of the genes which arise
as a result of mutation. They are found in the same place
on the chromosome and affect some characteristics or
trait but in alternative forms.
• Dominant alleles : When an allele affects the phenotype
of an organism, then it is a dominant allele. It is denoted
by the capital letter. For example- ‘T’to express tallness.
• Recessive alleles : An allele that affects the genotype in
the absence of the dominant allele is called a recessive
allele. It is denoted by a small letter. For example - ‘t’
for dwarfness.
• Homozygous : Each organism has two alleles for every
gene (each chromosome has one each). If both the alleles
are same it is called homozygous. If tallness is the trait,
it is expressed as 'TT'.
• Heterozygous : If the two alleles are different from each
other, then they are heterozygous in nature. If tallness is
the trait, then it is expressed as ‘Tt’.

Biofertilizers
Notes
• Over the years, chemical fertilizers have helped farmers
increase crop production to meet the increasing demand.
However, the use of these fertilizers is harmful because
they cause air and water pollution; and also deplete
minerals from the soil. Therefore, there is a need to now
switch to organic farming which involves the use of
biofertilizers.
• Biofertilizers increases the nutrients of host plants when
applied to their seeds, plant surface or soil by colonizing
the rhizosphere or the interior of the plant and promotes
their growth. It refers to the use of microbes instead of
chemicals to enhance the nutrition of the soil. As a result,
it is also less harmful and does not cause pollution.
Types of Biofertilizers :
• Followings are the type of biofertilizers—
1. Bacteria
2. Fungi
3. Cyanobacteria
1. Bacteria:
• The great example of biofertilizers is the nitrogen-fixing
nodules on the roots of legumes. The nodules are formed
by the association of the bacterium ‘Rhizobium’with the
roots of these plants. This association is beneficial and is,
therefore, called symbiotic.
• The nodules help in fixing atmospheric nitrogen into
organic forms which can then be used as nutrition by
plants. Adding Rhizobium culture to fields has become a
common practice to ensure an adequate amount of nitrogen
in the soil.
• Leghaemoglobin is the haeme protein found in root
nodules of leguminous plants, where they are crucial for
supplying sufficient oxygen to root nodule bacteria for
nitrogen fixation to occur. It is produced by legumes in
response to the roots being colonized by nitrogen-fixing
bacteria.
• Phosphate-solubilizing bacteria, such as Pantoea
agglomerans (P5 strain), Microbacterium laevani-
formans (P7 strain) and Pseudomonas putida (P13
strains), are able to solubilize the insoluble phosphate
from organic and inorganic phosphate sources.
• Other examples of bacteria that act as biofertilizers include
Azospirillum and Azotobacter. These bacteria are free-
living in the soil. Azotobactor is usually used with crops
like cotton, wheat, mustard, maize, etc. Azospirillum
inoculations are recommended mainly for sugarcane,
wheat, millets, maize and sorghum.
2. Fungi :
• Symbiotic association exist between plants and fungi
too. These associations are called Micorrhizae. In this
association the plant makes organic molecules such
as sugars by photosynthesis and supplies them to the
fungus, and the fungus supplies to the plant water and
mineral nutrients, such as phosphorus, taken from the soil.
Plants that grow with these associations also show other
advantageous characteristics such as—
1. Tolerance to drought conditions and salinity.
2. Resistance to root borne pathogens.
3. An overall increase in plant growth and development.
3. Cyanobacteria/Blue-Green Algae :
• These are blue-green bacteria found in water and on land.
They also help in fixing atmospheric nitrogen. Examples
are Oscillatoria, Nostoc, Anabaena etc.
• Some cyanobacteria can fix atmospheric nitrogen in
anaerobic conditions by means of specialized cells
called heterocysts. Heterocysts may also form under the
appropriate environmental conditions (anoxic) when fixed
nitrogen is scarce.
• The symbiotic association between the aquatic fern
Azolla and Anabaena is very important for rice fields.
In this association Azolla provides food to Anabaena and
Anabaena provides N2
to Azolla by fixing nitrogen.

Human Anatomy and Physiology

I. Skeletal and Muscle System
• Anatomy is the branch of biology concerned with the
shape, structure and relationship of parts of the organism.
• Skeletal and Muscle system serves as a framework for
the body of all vertebrates including human.
• The skeletal system composed of bones, cartilages,
ligaments and other tissues that perform essential functions
of the body.
• Bone tissue or Osseous tissue is the major structural and
supportive connective tissue of the body. It forms the rigid
part of the bones that make up the skeletal system. Bone
tissue is different form the bones themselves - bones are
organs made up of bone tissue as well as marrow, blood
vessels, epithelium and nerves. It helps in movement and
protect the internal organs of the animals.
• Cartilages, a resilient and semirigid connective tissue
found on the skeleton in areas of flexibility and smooth
surface support movement.
• Ligaments are the fibrous and dense connective tissues,
that connect bones to other bones.
• Tendon (or sinew) is a tough band of fibrous connective
tissue that connects muscle to bone, or muscle to muscle
and is designed to withstand tension.
The major functions of the skeletal system are body
support, facilitation of movement, protection of the
internal organs, storage of mineral and fat, and blood cell
formation.
• Bones serve as a site for fat storage and blood cell
production. The unique semi-solid tissue that fills the
interior of most bones is referred to as bone marrow.
• There are two types of bone marrow : (i) Yellow bone
marrow which contains adipose tissue and triglycerides
stored in the adipocytes of this tissue can be released to
serve as a source of energy for other tissues of the body
and (ii) Red bone marrow, where the production of blood
cells (named hematopoiesis, hemato = "blood", poiesis =
"to make") takes place. Red blood cells, white blood cells
and platelets are all produced in the red bone marrow.
• The skeleton has been divided into two parts :
1. Exoskeleton - a hard outer layer that covers, supports
and protects the body of an invertebrate animal such as
an insect or crustaceans which is made up of chitin.
• The exoskeleton of vertebrates includes scales in fishes and
reptilians, feathers in birds and hair, nails, horns, hoops in
mammals. These are made of α-keratin protein.
2. Endoskeleton - a hard frame that supports the body of a
vertebrate animal on the inside, which is made of bones
and cartilages.
(i) Bone : Bone is the substance that forms the skeleton of
the body. It is composed chiefly of calcium phosphate
and calcium carbonate. It also serves as a storage area
for calcium, playing a large role in calcium balance in
the body. Collagen is the main structural protein which
is found in the organic matrix of bone (and various
connective tissues in the body).
(ii) Cartilage : Cartilage is a resilient and smooth elastic
(but semirigid) tissue, a rubber-like padding that covers
and protects the ends of long bones at the joints, and is
a structural component of the rib cage, the ear, the nose,
the bronchial tubes, the intervertebral discs, and many
other body components. It is much stiffer and much less
flexible than muscle. The matrix of cartilage is made up
of glycosaminoglycans, proteoglycans, collagen fibres
and, sometimes, elastin. Cartilage does not contain blood
vessels (avasular) or nerves (aneural). Nutrition is supplied
to the chondrocytes (the only cells found in healthy
cartilage) by diffusion.
Endoskeleton of Human :
• The endoskeleton of human is an internal skeleton
composed of hard, mineralized tissues that also enables
movement by attachment of muscles.
• In adult human endoskeleton, 206 bones are found. It is
comprised of the axial and appendicular skeleton. Short
details are given as below-
(i) Axial Skeleton :
• Axial Skeleton of the human comprises of-
(a) Skull : There are basically 22 bones (8 - cranial, 14 - facial)
in human skull. Including the hyoid (in the neck) and the
bones of the middle ears, the head contains 29 bones. In
general classification, these 29 bones are all considered
as part of skull. These are as follows :
(i) Cranium – 8
(ii) Face – 14
(iii) Ears – 6 (three in each ear)
(a) Malleus – hammer (2)
(b) Incus – anvil (2)
(c) Stapes – stirrup (2)
(iv) Hyoid - 1
Stapes is the smallest bone in human
(b) Vertebral Column : The vertebral column usually consists
of 26 vertebrae as follows :
(i) Cervical Vertebrae – 7 (its first vertebra is called as
atlas vertebra)
(ii) Thoracic Vertebrae – 12
(iii) Lumber Vertebrae – 5
(iv) Sacram Vertebra – 1 (5 fused sacral vertebrae)
(v) Coccyx Vertebra – 1 (4 fused sacral vertebrae)
(c) Ribs : 12 paired ribs (total - 24), each is symmetrically
paired on a right and left side.
• Our thoracic cage or rib cage is composed of 12 pairs
of ribs, sternum, cartilages and thoracic vertebrae. Of the
12 pairs of ribs the first 7 pairs are attached to vertebrae
posterior and sternum anteriorly (with costal cartilage).
These rib pairs are called true ribs.
• No. 8-12 rib pairs are attached to vertebrae posteriorly but
anteriorly they are not attached to the sternum directly.
These rib pairs are called false ribs.
• The 8-10th rib pairs connect to the sternum indirectly via
the costal cartilages of the ribs above them.
• The 11 & 12th rib pairs do not connect to the sternum at
all. So these two rib pairs are called floating ribs.

(d) Sternum : The sternum or breastbone (1) is a long flat

bone located in the central part of the chest. It serves as
the keystone of the rib cage and stabilizes the thoracic
skeleton.
Total number of Bones in Axial skeleton - 80
(ii) Appendicular Skeleton :
• The appendicular skeleton of a human includes the bones
of the shoulder girdle, upper limbs, pelvic girdle and the
lower limbs.
(a) Pectoral Girdle (Shoulder Girdle) : Total 4 bones
(i) Scapula (Shoulder blade) – 2
(ii) Clavicle (Collarbone) – 2
(b) Pelvic Girdle : 2 bones
(i) Os innominatum (Hip bone) – 2
(c) Forelimb : Total 60 bones
(i) Upper arm (Humerus) – 2 (one in each forelimb)
(ii) Forearm (Radioulnar) – 4 (two in each forelimb)
(iii) Wrist (Carpal) – 16 (8 in each forelimb)
(iv) Palm (Metacarpal) – 10 (5 in each forelimb)
(v) Fingers (Phalanges) – 28 (14 in each forelimb)
(d) Hindlimb : Total 60 bones
(i) Thigh (Femur) – 2 (1 in each hindlimb)
(ii) Shank (Tibiofibula) – 4 (2 in each hindlimb)
(iii) Kneecap (Patella) – 2 (1 in each hindlimb)
(iv) Ankle (Tarsal) – 14 (7 in each hindlimb)
(v) Foot (Metatarsal) – 10 (5 in each hindlimb)
(v) Fingers (Phalanges) – 28 (14 in each hindlimb)
Total number of Bones in Appendicular skeleton - 126
Femur (Thigh bone) is the longest bone of human skeleton
Arthritis :
• The word arthritis is used to describe pain, swelling and
stiffness in a joint or joints.
• Osteoarthritisis the most common type of arthritis. When
the cartilage - the slick, cushioning surface on the ends of
the bones - wears away, bones rub against bone, causing
pain, swelling and stiffness. It can affect both the larger
and smaller joints of the body, including the hand, wrists,
feet, back, hip and knee.
• Rheumatoid arthritis (RA) is a disorder in which the
body’s own immune system start to attack body tissue. It
typically results in warm, swollen and painful joints. In
RA, most damage occurs to the joint lining and cartilage
which eventually results in erosion of two opposing bones.
RA often affects joints in the knees, wrists, elbows and
fingers, is symmetrical (appears on both sides of the body),
and can lead to severe deformity in a few years, if not
treated.
• Metabolic arthritis (Gout) is that when uric acid is
formed as the body breaks down purines, a substance
found in animal cells and in many foods. The crystals of
uric acid are deposited in the joint, resulting in sudden
spikes of extreme joint pain or a gout attack.
• Arthroplasty is an orthropaedic surgical procedure
where the articular surface of a musculoskeletal joint is
replaced, remodeled or realigned by osteotomy or some
other procedure. It is an elective procedure that is done to
relieve pain and restore function to the joint after damage
by arthritis or some other type of trauma.
Water Percentage in the Human Body :
• The percentage of water varies generally between about
55-70% according to the age and gender of human.
• Average Water % in adult men – about 60-65%
• Born infants – about 75-78%
• Infants by one year of age – about 65-70%
• In adult women, fats make up more of the body than men,
so they have about 55-60% of water in their bodies.
• According to H.H. Mitchell, Journal of Biological
Chemistry :
• The brain and heart composed of 73% water,
• Lungs are about 83% of water,
• Skin contains 64% water,
• Muscles and Kidneys contain 79% water, and
• Bones contain 31% of water.
• An adult male needs about 3 Litres water per day while
an adult female needs about 2.2 litres water per day.
• Water serves a number of essential functions to keep us
all going :
• A vital nutrient to the life of every cell, acts first as a
building material.
• It regulates our internal body temperature by sweating
and respiration.
• The carbohydrates and proteins that our body uses as
food are metabolized and transported by water in the
bloodstream.
• It assists in flushing waste mainly through urination.
• It acts as a shock absorber for brain, spinal cord and
fetus,
• forms saliva,
• lubricates joints.
Chemical Composition of Human Body :
• Almost 99% of the mass of human body is made of six
elements : oxygen, carbon, hydrogen, nitrogen, calcium
and phosphorus.
• Only about 0.85% is composed of another 5 elements :
potassium, sulphur, sodium, chlorine and magnesium.
• All 11 elements mentioned above are necessary for life.
• The approximate percentage of different elements in
human body is shown in following table :
Element Symbol % in body
Oxygen O 65.0
Carbon C 18.5
Hydrogen H 9.5
Nitrogen N 3.2
Calcium Ca 1.5
Phosphorus P 1.0
Potassium K 0.4
Sulphur S 0.3
Sodium Na 0.2
Chlorine Cl 0.2
Magnesium Mg 0.2
• Trace elements including boron, chromium, cobalt, copper,
fluorine, iodine, iron, manganese, molybdenum, selenium,
silicon, tin, vanadium and zinc are less than 0.1% of the
human body.
Calcium phosphate compound is found in
maximum amount in human bone
Human Tooth :
• The human teeth function to mechanically breakdown
items of food by cutting and crushing them in preparation
for swallowing and digesting.
• Humans have four types of teeth :
Incisors – cut the food
Canines – tear the food
Premolars and Molars – crush or grind the food
• The roots of the teeth are embedded in the maxilla (upper
jaw) or the mandible (lower jaw) and are covered by gums.
• Human teeth are diphyodont meaning that they develop
two sets of teeth. The first set (called baby ‘milk’, primary
or deciduous set), normally starts to appear to about six
months of age, although some babies are born with one
or more visible teeth, known as natal teeth.
• Normal tooth eruption at about six months is known as
teething and can be painful.
• Humans usually have 20 primary teeth and 32 permanent
(adult) teeth.
• Among permanent teeth, 16 are found in maxilla and 16
in the mandible.
• Third molars are commonly called ‘wisdom teeth’ and
may never erupt into the mouth or form at all.
• If any additional teeth form (eg. fourth and fifth molars),
which are rare, they are referred to as supernumerary teeth
(hyperdontia).
• Tooth enamel is the hard mineralized surface of the teeth.
It is the hardest substance of the body and it is whitish and
shining substance.
• Essential nutrients for a healthy tooth include calcium,
phosphorus, fluorine and vitamin A, D, C.
• Calcium and phosphorus are needed to properly form
the hydroxyapatite crystals (which is enamel’s primary
mineral) and their levels in blood are maintained by
Vitamin D.
• Demineralization begins with the bacteria in the plaque on
teeth. They feed on sugar and other carbohydrates in mouth
and produce acids. The acids dissolve crystals in tooth
enamel. The loss of enamel is balanced by remineralization
with the help of fluorine, calcium, phosphate, etc. Too
much loss of minerals without enough replacement leads
to tooth decay.
• Sartorius muscle is the longest muscle in the human
body which runs diagonally down the thigh.
• Stapedius is the smallest muscle which is less than 2
millimeter long located in the middle ear.
• Strongest muscle in the human body is masseter,
muscle known as jaw muscle that plays a major role in
the chewing of the solid foods.
• Record of lifting 975 pound weight by jaw muscle for 2
seconds is registered in Guinness World Records.

II. Digestive System

Notes
Digestion :
• Digestion is the breakdown of large insoluble food
molecules into small water-soluble food molecules so
that they can be absorbed into the watery blood plasma.
Digestion is a form of catabolism that is often divided
into two processes based on how food is broken down :
mechanical and chemical digestion.
• Mechanical digestion refers to the physical breakdown
of large pieces of food into smaller pieces which can
subsequently be accessed by digestive enzymes.
• In chemical digestion, enzymes break down food into the
small molecules the body can use.
Human digestive system :
• The human digestive system consists of the alimentary
canal (gastrointestinal tract) plus the accessory organs of
digestion (the tongue, salivary glands, pancreas, liver and
gall bladder). The alimentary canal is a long tube through
which food is taken into the body and digested.
• In human, this passage is about 30 feet (9 metre) long
from the oesophagus to the anus. The buccopharyngeal
cavity, oesophagus, stomach and intestines are the main
parts of the alimentary canal.
Digestion in Mouth :
• Saliva is the watery and usually somewhat frothy
substance produced in the mouth by salivary glands.
• Human saliva comprises about 99.5% water plus
electrolytes, mucus, white blood cells, epithelial cells
(from which DNA can be extracted), enzymes such as
amylase (ptyalin) and lipase, antimicrobial agents such
as secretory IgA, and lysozymes.
• The amount of saliva that is produced in a healthy person
per day ranges from about 0.75 to 1.5 litres.
• The digestive functions of saliva include moistening food,
and helping to create a food bolus, so it can be swallowed
easily.
• Amylase enzyme (ptyalin) breaks some starches into
maltose and dextrin.
• The enzyme lysozyme hydrolyzes the cell wall of bacteria
resulting in their killing.
In human, digestion starts from the mouth
Oesophagus :
• Oesophagus or esophagus is also called the gullet or food
pipe.
• It is a muscular tube about 25 cm. long. It connects mouth
to the stomach.
• When the food is swallowed, the walls of the oesophagus
squeeze together (contract). This moves the food down the
oesophagus to the stomach.
Digestion in Stomach :
• The stomach is a muscular sac that lies between the
oesophagus and small intestine, in the upper abdomen.
• The stomach is with strong muscular walls.
• In addition to holding the food, it is also a mixer and
grinder.
• The stomach secretes acid and powerful enzymes that
continue the process of breaking down of the food.
• Substances secreted by gastric glands of the stomach and
their functions are as follows :
(i) Hydrochloric acid (HCl) :
• Hydrochloric acid provides the acidic medium to the food
for digestion.
• It kills the bacteria.
• It dissolves the foreign matter such as small stones, or
bones that come along with food.
• It activates the enzyme pepsin and renin.
(ii) Mucin :
• Mucin is a glycoprotein. It forms a thin layer over the
internal layer of the stomach to protect it from being
damaged by hydrochloric acid.
(iii) Pepsin and Renin :
• Pepsin and Renin are protein digestive enzymes.
• It breaks down the protein into peptone and polypeptides.
(iv) Lipase :
• It breaks down fat into glycerol and fatty acids.
Liver :
• The liver is the largest gland of the human body.
• The liver is an essential organ that has many functions in
the body, including making proteins and blood clotting
factors, manufacturing triglycerides and cholesterol,
glycogen synthesis, bile production, the synthesis of urea,
breakdown of R.B.C. etc.
Bile :
• Bile or gall is a dark green to yellowish brown fluid
produced by the liver, that aids the digestion of lipids in
the duodenum.
• The composition of hepatic bile is 97% water, 0.7% bile
salts, 0.2% bilirubin, 0.51% fats (cholesterol, fatty acids
and lecithin) and little amount of inorganic salts.
• About 800 to 1000 ml of bile is produced per day in adult
human beings.
• Bile or gall acts to some extent as a surfactant, helping to
emulsify the fats/lipids in food.
Pancreas :
• The pancreas is an organ of the digestive system and
endocrine system of vertebrates. It is both an endocrine
gland and exocrine gland. Hence it is called the mixed
gland. In adults, it is about 12-15 cm long, lobulated and
salmon-coloured in appearance.
• It is the second one of the largest gland in human.
• In human, it is located in the abdomen behind the stomach.
• As an endocrine gland, it functions mostly to regulate
blood sugar levels, secreting the hormones insulin,
glucagon and somatostatin, and pancreatic polypeptide.
Pancreatic juice :
• Pancreatic juice is a liquid secreted by the pancreas, which
contains a variety of enzymes.
• The enzymes present in pancreatic juice are as follows :
(i) Amylase– It converts starch into disaccharides.
(ii) Trypsin– It converts protein into smaller peptides
which are then further hydrolized into amino acids.
(iii) Lipase– It converts fat into glycerol and fatty acids.
(iv) Elastase– It break down proteins.
(v) Nuclease– It breaks down the nucleic acid into
nucleotide.
• Since all types of food are digested by pancreatic juice,
so it is called complete digestive juice.
Digestion of food in duodenum takes
place in alkaline medium
Small Intestine :
• The small intestine is a long, narrow, folded or coiled tube
extending from the stomach to the large intestine; it is the
region where most digestion and absorption of food takes
place.
• It is about 6.7 to 7.6 metres (22 to 25 feet) long in adults,
highly convoluted and contained in the central and lower
abdomen.
• Three successive regions of the small intestine are
distinguished : duodenum, jejunum and ileum whose
length is about 25 cm., 2.5 metre and 3.5 metre respectively.
Digestion in Duodenum :
• The first part of small intestine, the duodenum, is adjacent
to the stomach.
• Ducts from the liver, gallbladder and pancreas, enter
the duodenum to provide the juices that neutralize acids
coming from the stomach and help to digest proteins,
carbohydrates and fats.
Digestion in Jejunum :
• The jejunum is the second part of the small intestine.
Its lining is specialized for the absorption by enterocytes
or small nutrient molecules which have been previously
digested by enzymes in the duodenum.
• Once absorbed, nutrients (with the exception of fat, which
goes to the lymph) pass from the enterohepatic circulation
and enter the liver, where the blood is processed.
• The jejunum is involved in magnesium absorption.
Digestion in Ileum :
• The ileum is the lower part of the small intestine and the
largest section of the alimentary canal.
• The inner wall of the ileum contains secretary cells, some
of which secrete mucus and other secrete an alkaline fluid
known as internal juice succus entericus.
• The arrival of chyme in the ileum stimulates the secretion
of intestinal juice.
• The juice contains the following enzymes that carry out
digestive functions which are as follows–
(i) Erepsin–breaks down peptones into amino acids.
(ii) Lipase–breaks down fats into fatty acid and glycerol.
(iii) Maltase–breaks down maltose into glucose.
(iv) Sucrase–speeds up the breakdown of sucrose into glucose
and fructose.
(v) Nucleotidase–It breaks down the nucleotide into nitrogen
base, sugar and phosphoric acid.
The process of digestion is completed in the ileum
• The resulting watery substance of food is called chyle
and contains soluble products of digestion ready to be
absorbed.
Absorption of digested food :
• Absorption is the transfer of digested food to the blood or
lymph through the mucosa of the ileum.
• The inner epithelial lining of the ileum is folded to form
villi.
• Villi are many folds in the inner wall of the ileum which
causes an increase in the surface area of the small
intestine that is subjected to the absorption of digested
food.
Large Intestine (Colon) and Defecation :
• The undigested food passes to the large intestine.
• Water and salts from the undigested food are absorbed
through the lining of the epithelial wall of the large
intestine, as it has many convolutions to help in the
absorption.
• Wastes become semisolid faeces and have a bad odour, due
to the presence of certain types of bacteria. These bacteria
decompose the undigested food producing different gases
like methane, sulphur dioxide, ammonia, carbon dioxide,
etc.
Caecum and Vermiform Appendix :
• The appendix is a finger-like, blind-ended tube connected
to the caecum.
• The caecum is a pouch-like structure of the colon, located
at the junction of the small intestine and the large intestine.
• The main functions of the caecum are to absorbs fluids and
salts that remain after completion of intestinal digestion
and absorption, and to mix its contents with a lubricating
substance, mucus.
• In human vermiform appendix is a vestigial remnant,
that is, it was once useful to humans in the digestion of
food but as human has evolved, it has lost its functions
and become redundant.
• In herbivores, the vermiform appendix is well developed
and helps in the digestion of cellulose.
Enzyme :
• Enzyme is basically protein.
• Enzyme is a substance produced by a living organism
which acts as a catalyst to bring about a specific
biochemical reaction.
• Zymase enzyme converts glucose into ethyl alcohol and
carbon dioxide. It occurs naturally in yeasts.

III. Vitamins and Nutrition

Notes
Food :
• Food is any substance consumed to provide nutritional
support for an organism.
• It is usually of plant or animal origin and contains essential
nutrients such as carbohydrates, fats, proteins, vitamins
and minerals.
• The substance is ingested by an organism and assimilated
by the organism’s cell to provide energy, maintain life or
stimulate growth.
Components of Food :
• The major components of our food are-
(i) Carbohydrates
(ii) Fats
(iii) Proteins
(iv) Minerals (salts)
(v) Nucleic Acids
(vi) Vitamins
(vii) Water
Carbohydrates :
• A carbohydrate is a biomolecule consisting of carbon
(C), hydrogen (H) and oxygen (O) atoms, usually with a
hydrogen - oxygen atom ratio of 2 : 1 and thus with the
empirical formula Cx
(H2
O)y (Where x may or may not be
different from y).
• Carbohydrates are the main component of food and source
of immediate energy to the body.
• Approximately 55-75% energy is provided by
carbohydrates to the total energy requirement of the body.
• It is stored in the liver and skeletal muscles in the form of
glycogen which gives energy on requirement.
• One gram of glucose gives 4.5K calories energy on
oxidation.
• Lactose is a natural sugar (a carbohydrate). It is milk sugar.
It is responsible for the mildly sweet taste of milk.
• Lactobacillus bacteria converts lactose into lactic acid.
These bacteria are employed in the manufacturing of curd
and cheese.
• The starch and cellulose both are of plant origin. Starch
is composed of glucose molecules linked in long chains.
Cellulose is also a long chain of glucose molecules.
• The iodine test is used to test for the presence of starch.
Starch turns into an intense ‘blue-black’ colour upon
addition of aqueous solutions of the triodide ion, due to the
formation of an intermolecular charge - transfer complex.
• Cellulose does not turn into blue-black colour in the
presence of iodine.
Fats :
• Fats are the compounds of Carbon, Hydrogen and Oxygen.
• In fats, the ratio of oxygen to hydrogen atom is less.
• The fats are formed with the chemical reaction of one
molecule of glycerol and three molecules of fatty acids.
• Fats are the source of stored energy. Fats are broken down
in the healthy body to release their constituents, glycerol
and fatty acids. Glycerol itself can be converted to glucose
by the liver and so become a source of energy.
• 9.0-9.3K calories energy is produced by total combustion
of one gram of fat.
• It provides almost15-20% energy to the total energy
requirement of the body.
• The percentage of fat in a healthy man is about 7% to its
total body weight.
• The fats have been classified into two groups on the basis
of carbon atom bonds in their fatty acids–
(i) Saturated fats.
(ii) Unsaturated fats.

(i) Saturated Fats :

• Asaturated fat is a type of fat in which the fatty acid chains
have all or predominantly single bonds.
• Saturated fatty acids are important to nutrition because of
their ability to elevate blood lipid levels in humans.
• Saturated fatty acids are not essential because the
body can synthesize these fatty acids, hence nutritional
recommendation around the world suggest that saturated
fatty acid intake be kept low to promote health and reduce
the risk from cardiovascular diseases.
• Saturated fatty acids in the diet raise plasma cholesterol
and PUFA (polyunsaturated fatty acid) lowers it,
decreasing the risk of heart disease.
• Following are some saturated fatty acids–
• Butyric acid (contained in butter)
• Lauric acid (contained in coconut oil, palm kernel oil
and breast milk)
• Myristic acid (contained in cow’s milk and dairy
products)
• Palmitic acid (contained in butter, palm oil and meat)
• Stearic acid (contained in meat and cocoa butter)
(ii) Unsaturated Fats :
• An unsaturated fat is a fat or fatty acid in which there is at
least one double bond or triple bond within the fatty acid
chain. Afatty acid chain is monounsaturated if it contains
one double bond, and polyunsaturated if it contains more
than one double bond.
• Such fatty acids are found in fish, corn, walnuts, sunflower
seeds, soyabeans, cotton seeds, olive oil and sunflower oil.
• Diet high in unsaturated fatty acids and low in saturated
fatty acids have been correlated with low serum cholestrol
levels.
• The unsaturated fats have lower melting point and most
are liquid at room temperature.
• Following are the examples of unsaturated fatty acids–
• Palmitoleic acid (found in macadamia nuts)
• Oleic acid (found in olive oil and canola oil)
• Myristoleic acid (found in whale blubber)
• Linoleic acid (found in peanut oil, chicken fat and
olive oil)
• Linolenic acid (found in linseed oil)
• Unsaturated fatty acid can not be synthesized by the body
and is therefore essential to the diet. In humans, linoleic
acid and α-linolenic acid are the primary essential fatty
acids.
• Among oilseeds, linseed oil is with maximum quantity of
α-linolenic fatty acid.
• α-Linolenic acid is an omega-3 fatty acid which prevents
the accumulation of fat in blood vessels.
• Arachidonic fatty acid is a polyunsaturated omega-6
essential fatty acid. It is found in the liver, brain and
glandular organs and is a constituent of animal's
phosphatides. It is formed by the synthesis from dietary
linoleic acid and is a precursor in the biosynthesis of
prostaglandins, thromboxanes and leukotrienes while
other fatty acids (non-essential) are synthesized in
mammals by acetyl coenzyme A, which is formed during
oxidation of glucose.
• Hydrogenation is a process in which unsaturated fats such
as vegetable oils are hydrogenated to produce saturated
fats, which have more desirable physical properties e.g.
they melt at a desirable temperature (about 30ºC to 40ºC).
Trans fats :
• The majority of trans fats are artificial fats created by
adding hydrogen to liquid vegetable oil to make it a solid.
• Trans fats raise bad LDLcholesterol levels and lower good
HDLcholesterol levels. Eating trans fats increases the risk
of developing heart disease and stroke. It is also associated
with a higher risk of developing type 2 diabetes.
Proteins :
• Proteins are the essential nutrients for the human body.
• They are one of the building blocks of body tissue and
can also serve as a fuel source.
• As a fuel, proteins provide 4.0K cal energy per gram.
• Amino acids are the structural units of the protein.
• There are 10 essential amino acids and 10 non-essential
amino acids which are required to synthesize protein in
human body.
Essential Amino Acids :
• Essential amino acids are not synthesized in human body.
Human must obtain them from their diet in order to prevent
protein energy malnutrition and resulting death.
• Essential amino acids include : phenylalanine, valine,
threonine, tryptophan, methionine, leucine, isoleucine,
lysine, histidine and arginine.
• Arginine and histidine are essential only for juveniles but
not for adults because these are synthesized in adults.
(ii) Non-essential Amino Acids :
• Non-essential amino acids are such amino acids which
are synthesized within the human body.
• These are alanine, asparagine, aspartic acid, cysteine,
glutamic acid, glutamine, glycine, proline, serine, and
tyrosine.
• α-Keratin is a protein, which is the main constituent of
horn, nail, hoof, hair, skin etc.
• Tyrosine helps in synthesis of neurotransmitters such as
adrenaline, noradrenaline and dopamine in the brain.
In milk, water percentage is approximately 87%. Besides it
contains fats, proteins, carbohydrates, calcium, potassium,
so it is considered as Complete Diet, which is globally
accepted food for all ages.
• Nursing mothers need at least 65 grams of protein per day,
while in other females its requirement per day is 45-46
grams.
• Due to protein deficiency, marasmus and kwashiorkor
diseases are developed in humans.
Vitamins :
• It has been observed that certain organic compounds are
required in small amounts in our diet but their deficiency
causes specific diseases. These compounds are called
vitamins.
• Most of the vitamins cannot be synthesised in our body
but plants can synthesise almost all of them, so they are
considered as essential food factors.
• Vitamins are classified into two groups depending upon
their solubility in water or fat.
(i) Fat soluble vitamins : These are vitamins A, D, E and K.
They are stored in liver and adipose (fat storing) tissues.
(ii) Water soluble vitamins : B group vitamins and vitamin
C are soluble in water. Water soluble vitamins must be
supplied regularly in diet because they are readily excreted
in urine and cannot be stored (except vitamin B12) in our
body.
IV. Respiratory System
Notes
• There are three major parts of the respiratory system : the
airway, the lungs and the muscles of respiration.
• The airway, which includes the nose, mouth, pharynx,
larynx, trachea, bronchi and bronchioles, carries air
between the lungs and body's exterior.
• Human have two lungs, a right lung and a left lung. They
are situated in the thoracic cavity of the chest. The right
lung is bigger than the left, which shares space in the chest
with the heart. The right lung has three lobes and the left
has two.
• The lungs act as the functional units of the respiratory
system. Their function in the respiratory system is to
extract oxygen from the atmosphere and transfer it into
the bloodstream and to release carbon dioxide from the
bloodstream into the atmosphere, in a process of gas
exchange.
• Air is breathed in through the nose or the mouth. In the
nasal cavity, a layer of mucous membrane acts as a
filter and traps pollutants and other harmful substances
found in the air. Next, the air is moved into the pharynx
(also known as the throat), a passage that contains the
intersection between the oesophagus and the larynx. The
opening of the larynx has a special flap of elastic cartilage,
the epiglottis, that opens to allow air to pass through but
closes to prevent food from moving into the airway.
• From the pharynx, air moves into the trachea (or
windpipe) and down to the intersection that branches
to form the right and left primary bronchi. Each of
these bronchi branches into secondary (lobar) bronchi,
that branches into tertiary (segmental) bronchi and that
split into many smaller airways called bronchioles, that
eventually connect with tiny specialized structures called
alveoli (approx. 15 crore in each lung) that function in gas
exchange.
• The lungs are encased in a serous membrane that folds
in on itself to form the pleurae, a two-layered protective
barrier. The inner visceral pleura covers the surface of the
lungs and the outer parietal pleura is attached to the inner
surface of the thoracic cavity. The pleurae enclose a cavity
called the pleural cavity that contains pleural fluid. This
fluid is used to decrease the amount of friction that lungs
experience during breathing.
• At the base of the lungs is a sheet of skeletal muscle
called the diaphragm. The diaphragm is the main muscle
of respiration involved in breathing and is controlled by
the sympathetic nervous system. When the diaphragm
contracts, it moves inferiorly a few inches into the
abdominal cavity, expanding the space within the thoracic
cavity and pulling air into the lungs. Relaxation of the
diaphragm allows air to flow back out the lungs during
exhalation.
• Between the ribs are many small intercostal muscles that
assist the diaphragm with expanding and compressing the
lungs.
• Respiration through the lung is called pulmonary
respiration.
Respiratory Volumes :
• The recording of the volume of movement of air into and
out of lungs is called spirometry and it is measured with
the help of spirometer.
• The volume of air animal inhales and exhales with each
normal breath is called tidal volume. It averages about
500 ml. in humans.
• The maximum volume of air a person can inhaled or
exhaled during forced breathing is called vital capacity. It
is about 3.5-4.5 litres. Vital capacity is higher in athletes,
mountain dwellers, and lower in woman, old age, cigarette
smoking persons.
• The volume of air remaining in lungs even after forceful
expiration is called residual volume. It is about 1200
ml. Additional volume of air, a person can inspire by a
forcible inspiration is called inspiratory reserve volume
or IRV (2500-3000 ml.). Additional volume of air, a person

can expire by a forcible expiration is called exspiratory

reserve volume or ERV (approx. 1100 ml.). Dead space
is the volume of air (150 ml.) in nasopharynx, trachea and
bronchi which is not available for gas exchange.
• Total volume of air accomodated in the lungs at the end
of a forced inspiration is known as total lung capacity.
Mechanism of Breathing :
• The breathing includes two processes inspiration and
expiration.
• Inspiration is a process of intake of air into the lungs. It is
an active process. When the external intercostal muscles
contracts, the diaphragm becomes flat and space inside
the thoracic cavity increases. Simultaneously the high
pressure air from outside rushes into the lungs.
• Expiration is a process of expulsion of air from the lungs.
In this process the internal intercostal muscles contract and
the diaphragm become original domeshaped and the space
inside thoracic cavity decreases, lungs are compressed and
the air is expelled out.
• In female, diaphragm does not play an important role in
inspiration to prevent injury to foetus in uterus. Therefore,
ribs play important role in female whereas diaphragm in
male.
• The rate of respiration in human is 15-25 times per minute.
In babies, it is about 35 per minute.
• Gas exchange is the delivery of oxygen (O2
) from the
lungs to the bloodstream, and the elimination of carbon
dioxide (CO2
) from bloodstream to the lungs. It occurs in
the lungs between the alveoli and a network of tiny blood
vessels called capillaries, which are located in the walls
of the alveoli.
• Alveoli are the primary sites of exchange of gases.
Exchange of gases also occur between blood and tissues.
O2 and CO2 are exchanged in these sites by simple
diffusion mainly based on pressure/concentration gradient.
• Blood is the medium of transport for O2 and CO2
. About
97 percent of O2 is transported by RBCs in the blood. The
remaining 3 percent of O2 is carried in a dissolved state
through the plasma.
• Nearly 20-25 percent of CO2 is transported by RBCs
whereas 70 percent of it is carried as bicarbonate.
Remaining percent of CO2 is carried in a dissolved state
through plasma.
• The haemoglobin present in RBCs acts as a carrier of
oxygen, transporting oxygen to different tissues of organs.
• In a healthy person, generally, the haemoglobin amount is
12-18 gm/100 ml. blood. Approximately 1.34 ml. oxygen
is bound with 1 gram of haemoglobin. Thus about 20 ml.
oxygen is bound with 100 ml. of blood.
• Carbon monoxide binds to haemoglobin at the same sites
as oxygen, but approximately 250 times more tightly. This
gas is fatal to life. It displaces oxygen and quickly binds,
so very little oxygen is transported through the body cells.
• During the inspiration and expiration process of breathing
generally the percentage of nitrogen gas remains constant.
• Hypoxia is a condition in which the body or a region of the
body is deprived of adequate oxygen supply at the tissue
level. Hypoxia may be classified as either generalized,
affecting the whole body, or local, affecting a region of
the body.
• Hypoxemia is abnormally low level of oxygen in the
blood which can cause hypoxia, when blood does not carry
enough oxygen to tissues to meet the need of the body.
• Hypoxia and Hypoxemia are dangerous conditions.
Without oxygen brain, liver and other organs can be
damaged just minutes after symptoms start.
Cellular Respiration :
• The term Cellular respiration refers to the biochemical
pathway by which cells release energy from the chemical
bonds of food molecules and provide that energy for
essential processes of life. It can be anaerobic respiration
or aerobic respiration.
a. Anaerobic Respiration :
• In anaerobic respiration, glucose breaks down without
oxygen. Incomplete oxidation of glucose takes place
producing alcohol and carbon dioxide.
C6
H12O6 → 2C2
H5
OH + 2CO2
+ 56Kcal energy.
• Such type of respiration is found in resting seeds, pericarps
of fruits, microorganisms and muscles of animals.
• The formation of lactic acid in the muscle cell is also an
example of anaerobic respiration.
• Fermentation is a type of anaerobic respiration.
b. Aerobic Respiration :
• Aerobic Respiration is a biochemical reaction which takes
place in the presence of oxygen.
• The by-products of aerobic respiration are carbon dioxide
and water.
C6
H12O6
+ 6O2 → 6CO2
 + 6H2
O + 656Kcal energy.
• Anaerobic respiration (both glycolysis and fermentation)
takes place in the fluid portion of the cytoplasm whereas
the bulk of the energy yield of aerobic respiration takes
place in mitochondria.
• Aerobic respiration involves two stages -
(i) Glycolysis (ii) Kreb's or Citric Cycle
(i) Glycolysis :
• Glycolysis is the metabolic pathway that converts glucose
into pyruvic acid. The free energy released in this process
is used to form the high energy molecule ATP (adenosine
triphosphate) and NADH (reduced nicotinamide adenine
dinucleotide).
• Two molecules of pyruvic acid are formed from one
molecule of glucose during glycolysis.
• During glycolysis four ATP molecules are formed, but
two ATP are consumed in phosphorylation. Hence, in
complete process of glycolysis, the net gain of ATP is
4 – 2 = 2 ATP.
• Glycolysis is also known as EMP Path because it was
discovered by Embden, Meyerhof and Parnas.
• Glycolysis takes place in the cytoplasm.
(ii) Kreb's cycle :
• Kreb's cycle was discovered by British Scientist Hans
Krebs.
• This cycle takes place in mitochondria of eukaryotes and
in cell membrane of prokaryotes.
• In Kreb’s cycle, the total oxidation of pyruvic acid is
completed in the presence of oxygen and different enzymes
and the end product is carbon dioxide, water and released
energy.
• Net gain of ATP in Kreb's cycle is 36ATP (oxidation of 2
molecules of pyruvic acid).
• Total net gain of ATP in aerobic respiration is 38 ATP.
Respiratory Quotient (RQ) :
• The ratio of the volume of carbon dioxide evolved to that
of oxygen consumed by an organism, tissue, or cell in a
given time.
• The RQ value indicates which macronutrients are being
metabolized, as different energy pathways are used for
fats, carbohydrates, and proteins.
• RQ for fat is 0.7, for protein is 0.8 and for carbohydrate
is 1.0.
• It is measured by Ganong’s respirometer.

Circulatory System
Notes
• The circulatory system is a network consisting of blood,
blood vessels and the heart. This network supplies tissues
in the body with oxygen and other nutrients, transport
hormones and removes unnecessary waste products.
• There are two main types of circulatory systems : open
circulatory systems and closed circulatory systems.
• Open circulatory systems are systems where internal
organs and body tissues are surrounded by circulatory
fluid, e.g. in crustaceans, insects, molluscs and other
invertebrates.
• Closed circulatory systems have the blood closed at all
times within vessels of different size and wall thickness.
In this type of system, blood is pumped by a heart through
vessels and does not normally fill body cavities. Large
and more active animals, including all vertebrates, have
a closed circulatory system.
Human Heart :
• The human heart is a muscular organ, which pumps blood
throughout the body via the blood vessels of the circulatory
system, supplying oxygen and nutrients to the tissues and
removing carbon dioxide and other wastes.
• In human, the heart is roughly the size of a large fist and
weighs between about 250-300 grams in adults.
• The human heart is located between the lungs, in the
middle compartment (mediastinum) of the chest.
• The Pericardium is a double-walled sac enclosing the
heart, consisting of an outer fibrous membrane and an
inner double layer of serous membrane. The intervening
space between these layers is filled with pericardial fluid
which protects the heart from outer shocks and acts as a
lubricant to allow normal heart movement within the chest.
• The wall of heart is made up of three layers : epicardium,
myocardium, and endocardium.
• The human heart has four chambers- two upper chambers
(the atria or auricles - receiving chambers) and two lower
ones (the ventricles-discharging chambers).
• The right atrium and right ventricle together make up the
‘right heart’ and the left atrium and left ventricle make
up the ‘left heart’. A wall of muscle called the septum
separates the two sides of the heart.
• In a healthy heart, blood flows one way through the heart
due to heart valves which prevent backfl ow.
• The heart pumps blood with a rhythm determined by a
group of pacemaking cells in the sinoatrial node. These
generate a current that causes contraction of the heart,
travelling through the atrioventricular node and along
the conduction system of the heart. The heart receives
blood low in oxygen from the system circulation, which
enters the right atrium from the superior and inferior
vena cava and passes to the right ventricle. From there
it is pumped into the pulmonary circulation, through
the lungs where it receives oxygen and gives off carbon
dioxide. Oxygenated blood then returns to the left atrium,
passes through the left ventricle and is pumped out through
the aorta to the systemic circulation– where the oxygen
is used and metabolized to carbon dioxide.

The heart beats at a resting rate close to 72-75 beats per

minute.
• Trachycardia is considered a heart rate of greater than
100 per minute. This may be due to stress, medications
or it may be a sign of serious heart condition.
• The cardiac cycle is the sequence of events that occurs
when the heart beats. As the heart beats, it circulates blood
through pulmonary and systemic circuits of the body.
There are two phases of the cardiac cycle. In the diastole
phase, the heart ventricles are relaxed and the heart refills
with blood. In the systole phase, the ventricles contract
and pump blood out of the heart and to arteries. One
cardiac cycle is completed when the heart chamber fills
with blood and blood is then pumped out of the heart.
• Double circulation : During a single cardiac cycle blood
goes twice in the heart. It is necessary in human being to
separate oxygenated and deoxygenated blood because this
makes their circulatory system more efficient and helps in
maintaining body temperature.
• William Harvey discovered the blood circulation system
firstly.
• Dr. Christian Barnard was a South African cardiac
surgeon who performed the world’s first highly publicized
heart transplant and the first one in which the patient
regained consciousness (1967).
• Natural Pacemaker : Electrical impulses from the heart
muscles cause to beat. This electrical signal begins in the
sinoatrial node (S-Anode) located at the top of the heart’s
upper right chamber (the right atrium). The S-A node is a
natural pacemaker.
• Artificial Pacemaker : It is a medical device which uses
electrical impulses, delivered by electrodes contacting
the heart muscles, to regulate the beating of the heart.
The most common reasons to need a pacemaker are
bradycardia and heart block. Bradycardia is a heartbeat
that is slower than normal. Heart block is a disorder that
occurs if an electrical signal is slowed or disrupted as it
moves through the heart. Apacemaker can help to regulate
heartbeat.
• Jarvik-7 (Artificial heart) : A mechanical pump used to
replace the function of a damaged heart, either temporarily
or as a permanent prosthesis. It was invented by Robert
Jarvik. Barny Clark was the first recipient of an artificial
heart in 1982.
Blood Pressure :
• Blood pressure is the pressure of blood on the walls of
arteries as the heart pumps it around the body. It is a vital
part of how heart and blood circulation works.
• The normal blood pressure of human is 120/80 mm
Hg. The top number refers to the amount of pressure in
arteries during the contraction of the heart muscle. This
is called systolic pressure. The bottom number refers to
blood pressure when heart muscle relaxes. This is called
diastolic pressure.
• High blood pressure is when blood pressure is persistently
higher than normal.
• Blood pressure that's high over a long time is one of the
main risk factors for heart disease. As humans get older,
the chances of having persistently high blood pressure
increases.
• It is very important to get blood pressure checked regularly,
and if it is persistently high it needs to be controlled.
• Uncontrolled high blood pressure can lead to a heart attack
or stroke. It may attack kidneys.
• The medical name for high blood pressure over a long
period of time is hypertension.
• The causes of high blood pressure are as follows-
• family history
• eating patterns including salty foods
• alcohol and tobacco intake
• weight gain
• low physical activity
• mental tension
• Low blood pressure is when blood pressure is much
below than the normal range. In this condition flow of
blood to the organs of the body is inadequate. The medical
term for low blood pressure is hypotension.
• Low blood pressure alone, without symptoms or signs,
usually is not unhealthy.
• The symptoms of low blood pressure include light-
headedness, dizziness, blurred vision and fainting. These
symptoms are most prominent when individuals go
from the lying or sitting position to the standing position
(Orthostatic hypotension).
• Low blood pressure that causes an inadequate flow of
blood to the body's organs can cause strokes, heart attacks
and kidney failure. The most severe form of low blood
pressure is shock.
• Common causes of low blood pressure include a
reduced volume of blood, dehydration, heart disease and
medications.
• The blood pressure is measured by an apparatus called
sphygmomanometer.
Blood Vessels :
• The blood vessels are part of the circulatory system and
function to transport blood throughout the body.
• The most important types, arteries and veins, carry blood
away from or towards the heart respectively.
• Around this, there is a layer of vascular smooth muscle,
which is highly developed in arteries.
• Semilunar valves are found in veins which only permit
the flow of blood towards the heart and not in the opposite
direction. No such valve is found in arteries.
• Arteries from the heart branch into small passages called
arterioles and then into the capillaries. Capillaries merge
into venules (to bring blood into the venous system),
which merge into veins leading back to the heart.
• In humans, the hepatic portal vein combines from
capillaries around the gastrointestinal tract where the
blood absorbs the various products of digestion, and rather
than leading directly back to heart, the hepatic portal vein
branches into a second capillary system in the liver.
Blood :
• It is a fluid, a specialized form of connective tissue.
• Its pH is about 7.4 (alkaline solution).
• The amount of blood in the human body is generally
equivalent to about 7% of body weight. Its average density
around 1060 kg/m3
. The average adult has a blood volume
of roughly 5-6 litres.
• Blood is essential to life. It circulates through the body and
delivers essential substances like oxygen and nutrients to
the body's cells. It also transports metabolic waste products
away from those cells. There is no substitute for blood. It
cannot be made or manufactured. Generous blood donors
are the only source of blood for patients in need of a blood
transfusion.
Components of the blood :
• The main components of the blood are-
(A) Plasma
(B) Blood cells or corpuscles
(A) Plasma :
• Plasma is the relatively clear, yellow tinted water
(about 91-92%), sugar, fat, protein and salt solution which
carries the blood corpuscles.
• Normally about 55% of our blood volume is made of
plasma.
• Plasma also contains blood clotting factors, vitamins,
enzymes, hormones, antibodies and other proteins.
(B) Blood corpuscles :
• There are three types of blood corpuscles in human
blood :
(a) Red Blood Corpuscles (Erythrocytes)
(b) White Blood Corpuscles (Leucocytes)
(c) Blood Platelets (Thrombocytes)
(a) Red Blood Corpuscles (Erythrocytes) :
• In humans and other mammals, mature red blood cells
are flexible and oval biconcave disks. They lack a nucleus
(exception – the RBCs of Camel and Lama) and most
organelles, in order to accommodate maximum space for
haemoglobin.
• Approximately 2.4 million new erythrocytes are produced
per second in human adults.
• The red blood cells develop in the bone marrow of the
human bones (in the liver in embryo) and circulate for
about 100-120 days in the body before their components
are recycled by macrophages. Each circulation takes about
60 seconds.
• In human body, nearly half of the blood volume (about
40% to 45%) is red blood cells.
• The number of RBCs in male human is about 55 lakh per
microlitre (cubic mm) of blood; in female about 50 lakhs
per microlitre and in person of the hilly area 70-75 lakhs
per microlitre.
• Spleen is the blood bank of the body and old red blood
cells are recycled in the spleen.
• Haemoglobin is the iron-containing oxygen-transport
metalloprotein in the red blood cells of almost
all vertebrates (the exception being the fish family
Channichthyidae) as well as the tissues of some
invertebrates.
• Haemoglobin in blood carries oxygen from the lungs or
gills to the rest of the body (i.e. tissues). There it releases
the oxygen to permit aerobic respiration to provide energy
to power the functions of the organism in the process called
metabolism.
• Ahealthy person has about 12 to 18 grams of haemoglobin
in every 100 ml. of blood.
• Anaemia means that either the level of RBCs or the level
of haemoglobin is lower than normal in the blood. When a
person has anaemia, his heart has to work harder to pump
the quantity of blood needed to get enough oxygen around
their body.
• Polycythemia, or erythrocytosis, is a disease state in which
the volume percentage of red blood cells in the blood is
elevated, which causes blood to get too thick. It can be
due to an increase in the number of RBCs or to a decrease
in the volume of plasma. That can make you more likely
to have clots, a stroke or heart attack.
• The haemoglobin is also known as respiratory pigment.
(b) White Blood Corpuscles (Leucocytes) :
• White blood corpuscles (WBCs) are the cells of the
immune system that are involved in protecting the body
against both infectious diseases and foreign invaders.
• All WBCs are produced and derived from multipotent cells
in the bone marrow known as hematopoietic stem cells.
• All WBCs have nuclei, which distinguishes them from
the other blood cells (RBCs and Platelets).
• White blood cells make up merely about 0.7-1% of the
total blood volume in a healthy adult, but body's immunity
depends on it.
• Normally white blood cell's number is near about 4000-
11000 per microlitre of blood.
• The life of white blood cells is generally a few hours to a
few days.
• The WBCs have been classified into two classes-
(i) Granulocytes
(ii) Agranulocytes
(i) Granulocytes - Their Cytoplasm contains granules.
Granulocytes have been divided in 3 parts as follows-
1. Eosinophils : Eosinophils are specialized cells of the
immune system. This pro-inflammatory white blood cells
have a nucleus with two lobes and cytoplasm filled with
about 200 large granules containing enzymes and proteins.
These are implicated in numerous inflammatory processes,
especially in allergic disorders.
• Eosinophils compose about 2-4% of the WBCs.
• Eosinophilia is a condition in which the eosinophil count
in the blood exceeds. The symptoms of eosinophilia are
wheezing and breathlessness.
2. Basophils : Basophils contain anticoagulant heparin (a
carbohydrate) which prevents blood from clotting in blood
vessels. They also contain the vasodilater histamine,
which promotes blood flow to tissues.
• Basophils are the least common of the granulocytes,
representing about 0.5 to 1% of circulating WBCs.
• Basophils contain large cytoplasmic granules. The nucleus
usually has two lobes.
3. Neutrophils : Neutrophils are also known as the most
abundant type of granulocytes and the most abundant (60%
to 65%) type of WBCs. They form an essential part of the
innate immune system. Neutrophils help heal damaged
and resolve infections.
• Neutrophils levels in blood increase naturally in response
to infections, injuries and other types of infections.
• Neutrophils contain a nucleus divided into 2-5 lobes.
(ii) Agranulocytes - Agranular cells are noted by the absence
of granules in their cytoplasm. They are of two types :
1. Lymphocytes, 2. Monocytes.
1. Lymphocytes : Lymphocytes are one of the body's main
types of immune cell. The two main types of lymphocytes
are B lymphocytes and T lymphocytes. B lymphocytes
make antibodies and T lymphocytes help kill tumour cells
and help control immune responses.
• T lymphocyte cells and B lymphocyte cells derive their
names from the organs in which they develop. T cells
develop in the thymus, and B cells, in mammals, develop
in the bone marrow in adults (or the liver in fetuses).
• In mature individuals, development of new T cells in the
thymus slows down and T-cell numbers are maintained
through division of mature T cells in spleen and lymph
nodes. New B cells, on the other hand, are continually
produced from the bone marrow.
2. Monocytes : A type of immune cell that is made in the
bone marrow and travels through the blood to tissues in
the body where it becomes a macrophage. Macrophages
surround and kill microorganisms, ingest foreign material,
remove dead cells and boost immune system. Monocytes
are the largest in all WBCs.
• Leukaemia is a cancer of the blood or bone marrow.
It leads to the over-production of abnormal white blood
cells – the part of the immune system which defends the
body against infection.
(c) Blood Platelets (Thrombocytes) :
• Platelets are tiny blood cells formed in the bone marrow.
• Platelets have no cell nucleus.
• They generally live for almost 8 to 10 days.
• A normal platelet count is 1,50,000 to 4,50,000 per
microlitre.
• The risk for spontaneous bleeding develops if a platelets
count falls below 10,000 to 20,000. But when the platelet
count is less than 50,000, bleeding is likely to be more
serious if an individual is cut or bruised.
• Platelets help body in forming clots to stop bleeding.
Production of Blood Cells :
• In the human adult, the bone marrow alone produces
all of the RBCs, 60-70 percent of the WBCs (i.e., the
granulocytes), and all of the platelets.
• The bone marrow and the lymphatic tissues, particularly
the thymus, the spleen, and the lymph nodes, produce the
lymphocytes (20-25 percent of the WBCs).
• Monocytes (4-8 percent of the WBCs) are produced by
the reticuloendothelial tissues of the spleen, liver, lymph
nodes, and other organs.
Blood Group :
• Blood Group was discovered by Landsteiner in 1900.
• Blood Group is a classification of blood, based on
the presence and absence of antibodies and inherited
antigenic substances. The antigen is present on the surface
of RBC while antibody is present in the plasma.
• The antigen is a glycoprotein. It is of two types, antigen-A
and antigen-B.
• In the absence of antigen, a special type of protein is
found in plasma known as antibodies. It is of two types,
antibody-a and antibody-b.

There is an agglutination reaction between similar antigen

and antibody (for example, antigen-A agglutinates the
antibody-a and antigen-B agglutinates the antibody-b).
Thus transfusion can be considered safe as long as the
serum of the recipient does not contain antibodies for the
blood cell antigens of the donor.
• Due to the absence of antigen in blood group O, it is
universal donor and due to the absence of antibody in
blood group AB, it is universal recipient.
According to Bernstein (1924) blood groups A, B, O are
the heritable trait of human which passes to progeny in
accordance with Mendel's law of Inheritance.

Rh-Factor :
• In 1937 Landsteiner and Wiener, discovered another
antigen in blood of monkey Rhesus, hence the name Rh-
factor was given to this antigen.
• Rh-factor is an inherited protein found on the surface of
RBCs. If blood has that protein, the blood is Rh-positive
and if blood lacks that protein, the blood is Rh-negative.
• Rh-positive is the most common blood type.
• During blood transfusion, the same Rh-factor must be
considered to avoid the agglutination.
• With consideration of Rh-factor, the universal donor is
O-negative blood group while the universal recipient is
AB-positive blood group.
Erythroblastosis fetalis :
• Erythroblastosis fetalis, also known as hemolytic
anaemia, is a serious medical condition that most
commonly results from maternal-fetal blood type (Rh-
factor) incompatibility.
• If a woman who is Rh-negative and a father who is Rh-
positive conceive a child, the fetus may be Rh-positive.
This can lead to Rh incompatibility and pregnancy
complications..
• If mother’s blood and fetus’s blood mix, mother’s body
will start to make antibodies that can damage fetus’s blood
cells (RBCs). This could cause the baby to develop severe
anaemia and other problems.
• Treatment options for newborns with the condition
include -
• blood transfusion
• intravenous (IV) fluids
• managing breathing problems
• IV immunoglobulin

VI. Excretory System

Notes
• Excretion is a process by which metabolic waste is
eliminated from an organism.
• In vertebrates, this is primarily carried out by the lungs,
kidneys and skin.
• This is in contrast with secretion, where the substance may
have specific tasks after leaving the cell.
• Excretion is an essential process in all forms of life.
Classification of animals on the type of nitrogenous waste :
• The animals have been classified into three groups on the
basis of the type of nitrogenous waste :
(a) Ammonotelic animals : Their main nitrogenous
waste is ammonia e.g. certain protozoans, polychaete
annelids, crustacean arthropods, molluscs (aplysia, sepia
and octopus), fresh-water teleost fishes, tadpoles of
amphibians and crocodiles.
(b) Ureotelic animals : These animal’s main nitrogenous
waste is urea e.g. elasmobranch fishes, amphibian and
mammals.
(c) Uricotelic animals : Their main nitrogenous waste is
uric acid e.g. insects, some gastropods, lizards, snakes
and birds.
Excretion of nitrogenous waste in human :
• The nitrogenous waste in human is excreted by kidneys.
• The kidneys are bean-shaped organs which are present on
each side of the vertebral column in the abdominal cavity.
• Humans have two kidneys and each is supplied with blood
from the renal artery.
• The kidneys remove the nitrogenous waste from the blood
such as urea as well as salts and excess water, and excrete
them in the form of urine.
• This is done with the help of about one million nephrons
present in the each kidney. Nephrons are the structural and
functional unit of the kidney.
The filtered blood is carried away from the kidney by the
renal vein.
• Each kidney is attached to a ureter, a tube that carries
excreted urine to the urinary bladder.
• The urinary bladder collects and stores the urine until
urination.
• The urine collected in the bladder is passed into the
external environment from the body through an opening
called the urethra.
• The kidney's primary function is the elimination of waste
from the bloodstream by the production of urine. They
perform several homeostatic functions such as–
(1) maintain volume of extracellular fluid.
(2) maintain ionic balance in extracellular fluid.
(3) maintain pH and osmolality of extracellular fluid.
(4) regulate blood pressure in long term through
maintenance of the extracellular fluid compartment.
(5) excrete toxic metabolic by-products such as urea,
ammonia and uric acid.
• The way the kidneys do this is with nephrons. These
nephrons act as filters inside the kidneys.
• The kidney filter contains the needed materials and waste.
The needed materials go back into the bloodstream and
unneeded materials are excreted.
• In some cases, excess waste crystalizes as kidney stones
(calcium oxalate). They grow and become painful that
may require surgery or lithotripsy treatments. Some stones
are small enough to be forced into the urethra.
• Urea is formed in the liver but it is separated from the
blood in the kidney by ultrafiltration.
• The urea is transported to kidney by circulatory system
where it is filtered.
• The normal range for 24-hour urine volume is 800 to 2000
ml. per day with an average of about 1.5 litre per day (with
a normal fluid take of about 2 litres per day).
• The urine is acidic with pH 6.0.
• Its pale yellow colour is due to the presence of pigment
urochrome (urobilin).
• In urine, water about 91-96%; urea- about 2.6%; ions of
unnecessary salts-about 2%; cretanin-about 0.3% and
very small amount of uric acid and other waste materials
in trace amount is found.
• The kidneys secrete a variety of hormones, including
erythropoietin, calcitriol and renin.
Dialyzer or Artificial Kidney
• A dialyzer is an artificial filter containing fine fibres. The
fibres are hollow with microscopic pores in the wall, also
known as a semipermeable membrane.
• Its function is to remove the excess waste and fluid
from the blood when the patient's kidneys can no longer
perform that task.
• The process of purifying blood in body is known as
dialysis.
• Most alcohol is broken down or metabolized by an
enzyme by liver cells known as alcohol dehydrogenase.
It breaks down alcohol into acetaldehyde and then another
enzyme aldehyde dehydrogenase, rapidly breaks down
acetaldehyde into acetate.
• From drugs and alcohol to unknown foreign substances,
the liver helps filter and detoxify the materials not meant
to be in our body. Ensuring toxins are safely removed from
blood is one of the liver's most critical jobs.
• Sweat glands in the skin secrete a fluid waste called
sweat, its primary functions are temperature control and
pheromones release. Therefore, its role as a part of the
excretory system is minimal. Sweating also maintains the
level of salt in the body.
• Skin is considered an excretory organ because it excretes
water, salt and urea from the body through sweat.

VII. Nervous System

Notes
• The nervous system is a complex collection of nerves and
specialized cells known as neurons that transmit signals
between different parts of the body. It is essentially the
body's electrical wiring.
• In other words, we can say that a nervous system is a
group of organized cells specialized in the conduction of
electrochemical stimuli from sensory receptors through a
network to the site at which a response occurs.
• A neuron or nerve cell is a cell that carries electrical
impulses.
• Neurons are the basic unit of the nervous system.
• Every neuron is made of a cell body (also called a soma),
dendrites and a single axon.
• Dendrites and axons are nerve fibres.
• Nerve cells are the longest cell of the body.
• Aneuron is an electrically excitable cellthat communicates
with another cell via specialized connections called
synapses.
• All animals except sponges and placozoans have neurons,
but other multicellular organisms such as plants do not.
• Neurons fall into following types-
(a) Sensory neurons (Afferent neurons) respond to
stimuli such as touch, sound or light that affect the
cells of sensory organs and sends signals to the spinal
cord or brain.
(b) Motor neurons (Efferent neurons) receive signals
from the brain and spinal cord and carries it toward
the peripheral effector organs (mainly muscles and
glands).
(c) Interneurons connect neurons to other neurons
within the specific regions of the brain or spinal cord
in neural networks.
• In vertebrates, the nervous system has two major parts -
(i) Central Nervous System (CNS)
(ii) Peripheral Nervous System (PNS)
• The Central Nervous system (CNS) consists of the brain
and spinal cord.
• The Peripheral Nervous system (PNS) consists mainly
of nerves, which are enclosed bundles of the long fibres
or axons, that connect the CNS to every other part of the
body.
• The peripheral nervous system is further subdivided into
the somatic, autonomic and enteric nervous system.
(a) Somatic Nervous System :
• The somatic Nervous system is also called voluntary
nervous system.
• It is the part of the peripheral nervous system associated
with the voluntary control of body movements via skeletal
muscles. The somatic nervous system consists of afferent
nerves or sensory nerves, and efferent nerves or motor
nerves.
(b) Autonomic nervous system :
• The part of the peripheral nervous system that controls
and regulates the internal organs without any conscious
recognition or effort by the organism.
• The autonomic nervous system comprises two antagonistic
sets of nerves.
(i) Sympathetic- Connects the internal organs to the brain by
spinal nerves, when stimulated, these nerves prepare the
organisms for stress by increasing the heart rate, increasing
blood flow to the muscles and decreasing blood flow to
the skin. The sympathetic nervous system is activated in
case of emergencies to moblize energy.
(ii) Parasympathetic- The nerve fibres of the parasympathetic
nervous system are the cranial nerves, primarily
the vagus nerve and the lumbar spinal nerve. When
stimulated these nerves increase digestive secretions and
reduce the heartbeat. The parasympathetic nervous system
is activated when organisms are in relaxed state.
• Within the brain, the autonomic nervous system is
regulated by the hypothalamus. The autonomic nervous
system controls internal body processes such as following-
• Blood pressure
• Heart and breathing rates
• Body temperature
• Digestion
• Body metabolism (thus affecting body weight)
• The balance of water and electrolytes (such as sodium
and calcium)
• The production of body fluids (saliva, sweat & tears)
• Urination
• Defecation
• Sexual response
• Many organs are controlled primarily by either the
sympathetic or the parasympathetic division. Sometimes
the two divisions have opposite effects on the same organs.
For example - the sympathetic division increases blood
pressure and the parasympathetic division decreases it.
Overall, the two divisions work together to ensure that
the body responds appropriately to different situations.
• The two chemical messengers (neurotransmitters) are used
to communicate within the autonomic nervous system :
• Acetylcholine
• Norepinephrine (Noradrenaline)
• Nerve fibres that secrete acetylcholine are called
cholinergic fi bres and which secrete norepinephrine are
called adrenergic fibres.
• Generally, acetylcholine has parasympathetic (inhibiting)
effects and norepinephrine has sympathetic (stimulating)
effects. However, acetylcholine has some sympathetic
effects too. For example -it sometimes stimulates sweating
or makes the hair stand.
(c) Enteric nervous system :
• It consists of a mesh-like system of neurons that
governs the function of the gastrointestinal tract. It is
capable of acting independently of the sympathetic and
parasympathetic nervous system, although it may be
influenced by them. It is also called the second brain.
• Some scientists include the enteric nervous system as part
of autonomic nervous system.
Cranial and Spinal nerves :
• Nerves that exit from the cranium are called cranial
nerves while those exiting from the spinal cord are called
spinal nerves.
• The cranial nerves are 12 pairs of nerves which are found
on the ventral (bottom) surface of the brain.
• Cranial nerves relay information between the brain and
parts of the body, primarily to and from regions of the
head and neck.
• A spinal nerve is a mixed nerve, which carries motor,
sensory, and autonomic signals between the spinal cord
and the body. In the human body there are 31 pairs of
spinal nerves, one on each side of the vertebral column.
• The cranial nerves are considered components of the
peripheral nervous system although on a structural level
the olfactory (I), optic (II), and trigeminal (V) nerves are
more accurately considered part of the central nervous
system.
• The spinal nerves are parts of the peripheral nervous
system.
Human Brain :
• The human brain is the command centre of the human
nervous system.
• The brain is one of the largest and most complex organs
in the human body.
• The brain consists of - the cerebrum, the cerebellum and
the brainstem (which is composed of the midbrain, the
pons, and the Medulla oblongata).
• The cerebrum is the largest part of the brain and is
composed of the right and left hemisphere. It contains the
cerebral cortex, as well as several subcortical structures,
including the hippocampus, basal ganglia, and olfactory
bulb. It performs higher functions like interpreting touch,
smell, vision and hearing, as well as speech, reasoning,
emotions, learning and fine control of movement.
• Cerebellum receives information from the sensory
systems, the spinal cord and other parts of the brain and
then regulate motor movement. It coordinates voluntary
movements such as postures balance, coordination and
speech, resulting in smooth and balanced muscular
activity.
• Medulla oblongata is the lower part of the brainstem
where the brain transitions to the spinal cord. It is only
about 3 cm. long but the medulla is an indispensable nerve
tract which contains the control centres for our autonomic
vital functions - heart rate, blood pressure, breathing,
vomiting, coughing, sneezing and many involuntary
reflexes.
Reflex Actions :
• When you touch a hot object or when a pin picks your
finger, what is your immediate reaction? Of course, you
remove your hand away from the source of pain, either
the hot object or the pin. In situations like these, your
reactions are always immediate, involuntary and sudden.
These happen without much thinking process. In scientifi c
terms, this action is called the reflex action. Here, the
spinal cord has a major role to play.
• The whole mechanism of reflex action occurs in such
a fashion that there is no conscious control of brain.
Stimulation occurs through the peripheral nervous system
and the response to this peripheral nerve stimulation is
involuntary. In a reflex action, the spinal cord along with
brainstem is responsible for the reflex movements.
• The two extremes in the animal kingdom are endothermic
homeotherms and ectothermic poikilotherms.
• Most mammals, including humans as well as most
birds are endothermic homeotherms – maintains a
stable internal body temperature regardless of external
influence, while most fish, invertibrates, reptiles and
amphibians are ectothermic poikilotherms–whose
internal temperature varies considerably.
• In humans, the average normal internal temperature is
98.6ºF (37ºC or 310K).

VIII. Endocrine System

Notes
Gland :
• A gland is a group of cells in an animal's body that
synthesizes substances (such as hormones) for release
into the bloodstream (endocrine gland) or into cavities
inside the body or its outer surface (exocrine gland/duct
gland).
Endocrine system :
• The endocrine system is made up of the glands that
produce and secrete hormones-chemical substances
produced in the body that regulate the activity of cells
or organs. These hormones regulate the body's growth,
metabolism (the physical and chemical processes of the
body), sexual development, reproduction, mood, and many
other functions.
Major Endocrine Glands :
• It includes the following endrocrine glands -
1. Thyroid Gland :
• The thyroid gland lies in the front of the human neck in a
position just below Adam's apple.
• It is made up of two lobes. These two lobes are joined by
a small bridge of thyroid tissue called the isthmus.
• The thyroid makes three hormones that it secretes into the
bloodstream, viz. two thyroid hormones (thyroxine - T4
and triiodothyronine - T3
) and calcitonin.
• In the cells and tissues of the body, the T4 is converted to
T3
. The T3 is biologically active and influences the activity
of all the cells and tissues of the body.
• T3 and T4 are partially composed of iodine. A deficiency
of iodine leads to decreased production of T3
and T4
.
• The thyroid hormones primarily influence the metabolic
rate and protein synthesis. These hormones also regulate
vital body functions, including - differentiation, breathing,
heart rate, body temperature, central and peripheral
nervous system etc. Calcitonin plays a role in calcium
homeostasis. It lowers the level of calcium and phosphate
in the blood and promotes the formation of bones.
• Disorders of Thyroid Hormone :
(a) Hyposecretion (Hypothyroidism) - Following disorders
occur in case of insufficient production or hyposecretion
of thyroxine hormone :
(i) Cretinism : Physical and mental growth of the child is
retarded.
(ii) Myxoedema : Myxoedema is used to describe skin
changes in someone - as swelling of the face which can
include lips, eyelids and tongue; swelling and thickening
of skin anywhere on the body, especially in lower legs.
(iii) Goitre : an abnormal enlargement of thyroid gland.
The most common cause of goitre is lack of iodine in
diet. Goitre is common in hilly area because of iodine
deficiency in water.
(iv) Hashimoto Disease : Hashimoto disease is a condition in
which the immune system attacks thyroid resulting in its
complete loss. It is also known as the suicide of thyroid
gland.
(b) Hypersecretion (Hyperthyroidism)-
(i) Thyroxine regulates the behaviour of the person. In a high
quantity of secretion, it enhances the mental activity of
a person changing his behaviour so thyroid gland is also
known as temperament gland.
(ii) The high secretion of thyroxine is related to exophthalmia
(abnormal protrusion of the eyeball or eyeballs) or
Grave’s disease and Plummer disease (also called toxic
multinodular goitre, thyroid condition characterized by
marked enlargement of the thyroid gland, firm thyroid
nodules and overproduction of thyroid hormone).
2. Parathyroid Glands :
• Parathyroid glands are four small glands located in the
neck on the dorsal side of the thyroid gland.
• The parathyroid gland is independent of the pituitary
gland.
• Parathyroid hormone parathormone (PTH) is secreted by
this gland which regulates the serum calcium in our body.
It plays an important role to provide electrical energy to
the nervous system, muscular system and provide strength
to our skeletal system.
• Hyposecretion of parathormone can lead to low levels of
calcium in the blood often causing cramping and twitching
of muscles or tetany (involuntary muscle contraction), and
the proper growth of bones, teeth and brain is inhibited.
• In case of hypersecretion, bones become fragile
(osteoporosis) and development of polyuria, polydipsia,
loss of appetite and kidney stones formation may take
place.
3. Adrenal Glands (Suprarenal Glands) :
• The adrenal glands are located above the kidneys.
• Each gland has an outer cortex and an inner medulla.
(i) Hormones secreted by adrenal cortex-
(a) Mineralocorticoids (Aldosterone) : It regulates the
quantity of sodium and chloride in ECF (extracellular
fluid) maintaining the blood pressure and osmotic
pressure.
(b) Glucocorticoids (Cortisol) : It promotes the release of
glucose, fats and Protein (amino acids) in the blood. It also
promotes the glycogenesis in the liver. It helps to maintain
blood pressure and blood glucose (sugar) levels. Cortisol
is also called 'stress hormone' as it is produced in larger
amount when we are under stress.
• Due to hyposecretion of glucocorticoids Addison's
disease–dehydration due to excess excretion of water and
sodium is caused.
• Due to hypersecretion of these hormones fat storage and
the sugar level in blood increases, which is responsible
for Cushing disease.
(c) Androgen : The adrenal cortex of both men and women
make androgen. Androgens help the organs of the
reproductive system grow, develop and function.
• Androgens also control the development of male physical
traits such as deep voice, body and facial hair growth and
body shape.
• Adrenal virilism is the development of male secondary
sexual characteristics in women as facial hair caused by
male sex hormones (androgens) excessively produced by
the adrenal gland.
(ii) Hormones secreted by adrenal medulla-
• The hormones secreted by medulla of adrenal glands are
as follows :
(a) Epinephrine/Adrenaline
(b) Norepinephrine/Noradrenaline
(a) Epinephrine/Adrenaline : It is also called the emergency
hormone and fight or flight hormone because strong
emotions such as fear or anger cause epinephrine to be
released into the bloodstream, which causes an increase
in heart rate, muscle strength, blood pressure and sugar
metabolism. It regulates such actions which are controlled
by the sympathetic nervous system.
• This hormone has an important role in medical science.
When the heart fails to function, it is injected into the heart
to start the pulse of the heart.
(b) Norepinephrine/Noradrenaline : This hormone works
with epinephrine in responding to stress.
4. Thymus Gland :
• The thymus gland located behind the sternum and between
lungs.
• The thymus gland is most active until puberty.
• After puberty, the thymus will become less and less active
and starts to slowly shrink until it is almost completely
replaced by the fat.
• It is an important part of the immune system as it plays a
major role in cell-mediated immunity.
• The thymosin and thymopoietin hormones are secreted
by the thymus gland which stimulate the development
and maturation of disease-fighting T-cells, which are
derivatives of white blood cells.
5. Pineal Gland (Biological clock) :
• The pineal gland, or conarium is the smallest endocrine
gland which is found in the brain of most vertebrates. It
is located in the epithalamus, near the centre of the brain.
Pineal gland size is about 7.5 mm in length and it is cone
shaped.
• Named for its pine cone shape, this gland secretes
melatonin hormone which plays a crucial role in the
internal clock of our body.
• The pineal gland is key to the body's internal clock because
it regulates the body's circadian rhythm. Circadian
rhythm is the daily rhythm of the body, including signals
that make someone feel tired, sleep, wake up, and feel
alert around the same time each day.
• Melatonin is produced according to the amount of light
a person is exposed to. The pineal gland releases greater
amounts of melatonin when it is dark, which points to
melatonin's role in sleep.
• The pineal gland also appears to exert an important role
in the neuroendocrine regulation of human reproductive
physiology. It is involved in the control of sexual
maturation.
6. Pituitary Gland :
• The Pituitary gland is one of the smallest endocrine gland
in human. It is about the size of a pea (about 10 mm
diameter) and weighing about 0.5 grams in human. It is
located in the anterior brain. It is also called MasterGland
because it directs other organs and endocrine glands to
either suppress or induce hormone production.
• It secretes-
(i) Somatotropin (STH or Growth Hormone-GH) : It
controls the general growth of the body. Its hypersecretion
leads to acromegaly in adults and gigantism in children.
Its hyposecretion leads to dwarfness in children.
Gonadotropin (GtH) : It stimulates the primary sex
organs i.e. ovaries and testes. GtH includes follicle
stimulating hormone (FSH) and luteinizing hormone (LH).
• Follicle Stimulating Hormone (FSH) : It is secreted
in male and female both. In males, it stimulates
spermatogenesis and development of seminiferous
tubules. In females, it stimulates the formation and growth
of ovarian follicle and producing estrogen in the ovary.
• Luteinizing Hormone (LH) : This hormone stimulates
testosterone production in men and egg release (ovulation)
in women. Final maturation of ovarian follicle and
ovulation takes place by LH only.
(iii) Lactogenic Hormone (Prolactin) : This hormone
stimulates breast milk production after childbirth. High
prolactin can affect menstrual periods, sexual function
and fertility.
(iv) Thyroid Stimulating Hormone (TSH) : It aids in the
regulation of thyroid secretion.
(v) Adrenocorticotropic Hormone (ACTH) : It stimulates
the secretion of cortisol (stress hormone) from the cortex
of adrenal glands.
(vi) Metabolic Hormone : This hormone influences
metabolism of carbohydrates, fats and proteins.
(vii) Vasopressin or Antidiuretic Hormone (ADH) : It
regulates reabsorption of water from the kidney tubules
and maintain water balance in the body and sodium levels
in the blood. Its hypoactivity leads to diabetes insipidus
in which patients excrete a large amount of urine. Its
hyperactivity leads to decrease in amount of urine.
(viii) Melanocyte Stimulating Hormone (MSH) : It regulates
the number of melanin pigments in skin cells. Melanin
is a pigment found in skin cells which is responsible for
skin colour.
(ix) Oxytocin or Pitocin : It is also called binding hormone,
love hormone, birth hormone etc. It regulates smooth
muscle contraction, especially of the uterus during
childbirth. It also helps in the secretion of milk in females.
It creates a bonding emotion between mother and child,
hence known as binding or love hormone.
• The milkman injects the artificial oxytocin to domestic
animals to draw much milk from them. This act is harmful
to both domestic animals as well as the person who uses
such milk. It may be carcinogenic.
7. Pancreas :
• It is an exocrine as well as an endocrine gland i.e. mixed
gland.
• As an endocrine gland, it functions mostly to regulate
blood sugar levels, secreting the hormones insulin,
glucagon, somatostatin and pancreatic polypeptide.
• As a part of the digestive system, it functions as an
exocrine gland secreting pancreatic juice into the
duodenum through the pancreatic duct.
• Its endocrine part is known as islets of Langerhans.
• Its three types of cells secrete 3 different hormones :
(a) Beta (β) cells : Beta cells secrete insulin (a protein) which
controls the amount of sugar in the blood.Its hyposecretion
leads to diabetes mellitus.
• Diabetes mellitus is of two types :
(i) Type I - People with type I diabetes do not produce insulin.
It may be heritable.
(ii) Type II - People with type II diabetes, do not respond to
insulin as they should and later in the disease often do not
make enough insulin. This type of diabetes is common in
fat persons.
• Both types of diabetes can lead to chronically high
blood sugar levels. That increases the risk of diabetes
complications.
• The symptoms of diabetes are – frequent urination, feeling
very thirsty and drinking a lot, feeling very hungry, feeling
very fatigue, blurry vision and cuts or sores that do not
heal properly.
(b) Alfa (α) cells :Alfa cells secrete glucagon which converts
glycogen into glucose.
(c) Delta (δ) cells : Delta cells secrete somatostatin which
regulates the assimilation process. It acts as an inhibitor
of growth hormone (GH), insulin and glucagon.
Organs which act as endocrine glands :
1. Gonads :
• The gonads, the primary reproductive organs, are the
testes in male and ovaries in female. These organs are
responsible for producing the sperm and ovum, but they
also secrete hormones and are considered to be endocrine
glands.
(i) Testes :
• The testes produce androgens which allow for the
development of secondary sexual characters and the
production of sperm cells.
• Androgen hormones are secreted mainly by Leydig cells.
Leydig cells, also known as interstitial cells of Leydig, are
found adjacent to the seminiferous tubules in the testicle.

• The hyposecretion of androgen leads to undeveloped sex

organ and sperm formation is badly affected. In case of
high shortage of this hormone the reproductive capacity
of the male is lost and become sterile.
• The hypersecretion leads to prior maturity of the male in
respect of reproduction before the fixed period.
• The major androgen in male is testosterone.
Dihydrotestosterone and androstenedione are of equal
importance in male development.
Note : Ovaries in women and adrenal gland in both men and
women also produce androgen but at much lower level
than the testes.
(ii) Ovaries :
• In human two ovaries are found in abdomen cavity in
females which produce female hormones.
• The female hormones estrogen, progesterone and relaxin
contribute to the development and function of the female
reproductive organs and sex characteristics.
• Estrogen : At the onset of puberty, estrogen promotes -
• The development of the breast.
• Distribution of fat evidenced in the hip, legs and breast.
• Maturation of reproductive organs such as the uterus and
vagina.
• The related hormones in the estrogen family include :
estrone, estradiol, estriol.
• Menopause is the normal natural transition in life that
begins between the age of 40-50 years. During this ovaries
get smaller and stop producing the hormones estrogen and
progesterone that control the menstrual cycle. Eventually,
females are no longer able to become pregnant.
• Progesterone : Progesterone is a hormone produced by the
corpus luteum of the ovaries. It involved in the menstrual
cycle, pregnancy and embryogenesis. Progesterone is
essential to achieve and maintain a healthy pregnancy.
• In the second half of the menstrual cycle after ovulation,
progesterone prepares the uterine lining (endometrium)
to receive the fertilized egg (zygote).
• If implantation is successful and pregnancy occurs,
progesterone continues to support the uterine lining
providing the ideal environment for the growth of the
embryo.
• Pregnancy is dependent on the ovary for progesterone
production for the first 10 weeks of pregnancy, after
that the placenta is fully capable of making enough
progesterone for pregnancy support.
• If pregnancy does not occur, then progesterone levels fall
bringing on menstrual bleeding.
• Relaxin : Relaxin is a hormone produced by the ovary and
placenta with important effects in the female reproductive
system and during pregnancy. In preparation for childbirth,
it relaxes the ligaments in the pelvis and softens and
widens the cervix.
2. Placenta :
• The placenta is a temporary organ that connects the
developing fetus via the umbilical cord to the uterine
wall to allow nutrient uptake, thermo-regulation, waste
elimination, and gas exchange via the mother's blood
supply; to fight against internal infection; and to produce
hormones which support pregnancy.
• Following hormones are secreted by the placenta–
(i) Estrogen : It is a crucial hormone in the process of
proliferation. This involves the enlargement of the breasts
and uterus, allowing for growth of the fetus and production
of breast milk.
(ii) Progesterone and Relaxin
(iii) Placental Lactogen : It is a hormone used in pregnancy
to develop fetal metabolism and general growth and
development.
(iv) Chorionic Gonadotropic Hormone : It is a proteinous
hormone which maintains the pregnancy and prevents
luteal regression. It is the First hormone released by the
placenta.
• Pregnancy test : The chorionic gonadotropic hormone is
secreted in large quantity which is excreted through the
urine. After a test of urine, the presence of this hormone
in urine indicates the pregnancy.
3. Kidney :
• Following hormones are secreted by the kidney -
(i) Renin : It is secreted by the pericytes (mural cells) in the
kidney. It increases heartbeat and ultrafiltration in kidney
to enhance the reabsorption of water and Na+
. It regulates
angiotensin and aldosterone levels and maintains body’s
mean arterial blood pressure.
(ii) Erythropoietin : It stimulates the formation of red blood
cells in the bone marrow.
(iii) Calcitriol : It is the activated form of vitamin D, which
promotes intestinal absorption of calcium and the renal
reabsorption of phosphate.
4. Mucous glands of Alimentary Canal :
• The mucous glands of stomach and intestine secrete some
hormones with mucous. These are as follows-
a . Hormones secreted by stomach-
(i) Gastrin : It promotes the secretion of gastric juice.
(ii) Enterogastrone : It inhibits the secretion of gastric juice.
(iii) Ghrelin : When the stomach is empty, ghrelin is secreted.
It acts on hypothalamic brain cells both to increase hunger,
and to increase gastric acid secretion and gastrointestinal
motility to prepare the body for food intake.
b . Hormones secreted by intestine-
(i) Hepatocrinin : Stimulates liver to secrete bile juice.
(ii) Secretin : Stimulates pancreas to secrete pancreatic juice.
(iii) Pancreozymin : Stimulates to the secretion of pancreatic
juice thus increasing the high concentration of enzymes.
(iv) Cholecystokinin : It stimulates the contraction of the gall
bladder to pass the bile juice in duodenum. It is responsible
for stimulating the digestion of fat and protein.
(v) Enterocrinin : It stimulates the wall of the intestine to
secrete the intestinal enzymes.
5. Skin :
• Some cells of our skin act as endocrine gland responsible
for the secretion of ergocalciferol and cholecalciferol
hormones. These hormones stimulate the absorption of
calcium and phosphorus and help in bone formation. Its
hyposecretion leads rickets in children and osteomalacia
in adults.
• Hormones are designated as messengers and regulators.
• Ernest Henry Starling introduced the word Hormone
in 1905.
Pheromones
• Pheromones are chemical substances which are
secreted by exocrine glands to the outside by an
individual and received by a second individual of the
same species.
• Pheromones are also known as ectohormones.
• Example of pheromone is the secretion of bombykal
or gyplur by female silkworm which attracts the male
silkworm for mating.
• The social insects as bees, ants, mites also secrete
pheromones which help them to accumulate at a
particular place.

Reproduction and
Embryo Development
Notes
Reproduction :
• Reproduction is the biological process by which new
individual organisms - ‘offspring’ - are produced from
their parents.
• Reproduction is a fundamental feature of all known
life ; each individual organism exists as the result of
reproduction.
• There are two forms of reproduction : asexual and sexual.
• In asexual reproduction, an organism can reproduce
without the involvement of another organism.
• By asexual reproduction, an organism creates a genetically
similar or identical copy of itself.
• Asexual reproduction is not limited to single-celled
organisms. The cloning of an organism is a form of asexual
reproduction.
• Sexual reproduction typically requires the sexual
interaction of two specialized organisms, called gametes,
which contains half the number of chromosomes of
normal cells and are formed by meiosis, with typically a
male fertilizing a female of the same species to create a
fertilized zygote.
• This produces offspring organisms whose genetic
characteristics are derived from those of the two parental
organisms.
Human Reproduction :
• Reproduction in human beings is by sexual reproduction
where both the male and female gametes fertilize to give
rise to an embryo.
• In human, fertilization (fusion of male gamete-sperms
with female gamete - ovum) occurs inside the body of
female i.e. in the oviduct or fallopian tube hence this
fertilization is known as internal fertilization.
• Human beings are viviparous. It means that they give
birth to a child.
Male reproductive organs :
• Testes : The testes are the primary organs of male
reproduction. They are situated in a bag of skin known
scrotum. It lies outside the abdomen cavity.
• Testes are responsible for producing the male gamete
known as sperm by a process called as spermatogenesis.
This takes place in seminiferous tubules of the testes.
Leydig cells of these testes synthesize testosterone. The
hormone testosterone not only helps in the formation of
the sperm but also in the development of secondary sexual
characters in males such as deepening of the voice and
development of facial and pubic hair during puberty.
• Sperm Duct : These are thin ducts that arise from the
testes.
• Prostate Gland : This gland is an accessory exocrine
gland. It pours its secretions into the sperm duct along
with the seminal fluid from the testes and into the penis.
• Urethra : It functions as a common pathway for the
seminal fluid and urine in males. It is longer in males than
females.
• Penis : It is an external intromittent organ that functions
to discharge both urine and semen.
Female reproductive organs :
• The female reproductive organs in human are entirely
within the abdominal cavity. It comprises of the following
structures :
• Ovaries : They give rise to the female gamete or the egg.
Each ovary releases one egg (ovum) alternatively each
month. Ovulation is the process of release of an egg from
either one of the ovaries.
• Fallopian tubes : It is also known as the oviducts. These
tubes arise from the ovaries and end at the uterine fundus.
Their function is to pick up the egg and usually fertilization
takes place in it.
• Uterus : It is a large muscular organ. It is the region of
the development of the fetus.
• Cervix : It is a cylindrical muscle ring that is present
towards the lower end of the uterus that dilates at the time
of delivery of the baby.
• Vagina : It is a muscular tube-like structure that is present
at the lower end of the cervix and leads towards the outside
of the female body. The vagina functions as the pathway
for the penis to enter the female body and deposit the
sperms.
• Urethra : In females, urethra serves only for the passage
of urine.
Fertilization and Embryo Development :
• The egg is formed under the influence of both female
sex hormones estrogen and progesterone. This process is
known as Oogenesis.
• The fertilization capacity of sperm is about 48 hours to 72
hours while egg’s capacity is about 12 hours to 24 hours
after ovulation.
• Both the egg and sperm fertilize in oviduct and form the
diploid zygote which contains 23-23 chromosomes from
each parent.
• After fertilization, zona pellucida from the egg forms a
thick layer around the zygote to prevent more than one
sperm to fertilize the egg.
• Zygote now turns into a morula and then into a blastocyst.
It then develops chorionic villi from the outer layer of the
blastocyst known as the chorion.
• These villi attach themselves to the inner wall of the uterus.
Implantation is the process of attachment of the embryo
to the uterine wall. The tissue between the growing embryo
and the mother's uterine wall form the placenta.
• Placenta functions to provide nutrition to the embryo until
its birth.
• The hormones estrogen and progesterone both help in
maintaining the placenta and the fetus inside the uterus.
• The normal gestation period for human is about 38 weeks
which is a little over 9 months.
• At the end of this term, the uterine contractions begins
under the influence of oxytocin hormone. It affects the
cervix and causes it to dilate to allow the baby to pass
outside the body of the mother.
• The umbilical cord with its blood vessel and the placenta
are also expelled along with the baby.
• Prenatal stages and development include germinal,
embryonic and fetal period.
• The first two weeks of development is the germinal
period, which begins with conception and ends when the
blastocyst is fully implanted into uterine tissue.
• Embryonic period of prenatal development lasts from
implantation until about 8 weeks from the time of
conception (or the 10th week of pregnancy). This is the
most important time of prenatal development because the
embryo is developing the foundations for a healthy baby.
• Three germ layers are formed in this period – The outer
layer is called the ectoderm, the middle layer is called the
mesoderm and inner layer is called the endoderm.
• Each germ layer is differentiated into different structures.
The ectoderm forms many outer tissues such as skin, hair,
nervous system tissues including brain. The mesoderm
forms tissues inside the body such as lungs, bones and
muscles including the heart. The endoderm forms tissues
such as the digestive tract and bladder as well as other
internal organs.
Fetal period : Once cell differentiation is mostly complete,
the embryo enters the fetal period and becomes known
as a fetus. This period of development begins during the
ninth week and lasts until birth. In this period the formed
organs are mature and growth takes place.
The heart of fetus starts to beat in 4th-5th
week of its development.
• Amnion : The amnion is a membrane that closely covers
the embryo when it first formed. It is filled with amniotic
fluid, which causes the amnion to expand and become
the amniotic sac, which serves to provide a protective
environment for the developing embryo or fetus.
• The amnion along with chorion, the yolk sac and the
allantois form a protective sac around the embryo.
• Chorion regulate, the gaseous exchange while;
• Allantois helps the embryo exchange gases and handle
the liquid waste.
Plant Physiology
I. Photosynthesis
Notes
• The process of photosynthesis is one of the most
remarkable activities of green plants.
• The autotrophic plants synthesize enormous amounts of
organic food with the help of the light energy available
from the sun.
• Carbohydrates produced through photosynthesis constitute
the basic raw materials, which directly or indirectly give
rise to all the organic components of virtually all plants
and animals.
• The entire humanity depends upon the prepared food of
plants.
• It is one of the most massive biochemical event going on
the earth.
• Most plants, most algae, and cyanobacteria perform
photosynthesis; such organisms are called photoautotrophs.
• Approximately 90% of the world's photosynthesis is
carried out by marine and freshwater algae.
• Photosynthesis is the process of synthesis of carbohydrate
from carbon dioxide and water in presence of sunlight and
chlorophyll.
• In photosynthesis, the solar energy is converted into
chemical energy which is stored in form of carbohydrates.
• Photosynthesis is also known as carbon assimilation
because inorganic carbon dioxide is converted into organic
components.
• The biochemical reaction of photosynthesis can be shown
as follows–
• During photosynthesis, oxygen is evolved by splitting of
a water molecule.
• The photosynthesis takes place in the green parts of
the plant body such as leaves, green stems and in green
floral parts etc. In leaves the photosynthesis takes place
in the mesophyll tissues which contain the green plastid-
chloroplast.
• Seaweeds (Algae) are also capable to synthesize food by
photosynthesis in the moonlight.
• It may take place in bulb light.
• The photosynthesis takes place in the chloroplast. The
chlorophylls are present in the grana of the chloroplast.
Magnesium is the main component (element) of
chlorophyll.
• Light is one of the most important factors of photosynthesis.
• Chlorophyll molecules absorb only red, blue and violet
in the visible spectrum. Wavelength of 655 nm in the
redlight to be the most effective and 440 nm in the
bluelight to be the second most effective wavelength in
photosynthesis. Although chlorophyll absorbs more blue
light than red light, the maximum rate of photosynthesis
has been observed in red light.
• Plants have been found to photosynthesize at very low
light intensities but at a much slower rate. The rate of
photosynthesis increases with the increase in the light
intensity until some other factors become limiting.
• Extremely high light intensities do not increase the rate
of photosynthesis partly because the other factors become
limiting and partly because of direct inhibitory effect on
the process, a phenomenon called solarization. During
solarization, photo-oxidation takes place, in which certain
cell constituents are oxidized by oxygen into CO2
. If
photo-oxidation continues for more than a few hours, the
whole photosynthetic apparatus is destroyed.
• Light also affects the rate of photosynthesis indirectly.
The very low intensity of light causes stomatal closure,
which restricts the entry of CO2 gas resulting in a decrease
of photosynthesis.
• High light intensity on the other hand increases the rate of
transpiration and consequently reduces the water content
of the mesophyll tissues. This has an inhibitory effect on
the rate of photosynthesis.
• Duration of the light period has also a significant effect on
the total photosynthetic yield of a plant. Aplant carries on
much photosynthesis if it is given light for 10 to 12 hours
per day.
• The carbon dioxide, oxygen, temperature and water also
affect the rate of photosynthesis.
• Photosynthesis occurs in a very wide range of temperatures.
Certain conifers can photosynthesize at as low temperature
as –35o
C while some algae photosynthe size at about
75o
C. In temperate regions, photosynthesis has a rapid
rate between 10o
C to 35o
C, provided other factors are not
limiting.
Process of Photosynthesis :
• Photosynthesis is a chemical oxidation-reduction (redox)
reaction, in which water is oxidized to release oxygen and
carbon dioxide is reduced to form the glucose.
• Process of photosynthesis is completed in two phases

(a) Light-dependent phase/Photochemical oxidation of

water/Light reactions/Hill reaction :
• These reactions takes place in grana of the chloroplast.
• In the light-dependent reactions, one molecule of the
pigment chlorophyll absorbs one photon and loses one
electron.
• This electron is passed to a modified form of chlorophyll
called pheophytin, which passes the electron to a quinone
molecule, starting the flow of electron down an electron
transport chain that leads to the ultimate reduction of
NADP to NADPH.
• In addition, this create a proton gradient (energy gradient)
across the chloroplast membrane, which is used by ATP
synthase (an enzyme) in the synthesis of ATP (adenosine
triphosphate) from ADP (adenosine diphosphate) and
inorganic phosphate (Pi
). ATP is the ‘energy currency’
of cells for all organisms.
• The chlorophyll molecule ultimately regains the electron
it lost when a water molecule is split in a process called
photolysis (a chemical reaction in which a chemical
compound is broken down by photons), which releases a
oxygen molecule (O2
).
• The overall equation for the light-dependent reactions is :
2H2
O + 2NADP+
+ 3ADP + 3Pi
+ light
→ 2NADPH + 2H+
+ 3ATP + O2
(b) Light-independent phase / Chemical dark reactions /
Non-photochemical reduction of CO2 / Blackmann's
reaction -
• The dark reactions occur in stroma of the chloroplast.
• It does not require the light, hence the name dark reaction.
Dark reaction is such a chemical reaction that converts
carbon dioxide and other compounds into glucose.
• Calvin cycle or Calvin-Benson-Bassham (CBB) cycle
is the set of biochemical redox reactions that take place
in chloroplast during light-independent phase. The key
enzyme of the cycle is called RubisCO.
• The enzyme RubisCO captures CO2 from the atmosphere
and, through Calvin cycle, it uses the newly formed
NADPH and releases three-carbon sugars, which is then
converted into the final carbohydrate products. This
process is also called carbon fixation.
• The overall equation for the light-independent reaction is :
3CO2
+ 9ATP + 6NADPH + 6H+
→ C3
H6
O3 -phosphate + 9ADP + 8Pi + 6NADP+
+ 3H2
O
• C-3 Plants : Plants in which the carbon fixation occurs by
Calvin cycle. This process converts carbon dioxide and
ribulose-1,5-bisphosphate into 3-phosphoglycerate.
• C-4 Plants (Hatch Slack Cycle) : The plants in which
during photosynthesis the first formed organic compound
is oxaloacetic acid (with 4 carbon atoms). These plants
are better photosynthesizer. It is found in monocots as
sugarcane, maize and cyperus.
• C-2 Plants/CAM Plant : CAM (Crassulacean Acid
Metabolism) occurs in certain succulent plants like
cactus and opuntia. CAM plants have to keep their
stomata shut during the day to avoid transpiration. The
metabolism is, therefore, devised in such a way that
they can photosynthesize during the day with the help of
CO2 released from organic acids. The organic acids are
synthesized in plenty during the night with the help of
CO2 released in respiration and the CO2 available from
the atmosphere through the open stomata. This is why
the succulents have open stomata and plenty of organic
acid during the night and closed stomata and plenty of
carbohydrates during the day.
Bacterial photosynthesis :
• Certain bacteria are also capable of photosynthesizing like
green plants.
• The only difference in bacterial photosynthesis is that
substances other than water act as hydrogen 'donor' and
consequently liberation of oxygen does not take place in
the process.
• Green SulphurBacteria : Have a pigment bacteriochloro-
phyll similar to chlorophyll. These bacteria grow in
hydrogen sulphide medium which acts as a source of
hydrogen.

II. Plant Nutrition

• Every organism is an open system linked to its environment
by a continuous exchange of energy and materials.
• In ecosystems, plants and other photosynthetic autotrophs
perform the crucial step of transforming inorganic
compounds into organic ones.
• Plants need sunlight as the energy source for photosynthesis.
• They also need inorganic raw materials such as water,
carbon dioxide (CO2
) and inorganic ions to synthesize
organic molecules.
• Plants obtain CO2 from the air. CO2 diffuses into leaves
from the surrounding air through stomata.
• Most vascular plants obtain water and minerals from the
soil through their roots.
• Plants require nine macronutrients and at least eight
micronutrients to sustain their life.
• Elements required by plants in relatively large quantities
are called macronutrients.
• There are nine macronutrients in all, including the six
major ingredients in organic compounds : carbon, oxygen,
hydrogen, nitrogen, sulphur and phosphorous. The
other three macronutrients are potassium, calcium and
magnesium.
• Elements required by plants in very small amounts are
called micronutrients.
• The eight micronutrients are iron, chlorine, copper, zinc,
manganese, molybdenum, boron and nickel.
• Most of these function as cofactors, non-protein helpers
in enzymatic reactions.
Macronutrients :
(i) Carbon (C)- Carbon forms the backbone of the most plant
biomolecules, including proteins, starches and cellulose.
• Carbon is fixed through photosynthesis; this converts CO2
from the air into carbohydrates, which are used to store
and transport energy within the plant.
(ii) Hydrogen (H)- Hydrogen is necessary for building sugars,
proteins, fats and other compounds in plant. It is obtained
almost entirely from water.
• Hydrogen ions are imperative for a proton gradient to help
drive the electron transport chain in photosynthesis and
for respiration.
(iii) Oxygen (O)- Oxygen is a component of many organic
and inorganic molecules within the plant, and is acquired
in many forms as O2 and CO2 (mainly from the air via
leaves) and H2
O, NO3
–
, H2
PO4
– & SO4
2– (mainly from soil
water via roots).
• Plants produce oxygen gas along with glucose during
photosynthesis and require O2 in aerobic respiration.
(iv) Nitrogen (N)- Nitrogen compounds comprise 40% to 50%
of the dry matter of protoplasm. It is a constituent of amino
acids (units of proteins), chlorophyll, some vitamins and
nucleic acids (DNA & RNA).
• Nitrogen deficiency often results in stunted growth, slow
growth, and chlorosis.
• The nitrogen is taken up by plants from the soil in form
of NO3
– (Nitrate ion), although in acid environments such
as boreal forests, where nitrification is less likely to occur,
ammonium ion NH4
+ is the dominating source of nitrogen.
(v) Phosphorus (P)- It is the structural component of nucleic
acids as well as constituents of fatty phospholipids that are
important in membrane development and function. It is a
part of the ATP which is the source of energy for all cells.
• Phosphorus is most commonly found in the soil in the
form of polyprotic phosphoric acid (H3
PO4
) but is taken
up most readily in the form of H2
PO4
–
.
• Plants can increase phosphorus uptake by a mutualism
with mycorrhiza. A phosphorous deficiency in plants is
characterized by an intense green coloration or reddening
in leaves due to lack of chlorophyll.
• Phosphorus deficiency can produce symptoms similar
to those of nitrogen deficiency but it differs in being
extremely difficult to diagnose.
(vi) Potassium (K)- Potassium regulates the opening and
closing of stomata by a potassium ion pump.
• Potassium deficiency may cause necrosis or interveinal
chlorosis. It may also result in higher risk of pathogens,
wilting, brown spotting and higher chances of damage
from frost and heat.
(vii) Sulphur (S)- Sulphur is a structural component of some
amino acids (including cysteine and methionine) and
vitamins.
• It is essential for chloroplast growth and functions.
• It is found in the iron-sulphur complex of the electron
transport chains in photosynthesis.
• It is needed for N2
fixation by legumes.
• Symptoms of deficiency include yellowing of leaves and
stunted growth.
(viii) Calcium (Ca)- Calcium regulates transport of other
nutrients into the plant and is also involved in the
activation of certain plant enzymes. It also involved in
photosynthesis and plant structure.
• Calcium deficiency results in stunting. Blossom end rot
is also a result of inadequate calcium.
(ix) Magnesium (Mg)- The outstanding role of magnesium
in plant nutrition is as a constituent of the chlorophyll
molecule.
• As a carrier it is also involved in numerous enzyme
reactions as an effective activator, in which it is closely
associated with energy-supplying phosphorus compounds.
Micronutrients (Trace elements) :
(i) Iron (Fe)- Iron is necessary for photosynthesis and is
present as an enzyme cofactor in plants.
• Iron is not a structural part of chlorophyll but very much
essential for its synthesis. It helps in the electron transport
of plant.
• Iron deficiency can result in interveinal chlorosis and
necrosis.
(ii) Molybdenum (Mo)- Molybdenum is a cofactor to
enzymes important in building amino acids and is involved
in nitrogen metabolism.
• It is part of the nitrate reductase enzyme (needed for the
reduction of nitrate) and the nitrogenase enzyme (required
for biological nitrogen fixation).
(iii) Boron (B)- Boron has many functions within a plant; it
affects flowering and fruiting, pollen germination, cell
division and active salt absorption.
• The metabolism of amino acids (proteins), carbohydrates,
calcium, and water are strongly affected by boron.
• Boron is essential for the proper forming and strengthening
of cell walls.
• Lack of boron results in short thick cells producing stunted
fruiting bodies and roots. Its lack also causes failure of
calcium metabolism which produces hollow heart in beets
and peanuts.
(iv) Copper (Cu)- Copper is important for photosynthesis.
Symptoms for copper deficiency include chlorosis.
• It is involved in many enzyme processes; involved in the
manufacture of lignin (cell walls) and involved in grain
production.
(v) Manganese (Mn)- Manganese is necessary for
photosynthesis, including the building of chloroplast.
• Manganese deficiency may result in coloration
abnormalities such as discolored spots on the leaves.
(vi) Zinc (Zn)- Zinc is required in a large number of enzymes
and plays an essential role in DNA transcription.
• Atypical symptom of zinc deficiency is the stunted growth
of leaves, commonly known as ‘little leaf’and is caused by
the oxidative degradation of the growth hormone auxin.
• Khaira disease of rice plant (Paddy plant) is due to the
deficiency of zinc.
(vii) Nickel (Ni)- In higher (vascular) plants, nickel is absorbed
by plants in the form of Ni2+.
• Nickel is essential for activation of urease, an enzyme
involved with nitrogen metabolism that is required
to process urea. Without nickel, toxic levels of urea
accumulate, leading to the formation of necrotic lesions.
• In lower (non-vascular) plants, nickel activates several
enzymes involved in a variety of processes.
(viii) Chlorine (Cl)- Chlorine as compounded chloride, is
necessary for osmosis and ionic balance. It also plays a
role in photosynthesis.
Vascular System :
• The separation between plants that have veins and plants
that do not is one of the great division within the plant
kingdom.
• This separates plants into vascular (higher) and non-
vascular (lower) plants.
• Most plants have xylem & phloem and are known as
vascular plants but some more simple plants such as algae
and mosses (bryophyta), do not have xylem or phloem and
are known as non-vascular plants.
• Xylem : Xylem tissue is also known as water-conducting
tissue.
• Xylem is for transporting water and minerals absorbed by
the roots.
• Xylem is made up of tracheids, vessels, wood parenchyma
and wood fibres cells.
• Phloem : Phloem is responsible for transporting food from
leaves (photosynthesis site) to non-photosynthesizing parts
of a plant such as roots and stems.
• Phloem is also known as bast tissue.
• It is made up of sieve elements, companion cells, fibres,
bast fibres (sclereids) and phloem parenchyma cells.
Amarbel (Cuscuta) :
• Amarbel is an angiospermic total stem Parasite.
• It grows over host plants with inter-twined stems, giving
it a common name of Devils' hair.
• The plant is leafless and rootless.
• The twining stem develops haustoria which are rootlike
and penetrate the host stem to draw water and nourishment.

III. Plant Hormones

Notes
• The plant hormones(also known as phytohormones) are
such organic substances which are formed in one tissue
or organ of the plants and are then transported to other
sites where they produce specifi c effects on growth and
development.
• Plant hormones are single molecules, produced within
plants, that occur in extremely low concentrations. Unlike
in animals (in which hormone production is restricted to
specialized glands), each plant cell is capable of producing
hormones.
• The plant hormones are either growth promoter or
growth inhibitor.
1. Growth Promoters :
• These plant hormones promotes the growth of plants.
Under this category three hormones have been placed-
(i) Auxins
(ii) Gibberellins
(iii) Cytokinins
(i) Auxins :
• Auxins are one of the most important groups of plant
hormones because of their many-sided role in plants.
These substances were also the first growth factors
identified as plant hormones.
• The chief natural auxin is indole-3-acetic acid (IAA-
C10H9
O2
N). It is the most common auxin found in plants.
• Other naturally occuring auxins are indole-3-acetaldehyde,
indole-3-pyruvic acid, indole-3-acetonitrile, indole-3-
ethanol.
• In addition to these auxins, certain synthetic chemicals
compounds have been found to act as auxins. These are-
• Indole-3-butyric acid
• 1-Naphthaleneacetic acid–NAA
• Phenylacetic acid
• 2, 4-D (dichlorophenoxyacetic acid)
• 2, 4, 5-T (Trichlorophenoxyacetic acid)
Functions of Auxins :
• The primary physiological effect of auxin on the growth
of a plant is by its effect on the prolongation of cells in
shoot.
• Auxins control the tropic movements as phototropism
and geotropism in plants.
• Auxins enhance the apical growth and retard the growth
of axillary buds.
• Auxins promote the differentiation of tissues and plant
organs; for example-root development in grafting by
applying auxins (root initiation).
• Auxins are used to produce parthenocarpic fruits (seedless
fruits).
• Auxins retard the abscission of fruits and leaves.
• 2-4D and 2,4,5-T are used as weedicides (to eradicate
weeds).
• Auxins retard the growth of buds. On applying auxins in
cold storage potato is stored for a long duration.
(ii) Gibberellins :
• The history of the discovery of gibberellins dates back to
the 19th century when the Japanese farmer noticed that
certain diseased rice plants grew abnormally thin and
tall. They called it ‘Bakaene’ or foolish seedling disease
because it made the young rice plants grow ridiculously
tall. Infection by a fungus – Gibberella fujikuroi was
responsible for the disease.
• Aplant hormone secreted by the above-mentioned fungus
was responsible for the foolish seedling disease, which
was given the name gibberellin.
• It was later discovered that gibberellins are also produced
by the plants themselves and they control multiple aspects
of development across the life cycle.
Functions of gibberellins :
• The gibberellins have been shown to be effective in
protecting the apical meristem from the inhibitory effect
of the endogenous growth inhibitors such as dormin.
• Gibberellins promote shoot growth mainly by accelerating
the roles of cell elongation and cell division in the sub-
apical meristem region where young internodes are
developing. Lang (1960) demarcated marked increased
in gibberellin level at the time of bolting when a rosette
growth form (dwarf) starts growing in a longitudinal
direction.
• Gibberellins do not affect the growth of roots.
• Other functions of gibberellins are flowering, germination
of seeds, parthenocarpy, breaking dormancy, cell division
in cambial zone, change in shape and size of leaves and
activity of enzymes.
• It is used as the spraying agent to increase sugarcane yield
by lengthing of the stem.
(iii) Cytokinins :
• Cytokinins are such organic substances which promote
the cytokinesis during cell division.
• The kinetin and zeatin act as cytokinins.
• Coconut milk has cytokinin.
• Cytokinins control cell division, morphogenesis,
counteraction of apical meristem, breaking the dormancy,
delay of senescence (chlorophyll disappearance and
protein degradation).
• They are used to keep flowers fresh for a longer time.
Growth Inhibitors :
• These hormones inhibit the growth of plants. Under this
category, two hormones are placed –
(i) Abscisic acid
(ii) Ethylene
(i) Abscisic acid (ABA) :
• The physiological roles of ABA are as follows :
• Regulation of dormancy of buds and seeds.
• Acceleration of senescence of leaves.
• Inhibits plant growth, metabolism and germination of
seeds.
• Inhibits gibberellin-stimulated growth. Hence it is also
known as anti-gibberellin.
• Inhibits gibberellin induced α-amylase formation in barley
aleurone.
• Promotes ageing and abscission of leaves.
• It is widely used as a spraying agent on trees to regulate
dropping of fruits.
(ii) Ethylene (CH2
= CH2
):
• Ethylene is a gaseous plant hormone.
• Ethylene is produced in minute quantity by plant tissues
but is active at extremely low concentrations.
• It is synthesized in plant from the methionine, an essential
amino acid produced in the chloroplast.
• Ethylene has several effects on the vegetative and
reproductive growth of plants. It is used as both plant
growth promoter and plant growth inhibitor.
• The effect of ethylene are as follows :
• Enhances respiration rate through the ripening of fruits.
This phenomenon is called as 'respiratory climacteric'.
• Induction of epinasty.
• Inhibition of elongation growth in stems and roots.
• Stimulation of cells to grow isodiametrically rather than
longitudinally thus enhancing radial growth rather than
elongation growth in stems and roots.
• Induction of root hair formation.
• Promotion of leaf and flower abscission and senescence.
• It is applied to rubber trees to stimulate the flow of latex.

IV. Plant Reproduction

Notes
• Plant reproduction is the production of new offspring in
plants, which can be accomplished by asexual or sexual
reproduction. Asexual reproduction produces new
individuals without the fusion of gametes, genetically
identical to the parent plants and each other, except when
mutations occur. Sexual reproduction produces offspring
by the fusion of gametes, resulting in offspring genetically
different from the parent or parents.
Asexual Reproduction in Plants :
• Plants have two main types of asexual reproduction
in which new plants are produced that are genetically
identical clones of the parents. Vegetative propagation,
which involves a vegetative piece of original plant
(budding, tillering, etc.) and apomixis, which is a
replacement for sexual reproduction. Seeds generated by
apomixis are a means of asexual reproduction, involving
the formation and dispersal of seeds that do not originate
from the fertilization of the embryos.
• Apomixis is the mechanism of seeds production without
involving the process of meiosis and syngamy.
It plays an important role in hybrid seeds production. The
method of producing hybrid seeds by cultivation is very
expensive for farmers. Also, by sowing hybrid seeds, it
is difficult to maintain hybrid characters segregate during
meiosis. Apomixis prevents the loss of specific characters
in the hybrid. It is cost effective method for producing
hybrid seeds.
• In case of apomixis, no meiotic division and fertilization
of gametes to form a zygote takes place. The entire process
is cut short and seeds formation occurs. It can be of two
types–
(1) Sporophytic–In this type apomixis occurs from the diploid
sporophyte.
(2) Gametophytic–In this type, apomixis occurs from the
haploid gametophyte.
• Since the apomixis involves the formation of seeds without
syngamy, all the seeds are genetically similar.
Stem Cutting -
• A Plant Cutting is a piece of a plant that is used in
horticulture for vegetative propagation. A piece of stem
of the plant is placed in a suitable medium such as moist
soil. If the conditions are suitable, the plant piece will
begin to grow as a new plant, independent of the parent.
This technique is adopted in sugarcane.
Vegetative Propagation by Layering–
• The stem that is attached to their parent plant is capable of
forming roots on coming in contact with a rooting medium.
• A layer is a rooted stem following detachment from the
parent plant. Many plants like strawberry, raspberry and
jasmine are propagated by natural layering method.
Grafting-
• Grafting is a horticulture technique whereby tissues of
plants are joined so as to continue their growth together.
The upper part of the combined plant is called the scion
while the lower part is called the root-stock.
• The success of this joining requires that the vascular tissue
grow together and such joining is called inosculation. This
technique is most commonly used in asexual propagation
of commercially grown plants for the horticultural and
agricultural trades.
Sexual Reproduction in Plants :
• Sexual reproduction in plants involves two fundamental
processes : meiosis, which rearrange the genes and reduces
the number of chromosomes, and fertilization, which
restores the chromosomes to a complete diploid number.
• Flowers are the sexual organs of the plant and help in
sexual reproduction.
Parts of flowers :
• Bisexual flowers typically contain male and female parts
in it.
• There are four main layers of the parts of the flower-
• Calyx : It is a collection of sepals forming the first circle of
the flower. These are typically green coloured. In some cases,
the sepals have a colour called petaloid. Their main function
is to protect the flower while it is still in the bud stage.
• Corolla : This layer is the collection of petals. It is the
second circle of the flower, superior to the calyx. The
petals are the colourful part of a flower that helps to attract
insects and birds to the flower to facilitate pollination.
• Androecium : It is the third layer of flower superior to
the corolla. It is the male part of the sexual reproduction
of a plant. The androecium is made up of a collection of
stamens. Each stamen has the following parts–
(i) Anther : It is present at the tip of the filament. It is
internally lobed. Pollen grains are formed inside the anther.
(ii) Filament : It is a thin stalk-like structure that holds
the anther.
• Gynoecium : It is the fourth layer of flowers. It is
a collection of carpels and considered the female
reproductive part of the plant. It has three parts–
(i) Stigma : It is a small and sticky landing structure. The
pollen grains from the same or different flower stick to
it. This structure acts as a landing for the insects or birds
that act as a pollinating agent.
(ii) Style : It is a thin stalk-like structure that holds the stigma.
Two or more carpels may be fused together to varying
degrees and the entire structure, including the fused styles
and stigmas may be called a pistil.
(iii) Ovary : It is a base of the style or the lower part of the
pistil and contains the ovules, which contain the female
gamete.
Pollination and Fertilization :
• The transfer of pollen grains from the anther of one flower
to the stigma of the same or another flowers is known as
pollination. It can be caused by insects, birds, wind, water,
and animals including human. These are together called
as pollinating agent.
Types of Pollination :
• Self-Pollination : Self-pollination is when the pollen of
one flower transfers to the stigma of the same flower or
other flowers of the same plant. Many flowers that are
hermaphrodite (bisexual) see this kind of pollination.
Many flowers have various mechanism to prevent self-
pollination or promote cross-pollination because the seeds
formed as a result of self-pollination are not of genetic
variation and healthy.
• Cross-Pollination : Cross-pollination is when the pollen
of one flower transfers to the stigma of flowers of another
plant. This type of pollination brings about genetic
variation in the species and allow the plant to withstand
changes in the environment better.
• Once the pollen has landed on the stigma of a flower, the
pollen tubes develop to transfer the pollen to the ovules
which contain the female gamete.
Dichogamy :
• The ripening of stamens and pistils of a flower at different
times, so that self-fertilization is prevented, known as
dichogamy.
• It is of two types–
(a) Protandry–Stamens mature before ovary.
(b) Protogyny– Ovary matures prior to stamens.
• Megasporogenesis results in the formation of female
gametes and microsporogenesis results in the formation
of male gametes.
Microsporogenesis :
• The anthers contain the pollen mother cell (2n-diploid)
that undergoes meiosis to form microspores.
• Tetrad is the result of the microspore mother cell dividing
and formation of 4 microspores.
• The anther releases the microspores/pollen grains when
it is mature.
Megasporogenesis :
• Megasporoangium are the ovules. They are in the ovary
and contain the female gametes. Megasporogenesis is
the formation of megaspores from megaspore mother
cell (diploid). The resultant of the meiosis of megaspore
mother cell is 4 haploid megaspore cells. Of the four cells
that form, only one is functional while other degenerate.
Double Fertilization :
• It happens in angiosperms (flowering plants). This is
because the male gamete that enters the ovule has two
nuclei, one of the male gametes fuses with the female
gamete to form a diploid zygote, whereas the other
one forms a triploid (3n) endosperm by fusing with the
diploid polar nuclei. The zygote divides to form future
plant whereas the endosperm provides nutrition to the
developing embryo. After fertilization ovary becomes
fruits and ovules become the seeds.

Plants : Economic Importance

Notes
• The primary necessities of man are threefolds–food,
clothing and shelter.
• The most essential need of man is food.
• The food primarily comes from the cereals (e.g. rice,
wheat, maize, oat, barley), millets (e.g. sorghum, pearl
millet), pulses, vegetables and fruits. For clothing plants
are indispensable.
• The plants that yield fibres are second only to food plants.
Besides above, coal, fuels, medicines and other useful
substances are obtained from the plants.
Sunflower oil :
• It is the non-volatile oil which is obtained by crushing
the seeds of sunflower (Helianthus annuus-Family-
Asteraceae).
• Nutritionally, it is better than many other cooking
mediums. It can be safely used by heart patients.
• Sunflower oil does not raise the cholesterol level in blood.
High cholesterol is bad for heart.
• Sunflower oil contains proteins and vitamin A, D and E.
• The oil is easily digested.
• Being of semi-drying and stable type, sunflower oil is also
used in making paint, varnish, and soap.
Essential Oils :
• The essential oils also known as volatile oils evaporates
in contact with the air and possesses a pleasant fragrance.
• Chemically the essential oils are very complex.
• They are found in many different species of plants of
various families.
• Some essential oil yielding plants are as follows :
1. Chandan (Sandalwood) : It is a tree, a native of the
highlands of South India and the Malayan Archipelago.
The major demand for sandalwood oil is from the
perfumery trade. It is also used medicinally.
2. CamphorOil :The camphor oil is obtained from the wood
and leaves of camphor tree (Cinnamomum camphora-
Family-Lauraceae). Camphor oil is mainly used in the
manufacture of celluloid and various nitrocellulose
compounds. They are widely used in the preparation of
medicines and perfumes.
3. Mint Oil : Mint oil is obtained from the leaves by
distillation process of Mentha arvensis. Mint oil is the
main source of menthol. It is used in the treatment of colds.

Indian Gooseberry–Amla (Phyllanthus emblica) :

• A common tree with edible fruits. The fruits are used in
diarrhoea and dysentery. The bark, leaves and fruits are
used in dyeing and tanning. The wood yields excellent
charcoal. The pickle or jam is prepared from the fruits.
The fruit is very rich in vitamin C.
• Highyield varieties of Amla are Kanchan, Krishna,
Chakaiya, BSR1, Banarsi, NA7 etc.
Mango (Mangifera indica) :
• Mango is the most popular and the choicest fruits of India
and occupies a prominent place among the best fruits of
the world.
• The mango fruit is one of the most widely cultivated fruits
in the tropics. It has a rich, luscious, aromatic flavour
and a delicious taste in which sweetness and acidity are
delightfully blended. Young and unripe fruits are used in
pickles, chutney, amchur etc.
• The unripe fruit has citric, malic, oxalic and succinic acids.
Ripe fruits constitute a rich source of vitamin A. The fruit
is also a rich source of potassium.
Banana (Musa paradisiaca) :
• The fruits have a high content of carbohydrates with some
proteins and fats. Their food value is three times that of
wheat.
Guava (Psidium guajava) :
• The fruits are edible. It is aromatic, sweet, juicy and highly
flavoured. It contains acid, sugar, and pectin.
• It is one of the richest sources of vitamins A, B and C. It
is commonly used for making jellies, jams and paste.
Apple (Malus domestica) :
• Apples are valued mainly as dessert fruits. Apples are rich
in pectin and are useful in diarrhoea. Apple juice, syrups
and vinegar reduce curd tension of milk used in infant
feeding.
• Apple murabba is regarded as a stimulant for the heart, it
is reported to relieve physical heaviness and mental strain.
• The vitamins, salts and organic acids are concentrated
particularly in and just below the skin and the fruit should
be eaten unpeeled. Apple is considered a good source of
potassium.
• The mineral constituents of apple are Ca, Mg, K, Na, P,
Cl, S, and Fe.
Grapes (Vitis vinifera) :
• Grape is a delicious, refreshing and nourishing fruit. It is
classed as a protective food, is easily digestible and has
large quantities of sugar, minerals like calcium, iron and
vitamin B.
• Grapes are also used in the preparation of wines.
Citrus Fruits :
• Citrus fruits contain considerable amounts of essential
vitamin C and some other fruit acids. The fruits are used
in the preparation of juices, squashes and other canned
products.
• Citrus fruit intake is associated with a reduced risk of
stomach cancer. Lemons have the highest concentration
of citrate of any citrus fruit, and daily consumption of
lemonade has been shown to decrease the rate of kidney
stone formation.
Neem (Azadirachta indica) :
• Neem is also known as village pharmacy. The components
extracted from the neem plant have been used in traditional
medicines for the cure of multiple diseases including cancer
for centuries. The extract of seeds, leaves, flowers, and
fruits of neem have consistently shown chemopreventive
and anti-tumor effects in different types of cancer.
• Azadirachtin and nimbolide are among the few bioactive
components of neem. Nimbolide is a terpenoid lactone
derived from neem tree that displays a variety of biological
activities including anti-malarial and anti-cancer activity.
Azadirachtin has a role as a hepatoprotective agent and it
is also the active ingredient in many pesticides.
• Neem is used as fungicides and insecticides to control the
fungal infection and insects in plant protection.
• Neem is a natural mosquito repellent which is 100%
effective. Camphor is also used as a natural mosquito
repellent.
Biodiesel :
• Biofuels made from plants could one day help us to reduce
our dependency on fossil fuel.
• Ratanjot (Jatropha curcas), Karanja (Pongamia pinnata)
and Neem (Azadirachta indica) are having great potential
as a future oil source for biodiesel that does not compete
with food. In biodiesel hydrocarbons and lipids are present
in abundant amount.
• The first biodiesel plant of our country has been established
at Kakinada (A.P.).
• Biofuel Ethanol is derived mainly from the sugarcane and
maize.
Chilgoza pine (Pinus geradiana) :
• Pinus seed is called chilgoza.
• Chilgoza is rich with carbohydrates and protein.
Tulsi (Ocimum tenuiflorum) :
• Tulsi/Holy Basil is an aromatic perennial plant.
• Tulsi has been used for thousands of years in Ayurveda
for its diverse healing properties. It has many medicinal
properties. The leaves strengthen the stomach and help in
respiratory diseases. It reduces kidney stone formation.

Haldi/Turmeric (Curcuma longa) :

• Turmeric has been used for thousands of years not only
for cooking but also as a medicine due to its incredible
healing properties.
• Turmeric has powerful anti-inflammatory properties and
can help to improve symptoms of arthritis and joint pains.
• Turmeric is also useful in dementia and Alzheimer’s
disease. It is antioxidant and lowers cholesterol.
• It slows the spread of breast cancer.
• Turmeric powder used as a mouthwash in improving oral
health.
Lemon :
• The fruit of lemon’s health benefits are as follows :
(a) It promotes hydration.
(b) It is a good source of vitamin C.
(c) It supports weight loss.
(d) Enhance the immune system of the body.
(e) It aids in digestion.
(f) It helps to prevent kidney stone formation.
Brahmi/Waterhyssop (Bacopa monnieri) :
• Waterhyssop or herb of grace is a perennial creeping herb
used in Ayurveda where it is also known as Brahmi.
• In Ayurveda, it is believed to sharpen the brain by
protecting cells and increasing chemicals associated with
learning and memory.
• It is used to treat Alzheimer’s disease, anxiety and ADHD
(Attention Deficit Hyperactivity Disorder-difficult for a
person to pay attention and control impulsive behaviour)
along with fighting stress and improving memory.
Pudina/Mint :
• Mint is a calming and soothing herb that has been used
for thousands of years to aid with upset stomach or
indigestion.
• It is thought to increase bile secretion and encourage bile
flow, which helps to speed and ease digestion (and which
may also support healthy cholesterol level).
Sadabahar or Vinca rosea (Cantharanthus roseus) :
• It is an evergreen shrub that works as an ornamental plant
and for medicinal purposes. The smooth, glossy, and dark
green colour leaves along with flowers are said to act as a
natural medicine for type-2 diabetes.
Beverages :
• Tea (Camellia sinensis) : Tea is the most important non-
alcoholic beverage; it is a safe and helpful stimulant. The
main chemical ingredient of tea is caffeine (an alkaloid),
which make a person feel refreshed.
• Coffee : Coffee is a brewed drink prepared from the roasted
coffee beans. Its main chemical ingredients are caffeine,
tannin, diterpenes, chlorogenic acid and melanoidins,
which may affect human health.
• Cocoa : Cocoa is the dried and fully fermented seeds of
Theobroma cacao, from which cocoa solids (a mixture of
non-fat substances) and cocoa butter (the fat) is extracted.
Cocoa beans are the basis of chocolate and used as a
beverage.
• Kasni (Chicory-Chichorium intybus): It is a woody,
perennial herbaceous plant, usually with bright blue
flowers. The chicory coffee is a beverage made using the
roots of the chicory plant.
Other important facts :
• The main source of iodine is the seaweeds (Algae).
• Vanilla is a flavouring substance derived from orchids.
• The main organic acids of tomato are citric acid and malic
acid. Oxalic acid is also found in little amount.
• The flour of kuttu is obtained from the seeds of Fagopyrum
esculentum which is enriched with carbohydrate and
protein.
• Peppermint is obtained from the leaves of Mentha
piperita. Peppermint oil has a high concentration of
natural pesticides. Its leaves and oil have a cooling effect
when used topically for muscle pain, nerve pain and relief
from itching.
• Quinine is a medicine which is used to cure malaria. It
is derived from the bark of cinchona tree which belongs
to the family Rubiaceae. This plant is evergreen shrub or
tree.
• Arteether is a potent antimalaria drug derived from
artemisinin, a sesquiterpene lactone isolated from
Artemisia annua. This medicine is used in severe malarial
condition when other medicine are uneffective to control
malaria.
• Chloroquine, primaquine, atovaquone are some other
medicines used to treat malaria.
• Cotton is a soft, fl uffy staple fibre that grows in a boll,
or protective case, around the seeds of the cotton plants
(Gossypium Malvaceae). Chemical composition of
cotton is as follows – Cellulose - 91%, Water - 7.85%,
Protoplasm 0.55%; Fats - 0.40%, and Minerals - 0.20%.
• Opium is the dried latex obtained from the opium poppy
(Papaver somniferum). Approximately 12% of the opium
latex is made up of the analgesic alkaloid morphine,
which is processed chemically to produce heroin and other
synthetic opioids for medicinal use and for illegal drug
trade. The latex also contains the closely related opiates
codeine and thebaine, and non-analgesic alkaloids such
as papaverine and noscapine. The morphine is obtained
from the unriped fruits of the plant.

Diseases and Treatment

I. Viral Diseases
Notes
x Word ‘VIRUS’is originated from the Latin neuter ‘virus’
which means ‘venomous substance’.
x The virus is an ultramicroscopic (20-300 nm in diameter),
metabolically inert, infectious agent that replicates only
within the cells of living hosts, mainly bacteria, plants and
animals; composed of an RNAor DNAcore, a protein coat
and in more complex type, a surrounding envelope.
x The protein coat is known as capsid and its subunit is
known as capsomere.
x Most viruses have either RNA or DNA as their genetic
material, which may be single or double-stranded.
x The entire infectious virus particle is called virion. Virus
is the nucleoprotein particle where as virion is the active,
infectious form of the virus.
x It was discovered by Russian scientist Dmitri Ivanovsky
in 1892. He found that a disease of tobacco plants could
be transmitted by an agent, later called tobacco mosaic
virus, passing through a minute filter that would not allow
the passage of bacteria.
x In 1898, Martinus Beijerinck independently replicated
Ivanovsky’s filtration experiments and then showed that
the infectious agent was able to reproduce and multiply
in the host cells of the tobacco plant. He coined the term
‘virus’.
x Tobacco mosaic virus was the first virus to be crystallized.
It was achieved by Wendel Meredith Stanley in 1935 who
also showed that TMV remains active after crystallization.
x The virus is a link between non-livings and livings. Viruses
are non-livings when they are outside the host cell as they do
not have any cellular machinery of their own. But when they
are present inside the body of the host, they are living. They
take over the host cell machinery to replicate themselves,
eventually destroying the host cell.
x The river Ganga is self-cleansing and has healing powers,
indeed its water has bacteriophages, who infect and kill
bacteria.
x Phage Therapy is the use of bacteriophages to treat
pathological infections caused by bacteria.
x The branch of biology which deals with the study of the
virus is called virology.
x In 1977, India was declared to be free from smallpox.
Guinea Worm Disease (GWD) :
x Guinea worm disease (Dracunculiasis) was an important
public health problem in many states of India before it
was eradicated in 2000.
x It is a parasitic infection by the Guinea worm. It is caused
by a large nematode, Dracunculus medinensis, which
passes its life cycle in two hosts - Man and Cyclops (water
fleas).
x A person becomes infected when they drink water that
contains water fleas (Cyclops) infected with guinea worm
larvae. Initially, there are no symptoms. About one year
later, the female worm forms a painful blister in the skin,
usually on the lower limb.
Polio :
x It is also called poliomyelitis.
x It is an infectious disease caused by the poliovirus.
x Poliovirus is usually spread from person to person through
infected fecal matter entering the mouth. It may also be
spread by food or water containing human feces and less
commonly from infected saliva.
x Those who are infected may spread the disease for upto
six weeks even if no symptoms are present.
x It may affect the spinal cord causing muscle weakness and
paralysis because poliovirus destroys the cells of the brain
and spinal cord-controlling the functions of muscles.
x The first polio vaccine was developed by Jonas Salk in
1952 and came into use in 1955.
x The oral polio vaccine was developed by Albert Sabin
and came into commercial use in 1961.
x They are on the World Health Organization’s List of
Essential Medicines, the most effective and safe medicines
needed in a health system.
x Trivalent Oral Polio Vaccine was used against for all three
types of poliovirus (Type 01, Type 02 and Type 03).
x The World Health Organization (WHO) presented the
official certification to India for its ‘Polio Free’status on
27March, 2014.
x In September, 2015 WHO declared that poliovirus type
2 has been eradicated from the earth- no cases caused by
this serotype had been detected since November, 1999.
For this reason WHO decided to remove the type 2 PV
and switch from trivalent to bivalent vaccine in April,
2016.
Rhinovirus :
x The Rhinovirus (from Greek rhinos ‘of the nose’ and the
Latin ‘virus’) is the most common viral infectious agent in
humans and is the predominant cause of the common cold.
x Rhinovirus infection proliferates in temperatures of 33-
35ºC (91-95ºF), the temperatures found in the nose.
x The three species of rhinovirus (A, B and C) include
around 160 recognized types of human rhinoviruses that
differ according to their surface proteins (serotypes).
x Its symptoms include sore throat, runny nose, nasal
congestion, sneezing and cough, fatigue, headache etc.
Hepatitis-B :
x Hepatitis-B is an infectious disease caused by the
hepatitis-B virus (HBV) that affects the liver.
x It can cause both acute and chronic infections. It can cause
scarring of the organ, liver cirrhosis and cancer.
x It spreads when people come in contact with the blood,
open sores, or body fluids of someone who has the
hepatitis-B virus. Infection around the time of birth or form
contact with other people’s blood during childhood is the
most frequent method by which hepatitis-B is acquired.
x Hepatitis-B symptoms include jaundice, fever, fatigue that
persists for weeks or months, stomach trouble like loss of
appetite, nausea and vomiting and belly pain.
Mumps :
x Mumps is a contagious disease caused by a virus (mumps
virus) that passes from one person to another through
saliva, nasal secretions, and close personal contact.
x The condition primarily affects the salivary glands, also
called the parotid gland.
x The hallmark symptom of mumps is swelling of the
salivary glands. Initial signs and symptoms often include
fever, muscle pain, headache, poor appetite, and feeling
generally unwell.
Symptoms are often more severe in adults than in children.
Complications may include meningitis, pancreatitis,
permanent deafness and testicular inflammation, which
uncommonly results in infertility.
Rabies (Hydrophobia) :
x Rabies lyssavirus, formerly rabies virus, is a neurotropic
virus that causes rabies in humans and animals.
x Rabies transmission can occur through the saliva of
animals like dog, cat, bat and wild animals like fox, etc.
It is spread when an infected animal scratches or bites
another animal or human.
x Early symptoms can include fever and tingling at the
site of exposure. These symtoms are followed by one or
more of the following symptoms : violent movements,
uncontrolled excitement, fear of water, confusion, and
loss of consciousness. Once symptoms appear, the result
is nearly always death.
Herpes Disease :
x It is a viral infectious disease. It is caused by the herpes
simplex virus.
x It causes sores around the mouth and lips and genital
organs.
Meningitis :
x Meningitis is an inflammation of the meninges. The
meninges are the three membranes that cover the brain and
spinal cord. Meningitis can occur when fluid surrounding
the meninges becomes infected.
x The most common symptoms are fever, headache and neck
stiffness. Other symptoms include confusion or altered
consciousness, vomiting and an inability to tolerate light
or loud noises.
x Meningitis may be caused by infection with viruses,
bacteria, or other microorganisms. Meningitis caused
by meningococcal bacteria may be accompanied by a
characteristic rash.
Dengue Fever :
x Dengue fever is transmitted by the bite of an Aedes
mosquito (mainly A. aegypti) infected with a dengue
virus.Tiger mosquito (Aedes albopictus) can also serve
as a vector for this virus.
x Symptoms typically begin three to fourteen days after
infection.
x This may include a high fever, headache, vomiting, muscle
and joint pains and a characteristic skin rash.
x It is also known as breakbone fever.
x Dengue fever affects the number of platelets in the blood.
Dengue virus, the main cause of dengue fever induces
bone marrow suppression. Since bone marrow is the
manufacturing centre of blood cells its suppression causes
deficiency of blood cells leading to low platelet count.
Chikungunya :
x It is a viral disease transmitted to humans by chikungunya
virus (CHIKV) infected mosquitos Aedes albopictus (the
Tiger mosquito) and Aedes aegypti.
x It causes fever and severe joint pain. Other symptoms
include muscle pain, headache, nausea, fatigue and rash.
x It is not a contagious disease because an infected man
cannot spread the infection directly to other persons.
Zika Fever :
x It is a viral infectious disease caused by the Zika Virus.
x Symptoms may include fever, red eyes, joint pain,
headache and maculopapular rash.
x Zika virus is transmitted to humans primarily through the
bite of infected Aedes aegypti and Aedes albopictus.
x It can also be sexually transmitted and potentially spread
by blood transfusions. Infections in pregnant women can
spread to the baby.
Yellow Fever :
x Yellow fever is an acute viral haemorrhagic disease
transmitted by yellow fever virus infected mosquito (mainly
Aedes aegypti). Tiger mosquito (Aedes albopicturs) can
also serve as a vector for this virus.
x Symptoms of yellow fever include fever, headache,
jaundice, muscle pain, nausea, vomiting and fatigue.
x Yellow fever is prevented by an extremely effective
vaccine, which is safe and affordable.
Japanese Encephalitis (JE) :
x Japanese Encephalitis (JE) is an infection of the brain
caused by the Japanese encephalitis virus (JEV).
x While most infections result in little or no symptoms,
occasional inflammation of the brain occurs. In these
cases, symptoms may include headache, vomiting, fever,
confusion and seizures.
x There is no specific treatment or cure for JE. Once a person
has the disease, treatment can only relieve the symptoms.
Prevention and care are the best form of treatment of JE.
x JE is a mosquito-borne viral infection. The species of
Culex mosquitoes are the main vector of JE.
Acquired Human Immunodeficiency Syndrome (AIDS) :
x AIDS is a spectrum of conditions caused by infection with
the human immunodeficiency virus (HIV). It is a fatal
disease.
x The virus responsible for AIDS belongs to the retro group
of viruses.
x It destroys the immune system, the body’s defence against
infections, leaving an individual vulnerable to a variety of
other infections and certain malignancies that eventually
cause death.
x HIV is not spread by coughing, sneezing or casual contact
(e.g. shaking hands).
x HIV is fragile and cannot survive long outside the body,
therefore a direct transfer of bodily fluids is required for
transmission as - unsafe sexual contact, contaminated
blood transfusion and to a child from infected mother with
the contact of the placenta.
x Western blot and ELISA (enzyme-linked immunosorbent
assay) tests are used to detect the AIDS. Western Blot is
used to confirm a positive ELISA and the combined tests
are 99.9% accurate.
x World AIDS Day - designated on 1 Dec. every year
since 1988, is an international Day dedicated to raising
awareness of the AIDS pandemic caused by the spread of
HIV infection and mourning those who have died of the
disease.
Ebola Virus Disease :
x Ebola virus disease (Ebola haemorrhagic fever) is a rare
and deadly disease in people and non-human primates.
x The disease was first identified in 1976 in two simultaneous
outbreaks : one in Nzara (South Sudan) and the other in
Yambuku (DR Congo), a village near the Ebola river
from which the disease takes its name.
x The virus that causes EVD are located mainly in, Sub-
Saharan Africa. People can get EVD virus through direct
contact with an animal (bat and non-human primates) or
a sick or dead person infected with Ebola virus
x It causes fever, body aches and diarrhoea and sometimes
bleeding inside and outside the body. As the virus spreads
through the body, it damages the immune system and
organs ultimately and this leads to severe uncontrollable
bleeding. The disease has a high risk of death, killing
between 25 to 90 percent of those infected.
x The largest Ebola outbreak to date was the epidemic in
West Africa (Dec. 2013 - Jan. 2016) with 28,646 cases
and 11,323 deaths.
Nipah Virus Infection :
x A Nipah virus infection is a viral infection caused by the
Nipah virus (Ni V). In May 2018, an outbreak of this
disease resulted in 17 deaths in Kerala (India).
x In September 2021, Nipah virus resurfaced in Kerala,
claiming the life of a 12 year old boy.
x This disease was first identified in Malaysia in 1998, and
it is named after a village in Malaysia, Sungai Nipah.
x Symptoms from infection vary from none to fever, cough,
headache, shortness of breath, and confusion. This may
worsen into a coma over a day or two.
x Complications can include inflammation of the brain and
seizures following recovery.
x The Nipah virus (NiV) is a type of RNAvirus. It normally
circulates among specific types of fruit bats.
x Its management involves supportive care. There is no
vaccine or specific treatment till date. Prevention is by
avoiding exposure to bats and sick pigs and not drinking
raw date palm sap (palm toddy).
x Endemic - (of a disease or condition) regularly found
among particular people or in a certain area.
x Epidemic - The rapid spread of a particular disease to
a large number of people in a given population within
a short period of time.
x Pandemic - (of an infectious disease) that has spread
across a large region, for instance whole country,
multiple continents or worldwide, affecting a substantial
number of people.
II. Bacterial Diseases
Notes
x Bacteria are single-celled, prokaryotic microorganisms.
x They are cosmopolitan. They can thrive in a diverse
environment. They can live within the soil, in the ocean
and inside the human gut.
x The human relationship with bacteria is complex.
Sometimes they lend a helping hand, such as by curdling
milk into yogurt or helping with our digestion. In other
cases, they are destructive, causing diseases.
x The pathogenic bacteria are capable to infect all the
systems of the human.

Botulism :
x Botulism poisoning is a rare but serious illness caused by
a toxin that attacks the body’s nerves and causes difficulty
in breathing, muscle paralysis and even death.
x This toxin is produced by the bacteria Clostridium
botulinum and sometimes C. butyricum and C. baratli.
x These bacteria can be spread by food and sometimes by
other means.
x The concerned bacteria are gram-positive bacteria.
DPT & BCG Vaccines :
x DPT vaccine conveys immunity to three different
infectious bacterial diseases. They are -
i. Diptheria
ii. Pertussis
iii. Tetanus
x Bacillus Calmette-Guerin (BCG) is a vaccine primarily
used against tuberculosis (TB)
Salmonella bacilli is responsible for food poisoning. It
is a gram-negative, flagellated facultatively anaerobic
bacilli. Flagella are found around it. Salmonella infection
(salmonellosis) affects the intestinal tract. Generally, it is
transmitted by means of contaminated water and food.
Botulism :
x Botulism poisoning is a rare but serious illness caused by
a toxin that attacks the body’s nerves and causes difficulty
in breathing, muscle paralysis and even death.
x This toxin is produced by the bacteria Clostridium
botulinum and sometimes C. butyricum and C. baratli.
x These bacteria can be spread by food and sometimes by
other means.
x The concerned bacteria are gram-positive bacteria.
DPT & BCG Vaccines :
x DPT vaccine conveys immunity to three different
infectious bacterial diseases. They are -
i. Diptheria
ii. Pertussis
iii. Tetanus
x Bacillus Calmette-Guerin (BCG) is a vaccine primarily
used against tuberculosis (TB).
Sulpha Drugs :
x Sulpha drugs are used to cure the diseases caused by
bacteria.
x Prontosil is the first sulpha drug to be discovered. The
discovery was made by the great German physician and
chemist Gerhard Domagk (1895-1964).
Sulpha drug, also called sulphonamide, is any member
of a group of synthetic antibiotics containing the
sulphanilamide molecular structure. Sulpha drugs were
the first chemical substances systematically used to treat
and prevent bacterial infections in humans.
Broad-spectrum antibiotic :
x The term broad-spectrum antibiotic can refer to an
antibiotic that acts on the two major bacterial groups,
gram-positive and gram-negative, or any antibiotic that
acts against a wide range disease-causing bacteria.
x These medications are used when a bacterial infection is
suspected but the group of bacteria is unknown or when
infection with multiple groups of bacteria is suspected.
This is in contrast to a narrow-spectrum antibiotic,
which is effective against only a specific group of bacteria.
x Ampicillin is the commonly used broad-spectrum
antibiotic.
Chloramphenicol :
x It is also known as chloronitromycin. It is a broad-spectrum
antibiotic.
x It is useful for the treatment of a number of bacterial
infections. This includes use as an eye ointment to treat
conjunctivitis.
x By mouth or by injection into a vein, it is used to treat
meningitis, plague, cholera, and typhoid fever.
III. Fungal Diseases
x The Fungi are a separate kingdom of living things.
x Afungus (plural fungi) is a kind of living organisms; yeast,
moulds (molds) and mushrooms are types of fungi.
x Fungi have cells with nuclei (eukaryotic organisms).
x Fungus cell wall contains chitin unlike the cell wall of
plants, which contain cellulose.
x Most fungi grow as tubular filaments called hyphae. An
interwoven mass of hyphae is called a mycelium. The
walls of hyphae are often strengthened with chitin, a
polymer of N-acetylglucosamine.
x The study of fungi is called Mycology.
x All fungi are heterotrophs either parasitic or saprotrophs.
x Fungi have a close relation to humans. Several species of
fungi are useful and harmful to humans.
x Some main fungal infections have been described as
below :
Aflatoxins :
x Aflatoxins are a family of toxins produced by certain fungi
that are found on agricultural crops such as maize, peanuts,
cotton seeds and tree nuts.
x The main fungi that produce aflatoxins are Aspergillus
flavus and Aspergillus parasiticus, which are abundant
in warm and humid regions of the world.
x Aflatoxin-producing fungi can contaminate crops in the
field, at harvest, and during storage.
x Aflatoxin is a natural carcinogen which is associated with
an increased risk of liver cancer.
x Aflatoxin causes DNA damage and with prolonged
exposure to aflatoxin, cells accumulate DNA mutations
and thus are at increased risk of developing into cancer
cells.
Aspergillosis :
x Aspergillosis is the name given to a wide variety of
diseases caused by infection by fungi of the genus
Aspergillus.
x Aspergillosis occurs in humans, birds and other animals.
x The majority of the cases occur in people with an
underlying illness such as tuberculosis or chronic
obstructive pulmonary disease.
Ergotism :
x Ergotism is the effect of long-term ergot poisoning,
traditionally due to the ingestion of the alkaloids produced
by the Claviceps purpurea fungus that infects rye and
other cereals and more recently by the action of a number
of ergoline based drugs.
x It is also known as ergotoxicosis, ergot poisoning and
Saint Anthony’s Fire.
x Toxins affect the nervous, vascular (vasoconstriction and
resultant gangrene), and endocrine system.
x Clinical signs include decreased food intake and growth,
necrosis of beak, comb and toes, distorted feather
development and enteritis.
x Ergotism primarily affects leghorns and other laying
breeds and only trace amounts remain in their meat.
Athlete’s Foot :
x Athlete’s foot (Tinea pedis) is a fungal infection that
usually begins between the toes. It affects the uper layer
of the skin of the foot.
x It commonly occurs in people whose feet have become
very sweaty while confined with tightfitting shoes.
x Signs and symptoms of athlete’s foot include a scaly rash
that usually causes itching, cracking, stinging and burning.
x Athlete’s foot is contagious and can be spread via
contaminated floors, towels or clothing.
x The fungal infection is called athlete’s foot because it is
commonly seen in athletes.
x Athlete’s foot is caused by the fungus Trichophyton,
Epidermophyton and Microsporum.
Mucormycosis :
x Mucormycosis (previously called zygomycosis) is a
serious but rare fungal infection caused by a group of
molds called mucormycetes. These molds live throughout
the environment.
x Mucormycosis mainly affects people who have health
problems or take medicines that lower the body’s ability
to fight germs and sickness.
x It is also known as black fungus.
x Symptoms depend on where in the body the infection
occurs. It most commonly infects the nose, sinuses, eye,
and brain resulting in a runny nose, one-sided facial
swelling and pain, headache, fever, blurred vision, bulging
or displacement of the eye (proptosis), and tissue death.
x Other forms of disease may infect the lungs, stomach and
intestines, and skin.
Dermatitis, baldness, candidiasis, geotrichosis are the
fungal borne diseases.
Amanita is a toxic mushroom. The genus is responsible
for approximately 95% of the fatalities resulting from
mushroom poisoning. The most potent toxin present in
Amanita mushroom is α amantin.

Other Parasitic Diseases

Notes
x Besides virus, bacteria and fungus some members of
phylum-protozoa, platyhelminthes and nematoda are
responsible for different diseases.
x Some parasites like Toxoplasma gondii and Plasmodium
spp. can cause disease directly, but other organisms can
cause disease by the toxins that they produce.
x The most important parasitic diseases are as follows-
Malaria :
x Malaria is a life-threatening disease. It is typically
transmitted through the bite of female Anopheles
mosquito. Infected mosquitoes carry the Plasmodium
parasite. When this mosquito bites, the parasite is released
into the bloodstream. The primary host of Plasmodium is
a man and the secondary host is female Anopheles.
x Once the parasites are inside the body, they travel to the
liver, where they mature. After several days, the mature
parasite enters the bloodstream and begin to infect red
blood corpuscles (RBCs).
x Within 48 to 72 hours, the parasites inside the red blood
corpuscles multiply, causing the infected cells to burst
open.
x The parasites continue to infect red blood cells, resulting
in symptoms that occur in cycles that last two to three
days at a time.
x Malaria is typically found in tropical and subtropical
climates where the parasites can live.
x There are four kinds of malaria parasites that can infect
humans : Plasmodium vivax, P. ovale, P. malariae and
P. falciparum (unicelled protozoan).
x P. falciparum causes a more severe form of the disease
(malignant malaria) and those who contract this form of
malaria have a higher risk of death.
x An infected mother can also pass the disease to her baby
at birth. This is known as congenital malaria.
x Malaria is transmitted by blood, so it can also be
transmitted through-
(1) An organ transplant
(2) A transfusion
(3) Use of shared needles or syringes
x The symptoms of malaria typically develop within 10
days to 4 weeks following the infection. In some cases,
symptoms may not develop for several months. Some
malarial parasites can enter the body but will be dormant
for long periods of time.
x Common symptoms of malaria include shaking chills that
can range from moderate to severe, high fever, profuse
sweating, headache, nausea, vomiting etc.
x Malaria can cause a number of life-threatening
complications. The following may occur :
(1) Swelling of the blood vessels of the brain or cerebral
malaria.
(2) An accumulation of fluid in the lungs that causes breathing
problems or pulmonary oedema.
(3) Organ failure of the kidney, liver or spleen.
(4) Anaemia due to the destruction of RBCs.
(5) Low blood sugar.
x Ronald Ross was a British Medical doctor who received
the Nobel Prize for Physiology or Medicine in 1902 for
his work on the transmission of malaria. His discovery
of the malarial parasite in the gastro-intestinal tract of
mosquito in 1897 proved that malaria was transmitted
by mosquitoes, and laid the foundation for the method of
combating the disease.
x Malaria can be prevented by avoiding mosquito bites by
using mosquito repellants (Pyrethrum) and nets.
x Quinine is a medication used to treat malaria. It was first
isolated in 1820 from the bark of cinchona tree.
x Some antimalarial drugs as chloroquine, amodiaquin,
atovaquone, proguanil, sulphonamides, mefloquine,
primaquine are also used to cure malaria.
x Use of antimalarial drugs to prevent the development
of malaria is known as chemoprophylaxis. These drugs
should be used regularly in malaria affected regions.
x To eradicate the Anopheles mosquito, pesticides such as
DDT should be used.
x Mosquito larvae eating fish Gambusia affinis is used to
control the population of mosquito.
x The ducks are also helpful in eradicating the larvae of
mosquito.
x World Malaria Day is an international observance
commemorated every year on 25 April and recognizes
global efforts to control malaria.
Kala-azar (Visceral leishmaniasis) :
x Kala-azar is a disease caused by a protozoan parasite of
the genus Leishmania. It is a chronic and potentially fatal
disease chiefly of tropical areas.
x The parasite primarily infects the reticuloendothelial
system and may be found in abundance in bone marrow,
spleen and liver.
x The signs and symptoms of kala-azar is light coloured
persons show greyish discolouration of the skin of hands,
feet, abdomen and face which gives the Indian name Kala-
azar meaning Black fever. Some symptoms may include
fever, loss of weight and inflammation of liver and spleen.
x The parasite lives and multiplies inside the female sandfl y
(Phlebotomus argentipes). This insect is most active in
humid environments during the warmer months and at
night from dusk to dawn. Domestic animals, such as dogs,
can serve as reservoirs for the parasite. Transmission may
occur from animal to sandfly to human.
x Humans can also transmit the parasite between each other
through a blood transfusion or shared needles.
x This disease is the second-largest parasitic killer in the
world (after malaria).
Sleeping Sickness :
x An infectious disease, especially common in tropical Africa,
caused by either of two trypanosomes (Trypanosoma
gambiense or Trypanosoma rhodesiense) that are
transmitted by the bite of the tsetse fly (genus Glossina).
This disease is also known as African trypanosomiasis.
x It is characterized by fever, drowsiness, and coma, usually
ending in prolonged coma and death.
x Sleeping sickness is characterized by two stages of illness.
In the first stage, infected persons typically experience
fever, headache, muscle and joint pain and inflammation
of the lymph nodes. The second stage, which develops
within several weeks (T- rhodesiense) or within one or two
years (T. gambiense), is marked by involvement of brain
and spinal cord, accompanied by personality changes,
sleep disturbances and profound lethargy (a lack of energy
and enthusiasm), frequently ending in death when left
untreated.
x Trypanosoma is a member of phylum Protozoa.
Amoebiasis (Amoebic Dysentery) :
x Amoebiasis is caused by an anaerobic parasite amoeba-
Entamoeba histolytica (Phylum-Protozoa).
x Amoebiasis can be present with no, mild or severe
symptoms. Symptoms may include abdominal pain,
diarrhea, or bloody diarrhea.
Schistosomiasis :
x Schistosomiasis is also known as Snail fever and
bilharzia.
x It is caused by parasitic flatworms called schistosomes.
x The urinary tract or intestines may be infected.
x Symptoms include abdominal pain, diarrhea, bloody stool
or blood in urine.
x In developing countries due to unsafe potable water
and lack of sanitation, the malaria, dysentery and
schistosomiasis have taken the form of the epidemic
(a widespread occurrence of an infectious disease in a
community at a particular time).
Fascioliasis :
x Fascioliasis (Liver rot) is a parasitic worm infection
caused by liver flukes viz. Fasciola hepatica and Fasciola
gigantica.
x It affects humans, but its main host is ruminants such as
cattle and sheep.
x People usually become infected by eating raw watercress
or other watergrown plants contaminated with immature
parasite larvae.
x The young worms move through the intestinal wall, the
abdominal cavity and the liver tissue, into the bile ducts.
x The symptoms of fascioliasis in humans are fever,
sweating, loss of weight, abdominal pain.
Neurocysticercosis :
x Neurocysticercosisis the result of accidental ingestion of
eggs of Taenia solium (i.e. pork tapeworm), usually due
to contamination of food by people with taeniasis.
x It is the parasitic disease of the central nervous system
and is the main cause of acquired epilepsy.
x It is a leading cause of seizures and epilepsy in the
developing world and most common parasitic disease of
the central nervous system.
x Tennis champion, Leander Paes was suffering from a
parasitic infection of Taenia solium.
x T. solium infection can be transmitted by consumption
of raw and/or undercooked pork product or contaminated
water with its eggs.
It is noteworthy that Fasciola, Schistosoma and Taenia are
the members of Phylum Platyhelminthes.
In human body approximately 50 species of phylum
Nematoda (roundworms) are found as parasitic worm
causing different diseases.
Filariasis :
x Filariasis is a parasitic disease caused by an infection with
roundworm named Wuchereria bancrofti.
x Filariasis is also known as elephantiasis. In elephantiasis
the lymph glands become swollen.
x W. bancrofti can affect the legs, arms, vulva, breasts and
scrotum (causing hydrocele formation).
x The female Culex mosquito acts as a vector in the
transmission of this disease.
Ascariasis :
x Ascariasis is a disease (infection of small intestine) caused
by the parasitic roundworms Ascaris lumbricoides.
x A person can become infected with ascariasis after
accidentally ingesting the eggs of A. lumbricoides
roundworm.
x The eggs can be found in soil contaminated by human
feces or uncooked food contaminated by soil that contains
roundworm eggs.
x Children often become infected when they put their hands
in their mouths after playing in contaminated soil.
x The symptoms of ascariasis are-
(i) coughing or gagging
(ii) wheezing or shortness of breath
(iii) blood in mucus
(iv) chest discomfort
(v) abdominal swelling and pain, diarrhea
x Roundworm can cause nausea, vomiting, loss of appetite,
and growth impairment in children due to malabsorption.
x Anthelminthic medications (drugs that rid the body of
parasitic worms) such as chenopodium oil, albendazole
and mebendazole are the drugs of choice for the treatment
of Ascariasis.

Genetic Disorders
Notes
• A genetic disease is any disease that is caused by an
abnormality in an individual genome.
• Some genetic disorders are inherited from the parents,
while other genetic disorders are caused by acquired
changes or mutations in pre-existing genes or group of
genes.
• Mutations can occur either randomly or due to some
environmental exposure.
• Some genetic disorders in man are Albinism, Haemophilia,
Muscular Dystrophy, Phenylketonuria, Alkaptonuria,
etc. These genetic disorders are transferred from one
generation to the next generation.
• Down syndrome, Klinefelter syndrome, Turner syndrome
are such genetic disorders which are caused due to
chromosomal abberations.
Sex chromosomes and sex-linked inheritance :
• Sex chromosome, either of a pair of chromosomes that
determine whether an individual is male or female.
• Besides sex-determining gene, there are some other genes,
which are found on the sex chromosomes, determining
the body character of an individual. Such characters are
termed as a sex-linked character and its inheritance is
called sex-linked inheritance.
Albinism :
• Albinism is a congenital genetic disorder characterized
in human by the complete or partial absence of pigment
(melanin) in the skin, hair and eyes.
• Lack of skin pigmentation makes to more susceptibility
to sunburn and skin cancer.
• This also affects essential granules present in immune cells
leading to increased susceptibility to infection.
• Albinism results from inheritance of recessive gene alleles.
• It is due to absence or defect of tyrosinase, a copper -
containing enzyme involved in the production of melanin.
Bubble Baby Disease :
• Bubble Baby Disease is also known as severe combined
immunodeficiency (SCID), alymphocytosis, Glanzmann-
Rinker syndrome, severe mixed immunodeficiency
syndrome and thymic alymphoplasia.
• In this disease, children are born without a functioning
immune system and in the past were protected from germs
within the sterile environment of a plastic bubble.
• This is a rare genetic disorder characterized by the
disturbed development of functional T cells and B cells,
caused by numerous genetic mutations.
• The only cure currently and routinely available for SCID
is bone marrow transplant which provides a new immune
system to the patient. Gene therapy treatment of SCID
has also been successful in clinical trails but not without
complications.
Phenylketonuria :
• Phenylketonuria (PKU) is a type of amino acid metabolism
disorder.
• It is an inherited disease.
• In this genetic disorder, due to the lack of phenylalanine
hydroxylase enzyme, the amino acid phenylalanine is
not converted into tyrosine. It results in increasing the
amount of phenylalanine in the body.
• It can damage the brain and cause severe intellectual
disability and mental disorders.
Haemophilia :
• Haemophilia is an inherited genetic condition, meaning
it is passed down through families. It impairs the body’s
ability to make blood clots, a process needed to stop
bleeding.
• It is caused by a defect in a gene that determines the
formation of factors responsible for blood clotting.
• These genes are located on the X-chromosome, making
haemophilia an X-linked recessive disease.
• This disease is generally found in male while the female
is the vector of disease.
• Haemophilia is not contagious.
• Haemophilia is also known as Bleeder’s Disease.
• Haemophilia is also known as Royal Disease because
the Queen of England Victoria was suffering from this
disease.
Alkaptonuria :
• Alkaptonuria (AKU) is a rare disorder of autosomal
recessive inheritance. In this disease the body cannot
process the amino acids phenylalanine and tyrosine, which
occur in protein.
• It is caused by a mutation in the HGD gene that results in
the accumulation of homogentisic acid (HGA).
• Characteristically, the excess HGA means sufferers pass
dark urine, which upon standing turns black.
• Over time patients develop other manifestations of AKU
due to deposition of HGA in collagenous tissue, namely
ochronosis (bluish/Black discoloration of tissue) and
ochronotic osteoarthropathy
Muscular Dystrophy :
• Muscular dystrophy is caused by an X-linked recessive
gene.
• In muscular dystrophy, abnormal genes interfere with
the production of proteins needed to form healthy
muscle.
• It is an inheritable disease.
Thalassemia :
• Thalassemia are inherited blood disorders characterized
by abnormal haemoglobin production.
• In this condition, body has fewer red blood corpuscles
and less haemoglobin than it should. Often there is mild
to severe anaemia.
• Haemoglobin is important because it lets RBC carry
oxygen to all parts of the body.
• Thalassemia is really a group of blood problems, not just
one.
• For synthesis of haemoglobin, two proteins, alpha & beta
are required. Without enough of one or the other, RBC
cannot carry oxygen as they should.
• Alpha thalassemia means you lack alpha haemoglobin,
with beta thalassemia, you lack beta haemoglobin.
Color Blindness :
• Color blindness (Daltonism), also known as Color
Vision deficiency is the decreased ability to see color or
differences in color.
• The most common cause of color blindness is an inherited
problem in the development of one or more of the three
sets of color sensing cones in the eye. It is a recessive
X-linked inheritance disease.
• Males are more likely to be color blind than females, as
the genes responsible for the most common forms of color
blindness are on the X-chromosome.
• As females have two X-chromosomes, a defect in one is
typically compensated for by the other, while males have
one X-chromosome.
• The females act as a carrier of this disease.
• There are four possibilities of inheritance of color
blindness to progeny.
(i) First probability : Marriage between normal female (XX)
and color blind male (XcY).
• In this condition, all the daughter will be carrier while all
the son will be normal.
(ii) Second probability : Marriage between carrier female
(XcX) and normal male (XY).
• In this case the probability among children are as
follows :
50% color blind son; 50% unaffected son;
50% carrier daughter; and 50% unaffected daughter
(iii) Third probability : Marriage between carrier female
(XcX) and color blind male (XcX).
• In this case, the probability of inheritance among progeny
is as follows :
50% color blind son; 50% unaffected son
50% color blind daughter; 50% carrier daughter
(iv) Fourth probability : Marriage between colorblind female
(XcXc) and normal male (XY).
• In this case the probability of inheritance among progeny
is as follows :
All the son will be color blind while all the daughter will be a
carrier.
Chromosomal aberrations :
• Chromosomal aberrations are departures from the normal
set of chromosomes. It is a missing, extra, or irregular
portion of chromosomal DNA.
• They can refer to changes in the number of sets of
chromosomes (ploidy), changes in the number of
individual chromosomes (somy) or changes in the
appearance of individual chromosome through mutation-
induced rearrangements.
• They can be associated with a genetic disease or with
species differences.
Down Syndrome (45+2 = 47 Chromosomes) :
• Down syndrome is usually caused by an error in cell
division called ‘non-disjunction’.
• Non-disjunction results in an embryo with three copies of
chromosome 21 instead of usual two.
• Prior to or at conception, a pair of the 21st chromosome
in either the sperm or the egg fails to separate.
• As the embryo develops, the extra chromosome is
replicated in every cell of the body.
• This type of Down Syndrome is called trisomy 21.
• At birth, babies with the Down syndrome usually have
certain characteristic signs, including flat facial features,
small head and ears, short neck, bulging tongue, eyes that
slant upward, typically shaped ears and poor muscle tone
and mild to moderate mental disability.
• Down syndrome is also known as Mongoloid idiocy.
Turner Syndrome (44 + X = 45 Chromosomes) :
• Turner syndrome, a condition that affects only females,
results when one of the X chromosomes (sex chromosomes)
is partly or completely missing.
• Turner syndrome can cause a variety of medical and
developmental problems, including short height, webbed
neck, low-set ears, failure of the ovaries to develop and
heart defects.
• The females are sterile.
Klinefelter Syndrome (44 + XXY = 47 chromosomes) :
• In this syndrome, there are three sex (an extra
X-chromosome) chromosomes instead of two sex
chromosomes.
• The affected male from this syndrome is sterile.
• The symptoms of this syndrome include - Larger breast
than normal (gynecomastia), less facial and body hair and
it comes later, lessmuscle tone and muscle grow slower
than usul, longer arms and legs, wider hips.

Deficiency, Non-Contagious
and Other Diseases
Notes
• Deficiency diseases caused by the lack of nutrients in the
diet usually a particular vitamin or mineral.
• It is noteworthy that diabetes, high blood pressure, cancer
etc. of human are the non-contagious diseases.
Cancer :
• Cancer is a group of diseases involving abnormal cell
growth with the potential to invade or spread to other parts
of the body. These contrast with benign tumours, which
do not spread.
• Possible signs and symptoms of cancer include a lump,
abnormal bleeding, prolonged cough, unexplained weight
loss and a change in bowel movements.
• A metastasis refers to the spread of cancer cells from
their primary location (the organ in which cancer began)
to another region of the body.
• Cancer cells may spread through the bloodstream, the
lymphatic vessels.
• An oncogene is a gene that has the potential to cause
cancer in tumour cells, they are often mutated or
expressed at high levels. Most normal cells will undergo
a programmed form of rapid cell death (apoptosis), when
critical functions are altered and malfunctioning.
• Rous sarcoma virus is a retrovirus and is the first
oncovirus to have been described. It causes sarcoma in
chickens.
Leukaemia :
• A malignant progressive disease in which the bone
marrow and other blood-forming organs produce increased
numbers of immature or abnormal leucocytes (a type of
white blood corpuscles).
• Common leukaemia signs and symptoms include :
Fever or chills; persistent fatigue, weakness; frequent or
severe infections; loosing weight without trying; swollen
lymph nodes, enlarged liver or spleen; easy bleeding
or bruising, recurrent nose bleed, excessive sweating,
especially at night; bone pain or tenderness.
• The radioactive phosphorus-32 (P32) and Cobalt-60 (Co60)
is used for the treatment of leukaemia.
• Cobalt-60 is a radioactive isotope of cobalt element.
It emits gamma-rays, hence used in radiotherapy for
treatment of cancer.
• Arsenic-74 is used to locate tumours with pinpoint
accuracy.
• Gold-198 (Au-198) is a radioactive isotope of gold. It
undergoes beta decay to stable Hg-198 with a half-life of
2.697 days. The decay properties of Au-198 have led to
widespread interest in its potential use in radiotherapy for
cancer treatments.
• Interferon Alfa-2A is used to treat various cancers like
leukaemia, melanoma, etc. It is also used to treat virus
infections as chronic hepatitis B, chronic hepatitis C. This
medication is the same as a protein that our body naturally
produces (interferon).
Epidemic Dropsy :
• Dropsy is a form of edema of extremities due to poisoning
by Argemone mexicana (Mexican prickly poppy).
Dropsy is a chemical state resulting from use of edible
oils adulterated with A. mexicana seed oil.
• Sanguinarine and dihydrosanguinarine are two major
toxic alkaloids of argemone oil, which cause capillary
dilation, proliferation and increased capillary permeability.
• When mustard oil is adulterated with argemone
oil, proteinuria (specifically loss of albumin) occurs,
with a resultant edema as would occur in nephrotic
syndrome.
Anthophobia :
• The Anthophobia is a combination of two Greek words
namely anthos meaning flowers and phobos meaning fear
or deep aversion.
• Anthophobia is an abnormal and persistent fear of flowers.
Sufferers experience anxiety even though they realize
they face no threat from flowers. Any genus or species of
flowers can instil fear, as can any flower part, such as a
petal or sepal.
Hysteria :
• Hysteria is an uncontrollable outburst of emotion or fear,
often characterized by irrationality, laughter, weeping etc.
• Hysteria is a psychoneurotic disorder characterized by
violent emotional outbreaks, disturbance of sensory and
motor functions and various abnormal effects due to auto-
suggestion.
Silicosis :
• Lung fibrosis caused by the inhalation of dust containing
silica.
• Any occupation where the earth crust is disturbed can
cause silicosis.
• Along list of occupations is known that expose workers to
crystalline silica that is inhaled. Some of these include—
(1) Coal and hard rock mining
(2) Construction work
(3) Tunnel work
(4) Masonry
(5) Sandblasting
(6) Glass manufacturing and Ceramic work etc.
Goitre :
• The goitre is an abnormal enlargement of the thyroid
gland.
• The thyroid is a butterfly-shaped gland located at the base
of the neck just below Adam’s apple.
• Although goitres are usually painless, a large goitre can
cause a cough and make it difficult for the swallow or
breathe.
• The goitre is caused mainly due to lack of iodine in the
body. Iodine is necessary for the synthesis of thyroxine
hormone.
• The main source of iodine is seafoods and iodised salt.
Beriberi :
• Beriberi is a disease caused by the deficiency of vitamin
B-1 and also known as thiamin deficiency disease.
• Beriberi is of two types-
(i) Wet beriberi- It affects the heart and circulatory system.
In extreme cases, it can cause heart failure.
(ii) Dry beriberi- It damages the nerves and can lead to
decrease muscle strength and eventually, muscle paralysis.
• Beriberi could be life-threatening if it is not treated.
• Due to the lack of vitamin B-1 (thiamine) in birds,
polyneuritis is caused.
• The main source of vitamin B-1 includes husk of cereals,
meat, liver, dried milk, nuts, oranges, legumes and yeast.
Bulimia Nervosa :
• Bulimia Nervosa is also known as bulimia.
• It is an eating disorder characterized by binge eating
followed by purging.

Binge eating refers to eating a large amount of food in a

short time.
• Purging refers to the attempts to get rid of the food
consumed. This may be done by vomiting or taking
laxatives.
Itai-itai Disease :
• Itai-itai disease was the name given to the mass cadmium
poisoning of Toyama Prefecture, Japan, starting around
1912.
• The term ‘itai-itai’was coined by locals for the severe pain
people with the condition felt in the spines and joints.
• Cadmium poisoning can also cause softening of the bones
and kidney failure.
• The cadmium was released into rivers by mining
companies in the mountains, which were successfully
sued for the damage.
• Itai-Itai disease is known as one of the FourBig Pollution
Diseases of Japan.
Minimata Disease :
• Minimata disease is a neurological syndrome caused by
severe mercury poisoning.
• Symptoms include ataxia, numbness in the hands and feet,
general muscle weakness, narrowing of the field of vision
and damage to hearing and speech.
• Minimata disease firstly took place in Minimata city of
Japan by consumption of mercury containing fish.
Blue Baby Syndrome (Methemoglobinemia) :
• The blue baby syndrome is potentially caused by nitrates in
drinking water. It results in blueness of the skin in babies.
• Nitrates from polluted drinking water form compounds
in the body that change haemoglobin to methemoglobin
(which cannot bind oxygen) decreasing the ability of blood
to carry oxygen.
• In infants, the condition can be fatal.
• Anumber of cardiovascular defects may also lead to the
blue baby syndrome. The most common cyanotic heart
defects include tetralogy of Fallot (a combination of
four congenital abnormalities. The four defects include
a ventricular septal defect, pulmonary valve stenosis, a
misplaced aorta and a thickened right ventricular wall);
persistent (patent) truncus arteriosus (a condition in
which the embryological structure known as truncus
arteriosus fails to properly divide into the pulmonary
trunk and aorta), tricuspid atresia (tricuspid heart valve
is missing or abnormally developed), transposition of
the great vessels (an abnormal spatial arrangement of
any of the great vessels : superior and/or inferior venae
cavae, pulmonary artery, pulmonary veins, and aorta) and
anomolus pulmonary venous connection.
Urine
• Urine is an aqueous solution of greater than 95% water.
• Other constituents include urea, chlorides of sodium
and potassium, creatinine, uric acid, and other dissolved
ions and organic and inorganic compounds.
• Urea is a non-toxic compound made of toxic ammonia
and carbon dioxide.
• Urobilin or Urochrome is the chemical primarily
responsible for the yellow colour of urine.
Cerebral Palsy :
• Cerebral Palsy is a group of permanent movement
disorders that appear in early childhood.
• Symptoms include poor coordination, stiff muscles, weak
muscles, and tremors.
• There may be problems with sensation, vision, hearing,
swallowing, and speaking.
• The case of cerebral palsy is a brain injury or brain
malformation that occurs while the brain is developing
before, during or after birth. As a result of the brain damage
during brain development a child’s muscle control, muscle
coordination, muscle tone, reflexes, posture and balance
can be affected.
Alzheimer’s Disease :
• Alzheimer’s disease is a chronic neurodegenerative disease
that causes brain cells to degenerate. It usually starts
slowly and gradually worsens over time.
• Alzheimer’s disease is the most common cause of
dementia- a continuous decline in thinking, behavioural
and social skills that disrupts the person’s ability to
function independently
• The early signs of the disease may be forgetting recent
events or conversations. As the disease progresses, a person
with Alzheimer’s disease will develop severe memory
impairment and loose ability to carry out everyday tasks.
• Dr. Alois Alzheimer a German psychiatrist and
neuropathologist firstly identified this disease.
• The leading cause of Alzheimer’s disease is characterized
by the accumulation of the β-amyloid precursor protein
within the brain along with hyperphosphorylated and
cleaved forms of the microtubule-associated protein tau.
Its cause may be genetic too.
Itching :
• Itch is a sensation that causes the desire or reflex to scratch.
• Scratching itchy skin causes the brain to release hormone
serotonin which intensifies itchy sensation.
Anosmia :
• The complete loss of smell is called anosmia. Without a
sense of smell food taste different, cannot smell the scent of
a flower, and could find yourself in a dangerous situation,
unknowingly. For example, without the ability to detect
an odour, you would not smell a gas leak, smoke from a
fire or sour milk.
• The most common cause of anosmia is nasal congestion
from cold, allergy, sinus infection or poor air quality. Brain
injury could also cause anosmia, and some people are born
without a sense of smell (congenital anosmia).
Lukoskin
• Lukoskin dual therapy is a scientifically developed,
innovative formation which provides effective approach
in the management of Vitiligo or Leucoderma
(depigmentation of skin).
• This unique formulation is developed by Defence
Institute of Bio-Energy & Research (DIBER), a wing
of Defence Research and Development Organization
(DRDO) situated at Haldwani (Uttarakhand), after
exhaustive scientific studies establishing its efficacy and
safety by restoring skin color.
• Lukoskin dual therapy includes oral liquid & ointment,
together provide a comprehensive treatment for
depigmentation of skin.
• Lukoskin oral liquid for internal medication to meet
out the nutritional deficiency and to restore the immune
system and ointment for tropical application on vitiligous
lesions.
Electroencephalogram (EEG)
• An electroencephalogram is a test to find problems
related to electrical activity of the brain.
• An EEG tracks and records brain wave patterns.
• Small metal discs with thin wires (electrodes) are placed
on the scalp and then send signals to a computer to record
the results.
• An electroencephalogram is a non-invasive test that
records electrical patterns of the brain. The test is used
to help diagnose conditions such as seizures, epilepsy,
head injuries, dizziness, headache, brain tumours and
sleeping problems.
• It can also be used to confirm brain death.
• Hans Berger, a German psychiatrist is best known as
the inventor of EEG.
Myopia (Near-sightedness) :
• Myopia is medically termed as a vision condition in which
people can see close objects clearly, but objects farther
away appear blurred.
• Myopia occurs if the eyeball is too long or the cornea (the
clear front cover of the eye) is too curved. As a result, the
light entering the eye is not focused correctly and distant
objects look blurred.
• The concave lens is used to treat myopia.
Hypermetropia (Long-sightedness) :
• Hypermetropia is a common condition where nearby
objects appear blurred but the vision is clearer when
looking at things farther away.
• The cause of hypermetropia is that eyeball are shorter than
usual. This means that the retina is closer to the pupil,
causing light to travel past the retina.
• Hypermetropia is corrected by use of the convex lens.
Astigmatism :
• Astigmatism is a common vision problem caused by an
error in the shape of cornea.
• In astigmatism distorted or blurred vision at all distances
is formed. It is a type of refractive error in which the eye
does not focus light evenly on the retina.
• Cylindrical lens is used for correction of astigmatism.
Cataract :
• A cataract is a clouding of the lens in the eye that affects
vision.
• Most cataracts are related to ageing. Cataracts are very
common in older people.
Sleep Apnea :
• Sleep Apnea is a serious sleep disorder that occurs when
a person’s breathing is interrupted during sleep.
People with untreated sleep apnea stop breathing
repeatedly during their sleep. This means the brain and
rest of the body may not get enough oxygen.
• A noticeable sign of sleep apnea is snoring.
Diabetes :
• Diabetes or Diabetes mellitus (DM) is a group of metabolic
disorders in which there are high blood sugar levels over
a prolonged period.
• Symptoms of high blood sugar include frequent urination,
increased thirst and increased hunger.
• If left untreated, diabetes can cause many complications.
Acute complications can include diabetic ketoacidosis,
hyperosmolar hyperglycemic state or death. Serious long
term complications include cardiovascular disease, stroke,
chronic kidney disease, foot ulcers and damage to the eyes.
• Diabetes is due to either the pancreas not producing
enough insulin or the cells of the body not responding
properly to the insulin produced.
• Type 1 diabetes : It is also called ‘insulin-dependent
diabetes’. It used to be called ‘juvenile-onset diabetes’,
because it often begins in childhood.
Fig.: Graphic representation of cause of diabetes disease
• Type1 diabetes is an autoimmune condition. It is caused
by the body attacking its own pancreas with antibodies. In
people with type 1 diabetes, the damaged pancreas does
not make enough insulin due to loss of beta cells.
• This type of Diabetes may be caused by a genetic
predisposition. It could also be the result of faulty β-cells
in the pancreas that normally produce insulin.
• Type 2 diabetes : It begins with insulin resistance, a
condition in which cells fail to respond to insulin properly.
With type 2 diabetes, the pancreas usually makes some
insulin, but either the amount made is not enough for the
body’s need, or the body’s cells resist it.
• This form was previously referred to as ‘non insulin-
dependent diabetes’ or ‘adult-onset diabetes’. The most
common cause is a combination of excessive body weight
and insufficient exercise.
• World Diabetes Day is celebrated each year on 14
November in the world which increases awareness about
diabetes.
• Each year World Diabetes Day is coordinated by the
International Diabetes Federation, carries a particular
theme. The theme for the World Diabetes Day, 2022 was
‘access to diabetes education’ which underpins the larger
multi-year (2021-2023) theme of ‘access to diabetes care’.
• Diabetes Insipidus : Diabetes Insipidus (DI) is a condition
caused by not enough antidiuretic hormone (ADH) in
the body. This condition is also called water diabetes.
• ADH is also known as vasopressin, secreted by the pituitary
gland (an endocrine gland). This is a hormone that helps
the kidneys keep thecorrect amount of water in the body.
• Methi (fenugreek) is an angiosperm plant which seeds
are used as a medicine to control the blood sugar level.
• The curry tree (Murraya koenigii) is a tropical to
subtropical tree in the family Rutaceae, a native of
India. Its leaves are used in many dishes in the Indian
subcontinent. Its leaves are also useful in the treatment
of diabetes mellitus.
• In the early 1920, Frederick Banting and Charles Best
discovered and isolated insulin under the directorship of
John Macleod at the University of Toronto. With the help
of James Collip insulin was purified, making it available
for the successful treatment of diabetes. Banting and
Macleod earned Nobel Prize for their work in 1923.
Emphysema :
• Emphysema is one of the diseases that comprises the term
COPD (chronic obstructive pulmonary disease).
Emphysema involves gradual damage of lung tissue,
specifically thinning and destruction of the alveoli or air sacs.
• It causes the shortness of breath.
Heart Attack :
• The common cause of heart attack is plaque buildup in the
arteries (atherosclerosis) that prevents blood from getting
to the heart muscle.
• Heart attack can also be caused by blood clots or a torn
blood vessel.
• The risk factors relating to heart attack include-
• smoking
• high cholesterol
• obesity
• lack of exercise
• diet and alcohol consumption
• stress
• Anticoagulants and antiplatelet drugs eliminate or reduce
the risk of blood clots.
• Aspirin, a neurologically active medicine used as
antipyretic, painkiller and anti-inflammatory, is also used
in the heart attack.
• Heart bypass Surgery : Heart bypass surgery or coronary
artery bypass surgery is used to replace damaged arteries
that supply blood to a heart muscle. A surgeon uses blood
vessel, taken from another area of the body, mainly
mammary artery or radial artery, to repair the damaged
arteries. The saphenous vein is used in bypass surgery.
• Cardiac Catheterization Laboratory (Cath Lab) : It is
a special hospital room where doctors perform minimally
invasive tests and procedures to diagnose and treat
cardiovascular disease.
Liver Cirrhosis :
• A chronic disease of the liver marked by degeneration of
cells, inflammation and fibrous thickening of tissue.
• This damage is characterized by the replacement of normal
liver tissue by scar tissue. Typically, the disease develops
slowly over months or years.
• As the disease worsens, a person may become tired, weak,
itchy, have swelling in the lower legs, develop yellow skin,
have fluid build up in the abdomen, or develop spider - like
blood vessels on the skin.
• It is typically a result of alcoholism or hepatitis or non-
alcoholic fatty liver disease.
Oral Submucous Fibrosis :
• Oral submucous fibrosis (OSF/OSMF) is a chronic
debilitating disease of the oral cavity characterized by
inflammation of and progressive fibrosis of the submucosal
tissue (lamina propria and deeper connective tissues). It
results in marked rigidity and an eventual inability to open
the mouth.
• The factors for causation of oral sub-mucous fibrosis is
habitually taking areca nut containing tobacco or gutkha.
Jaundice :
• Jaundice is when a buildup bilirubin in the blood causes
the skin, mucus membranes, and the white part of the eyes
to appear yellowish.
• Bilirubin is a reddish-yellow substance produced when
red blood corpuscles (RBCs) break down.
• Bilirubin is excreted through the liver in the bile and then
out of the body in the stool.
• Jaundice itself is not a dangerous condition, but rather it
may be a sign of a more serious condition or disease such
as gall bladder stone formation, liver cancer etc.
• Jaundice sometimes affects newborns (newborn jaundice)
because their livers are too immature to process the
bilirubin in their bodies.
• Other symptoms of jaundice may include :
• Itchy skin
• Change in urine and stool colour (Urine may be pale
or pale yellow-range, stool may be pale)
• Fatigue

VII. Main Plant Diseases

Notes
• Plant Pathology is the study of the diseases and disorders
of plants.
• Diseases can be defined as a harmful deviation from the
normal functioning of the physiological processes caused
by an infectious agent.
• In the case of plant diseases, the causal agent may be virus,
bacteria, fungus or a parasitic agent or lack of nutrients.
• Plant pathology is also known as phytopathology.
Powdery mildew :
• Powdery mildew are plant diseases of worldwide
occurrence which causes a powdery growth on the surface
of leaves, buds, young shoots, fruits & flowers.
• Powdery mildew diseases are caused by many different
species of fungi in the order Erysiphales, with Podosphaera
xanthii (Sphaerotheca fuliginea) being the most reported
case. Erysiphe cichoracearum was formerly reported to be
the primary causal organism throughout most of the world.
• Hundreds of species of trees, shrubs, vines, flowers,
vegetable, fruits, grasses, field crops and weeds can be
affected by powdery mildew.
• The white powdery appearance is due to a large number
of microscopic asexual spores (conidia) borne in chains.
• Sulphur dust is effective against many powdery mildew
diseases.
• Other organic treatments include copper based fungicides,
baking soda solutions and neem oil have also proven
effective.
Green ear disease :
• The green ear disease of bajra is a common disease and
has been reported from several countries including India,
Iran, Israel, China, Fiji, Japan and the countries wherever
bajra crop is grown.
• In this disease, the inflorescence gets converted into green
leafy ears.
• The causal organism of green ear disease of bajra is a
fungus named Sclerospora graminicola. It is an obligate
parasite.
Sugarcane Leafhopper :
• The Sugarcane Leafhopper (Pyrilla perpusilla) insect is
a serious pest of sugarcane in Northern India.
• The pest is found gregariously on the under surface of the
leaves where it sucks up plant sap that causes yellowing
and eventually drying of leaves.
• Under low infestation yellow patches appear on the leaves.
• Photosynthesis is reduced resulting in the reduction of
sucrose content of the juice by up to 30%.
• Leafhoppers secrete a sweet substance called honey dew
that coats the leaves and attracts a blackish fungus, which
reduces photosynthesis resulting in yield loss.
White Rust :
• White Rust is a disease in plants caused by the oomycetes
Albugo candida.
• Plants susceptible to the disease generally include
members of the family Brassica as mustard, broccoli,
cauliflower, cabbage, etc.
• Signs and symptoms of infection include chlorosis on
leaf surfaces, white blister-like growths on the underside
of leaves and on the stems of the plant, and swelling of
the roots.
• Fungicides are used for the treatment of white rust of
crucifers.
Kernal Bunt :
• Kernal Bunt, also known as partial bunt, is a fungal
disease of wheat, durum wheat, and triticale.
• It is caused by smut fungus Tilletia indica.
• It invades the kernels and obtains nutrients from the
endosperm, leaving behind waste products with a
disagreeable odour that makes bunted kernels too
unpalatable for use in flour etc.
• Kernal bunt affects the quality of wheat.
Ergot disease :
• Ergot of cereals and grassesis a plant disease caused by the
fungus Claviceps purpurea, which infects the developing
grains of cereals and grasses.
• Ergot symptoms become evident during kernel formation
when ergot bodies are formed in place of kernels.
• Ergot affects the productivity and quality of the crop and
if livestock eat infected grain or hay it may cause a disease
called ergotism.
Tungro disease :
• Tungro disease in rice is caused by the combination of two
viruses, which are transmitted by leafhoppers. Viruses are
(1) RTSV-rice tungro spherical virus and (2) RTBV-rice
tungro bacilliform virus.
• It causes leaf discoloration, stunted growth, reduced tiller
numbers and sterile or partly filled grains.
• It is one of the most destructive diseases of rice in South
and Southeast Asia.
List of some diseases in Plants Caused by Viruses :
(1) Tobacco mosaic virus
(2) Cucumber mosaic virus
(3) Barley Yellow Dwarf
(4) Bud Blight
(5) Sugarcane mosaic virus
(6) Cauliflower mosaic virus
(7) Lettuce mosaic virus
(8) Maize mosaic virus
(9) Peanut stunt virus
(10) Yellow vein mosaic of
Lady’s finger (okra) - Its
vector is Bemisia tebaci
(white flies)

eneral Science
16. Consider the following :
1. Birds 2. Dust blowing
3. Rain 4. Wind blowing
Which of the above spread plant diseases?
(a) 1 and 3 only (b) 3 and 4 only
(c) 1, 2 and 4 only (d) 1, 2 , 3 and 4
I.A.S. (Pre) 2018
Ans. (d)
Plant Pathology (also Phytopathology) is the scientific study
of plant diseases caused by pathogens and environmental
conditions (physiological factors). These factors include -
wind, rain, animals, soil, nursery graft, contaminated
equipment and tools, infected seed stock, pollen, dust storm,
irrigation water, birds and humans.
17. What causes ‘Blackheart’ in potato ?
(a) Copper deficiency (b) Boron deficiency
(c) Oxygen deficiency (d) Potassium deficiency
U.P.P.C.S. (Spl.) (Pre) 2008
Ans. (c)
Blackheart is an abiotic disease which is caused due to low
availability of oxygen during storage of potato.
18. Yellow vein mosaic disease in okra, caused by :
(a) Aphids (b) Whitefl y
(c) Leafhopper (d) Fungi
U.P.P.C.S. (Mains) 2002
Ans. (b)
Yellow vein mosaic disease in okra is a viral disease. Whitefl y
is a factor of this virus.
19. ‘Yellow Vein Mosaic’ is a serious disease of :
(a) Brinjal (b) Okra
(c) Pea (d) Cabbage
U.P. P.C.S. (Mains) 2016
Ans. (b)
See the explanation of the above question.
20. ‘Spongy Tissue’ is a serious disorder hampering the
export of mango variety. It is –
(a) Alphonso (b) Dashehari
(c) Neelum (d) Langra
U.P.P.C.S. (Mains) 2002
Ans. (a)
The spongy tissue, a ripening disorder is often described as soft
centre white corky tissue or internal breakdown in Alphonso
mangoes. This disorder is peculiar to South India only.

Plasmid :
• A plasmid is a small DNA molecule within a cell that is
physically separated from chromosomal DNA and can
replicate independently.
• They are most commonly found as small circular,
double-stranded DNA molecules in bacteria; however,
plasmids are sometimes present in archaea and eukaryotic
organisms.
• Often the genes carried in plasmids provide genetic
advantages, such as antibiotic resistance.
• Scientists have taken advantage of plasmids to use them
as tools to clone, transfer and manipulate genes.
• Plasmids that are used experimentally for these purposes
are called vectors.
• DNA fragments or genes are inserted into a plasmid
vector, creating a so-called recombinant plasmid. This
plasmid can be introduced into a bacterium by way of
the process called transformation. Then, because bacteria
divide rapidly, they can be used as factories to copy DNA
fragments in large quantities.
• pBR 322 is a plasmid and was one of the first widely
used E-coli cloning vectors. Created in 1977 in the
laboratory of Herbert Boyer at the University of California,
SanFrancisco. It was named after the post doctoral
researchers who constructed it. The ‘p’stands for ‘plasmid’
and ‘BR’ for ‘Bolivar’ and ‘Rodriguez’.
Restriction enzyme :
• A restriction enzyme or restriction endonuclease is an
enzyme that cleaves DNAinto fragments at or near specifi c
recognition sites within molecule known as restriction
sites. Restriction enzymes are one class of the broader
endonuclease group of enzymes.
• Werner Arber : A Swiss microbiologist and geneticist
along with American researchers Hamilton O. Smith and
Daniel Nathans, shared the 1978 Nobel Prize in Physiol-
ogy (Medicine) for the discovery of restriction nucleases
in Haemophilus influenzae.
DNA ligase :
• DNA ligase is a specific type of enzyme that facilitates
the joining of DNA strands together by catalyzing the
formation of a phosphodiester bond.
• These two enzymes are used for the production of
recombinant DNA in genetic engineering.
Recombinant DNA Technology :
• This technology is related to, joining together of DNA
molecules from two or more different sources that are
inserted into a host organism to produce new genetic
combinations that are of value to science, medicine,
agriculture and industry.
• Basic steps involved in recombinant DNAtechnology are
as follows :
Step I - Identification and isolation of gene of interest.
Step II - Joining of this gene into a suitable vector
(construction of recombinant DNA).
Step III - Introduction of this vector into a suitable
organism.
Step IV - Selection of transformed recombinant cells
with a gene of interest.
Step V - Multiplication or expression of the gene of
interest.
• It is noteworthy that recombinant DNAtechnology is used
to transfer the genes of bacteria or other microorganisms
to higher organisms.
• Deoxyribonucleic acid (DNA), is the hereditary material
in humans and almost all other organisms. Nearly every
cell in a person’s body has the same DNA.
Most DNA is located in the cell nucleus (nuclear DNA)
but a small amount of DNA can also be found in the
mitochondria and chloroplast (in plant cell).
• The information in DNA is stored as a code made up
of four chemical bases : Adenine (A), Guanine (G),
Cytosine (C) and Thymine (T).
• Human DNA consists of about 3 billion bases and more
than 99% of those bases are the same in all people.
• The order of sequence of these bases determines the
information available for building and maintaining the
organism.
• DNA bases pairup with each other, A with T by two
hydrogen bonds and C with G by three hydrogen bonds,
to form units called base pairs.
• Each base is also attached to a sugar molecule and a
phosphate molecule forming a nucleotide. Nucleotides
are arranged in two long strands, that form a spiral called
a double helix, which structure is somewhat like a ladder,
with the base pairs forming the ladder’srung and the sugar
and phosphate molecules forming the vertical side pieces
of the ladder.
• For the discovery of the model of DNA as mentioned
above, Watson and Crick shared the Nobel Prize in 1962,
along with Maurice Wilkins.
• It is noteworthy that Arthur Kornberg synthesized DNA
in vitro.
CRISPR-Cas9 Gene Editing
• CRISPR-Cas9 technology is a simple yet powerful tool
for editing genomes. It allows researchers to easily alter
DNA sequences and modify gene function.
• Its many potential applications include correcting genetic
defects, treating and preventing the spread of diseases and
improving crops. However, its promise also raises ethical
concerns.
• In CRISPR-Cas9 the ‘CRISPR’ stands for ‘clusters of
regularly interspaced short palindromic repeats’, which
are specialized stretches of DNA. While the protein
‘Cas9’ is an enzyme that acts like a pair of molecular
scissors, capable of cutting strands of DNA.
• This technology was adapted from the natural defence
mechanisms of bacteria and archaea.
• By delivering the Cas9 nuclease complexed with a
synthetic guide RNA (gRNA) into a cell, the cell’s
genome can be cut at a desired location, allowing existing
genes to be removed and/or new ones added.
Zygote :
• Azygote is a eukaryotic cell (a cell with a nucleus) formed
by a fertilization event between two gametes i.e. sperm
and oocyte.
• The zygote’s genome is a combination of the DNA in
each gamete and contains all of the genetic information
necessary to form a new individual.
• The zygote divides by mitosis to produce identical
offspring.
DNA Fingerprinting :
• The human DNA has four types of nitrogen base with
different sequences. But the nitrogen base sequence of all
the cells of an individual is similar, which is identical to
his family members. On this ground of the sequences of
nitrogen bases, the procedure to identify any individual
is known as DNA Fingerprinting.
• Sir Alec John Jeffreys is a British geneticist who
developed techniques for genetic fingerprinting and DNA
profiling which are now used worldwide in Forensic
Science to assist police detective work and to resolve
paternity and immigration disputes. It is also used in
judicial cases and for the preservation of threatened livings.
• In the identification of individuals, hair, blood, semen or
other biological samples are used.
• Dr. Lalji Singh was an Indian scientist who worked in
the field of DNA Fingerprinting technology in India. He
is the founder of this technology in India and he is called
as the ‘Father of Indian DNA Fingerprinting’.
• Colin Pitchfork is a British convicted murderer and rapist.
He was the first person convicted of rape and murder based
on DNA fingerprinting evidence and the first to be caught
as a result of mass DNA screening.
• With help of DNA profiling it may be possible to know
the cause and cure of different genetic disorders such as
- Alzheimer’s (a type of dementia that causes problems
with memory, thinking and behaviour), Cystic Fibrosis (a
genetic disorder that affects mostly the lungs, but also the
pancreas, kidneys and intestine) and Myotonic Dystrophy
(Along term genetic disorder that affects muscle functions.
Symptoms include gradually worsening muscles loss and
weakness. Muscles often contract but unable to relax) etc.
Biometric Identification :
• Biometric identification is any means by which a person
can be uniquely identified by evaluating one or more
distinguishing biological traits.
• The uses of biometric across the globe is time and
attendance in workforce management, airport security,
law enforcement, access control and single sign-on (SSO)
and in banking-transaction authentication, etc.
• Biometric identification systems can be grouped on the
main physical characteristics that lends itself to biometric
identification. Examples include :
• Fingerprint identification
• Hand geometry
• Palm vein authentication
• Retina scan
• Iris scan
• Face recognition
• Signature
• Voice analysis
• DNA matching
• Ear size
Biotechnology :
• Biotechnology is the broad area of biology involving
living systems and organisms to develop or make products,
or “any technological application that uses biological
systems, living organisms or derivatives thereof, to make
or modify products or processes for specific use”.
• Depending on the tools and applications, it often overlaps
with the (related) fields of molecular biology, bio-
engineering, biomedical engineering, biomanufacturing,
molecular engineering, etc.
• The earliest biotechnologists were farmers who developed
improved species of plants and animals by cross-
pollination or cross-breeding.
Cloning :
• It is a type of genetic engineering that uses cells from
one organism to create a second living organism that is
genetically identical to the first.
• In nature, many organisms produce clones through asexual
reproduction.
• Cloning in biotechnology refers to the process of creating
clones of organisms or copies of cells or DNA fragments
(molecular cloning).
• The term ‘clon’ first coined by Herbert J. Webber in
1903. It is derived from the Ancient Greek word ‘Klon’
referring to the process whereby a new plant can be created
from a twig. J.B.S. Haldane introduced the terms ‘clone’
and ‘cloning’ in 1963, modifying the earlier ‘clon’.
• Dolly, the sheep, a Finn-Dorset ewe, was the first mammal
to have been successfully cloned from an adult somatic
cell. She was cloned at the Roslin Institute in Scotland
and lived there from her birth in 1996 until her death in
2003 when she was six years old. It was cloned by Keith
Campbell, Ian Wilmut and colleagues.
• Dolly was formed by taking a cell from the udder of her
6-year old biological mother. Dolly’s embryo was created
by taking the cell and inserting it into a sheep ovum. It
took 434 attempts before an embryo was successful.
• This embryo later on transferred into the uterus of surrogate
sheep, and she gave the birth of Dolly which was identical
to her mother (whose cell nucleus was taken).
NDRI’s (National Dairy Research Institute, Karnal,
Haryana) some cloning milestones
• Feb. 6, 2009 : First cloned calf ‘Samrupa’ born; survives
only six days.
• June 6, 2009 : cloned calf ‘Garima’takes birth, survives
for more than two years, dies on August 18, 2011.
• August 22, 2010 : Female cloned calf ‘Garima-II’ born
from an embryonic stem cell.
• August 26, 2010 : Male cloned calf ‘Shrestha’born from a
somatic cell of an elite bull, produces good quality semen.
• January 25, 2013 : Garima II delivers female calf
‘Mahima’.
• March 18, 2013 : Male clone ‘Sawarna’ born from the
somatic cell of semen.
• September 6, 2013 : Female cloned buffalo ‘Purnima’
born.
• May 2, 2014 : Female cloned buffalo ‘Lalima’ produced.
• July 23, 2014 : Male cloned buffalo ‘Rajat’ produced by
normal parturition.
• December 27, 2014 : Garima II gives birth for the second
female calf ‘Karishma’.
• India’s first cloning of Chhattisgarh’s endangered wild
buffalo met success with the birth of a healthy female
named ‘Deepasha’ on Dec. 12, 2014 at NDRI, Karnal
Haryana. Donor mother Asha lives at Udanti wildlife
sanctuary, is lone buffalo of its species.
• It is notable that the first female cloned camel was
developed in Camel Breeding Center at Dubai (U.A.E.). Its
name was ‘Inzaj’. Inzaj was created using the ovarian cells
of an adult camel slaughtered in 2005, which were then
cultivated in tissue culture and frozen in liquid nitrogen.
• ‘Zhong Zhong’(born 27 Nov. 2017) and ‘Hua Hua’(born
5 Dec. 2017) are a pair of identical crab-eating macaques
(also referred to as cynomolgus monkeys) that were created
through somatic cell nuclear transfer (SCNT), the same
cloning technique that produced Dolly, the sheep. They
are the first cloned primates produced by this technique
Lulu and Nana Controversy
• The Lulu and Nana controversy revolves around twin
Chinese girls born in October 2018, who have been
given the pseudonyms Lulu and Nana. According to the
researcher He Jiankui, the twins are the world’s first
germline genetically edited babies.
• Gene-editing CRISPR-Cas9 technique is allegedly used
by He Jainkui in creating these babies. It raises many
ethical concerns worldwide.
Stem Cell :
• Stem cells are the master cell which acts as basic building
blocks of our body. Just like a seed of a plant that gives
rise to branches, leaves and fruits, these stem cells have
the potential to develop into specialized cells such as blood
cells, muscle cells, brain cells etc. of our body.
• When parts of our body or its functions are damaged or
affected by ageing, injury or illness, these stem cells have
the ability to both replace affected cells and/or repair the
affected parts and restore the normal functions of our body.
• All stem cells can self-renew (make copies of themselves)
and differentiate (develop into more specialized cells).
• Stem cells have the ability to treat over 80 blood and
bone-related conditions, including cancers of the blood,
autoimmue disorders and certain genetics disorders.
• Cord blood (umbilical cord blood) is blood that remains
in the placenta and in the attached umbilical cord after
childbirth. Cord blood is collected because it contains
stem cells which can be used to treat hematopoietic and
genetic disorders.
Types of Stem Cells :
1. Embryonic Stem Cells :
• Embryonic stem cells are obtained from the inner cell
mass of the blastocyst, a mainly hollow ball of cells that,
in the human, forms three to five days after an egg cell
is fertilized by a sperm. A human blastocyst is about the
size of the dot above this ‘i’.
• Embryonic stem cells are pluripotent (they can give rise
to every cell type in the fully formed body, but not the
placenta and umbilical cord).
• Human embryonic stem cells have been derived primarily
from blastocysts created by in vitro fertilization (IVF) for
assisted reproduction that were no longer needed.
2. Tissue-Specific Stem Cells (Somatic or Adult Stem
Cells) :
• These stem cells are more specialized than embryonic stem
cells because these stem cells can generate different cell
types for the specific tissue or organ in which they live.
• For example, blood-forming (hematopoietic) stem cells
in the bone marrow can give rise to RBCs, WBCs, and
blood platelets, but these do not generate liver or lung or
brain cells, and stem cells in other tissues and organs do
not generate RBCs/WBCs/blood platelets.
3. Induced Pluripotent Stem Cells (IPS) :
• These cells have been engineered in the lab by converting
tissue-specific cells, such as skin cells, into cells
that behave like embryonic stem cells. IPS cells are
critical tools to help scientists learn more about normal
development and disease onset and progression, and they
are also useful for developing and testing new drugs and
therapies.
4. Mesenchymal Stem Cells (MSCs) :
• MSCs refer to cells isolated from stroma, the connective
tissue that surrounds other tissues and organs.
• These cells are also known as ‘stromal cells’.
• The first MSCs were discovered in the bone marrow and
were shown to be capable of making bone, cartilage and
fat cells. Since then, they have been grown from other
tissues, such as fat and cord blood.
Amniocentesis :
• Amniocentesis (also referred to as amniotic fluid test)
is a medical procedure used in prenatal diagnosis of
chromosomal abnormalities and fatal infections, and also
for sex determination.
• In this procedure, a small amount of amniotic fluid, which
contains fetal tissues, is sampled from the amniotic sac
surrounding a developing fetus, and then the fetal DNA
is examined for genetic abnormalities.
• The most common reason to have an ‘amnio’ is to
determine whether a fetus has a certain genetic disorder
or a chromosomal abnormality, such as Down syndrome.
• This procedure is usually performed between 14-16 weeks
of pregnancy, though again, can be done at a later stage
of gestation as well.
• This procedure can be used for prenatal sex discernment
and hence this procedure has legal restriction in many
countries.
Applications of Genetic Engineering :
• The application and importance in daily life, of Gene
Engineering can be understood by following heads :
1. Genomic Library :
• Agenomic library contains all the sequences present in the
genome (an organism’s complete set of DNA, including all
of its gene) from a single organism. Each genome contains
all of the information needed to build and maintain the
organism. In human, a copy of the entire genome-having
more than 3 billion nitrogen base pairs - is contained in all
cells of the body. In the construction of genomic libraries,
it is feasible to use vectors that could accommodate the
large size of inserts.
• The first step in the construction of the genomic library
is the isolation of the genomic DNA, and entire DNA
is subjected to restriction digestion. The fragmented
DNA of suitable size is ligated in the appropriate
cloning vectors.
• The recombination vectors are transferred and maintained
in organisms such as bacteria, virus or yeast. Atarget DNA
sequence present in particular cell clones are identified,
sub-cultured and maintained as cell lives, widely known
as gene bank or a clone bank.
Human Genome Project
• The Human Genome Project (HGP) was the international
collaborative research program whose goal was the
complete mapping and understanding of all the genes of
human beings. All our genes together are known as our
‘genome’.
• As estimated by scientists, the human genome has
approximately 30,000 genes and analysis of majority of
genes has been completed.
• Human Genome Project will help in -
(i) Study all the genes in a genome.
(ii) Genes concerned with cancer can be found and sequenced
study the transcripts in a particular tissue or organ of the
tumour.
(iii) Study of interaction of various genes, proteins and their
interaction.
2. Gene Therapy :
• The main reason for approximately 3000 diseases in
human is the synthesis of fault enzymes under control
of faulty genes. Under gene therapy, we can cure such
diseases.
• Gene therapy includes :
i. Replacing a mutated gene that causes disease with a
healthy copy of the gene.
ii. Inactivating or knocking out a mutated gene that is
functioning improperly.
iii. Introducing a new gene into the body to help fight a
disease.
Pleiotropism
• This is the condition of a gene affecting more than one
characteristic of the phenotype.
• Example of pleiotropism is Sickle Cell Anaemia of
RBC - In this disease, the red blood cells become rigid
and sticky and are shaped like sickles or crescent moon.
A recessive gene is responsible for sickle cell anaemia.
3. High Resistance in Plants :
• Genetically transformed plants are grown by tissue culture
techniques and extra desired genes are inserted along with
natural genes by genetic engineering.
• The inserted extra desired genes produce the capacity to
resist against salinity of soil, drought and insects, virus
and bacteria.
• Through genetic engineering, some varieties have been
produced that could directly fix atmospheric nitrogen and
thus there is no dependence on fertilizers.
• Bacterium, Bacillus thuringiensis (Bt) produced a protein
which is toxic to insects. Using the technique of genetic
engineering, the gene coding for this toxic protein called Bt
gene has been isolated from the bacterium and engineered
into tomato and tobacco plants. Such transgenic plants
showed resistance to tobacco hornworms and tomato
fruitworms.
• In Bt Brinjal the gene of B. thuringiensis (Cry1Ac) has
been introduced which produces Bt toxin, which kills the
lepidopteron insects such as brinjal fruit- borer and shoot-
borer.
• This may be proved a good alternative for crop protection
but it is a doubt that the poison effect may be harmful to
the health of man and biodiversity, so the Government of
India has banned the field trials of Bt Brinjal in 2010.
• By the similar technology transgenic cotton (Bt cotton)
and transgenic Maize (Bt Maize) have been produced.
4. Change in Plant Genotype :
• Useful and good quality of plants like tomato, tobacco,
onion, maize, wheat, barley, rice, pea etc. can be developed
by inserting rDNA (Recombinant DNA) & cloned DNA
into the genotype of plants.
Flavr Savr :
• Flavr Savr also known as CGN-89564-2, a genetically
modified tomato was the first commercially grown
genetically engineered food to be granted a licence for
human consumption.
• It was produced by the Californian company Calgene, and
submitted to the U.S. Food and Drug Administration in
1992.
Through genetic engineering, Calgene hoped to slow
down the ripening process of the tomato and thus prevent
it from softening, while still allowing the tomato to retain
its natural colour and flavour.
• The Flavr Savr was made more resistant to rotting by
adding an antisense gene which interferes with the
production of the enzyme polygalacturonase.
Golden Rice :
• Golden rice is a variety of rice (Oryza sativa) produced
through genetic engineering to biosynthesize beta-
carotene, a precursor of vitamin A in the edible parts of
the rice.
• It is intended to produce a fortified food to be grown and
consumed in areas with a shortage of dietary vitamin A.
• Golden rice differs from its parental strain by the addition
of two beta-carotene biosynthesis genes. The two beta-
carotene biosynthesis genes are : psy (phytoene synthase)
from daffodil and crtl (phytoene desaturase) from he soil
bacterium Erwinia uredovora.

Miscellaneous
Notes
Scope of Biology :
• Human beings are the most intelligent organism due to the
capability of thinking and understanding. For a human,
the study of science has dual purposes. Firstly, they gain
scientific knowledge. Secondly, they apply that knowledge
for human welfare. The scope of biology can be discussed
in the following points :
1. Agriculture : Biology gives knowledge about the useful
and harmful plants. So that the farmer can get better pest
free crops.
2. Human health : Biology provides the knowledge to
maintain good health by following- proper food, exercises,
good habits, etc.
3. Human diseases : Several pathogens cause different
diseases. The habit, habitat, structure, life cycle etc. of
such pathogens can be studied in biology. So, we can be
away from different diseases to a considerable extent.
4. Industries : Most of the industries are based on the
products of plants and animals i.e. wood, jute, rubber,
gum, sugar, leather, etc.
5. Conservation of flora and fauna : Biology helps the
scientists or researchers to conserve endangered flora and
fauna.
6. Animal husbandry : Rearing of animals for food,
agriculture, transportation etc. is an old practice done
by man. Biology gives an idea to keep such animals in a
systematic way.
7. Entertainment or Aesthetic value : Rearing of animals
and preserving plants are done by the human for
entertainment as well i.e. zoo, circus, aquarium, park,
garden, etc.
8. Economic value : The products obtained by the rearing
animals and planting can be sold in the market which gives
financial aids. Tourist visit natural resources, wildlife,
medicinal plants, etc. By exposing flora and fauna, the
country can raise its economic status.
9. Practical scopes : The concept of biology is essential in
veterinary science, dairy science, pisciculture, apiculture,
biotechnology, biophysics, biochemistry, bioengineering,
etc. Biology accepted the challenges given by the world
regarding food, population, and diseases with solutions
i.e. new technologies in agriculture, family planning and
medicine.
Miscellaneous Important Facts :
• Jonas Edward Salk was an American medical researcher
and virologist. He discovered and developed one of the
first successful polio vaccines.
• Albert Bruce Sabin was a Polish American medical
researcher, best known for developing the oral polio
vaccines, which has played a key role in nearly eradicating
the disease.
• Robert Gordon Webster is a virologist of New Zealand.
He posited that pandemic strains of flu arise from genes
in flu virus strains in non-humans; for example, via a
reassortment of genetic segments (antigenic shift) between
viruses in humans and non-humans (especially birds)
rather than by mutations (antigenic drift) in annual human
flu strains. He identified the flu virus H5
N1
, isolated it
and his work is also responsible for the method of human
influenza vaccination that is commonly used.
• The most effective chemical agent (Chemical weapon)
of the First World War was Sulphur mustard known
as Mustard Gas. It is a volatile oily liquid. Mustard
gas has extremely powerful vesicant (blistering) effects
on its victims. In addition, it is strongly mutagenic and
carcinogenic as well as lipophilic. It produces chemical
burns on contacted skin within 24 hours of its exposure.
The Germans used mustard gas for the first time during
the war in 1917. They outfitted artillery shells and grenades
with mustard gas that they fired in the vicinity of the troop
target.
Tomography or CT Scan is imaging by sections or
sectioning, through the use of any kind of penetrating wave
like X-ray. The method is used in radiology, archaeology,
biology, atmospheric science, geophysics, oceanography,
plasma physics, material science, astrophysics, and other
areas of science.
• Electroencephalography (EEG) : It is an electrophysio-
logical monitoring method to record the electrical activity
of the brain. It is typically non-invasive with the electrodes
placed along the scalp.
• Electrooculography (EOG) : It is a technique for
measuring the corneo-retinal standing potential that
exists between the front and back of the human eye.
The resulting signal is called the electrooculogram. Its
primary applications are in ophthalmological diagnosis
and in recording eye movements.

Electromyography (EMG) : It is an electrodiagnostic

medicine technique for evaluating and recording the
electrical activity produced by skeletal muscles. EMG is
performed using an instrument called electromyograph to
produce a record called electromyogram.
• Audiogram : It is a graph that shows the audible
threshold for standardized frequencies as measured by an
audiometer. The Y-axis represents intensity measured in
decibels and the X-axis represents frequency measured
in hertz. The threshold of hearing is plotted relative to a
standardized curve that represents ‘normal’ hearing.
• Mammography : Mammography is the process of
examining human breast using low-energy X-ray.
The actual test is called mammogram. The purpose of
mammography screening is breast cancer detection.
• Endoscope : It is an illuminated optical, typically slender
and tubular instrument (a type of borescope) used to
look deep into the body and used in procedures called an
endoscopy.
• Cardiograph : It is an instrument that graphically registers
movements of the heart.
• Crescograph : Acrescograph is a device for measuring the
growth in plants. It was invented in the early 20th century
by Jagdish Chandra Bose.
• Tetraplegia : It is also known as quadriplegia. It is a
paralysis caused by illness or injury that results in the
partial or total loss of use of all four limbs and torso.
Paraplegia is similar but does not affect the arms.
The loss is usually sensory and motor which means
that both sensation and control are lost. Tetraparesis
(quadriparesis), on the other hand, means muscle weakness
affecting all four limbs.
• Electron Beam Therapy : It is a kind of external beam
radiotherapy where electrons are directed to a tumour site.
• Cardiologist : A cardiologist specializes in diagnosing
and treating diseases of the cardiovascular system. The
cardiologist will carry out tests, and they may do some
procedures, such as heart catheterizations, angioplasty or
inserting a pacemaker.
• Nephrologist : The nephrologist deals with the diagnosis
and management of kidney diseases. The kidneys are vital
for maintaining normal fluid and electrolyte balance in the
body.
• Urologist : Urologist treats general diseases of the urinary
tract.
• Oculist : An oculist is a person who examines or treats
people’s eye.
• Ultrasound Technique : Medical ultrasound (also
known as diagnostic sonography or ultrasonography) is
a diagnostic imaging technique based on the application
of the ultrasound. It is used to create an image of internal
body structures such as tendons, muscles, joints, blood
vessels, and internal organs.
• Fetal ultrasound is a test used during pregnancy that
creates an image of the fetus in the mother’s womb.
• Linus Carl Pauling : American Linus Carl Pauling has
given his important contribution for research in the field
of cancer and vitamin-C. He has researched in the field of
physics, chemistry and biology. He was awarded Nobel
Prize in 1954 (Chemistry) and in 1962 (Peace) for his
achievements.
• Honey Bees : These are eusocial flying insect within
the genus Apis of the bee clade. They are known for
construction of perennial, colonial nests from wax, for the
large size of their colonies and for their surplus production
and storage of honey, distinguishing their hives as a prized
foraging target of many animals, including honey badgers,
bears and human hunter-gatherers.
• Honey bees are trained to sniff out landmines.
• A honey bee colony has one queen, some males (drones)
and many workers. We obtain honey and wax from
honey bee hives. The average speed of honey bees are
normally about 12-15 miles/hour (17 to 21 km/hour). It
is noteworthy that the honey bee hive has a special odour
which helps each other members in identification.
• Karl Von Frisch discovered that bees communicate the
location of food sources to each other through the complex
circle and waggle dances. For this discovery, he was
awarded Nobel Prize in 1973.
• Round Dance : Round dance is a term used to describe
the communicative behaviour of a foraging honey bee, in
which she moves on the comb in close circles, alternating
right and then left. The round dance indicates that the
forger has located a profitable food source close to the
hive (approximately 75 m range).
• Waggle Dance : The waggle dance tells the watching bees
two things about a flower patch’s location-the distance and
the direction away from the hive. The dancing bee
waggles back and forth as she moves forward in a straight
line, then circles around to repeat the dance. It indicates
that the food source is far from the hive.
• Silica gel packets are used to absorb moisture and keep
things (as medicines) dry.
• Shanti Swarup BhatnagarAward : This is a prestigious
science award in India given annually by the Council of
Scientific and Industrial Research (CSIR) for notable
and outstanding research, applied or fundamental, in
biology, chemistry, environmental science, engineering,
mathematics, medicine and physics. The purpose of
this prize is to recognize outstanding Indian work in
science and technology. It is the most coveted award in
multidisciplinary science in India. This award is named
after the founder and Director of the CSIR-Shanti Swarup
Bhatnagar. It was first awarded in 1958.
• Human Eye : The human eye (sight sense organ) is a
spherical body also known as the eyeball. It lies in the eye
socket and is attached to various muscles. Ophthalmology
is a branch of medicine and surgery that deals with the
diagnosis and treatment of eye disorders.
• In Eye donation, the cornea is the part which is
transplanted.
• Dehydration : Dehydration is the loss of water or
liquid from the body in excessive quantity. In this state
the electrolytes mainly sodium chloride is lost from the
body.