Five kingdom classification

1. Diversity in Living Organisms & Classification Principles

• Diversity: There are millions of different types of organisms, from single-celled

microorganisms like bacteria to large-sized plants and animals.
• Species: A species is defined as an organism of a particular kind whose
members can interbreed to produce fertile young ones.
o Example: Humans (Homo sapiens) are a single species.
o Mule: A mule is a cross between a donkey (male) and a horse (female). It
is sterile and cannot reproduce, thus demonstrating that a donkey and a
horse belong to different species. Similarly, "Zenkkey" (zebra-donkey cross)
and "Tigon" (tiger-lion cross) are examples of crosses between different
species that produce sterile offspring.
• Classification Hierarchy (Taxonomic Categories): To study diversity, organisms
are grouped based on increasing similarity and complexity into categories. The
broad levels, from largest to smallest, are:
o Kingdom
o Phylum (or Division for plants)
o Class
o Order
o Family
o Genus
o Species
• Binomial Nomenclature (Scientific Naming):
o Introduced by Linnaeus (1707-1778).
o Two rules:
1. Scientific names are always written in italics.
2. The first letter of the genus-name should be a Capital letter, while
the species-name should begin with a small letter.
o Example: House crow is Corvus splendens, Jungle crow is Corvus
macrorhynchos. Both belong to the same genus (Corvus) but are different
species because they cannot interbreed.

2. Five Kingdom Classification

The five kingdoms are Monera, Protista, Fungi, Plantae, and Animalia.

• 1. Kingdom Monera:
o Unicellular and prokaryotic (no organized nucleus; DNA not enclosed).
o Contain cell wall.
o Lack membrane-bound organelles like mitochondria and chloroplasts.
o Examples: Bacteria, blue-green algae.
• 2. Kingdom Protista:
o Unicellular or more appropriately single-celled organisms.
 o Eukaryotic (well-defined nucleus with a nuclear membrane).
o Some have cell walls, others do not.
o Some are autotrophic (perform photosynthesis), others are
heterotrophic.
o Examples: Amoeba, Euglena, Paramecium, Pandorina.
• 3. Kingdom Fungi:
o Mainly multicellular (except yeast, which is unicellular).
o Eukaryotic.
o Saprophytic (obtain nutrition from decaying matter), lack chlorophyll.
o Have a cell wall.
o Examples: Bread mould, Mushroom, Toadstool, Yeast, Penicillium.
• 4. Kingdom Plantae:
o Multicellular and eukaryotic.
o Autotrophic (perform photosynthesis).
o Have cell walls.
o Major divisions:
▪ Thallophyta (Algae): Simple, no true roots, stems, or leaves.
Example: Spirogyra.
▪ Bryophyta (Mosses, Liverworts): Simple plant body, grow in moist
places. Example: Moss.
▪ Pteridophyta (Ferns): True roots, stems, leaves, but non-flowering.
Example: Fern.
▪ Gymnosperms (Cycads, Pines): Bear naked seeds, non-flowering.
Example: Cycas, Pine, Fir.
▪ Angiosperms (Flowering Plants): Bear enclosed seeds within fruits.
Divided into:
▪ Monocots: One cotyledon, fibrous root, parallel venation.
Example: Maize, Rice.
▪ Dicots: Two cotyledons, tap root, reticulate venation. Example:
Pea, Potato, Apple.
• 5. Kingdom Animalia:
o Multicellular and eukaryotic.
o Heterotrophic (obtain food by eating others).
o No cell wall and no chlorophyll.
o Generally mobile.
o Key differences from Plants: Animals lack chlorophyll, lack cell walls,
move freely, have a definite body shape, and respond quickly to stimuli.

3. Animal Kingdom Classification (Further Details)

The Animal Kingdom is broadly divided into Invertebrates (no notochord/backbone)

and Vertebrates (have notochord/vertebral column).
A. Invertebrates (No Backbone)

• 1. Phylum Porifera (Sponges):

o Simplest multicellular animals, porous body.
o Have a hollow body with numerous pores (ostia) and an exit (osculum).
o Example: Sycon, Bath sponge.
• 2. Phylum Cnidaria (Coelenterata):
o Have a two-layered body wall and radial symmetry.
o Possess stinging cells (cnidoblasts).
o Have a single cavity (mouth) for ingestion and egestion.
o Examples: Hydra, Jellyfish, Sea anemone, Red coral.
• 3. Phylum Platyhelminthes (Flatworms):
o Have a flat, unsegmented body.
o Acoelomate (no body cavity).
o Have a single opening (mouth/anus) for alimentary canal.
o Examples: Planarian, Liverfluke, Tapeworm.
• 4. Phylum Nematoda (Roundworms):
o Long, cylindrical, unsegmented body.
o Possess a false body cavity (pseudocoelom).
o Have two openings (mouth and anus) for the alimentary canal.
o Examples: Hookworm, Ascaris, Eelworm.
• 5. Phylum Annelida (Segmented/Ringed worms):
o Cylindrical body with ring-like segments.
o Possess a true body cavity (coelom).
o Have a well-developed digestive system with mouth and anus.
o Examples: Earthworm, Leech, Nereis.
• 6. Phylum Arthropoda:
o Largest phylum in the animal kingdom.
o Have jointed legs and an exoskeleton of chitin.
o Body is divided into head, thorax, and abdomen.
o Four classes:
▪ Crustacea: Two pairs of antennae, ten jointed legs (e.g., Crayfish,
Crab).
▪ Myriapoda: Many segments, many legs (e.g., Centipede, Millipede).
▪ Insecta: Three pairs of legs, often wings (e.g., Butterfly, Beetle,
Grasshopper).
▪ Arachnida: Four pairs of jointed legs, no antennae (e.g., Spider,
Scorpion).
• 7. Phylum Mollusca:
o Soft, unsegmented body, usually enclosed in a shell.
o Have a muscular foot for locomotion.
o Examples: Snail, Slug, Oyster, Mussel, Squid, Octopus.
• 8. Phylum Echinodermata (Spiny-skinned stars):
o Marine animals, radially symmetrical.
o Have spiny skin and tube-feet for locomotion.
 o Examples: Starfish, Brittle-star, Sea-urchin, Sea-cucumber.

B. Vertebrates (Phylum Chordata)

• Possess a notochord or vertebral column, a dorsal nerve cord, and haemoglobin

in red blood cells.
• Five classes of Vertebrates:
o 1. Class Pisces (Fishes):
▪ Aquatic animals.
▪ Have a two-chambered heart.
▪ Breathe by gills.
▪ Are cold-blooded (poikilothermal).
▪ Body covered with scales.
▪ Examples: Shark, Rohu, Catla, Dogfish.
o 2. Class Amphibia (Amphibians):
▪ Live partly on land and partly in water.
▪ Have a three-chambered heart.
▪ Breathe by gills (larval stage), lungs, or skin.
▪ Are cold-blooded.
▪ Have moist, slimy skin.
▪ Possess five-fingered limbs.
▪ Examples: Frog, Toad, Salamander, Newt.
o 3. Class Reptilia (Reptiles):
▪ Primarily land-dwelling.
▪ Have dry, scaly skin.
▪ Possess a three-chambered heart (except crocodiles, which have
four).
▪ Are cold-blooded.
▪ Lay leathery eggs.
▪ Examples: Lizard, Snake, Tortoise, Crocodile.
o 4. Class Aves (Birds):
▪ Aerial animals, forelimbs modified into wings.
▪ Have a four-chambered heart.
▪ Are warm-blooded (homoeothermal).
▪ Body covered with feathers.
▪ Lay eggs.
▪ Examples: Pigeon, Sparrow, Crow, Duck, Owl, Penguin.
o 5. Class Mammalia (Mammals):
▪ The most highly developed animals.
▪ Have hair or fur on their body.
▪ Possess a four-chambered heart.
▪ Are warm-blooded.
▪ Give birth to live young ones (viviparous) and possess mammary
glands to feed them.
▪ Examples: Dog, Cat, Monkey, Human, Whale, Bat.
4. Body Symmetry

• Asymmetry: No particular plane can divide the body into two equal halves (e.g.,
Amoeba).
• Radial Symmetry: Any line passing through the center can divide the body into
two similar halves (e.g., Starfish, Hydra).
• Bilateral Symmetry: Only one plane can divide the body into two similar halves
(e.g., Housefly, Humans, most vertebrates and invertebrates).

5. Body Directions

• Anterior: Towards the front.

• Posterior: Towards the hind end.
• Dorsal: Relating to the back or the upper side.
• Ventral: Belonging to the lower or underside.
• Lateral: Sides (right or left).

Economic Importance of Bacteria and Fungi

1. Economic Importance of Bacteria

Bacteria are primitive organisms, typically single-celled prokaryotes (without a true
nucleus). They lack chlorophyll and are mostly heterotrophic (cannot make their own
food), though some are autotrophic.

A. General Study of Bacteria

* Structure : Unicellular organisms with a single chromosome (nuclear material) not
enclosed in a nuclear membrane. They have a cell wall (containing peptidoglycan and
cellulose), cell membrane, cytoplasm, and sometimes a capsule or flagellum.
* Shape : Bacteria are typically of four types:
* Cocci : Spherical.
* Bacilli : Rod-shaped.
* Spirilla : Spiral or twisted.
* Vibrio : Comma-shaped.
* Habitat : Bacteria are ubiquitous, found in air, water, soil, food, skin, intestines, and
various other environments.
* Reproduction : Primarily by asexual means through binary fission , where one cell
divides into two daughter cells. Under favorable conditions, this can be very rapid.
Sexual reproduction occurs through conjugation , where genetic material is transferred
between two bacteria via a hollow tubelike extension.
* Nutrition : Most bacteria are heterotrophic . They can be saprophytic (derive
nourishment from decaying dead organisms) or parasitic (derive nourishment from
living hosts).
* Spore Formation : Bacteria can form spores under unfavorable conditions, which
are resistant, thick-walled structures that allow survival until conditions improve.

B. Useful Economic Role of Bacteria

* Medicine : Used to produce antibiotics (e.g., streptomycin, chloromycetin,
tetracycline, penicillin – though penicillin is from a fungus), serums, and vaccines.
* Antibiotics: Chemicals that stop the growth of disease-producing bacteria.
* Serums : Contain antibodies for passive immunity.
* Vaccines : Prepared from weakened or killed germs to stimulate active immunity.
* Agriculture : Crucial for the nitrogen cycle .
* Nitrogen-fixing bacteria (e.g., Rhizobium) convert atmospheric nitrogen into nitrates
in root nodules of leguminous plants.
* Nitrifying bacteria convert ammonia to nitrites and then nitrates.
* Denitrifying bacteria convert nitrates back to atmospheric nitrogen.
* Industry :
* Curing tea and tanning leather .
* Sewage treatment : Decompose organic matter in sewage plants.
* Production of dairy products : Lactobacillus curdles milk to make curd.
* Synthesis of vitamins : Bacteria in human intestines synthesize vitamins, such as
Vitamin B.
* Bioweapons : Anthrax, caused by Bacillus anthracis , is a potent bioweapon.

C. Harmful Economic Role of Bacteria

* Spoilage of Food : Cause putrefaction (decomposition of organic matter, often
producing foul smell).
* Plant Diseases: Cause diseases like black rot of mustard and cauliflower, and
bacterial blight of cowpea .
* Animal Diseases : Cause diseases like anthrax (swelling on body, reduced milk
yield) and tuberculosis (lung-affected, dry husky cough).
* Human Diseases : Cause cholera, tuberculosis, diphtheria, typhoid, pneumonia,
tetanus, whooping cough, and rickettsial fevers .

2. Economic Importance of Fungi

Fungi are eukaryotic organisms that are typically multicellular (except for yeasts,
which are unicellular) and lack chlorophyll, making them heterotrophic .
A. General Study of Fungi
* Structure : Composed of thread-like structures called hyphae , which collectively
form a mycelium . Yeast is a single-celled fungus.
* Reproduction : Primarily by spore formation. Spores are produced in sporangia
(spore sacs) or directly on sporophores . Sexual reproduction also involves the fusion of
hyphae.
* Types : Common examples include moulds (e.g., Penicillium, Aspergillus ), yeasts,
and mushrooms.

B. Useful Economic Role of Fungi

* Medicine : The first produced antibiotic, Penicillin, was discovered from the fungus
Penicillium notatum (now Penicillium chrysogenum ). Other antibiotics like
streptomycin and chloromycetin are from bacteria, not fungi.
* Food Source : Many mushrooms are edible and consumed globally.
* Cultivated mushrooms include White button mushroom ( Agaricus bisporus ),
Oyster mushroom ( Pleurotus ), and Morels. They are rich in vitamins and minerals like
niacin, pantothenic acid, and biotin.
* Industry:
* Bakeries: Yeast ( Saccharomyces cerevisiae ) is crucial in bread-making for
fermentation, which produces carbon dioxide, causing the dough to rise.
* Alcoholic Beverages : Yeast is used in fermentation to convert sugar into alcohol
(ethanol) in wine and beer production.
* Cheese Processing : Certain fungi contribute to the flavor and texture of cheese.
* Mushroom Cultivation : A significant industry involving several stages including
spawning, casing, cropping, harvesting, and preservation.

C. Harmful Economic Role of Fungi

* Spoilage of Food : Moulds commonly cause spoilage of bread, fruits, and other food
items. Putrefaction can be caused by fungi.
* Plant Diseases : Many fungi cause significant plant diseases like rusts and smuts.
* Human Diseases : Fungi can cause ringworm and athlete’s foot .
* Other Damage: They can damage leather, textiles, and timber.

Nutrition
* Nutrition is the process by which an organism obtains and uses essential organic
and inorganic chemical compounds (proteins, vitamins, salts, etc.) to sustain life.
* Food is any substance consumed for nourishment, such as milk, bread, eggs, and
apples.
* Diet refers to the combination of food items eaten at meals, which supplies all
necessary nutrients.
* Appetite is the desire to eat, while **hunger** is the unpleasant sensation due to
lack of food.

2. Need for Nutrition

Living organisms require food for six main purposes:
* Growth: Building up new protoplasm and cells.
* Repair: Providing material for the repair of worn-out or injured cells.
* Energy : Providing energy needed by the body to carry out vital life functions.
* Maintenance: Chemical composition of cells.
* Provision of raw materials: For the manufacture of various secretions such as
enzymes, hormones, and sweat.
* Protection: From disease and infection.

3. Classes of Nutrients (Food Substances)

There are six main classes of food substances: carbohydrates, fats, proteins, mineral
salts, vitamins, and water.
3.1. Carbohydrates
* Composition: Organic compounds of carbon, hydrogen, and oxygen, usually in a
1:2:1 ratio for H:O.
* Function: They are oxidised to release energy. They are the principal energy sources
for the body. (1 mole of glucose releases 686 kilocalories of energy).
* Types of Sugars:
* Monosaccharides (simple sugars):
* Glucose: The most common and simplest sugar, known as grape-sugar, and
present in blood sugar.
* Fructose: Found in plants and fruit sugar.
* Galactose: Found in milk.
* Disaccharides (double sugars):
* Sucrose: Commercial sugar, commonly obtained from sugarcane or sugar-beet
(glucose + fructose).
* Maltose: Malt-sugar (glucose + glucose).
* Lactose: Milk-sugar (glucose + galactose).
* Starch: An insoluble carbohydrate that stores carbohydrates in plants.
* Sources: Sugars, starch, cellulose.

3.2. Fats
* Composition: Organic compounds of carbon, hydrogen, and oxygen.
* Function: Produce energy (more energy than carbohydrates, 1g fat = 9.45 Kcal
compared to 4 Kcal/g for carbohydrates). They also protect the body against rapid loss
of heat (insulation).
* Sources: Butter, oils, cream, cheese, egg yolk, meat, and fish liver oils.

3.3. Proteins
* Composition: Large chemical molecules containing carbon, hydrogen, oxygen, and
nitrogen . Nitrogen is an essential element, and some proteins also contain sulphur and
phosphorus.
* Building Blocks: Amino acids are the simple, smaller units of proteins.
* Function: Provide material for the **growth and repair of body cells and tissues**.
They can also be oxidized to release energy.
* Sources: Rich protein foods include lean meat, fish, eggs, milk, cheese, nuts, beans,
peas, lentils, and groundnuts.
* Deficiency Diseases:
* Kwashiorkor: A severe protein deficiency disease primarily affecting young
children after being weaned. Symptoms include underweight, protruding body, thin
limbs, stunted growth, loss of appetite, repeated diarrhoea, enlarged liver, and oedema
(swelling) of the face and feet.
* Marasmus: A protein-energy deficiency disease.
3.4. Roughage (Non-digestible Cellulose)
* Definition: The cell walls of all plants have cell walls made of cellulose, which
humans cannot digest.
* Role: Helps in keeping the faecal matter soft and promotes smooth bowel
movement. It aids the movement of undigested food through the intestine and
stimulates muscle contraction.
* Sources: Vegetables, fruits, corn, and cabbage.
3.5. Vitamins
* Definition: Organic compounds required in small quantities for specific bodily
functions.
* Classification:
* Fat-Soluble Vitamins:
* Vitamin A (Retinol):
* Functions: Promotes growth, resists infection, maintains good vision (forms
visual purple in retina).
* Sources: Butter, egg yolk, liver, milk, carrots, leafy green vegetables, yellow
fruit, fish liver oils.
* Deficiency: Night-Blindness (poor vision in dim light), Xerophthalmia (dryness
of the cornea and conjunctiva).
 * Vitamin D (Calciferol):
* Functions: Helps the body to use calcium and phosphorus to form bones and
teeth.
* Sources: Fish liver oils, milk, eggs, produced by ultraviolet rays in the skin.
* Deficiency:Rickets (in children, bones lack calcium and turn soft),
Osteomalacia (in adults, fractures may occur).
* Vitamin E (Tocopherol):
* Functions: Prevents oxidation of Vitamin A.
* Sources: Meat, milk, whole wheat, leafy green vegetables, especially cabbage
and spinach.
* Deficiency: Sterility, Haemorrhage.
* Vitamin K (Phylloquinone):
* Functions: Increases growth and appetite, helps in digestion and functioning
of nervous system. Note: The primary function listed in the table is for blood clotting.
* Sources: Whole grains, yeast, liver, eggs, lean meat. Note: The primary source
listed in the table is green vegetables, especially cabbage and spinach.*
* Deficiency: Haemorrhage, delayed clotting time.
* Water-Soluble Vitamins:
* Vitamin B1 (Thiamine):
* Functions: Increases growth and appetite, helps in digestion and functioning of
nervous system.
* Sources: Whole grains, yeast, liver, eggs, lean meat.
* Deficiency: Beriberi (disease marked by inflammatory or degenerative changes
of the nerves, muscles become weak).
* Vitamin B2 (Riboflavin):
* Functions: Regulates oxidation of food.
* Sources: Eggs, liver, milk, yeast, green vegetables.
* Deficiency: Irritation in eyes and skin, gastrointestinal disorders, inflammation
of the tongue.
* Vitamin B3 (Niacin):
* Functions: Promotes health of the skin and nervous system.
* Sources: Lean meat, liver, milk, eggs, groundnuts, whole grains.
* Deficiency: Pellagra (Dermatitis, skin inflammation, loss of memory,
diarrhoea, skin lesions, rashes).
* Vitamin B5 (Pantothenic acid)
* Functions: Interconversion of amino acids.
* Sources: Several foods.
* Deficiency: Fatigue, loss of coordination, skin problems, nerve disorder.
* Vitamin B6 (Pyridoxine)
 * Functions: Synthesis of haemoglobin.
* Sources: Meat, fish, eggs, cereal bran, liver, leafy vegetables.
Deficiency: Anemia (blood deficient in red blood cells), nerve disorder.
* Vitamin B11 (Folic acid):
* Functions: Normal functioning of red blood cells.
* Sources: Liver, leafy vegetables.
* Deficiency: Anemia (red blood cell formation impaired)
* Vitamin B12 (Cobalamine):
* Functions: Normal functioning of red blood cells.
* Sources: Liver, meat, milk, cereals, pulses.
* Deficiency: Pernicious anemia (a severe anaemia coupled with great weakness
and gastrointestinal disturbance, degeneration of spinal cord).
* Vitamin C (Ascorbic acid):
* Functions: Promotes functioning of capillary walls.
* Sources: Fresh citrus fruit (lemon, orange, grapefruit), tomatoes, germinating
seeds.
* Deficiency: Scurvy (spongy and bleeding gums, loosening of teeth).

3.6. Mineral Salts

* Classification:
* Macronutrients: Needed in large quantities.
* Calcium: Constituent of bone, enamel; regulates blood clotting. Deficiency:
Rickets, poor skeletal growth.
* Sodium: Regulates acid-base equilibrium; nerve impulse transmission.
Deficiency: Muscular cramps.
* Potassium: Nerve and muscle activity, fluid balance. Deficiency: Soft bone.
* Phosphorus: Bone and tooth structure; component of enzymes. Deficiency:
Increased irritability of nervous system.
* Magnesium: Component of protein and co-enzymes. Deficiency: Skin problems.
* Sulphur: Component of protein and co-enzymes. Deficiency: Muscular cramps.
* Chlorine: Water balance, HCl in gastric juice. Deficiency: Muscular cramps.
* Micronutrients: Needed in small quantities.
* Iron: Synthesis of haemoglobin.
Deficiency: Anaemia.
* Cobalt: Development of red blood cells. Deficiency: Pernicious anaemia.
* Copper: Synthesis of haemoglobin, melanin, enzymes. **Deficiency: Loss of
body weight, anaemia**.
* Zinc: Synthesis of enzymes, hormones, Vitamin A. Deficiency: Retarded growth,
skin lesions, albinism.
 * Iodine: Component of thyroid hormone. Deficiency: Goitre, cretinism.
* Fluorine: Tooth enamel and bone development.
Deficiency: Dental decay.
* Manganese: Nitrogen-metabolism. Deficiency: Poor bone development.
* Molybdenum: Nitrogen-metabolism. Deficiency: Slight retardation of growth.

3.7. Water
• Importance: Indispensable, makes up about 2/3 of body weight. It serves as a
solvent, regulates body temperature, aids in digestion and absorption, and helps
transport food.
4. Balanced Diet
* Definition: A balanced diet is one which contains all the principal constituents of
food in proper quantity.
* It is essential for growth, repair, energy, and maintenance.
* Calorie Measurement: A kilocalorie (kcal) is the unit of energy measurement. **1
kilocalorie = 1000 calories.
* Typical Calorie Requirements (per day):
* Adult labourer: 3500 kcal
* A child (about 6 years): 1800 – 2500 kcal
* An adult lying at rest: 1600 kcal
* A woman at complete rest: 1450 kcal

5. Malnutrition
* Definition: Malnutrition is the condition in which a person suffers due to lack or
deficiency of one or more essential elements of food. It implies an imbalanced diet.
* Examples of Deficiency Diseases: Kwashiorkor and Marasmus (protein/energy
deficiency). Rickets (Vitamin D/Calcium deficiency). Beriberi (Vitamin B1 deficiency).
Pellagra (Vitamin B3 deficiency). Scurvy (Vitamin C deficiency). Anemia (Iron, Vitamin
B6, B11, B12 deficiency). Goitre (Iodine deficiency). Night-blindness (Vitamin A
deficiency).

The Digestive System

The digestive system is responsible for converting the food we eat into absorbable
simple forms that can pass through cell membranes and be utilized by the body. This
process involves:
* Digestion: The breakdown of naturally occurring foodstuffs into a diffusable form.
* Absorption: The change by which food passes through cell membranes.
* Assimilation: The conversion of absorbed digested food into body material.

The digestive system consists of two main parts: the alimentary canal and digestive
glands .

I. The Alimentary Canal

The alimentary canal is a muscular tube, about 9 meters long in humans, extending
from the mouth to the anus. It includes:

1. The Mouth (Buccal Cavity)

* Function: Forms the initial part of the digestive system, where food is chewed and
mixed with saliva.
* Lips: Help in closing the mouth, sucking, speaking, and perceiving sensations.
* Tongue: A muscular organ that helps in manipulating food while chewing, mixing it
with saliva, tasting, and cleaning food particles from teeth.
* Teeth (Dentition):
* Function: Chew, bite, and cut food, breaking it into smaller pieces for easier
digestion.
* Types and Functions:
* Incisors (4 front teeth): Cutting.
* Canines (2 conical and sharp): Tearing.
* Premolars (4, two on each side): Chewing and crushing.
* Molars (6, last three teeth): Principal grinders and crushers of food. Wisdom
teeth are the last molars to appear.
* Dentition Stages and Dental Formula:
* Human child (up to 2 years): Temporary (milk) teeth, 20 total.
* Dental formula: 2,1,2,0 / 2,1,2,0 = 20 (milk teeth).
* Human adolescent (up to 17-20 years): 28 permanent teeth.
* Dental formula: 2,1,2,3 / 2,1,2,3 = 28 (permanent teeth).
* Human adult: 32 permanent teeth (with wisdom teeth added).
* Structure of a Tooth: Consists of a crown (exposed above gum) and a root
(embedded in jawbone).
* Enamel: The hardest substance, covering the crown.
* Dentine: Forms the bulk, harder than bone but not as much as enamel.
* Pulp: Soft connective tissue inside the pulp cavity, containing blood capillaries,
lymph vessels, and nerve fibres.
* Cement: Bone-like structure covering and fixing the root in position.

2. The Salivary Glands

 * Location: Three pairs of glands secrete saliva: parotid (in front of and beneath
each ear), submandibular (lower jaw), and sublingual (below the tongue).
* Saliva Composition: Contains water (about 99%), salts, mucin, and the enzyme
ptyalin (salivary amylase).
* Functions of Saliva :
* Moistens and lubricates food for swallowing.
* Acts as a solvent to stimulate taste buds.
* Cleans teeth.
* Initiates starch digestion (ptyalin converts starch to maltose).
* Helps form the bolus (food mass).

3. Swallowing and Peristalsis

* Swallowing: The tongue presses food upward and back against the roof of the
mouth; the soft palate closes the opening to the nasal passage; the epiglottis closes
the larynx, directing food into the esophagus.
* Peristalsis: Muscular contractions that push food through the alimentary canal.
* Vomiting:* Reverse muscular contraction (antiperistalsis) expelling contents from
the stomach.

4. Esophagus (Food Pipe)

* A muscular tube (about 25 cm long) connecting the pharynx to the stomach.
* Function: Transports food from the mouth to the stomach via peristalsis; it does not
produce digestive enzymes.

5. Stomach
* An elastic bag located below the diaphragm, holding 2-3 litres of food.
* Pylorus: A ring of muscles (sphincter) that controls the opening of the stomach into
the small intestine, preventing backflow.
* Gastric Juice: Secreted by glands in the stomach lining.
* Composition: Contains hydrochloric acid (HCl) and pepsinogen (inactive form of
pepsin).
* Functions :
* HCl: Kills germs, activates pepsinogen to pepsin , and provides an acidic
medium for pepsin’s action.
* Pepsin: Digests proteins into peptones and proteoses.
* Rennin (in infants): Curdles milk protein (casein).

II. The Small Intestine

The small intestine is about 7 metres long and 2.5 cm wide. It is the primary site for the
complete digestion and absorption of food.
* Divisions:
* Duodenum: Shortest (about 25 cm), C-shaped; receives bile and pancreatic juice.
* Jejunum: About 2 metres long.
* Ileum: About 4 metres long; joins the large intestine.
* Villi: The inner lining of the small intestine has millions of tiny finger-like projections
called villi, which vastly increase the surface area for absorption.

III. Digestive Glands Associated with Small Intestine

1. Liver
* The largest gland in the body, weighing about 1500 gm.
* Functions (Key Exam Points):
* Controls blood sugar by regulating excess glucose into glycogen.
* Breaks down and removes dead red blood cells.
* Synthesizes red blood cells in the embryo.
* Produces heat.
* Excretes toxic and metallic poisons.
* Detoxifies substances.
* Produces bile.
* Bile:
* Production: Produced by the liver, stored in the gallbladder.
* Composition: Contains bile salts and bile pigments (bilirubin, biliverdin).
* Functions :
* Emulsifies fats: Breaks large fat globules into smaller ones, aiding lipase
action.
* Makes the acidic food from the stomach alkaline, providing an optimal
environment for pancreatic enzymes.
* Helps in the absorption of fat-soluble vitamins.
2. Pancreas
* A mixed gland (endocrine and exocrine) located behind the stomach.
* Produces **pancreatic juice.
* Pancreatic Juice Enzymes**:
* Amylopsin (Pancreatic Amylase): Digests starch into maltose.
* Trypsin: Digests proteins and polypeptides into smaller peptides and amino
acids (activated from trypsinogen by enterokinase).
* Steapsin (Lipase): Digests emulsified fats into fatty acids and glycerol.
3. Intestinal Glands (in the Small Intestine)
* Secretes intestinal juice (succus entericus).
 * Intestinal Juice Enzymes :
* Erepsin: Digests proteins and polypeptides into amino acids.
* Maltase: Digests maltose into glucose.
* Sucrase (Invertase): Digests sucrose into glucose and fructose.
* Lactase: Digests lactose into glucose and galactose.
* Lipase: Digests fats into fatty acids and glycerol.
Absorption in Small Intestine:
* The final products of digestion (glucose, amino acids, fatty acids, glycerol) are mainly
absorbed here into the bloodstream and lymphatic system.
* Simple sugars (glucose, fructose, galactose) and amino acids are absorbed through
the villi into blood capillaries.
* Fatty acids and glycerol are absorbed into the lymph vessels of the villi.
IV. The Large Intestine
The large intestine is about 1.5 metres long.
* Divisions: Caecum, colon, and rectum.
* Functions (Key Exam Points) :
* Absorption of water: About 75% of water is absorbed here.
* Absorption of some mineral salts and undigested food.
* Temporary storage of undigested food and waste material.
* Defecation: Expulsion of undigested remnants as feces.
V. Enzymes
Enzymes are biological catalysts that speed up chemical reactions in digestion.
* Characteristics of an Enzyme (Key Exam Points):
1. Protein in nature, destroyed by heating.
2. Specific to one kind of substance (substrate).
3. Forms the same end-product(s) from the substrate.
4. Affects the rate of a chemical reaction, always speeding it up.
5. Acts as a catalyst, remains unchanged after the reaction.
6. Acts best at a particular pH (acidity or alkalinity).
7. Acts best within a narrow temperature range (typically 35°C and 40°C is optimum).

Hygiene: A Key to Healthy Life

Hygiene is defined as the science and practice of maintaining good health. It

encompasses both personal hygiene (caring for one’s body) and social hygiene (caring
for surroundings).

I. Simple Personal Hygiene

The major aspects of personal hygiene include **cleanliness, physical exercise, rest
and sleep, and healthy habits. Personal cleanliness is most essential.

* Cleanliness Practices:
* Hands and Skin: Must be cleaned regularly. Wash hands with soap after using
toilets. Daily bathing keeps skin clean, removes dead cells, and opens sweat pores.
Undergarments and handkerchiefs should be washed daily.
* Hair: Kept clean by frequent washing and regular combing.
* Teeth and Mouth: Clean teeth at least twice daily (before bed and after meals).
Mouth should be washed after every meal. Excessive sweets can lead to dental caries
and gum infections.
* Nose: Always breathe through the nose. Use a handkerchief when blowing the
nose or sneezing.
* Eyes: Cleanse with clear water 2-3 times daily. Never share towels to prevent
spread of infections like trachoma and conjunctivitis.
* Ears: Keep clean. Wax can be cleaned with a soft moist swab. **Never put sharp
pointed objects into the ear.
* Physical Exercise: Essential for all age groups, improving blood circulation.
* Rest and Sleep: Adequate rest, especially sleep, is crucial for the brain and body.
Adults typically need 6-7 hours of undisturbed sleep.

II. Healthy Habits

* Maintain regular timings for meals and sleep.
* Bowels: Clear bowels daily, preferably in the morning.
* Avoid: Tobacco (injurious to health, may cause cancer), stimulants, sedatives, and
alcoholic beverages.
* Living Rooms: Should be well-ventilated with fresh air and sunlight.

III. Social Hygiene and Sanitation

* Public Places: Schools, offices, bathrooms, and cinema halls must be kept clean.
* Eating Places: Hotels, restaurants, and their surroundings should be clean and free
of flies. All utensils should be thoroughly washed with soap and hot water.
* Waste Management: Public drains and garbage must be covered and disinfected
(e.g., with bleaching powder).
* Municipal Bodies: Responsible for providing clean, germ-free drinking water and
efficient sewage disposal.

IV. Control of Disease-Carriers (Vectors)

*Vectors are agents (animals/insects) that transmit diseases. Mosquitoes and
cockroaches are prioritized for control.
* Housefly (Public Enemy No. 1): Spreads diseases like dysentery, cholera, typhoid,
and hepatitis.
* How it spreads disease: Its hairy body and legs pick up filth and germs. It vomits
(regurgitates) food (saliva) which is then contaminated. It deposits excreta while
feeding, further contaminating food. Sometimes directly conveys infection (e.g.,
trachoma).
* Control Methods:
1. Elimination of breeding places: Regular removal and covering of house refuse,
animal, and human excreta.
2. Spraying: Houses and breeding places with DDT or other insecticides.
3. Avoidance: Keep food protected and covered. Prevent flies from sitting on body;
use baby umbrellas for sleeping babies.

* Mosquitoes:
* Anopheles mosquito transmits malaria (caused by *Plasmodium* protozoan).
* Culex mosquito transmits elephantiasis (filaria, caused by *Wuchereria* worm).
* Aedes mosquito transmits yellow fever and dengue .
* Control Methods:
1. Spraying: Adult mosquitoes with DDT/insecticides.
2. Elimination of breeding places: Fill small ponds and puddles.
3. Spraying stagnant water: Use kerosene or oily film to kill larvae and pupae.
4. Biological control: Introduce fish like Gambusia which eat mosquito larvae.

* Cockroaches: Common household pests, found in plumbing, manholes, sewers,

kitchens, cupboards. Suspected carriers of viral diseases. Controlled by spraying
insecticides.
* Rats: Serious domestic pests that eat grains and food. Spread germs of certain
diseases, notably plague (carried by rat-flea). Controlled by trapping or raticides.

V. Common Water-borne Diseases

These diseases result from using **unpurified water**. **Contamination refers to the
unwanted entry of disease germs into drinking water or edible foods.

* Main Forms: Cholera, typhoid, dysentery, hepatitis.

* Sources of Contamination:
* Improperly disposed sewage.
* People defecating or urinating near water bodies.
 * Animal wastes from dairies/poultries.
* Industrial wastes (e.g., mercury causing nervous system abnormalities; tannery
wastes with anthrax bacilli; pesticides like DDT, which are serious water pollutants and
can cause cancer).
* Fluorides in drinking water can cause tooth/bone disorders.

* Cholera:
* Caused by the bacterium Vibrio cholerae.
* Symptoms: Sudden onset of sickness, severe diarrhoea and vomiting , no urination
(due to water shortage), and accumulation of urea in blood, which can be fatal.
* Infection occurs through contaminated water and food.

* Dysentery: Two forms:

1. Bacillary Dysentery (Shigella): Caused by a bacterium . Common among children.
Symptoms: Loose motions (diarrhoea), intestinal pain, mild fever. Treated with
antibiotics.
2. Amoebic Dysentery (Entamoeba histolytica): Caused by a protozoan.
* Hepatitis:
* Meaning: Inflammation of the liver.
* Types: Hepatitis A, B, and C.
* Hepatitis A (infectious hepatitis) is transmitted through contaminated water.
* Hepatitis B and C are transmitted through blood and body fluids.
* Symptoms: Body ache, yellowish/deep yellow urine (due to bile pigments),
enlarged liver.
* Prevention: Hepatitis vaccine, proper hygiene, avoiding fatty substances.

Diseases – causes and control

1. What is a Disease?

A disease is a condition in which the normal functioning of the body is disturbed,

causing an abnormal structural or functional disorder. Diseases can vary in severity,
from minor discomforts to life-threatening conditions. Early beliefs attributed diseases
to divine or evil spirits, but modern science focuses on identifiable causes, allowing for
prevention and control.

2. Categories of Diseases

Diseases can be categorised in several ways:

• Based on Extent of Occurrence:

 o Endemic: Found in a certain area, affecting a few people, e.g., yellow fever
in African countries, goitre in sub-Himalayan regions.
o Epidemic: Breaks out and spreads quickly to affect a large number of
people at the same time, e.g., plague in India (1994).
o Pandemic: Widely distributed worldwide, e.g., AIDS.
o Sporadic: Scattered individual cases of a disease, e.g., malaria and
cholera.
• Based on Communicability:
o Non-communicable or Non-infectious Diseases: These diseases are not
caused by germs and cannot spread from person to person by contact or
any other method. Examples include diabetes, colour blindness, heart
attack, beri-beri, cancer, mental illness, allergies, degenerative
diseases, and physical/chemical causes.
o Communicable or Infectious Diseases: These are caused by germs
(pathogens) and can spread from one person to another. The spread is
called infection. The time between germ entry and symptom appearance is
the incubation period.

3. Causes of Diseases

Communicable diseases are caused by various pathogens:

• Bacteria (e.g., Cholera, Typhoid, Tuberculosis, Diphtheria, Whooping Cough,

Pneumonia, Leprosy, Gonorrhoea, Tetanus, Syphilis).
• Viruses (e.g., AIDS, Chickenpox, Hepatitis, Poliomyelitis, Common cold,
Influenza, Smallpox, Mumps, Rabies).
• Protozoa (e.g., Malaria, Amoebic dysentery, Sleeping sickness).
• Helminths (worms) (e.g., Ascariasis, Taeniasis, Filariasis).

Diseases can be transmitted through different agents:

• Water-borne: Cholera, Typhoid.

• Food-borne: Cholera, Amoebic dysentery, Typhoid, Tapeworm.
• Air-borne (droplet infection): Tuberculosis, Diphtheria, Whooping Cough,
Pneumonia, Chickenpox.
• Insect-borne: Malaria (mosquito), Filariasis (mosquito), Sleeping Sickness
(tsetse fly).
• Sexual contact: AIDS, Syphilis, Gonorrhoea.
• Contaminated blood/needles: AIDS, Hepatitis.
• Direct contact: Leprosy, Pneumonia, Chickenpox.
• Mother to child: AIDS.
4. Key Infectious Diseases for Exam

This section summarizes specific diseases with their causative agent, incubation
period, mode of transmission, key symptoms, and prevention/control:

• Cholera:
o Agent: Vibrio cholerae (bacterium).
o Incubation: Few hours to 6 days.
o Transmission: Contaminated water and food (faeco-oral route), flies.
o Symptoms: Severe watery diarrhoea, vomiting, dehydration, muscle
cramps.
o Prevention: Proper sanitation, safe drinking water, cooked food, anti-
cholera injection.
• Typhoid Fever:
o Agent: Salmonella typhi (bacterium).
o Incubation: 7-21 days.
o Transmission: Contaminated water, food, and milk; flies.
o Symptoms: High fever, headache, rose-red rash on chest/abdomen,
constipation then diarrhoea.
o Prevention: Anti-typhoid vaccination, proper sanitation, clean water.
• Tuberculosis (TB):
o Agent: Mycobacterium tuberculosis (bacterium).
o Incubation: 2-10 weeks.
o Transmission: Air (droplets from cough/sneeze), contaminated food.
o Symptoms: Persistent cough (often with blood), fever, body pain, weight
loss, night sweats.
o Prevention: BCG vaccination, proper sanitation, good nutrition.
• Malaria:
o Agent: Plasmodium (protozoan).
o Incubation: 3 days to 4 weeks.
o Transmission: Bite of infected female Anopheles mosquito.
o Symptoms: Recurrent chills and fever (malaria attacks), sweating.
o Control: Mosquito control (spraying insecticides, mosquito nets,
repellents).
• Amoebic Dysentery (Amoebiasis):
o Agent: Entamoeba histolytica (protozoan).
o Incubation: 1 day to over a month.
o Transmission: Contaminated food/water (faecal-oral route), flies.
o Symptoms: Inflammation of large intestine, severe diarrhoea with blood
and mucus (dysentery).
o Prevention: Proper sanitation, food/water hygiene.
• AIDS (Acquired Immunodeficiency Syndrome):
o Agent: HIV (Human Immunodeficiency Virus).
o First identified: USA in 1981.
o Impact: Damages the body's immune system.
 o Incubation: The period between infection and symptoms can be 10-12
years or more.
o Transmission:
▪ Sexual intercourse with an infected person.
▪ Contaminated blood transfusion.
▪ Sharing infected needles/syringes (e.g., among drug users).
▪ From infected mother to child during pregnancy, birth, or
breastfeeding.
o NOT Transmitted by: Contact with clothes, shaking hands, eating together,
sharing bathrooms, coughing/sneezing.
o Prevention: Avoiding high-risk behaviours, ensuring safe blood
transfusions, not sharing needles.
• Chickenpox:
o Agent: Varicella Zoster virus.
o Incubation: 12-18 days.
o Transmission: Direct contact, droplet infection.
o Symptoms: Itchy rash, fever, blisters.
o Treatment: Bed rest, calamine lotion.
• Diphtheria:
o Agent: Corynebacterium diphtheriae (bacterium).
o Incubation: 2-10 days.
o Transmission: Droplet infection (coughing, sneezing).
o Symptoms: Sore throat, skin ulceration, fever, rash.
o Prevention: DPT vaccine.
• Whooping Cough (Pertussis):
o Agent: Haemophilus pertussis (bacterium).
o Incubation: 10-15 days.
o Transmission: Contact, droplet infection.
o Symptoms: Severe bouts of coughing ending in whoop sound, vomiting.
o Prevention: DPT immunization.
• Tetanus:
o Agent: Clostridium tetani (bacterium).
o Incubation: 4-20 days.
o Transmission: Through cuts or wounds in skin, especially from soil.
o Symptoms: Muscle spasms, lockjaw.
o Prevention: Immunization, anti-toxin in case of wounds.
• Syphilis:
o Agent: Treponema pallidum (bacterium).
o Incubation: 1-12 weeks.
o Transmission: Sexually transmitted.
o Symptoms: Sores, skin lesions.
o Prevention: Avoid sexual contact.
• Ascariasis (Roundworm):
o Agent: Ascaris lumbricoides (helminth).
o Transmission: Contaminated food/water (eggs from faeces).
 o Symptoms: Abdominal pain, malnutrition.
o Prevention: Personal hygiene, proper disposal of faeces.
• Taeniasis (Tapeworm):
o Agent: Taenia solium (pork tapeworm), Taenia saginata (beef tapeworm).
o Transmission: Eating undercooked infected pork or beef.
o Symptoms: Mild abdominal pain.
o Prevention: Thoroughly cook meat.
• Filariasis ('Elephantiasis'):
o Agent: Wuchereria bancrofti (helminth).
o Transmission: Mosquito bite (Culex mosquito).
o Symptoms: Swelling of limbs and lymph vessels due to lymph circulation
blockage.

5. Important Concepts for Exam

• Incubation Period: The time interval between the entry of germs into the body
and the appearance of the first symptoms of the disease. Specific incubation
periods for various diseases are crucial (refer to Table 16.1 in the sources).
• Pathogens: Disease-causing organisms, including bacteria, viruses, protozoa,
and helminths.
• Vector: An organism that transmits a pathogen from host to host (e.g.,
mosquitoes for malaria/filariasis, tsetse fly for sleeping sickness).
• Prevention and Control: Emphasizes hygiene, sanitation, vaccinations, vector
control, safe food/water practices, and avoiding risky behaviours.

6. Distinction between Viruses and Bacteria

Feature Viruses Bacteria

Very small (visible only by Larger (can be seen by light

Size
electron microscope) microscope)

Cellular
Non-cellular Single-celled
Structure

Metabolism No metabolism Have metabolism

Grow in size and divide to produce

Growth/Division Do not grow and do not divide
more bacteria

Crystallization Can be crystallized Can be crystallized

Command the host cell to

Reproduction Self-reproduce
produce viruses
 All produce diseases in man, Some harmful, some useful and
Disease Causing
animals or plants some disease producing