Digestive system

Balanced diet
A diet that contain all of the required nutrients in suitable proportions and the right amount
of energy

Nutrient Sources Importance

Carbs Grains, fruits, vegetables Energy source

Fats Nuts, seeds, oils, fatty fish Energy, vitamin absorption

Proteins Meat, fish, eggs, legumes Tissue growth/repair

Collagen synthesis, immunity (deficiency can

Vitamin C Citrus fruits, bell peppers
cause scurvy

Bone health, immune function (deficiency can

Vitamin D Sunlight, fatty fish, eggs
cause rickets)

Calcium Dairy, leafy greens, tofu Bone health, muscle function

Iron Red meat, lentils, spinach Oxygen transport

Fibre Whole grains, fruits, vegetables Prevents constipation

Water Drinking water, fruits, veggies Hydration, nutrient transport

Human digestion

Ingestion takes place in the mouth, it

means taking of substances, e.g. food and
drink, into the body

digestion – the breakdown of food

absorption – the movement of nutrients

from the intestines into the blood

assimilation – uptake and use of nutrients

by cells

egestion – the removal of undigested food

from the body as faeces
 Types of digestion
1. Physical digestion - It is the breakdown of food into smaller
pieces without chemical change to the food molecules. This
causes the surface area of the food molecules to increase,
making it easier for the enzymes to act on it. There are 4
types of human teeth. Incisor and canines are used to bite
and tear the food. Whereas, Molar and premolars are used
to grind the food. Stomach converts large pieces of food to
smaller ones by churning movement. Bile is used in
emulsifying fats and oils to increase the surface area for
chemical digestion
2. Chemical digestion – It is the break down of large insoluble molecules into small
soluble molecules. Enzymes are used in chemical digestion. In the stomach, the
enzyme pepsin acts. This enzyme require acidic conditions which are provided by
HCL (pH - 2). HCL also kills any microorganisms in the food. Bile is used to convert
the food molecules form acidic to alkaline for other enzymes to act on it. The table
below will show all enzymes and its product

Enzyme Substrate Product(s)

Amylase Starch Maltose, glucose

Lipase Fats (triglycerides) Fatty acids, glycerol

Protease Proteins Peptides, amino acids

Lactase Lactose Glucose, galactose

Maltase Maltose Glucose

Trypsin Proteins Smaller peptides

Villi
Villi is a finger like projection that line the inner surface of small intestine. Each villus is
covered with microvilli causing the surface area to increase massively. Villi has a outer
layer called Epithelium made with epithelial cells and
microvilli. There are goblet cells present which
secrete mucus, this structure traps pathogens and
lubricate the surface . The core is made up of a
network of blood vessels and lacteal. Blood vessels
are used to absorb water-soluble nutrients like amino
acids, sugars and vitamins. Lacteals absorb fat-
soluble nutrients like fatty acids and glycerol, these
are carried through the lymphatic system before
entering the bloodstream.
 Circulatory System
Different types of circulatory systems
There are 2 types of circulatory systems, Single an double circulatory system.

The advantages of double circulatory systems system compared to single

It has a muscle know as septum separating oxygenated and deoxygenated blood
Blood flows in high pressure
Transport of oxygen to the cells is more efficient
Enhanced metabolic rate
Efficient removal of waste products

The heart
The deoxygenated blood enters through the vena cava and
moves towards the right atrium. The atrioventricular valve
contract then the deoxygenated blood flows towards the right
ventricle from the right atrium. The atrioventricular valve
relaxes and the semilunar valve contract, causes the
deoxygenated blood flow towards the lungs through
pulmonary artery. In the lungs gas exchange takes place. Then
the semilunar valve contract allowing the oxygenated blood to
flow through the pulmonary vein. The semilunar valve relax
and the atrioventricular valve contract , allowing the
oxygenated blood to move form the left atrium to the left
ventricle. Then the oxygenated blood goes to the rest of the
body through the aorta.

The reason why the left side of the heart has muscular walls as it needs to pump blood at high
pressure. Both ventricles has strong walls as it needs to pump blood but the left one has stronger
walls.

Blood Vessel Type Function Adaptations

- Thick, elastic walls to withstand high pressure

Arteries Carry blood away from the heart - Narrow lumen to maintain high pressure

- Elastic fibers to allow for stretching and recoiling

- Thinner walls than arteries, with less elastic tissue

Veins Carry blood to the heart - Wider lumen to accommodate larger volumes of blood

- Valves to prevent backflow of blood

- One-cell-thick walls for easy diffusion of substances

Exchange of nutrients, gases, and
- Extensive branching to increase surface area for exchange
Capillaries waste products between blood
and tissues - Narrow lumen to slow down blood flow and allow for efficient
exchange

Valves like the semilunar and the atrioventricular ones are used to prevent backflow of blood

The activity of the heart can be measure in the following ways –

 • By measuring the pulse rate
• Using an ECG
• Listening of sounds of valves closing

Coronary heart disease is caused by the blockage of the coronary artery. A

coronary artery is the blood vessel that provides the heart with blood to
function. When the cholesterol deposit in the coronary artery, it causes the
lumen to narrow causing the blood pressure to increase. We can prevent
CHD by having a good diet with less of fat, daily exercising. This can be
caused by genetics, age, sex or smoking.

Blood vessel

Organ Main Arteries Main Veins Hepatic portal vein is from

the small intestine to the
Lungs Pulmonary Arteries Pulmonary Veins liver

Liver Hepatic Artery Hepatic Vein, Hepatic Portal Vein

Kidneys Renal Arteries Renal Veins

Blood contents
Substance Function There are 2 types of white
blood cells
Transport oxygen from the lungs to body tissues and carry carbon
Red Blood Cells lymphocytes – antibody
dioxide back to the lungs for exhalation.
production
White Blood Cells Defend the body against infections and foreign invaders.
phagocytes – engulfing
Platelets Play a crucial role in blood clotting and wound healing. pathogens by phagocytosis

The liquid component of blood that transports nutrients,

Plasma
hormones, waste products, and other substances.

 Lymphocyte

 Phagocyte
Red blood cells have a biconcave shape, this would increase the surface area. They don’t contain a
nucleus or mitochondria which helps them to store millions of hemoglobin molecules. They are 1
cell thick so they can fit in capillaries

When a blood vessel is damaged, platelets are activated. Then the soluble fibrinogen is converted
into insoluble fibrin. This insoluble fibrin form a mesh like structure, to trap the red blood cells and
to seal the wound. This would prevent entry of pathogens into the body.

Respiratory system
Gas exchange
Gas exchange occurs in the lungs and the alveoli does the job

The features include

• Large surface area

• Thin surface
• Good blood supply
• Good ventilation of air
Inspiration occurs when you breath in. This causes the volume in the thorax to increase
and the pressure to decrease. The internal
intercostal muscles contract and the external ones
relax. This whole process causes the rib cage to
raise.
Expiration occurs when you breath out. This causes
the volume in the thorax to decrease and the
pressure to increase. The internal intercostal
muscles relax and the external ones contract. This whole process causes the rib cage to
lower.
Function of cartilage Function of Tracea

• Prevents the air way from collapsing • Voice production

• Provides structural support • Filtration of air
through mucus as it
can trap dust particle

When you exercise a lot the breathing rate would increase, this is because cells would carry out
more respiration to provide the body with energy. The body would require more oxygen in this case.
If the body is not provide with enough oxygen, anerobic respiration takes place in the muscles. This
would produce lactic acid. The brain would detect the increased concentration of lactic acid and
increase the breathing rate. This process is known as oxygen dept

Substance Inspired air (%) Expired air (%)

Oxygen 21 16
Carbon dioxide 0.04 4
Water vapour Variable Usually high

Uses of energy
 • Cell division
• Growth
• Protein synthesis
• Active transport

Yeast carries out anerobic respiration. This type of respiration doesn’t require oxygen. If we increase
the temperature significantly, this would cause the yeast to die.

Factors Anaerobic Aerobic

Chemical reactions Break down glucose to release energy
Oxygen requirement No Yes
Equation C6 H12 O6 → 2C2 H5 OH + 2CO2 C6 H12 O6 + 6O2 → 6CO2 + 6H2 O
Energy released Less More

Nervous and endocrine system

Nervous system
There are 2 types of nervous system that transfer electrical impulse through neurons. Both are used
for coordination and regulation of body functions

• Central nervous system (CNS) – Brain and spinal cord

• Peripheral nervous system (PNS) – Everything except the brain and spinal cord

A simple reflex arc is a means of automatically and rapidly integrating and coordinating with stimuli
with the response of effectors

For example – When you accidently burn your tip of the finger

When you burn your finger, the receptor detects the heat and
sends signals via sensory neurons to the spinal cord. Relay
neurons transmit the signal to motor neurons, which cause
the effector muscles in your hand to contract and pull away.
The pain signal then reaches your brain, making you aware of
the burn. The muscle is known as an effector

A synapse is a junction between 2 neurones

When a an impulse stimulates the release of neurotransmitter molecules

from the vesicles into the synaptic gap. The neurotransmitter molecules
diffuse across the synaptic gap. After reaching the other end, They bind
with the receptor proteins on the next neurone. This causes an impulse to
be stimulated in the next neurone

The synapse would ensure the impulse travel in a single direction only

Sense organs
Sense organs are groups of receptor cells responding to specific stimuli
 contains light receptors
refracts light

controls how much

light enters the pupil

focuses light on to the retina carries impulses to

the brain

When the room is bright or you are exposed to bright light, your circular muscles
present in you eyes would contract and the radial muscles would relax. This
would cause less light to enter your eyes. In the complete opposite situation,
the radial muscles would contract the circular ones would relax. This would
allow more light to enter your eye. Both of these muscles are considered to be
antagonistic. The whole process is known as pupil reflex.

When an object is away from you, to see it your suspensory ligaments tighten and
your ciliary muscles relax. This causes the Lense to pull thin and the light is
refracted more. When the object is near you the muscles switch their roles and the lens is allowed to
bulge, causing less refraction of light

Rod and cone cells

• Rods are more sensitive to dim light. They are located in most of regions of the retina (except
fovea and blind spot)
• Cones are sensitive to bright light. The highest number of cone cells are found in the fovea
(none in the blind spot)

Homeostasis
Homeostasis as the maintenance of a constant internal environment. One of the examples
of it is to control the level of blood sugar in your body.
A set point is a given point of a condition in your body that is described as the perfect
requirement for the body
• On a hot day vasodilation occurs when the body needs to lose heat. This process is when the
surface capillaries widen allowing heat to
escaped form the body. This would cause a
cooling effect. The surface hair lay flat as the hair
erector muscle would relax and the body sweats
to lose as much heat as possible.
• On a cold day vasoconstriction is when the
surface capillaries present narrow causing the
heat to remain inside the body. You would start
shivering causing heat to build up in the body.
The surface hair would lie up as the hair erector muscle would contract reducing heat loss
from the body.

Type 1 diabetes occurs when the body cannot produce insulin to control the blood sugar level.
This can cause blurred vision and a high breathing and heart rate. To solve this issue, people are
injected with insulin injections.

Endocrine system
 A hormone is a chemical substance, produced by a gland and carried by the blood, which alters
the activity of one or more specific target organs.

Hormone Function Site of Production

Insulin Regulates blood glucose levels by facilitating the uptake of glucose into cells. Pancreas

Glucagon Raises blood glucose levels by promoting the release of glucose from liver stores. Pancreas

Adrenaline Increases heart rate, blood pressure, and energy supply during the "fight or flight" response. Adrenal glands

Testosterone Regulates male reproductive system and secondary sexual characteristics. Testes

Oestrogen Regulates the female reproductive system and secondary sexual characteristics. Ovaries

The brain controls the function of these hormones

Condition Nervous Endocrine

Information transmission Electrical impulse Chemicals
Travel speed Fast Slow
Effect time Short Long
Transmitted along Neurons Blood plasma

Gravitropism is a response in which parts of a plant grow towards or away from gravity

Phototropism is a response in which parts of a plant grow towards or away from the direction of the
light source

Auxin is used to control the growth of the shoot. The whole process starts when the auxin is made
on the tip of the shoot. It diffuses form the plant to the shoot tip. It is unequally distributed in
response to light or gravity. This causes cell elongation

Reproductive system
Asexual reproduction
Asexual reproduction is a process resulting in the production of genetically identical offspring from
one parent

Advantages of asexual reproduction Disadvantages of asexual reproduction

Rapid population growth Lack of genetic diversity

Energy efficient Cannot survive in different
Uniform crop production environments
Suspectable to diseases

Sexual reproduction
Sexual reproduction is a process involving the fusion of the nuclei of two gametes to form a zygote
and the production of offspring that are genetically different from each other

Fertilisation is known as the fusion of gametes

Advantages of sexual reproduction

Increases genetic diversity

Enhanced survival skills
 Can conduct breeding programs

Disadvantages of sexual reproduction

Is energy and time consuming

Fewer offsprings
Variable offspring

Sexual reproduction in plants

Captures pollen grains Used to attract insects

Connects the stigma to the ovary Production of pollen grains

Site of fertilisation Support the anther

Hold the organs present

They provide support to the plant

Condition Wind-pollinated Insect-pollinated

Pollen Large amounts, small in size Sticky pollen grains
Anthers Inside Outside
Scent, Nectar and petals None Yes all
Stigma Inside the flower Outside the flowers (large)

The pollen grains transfer from the anther to the sigma. Once the stigma has detected the pollen
grains a pollen tube starts to form. This tube connects the stigma with the ovary. Once the pollen
grain. Fertilisation occurs in the ovary where the pollen grain fuses with the ovule to form a seed.

Self-pollination –

• Transfer of pollen grains from the anther of the flower to the stigma of the same flower or a
different flower on the same plant
• Low Genetic Variation
• Less dependent on pollinators

Cross pollination –

• Transfer of pollen grains from the anther of a flower to the stigma of a flower on a
different plant of the same species
• High genetic variation
• Highly dependent on pollinators but not dependent on windy conditions

Sexual reproduction in humans

Stores urine

Carries urine Produces semen. Provides

nutrition to the sperm

Organ used to deliver sperm They produce sperm and

testosterone
 They produce the egg
Transports eggs from the ovaries to
the uterus
The location where the
fertilized egg implants

Acts as a gateway between

the uterus and the vagina

A passage for menstrual flow, sexual

intercourse and child birth

Sperm Egg
Has flagellum to move Large energy stores
Has acrosome to move through the jelly coating Jelly coating to allow limited number of sperms
Too many mitochondria to provide with energy
Many are released Only one is released every month

During a sexual intercourse, sperm is ejected from the male’s penis into the female’s vagina. The
sperm travels through the cervix and uterus where it meets the egg in the oviduct. When both the
egg and the sperm meet together, they fuse to form a zygote this process is known as fertilization.
Eventually the zygote forms a ball of cells which implants into the lining of the uterus.

Both are used in exchange of nutrients form the

mother to the fetus. Some pathogens can pass
through the placenta form the mother to the
fetus

The menstrual cycle is a monthly process that prepares the female body for
pregnancy, regulated by several hormones. It starts with menstruation and is
followed by the follicular phase, where the pituitary gland releases FSH to
stimulate the growth of an egg in the ovary. The maturing follicle produces
oestrogen, which thickens the uterus lining. Around day 14, hormone LH
triggers ovulation, releasing the mature egg. The follicle is converted into a
corpus luteum secretes progesterone to maintain the uterine lining. If
fertilization does not occur, the corpus luteum breaks down, leading to a
drop in progesterone levels and the start of a new menstrual cycle.

Sexual transmitted diseases

Sexually transmitted infection (STI) as an infection that is transmitted through sexual contact

HIV is a pathogen that can cause STI. HIV can cause AIDS

How can STIs be controlled

• Make use of condoms or any other barrier protection

• Raise awareness regarding this issue
• Always use a brand new needle when taking blood form the body (Not from STI)
 Genetics and variation
Inheritance
Inheritance is known as the transmission of information from generation to generation

Gene is a length of protein that codes for a DNA

Allele is known as an alternative form of gene

DNA is used to control the function of the cell by controlling the production of proteins

The process by which proteins are made –

• The gene that codes for the protein remains in the nucleus
• The mRNA is a copy of the gene
• The mRNA molecules made in the nucleus is transported through the cytoplasm
• The ribosomes assemble the amino acid based on the sequence of the mRNA to create the
protein molecule

A diploid nucleus contains 23 pairs of chromosomes whereas a haploid nucleus only contains 23
chromosomes

Mitoses is known as nuclear division where genetically identical cells are made. During the process
the copies of the chromosomes would separate maintaining the same chromosomes number in
every cell

Meiosis is also known as reduction division. During this process the chromosomes number is
halved form a diploid to haploid, this would result in genetically different cells

Stem cells are known as unspecialised cells that divide by mitosis to produced daughter cells that
are specialised

Genotype It is the genetic make up Punnett square

Phenotype It is the observable features
Heterozygous 2 different alleles (Ff)
Homozygous Both are the same allele (FF or ff)

Remember the capital letter will always represent the

dominant allele

Codominance is when both alleles in heterozygous organisms contribute to the phenotype

One of the most used examples for codominance is blood groups

Sex-linked characteristic as a feature in which the gene responsible is located on a sex

chromosome and that this makes the characteristic more common in a specific gender.

One of the most used examples for sex-linked characteristic is red-green colour blindness

Variation and Selection

Variation is known as the differences between individuals

Continuous variation would mean that there are a range of results ( mass, length). It is caused both
by genes and the environment

Discontinuous variation would mean that there are a limited number of results ( blood group, shape
of peas). It is only caused by the genes

Mutation is a genetic change caused by the change in the sequence of the bases. This would cause
new alleles to form. This is caused by some chemical changes and ionizing radiation
 An adaptive feature allows an organism to survive in certain condition

• Xerophytes – 1. Reduced leaves to needles 2. Thick cuticle 3. Deep root system

• Hydrophytes – 1. Large number of stomata 2. Thin cuticle 3. Reduced root system

All about environment

Food chains
The sun is the principle source of energy input

A food chain can be used to resemble the energy transfer to different organisms

Trophic level Name

1 Producer
2 Primary consumer
3 Secondary consumer
4 Tertiary consumer
5 Quaternary consumer

Secondary consumer

Primary consumer

Pyramid of biomass

Producer

Note that a pyramid of biomass will always be in the shape of a pyramid

Pyramid of numbers

Pyramid of energy

The energy decreases as we go up a trophic level. This is because energy is consumed and lost to
the environment meaning the next organism (the predator) would not receive complete energy from
the prey. This is the main reason there are not above 4 trophic levels in a food chain
 Advantages of using a pyramid of energy Advantages of using a pyramid of
biomass compared to one with
numbers
Are universally accepted Can easily see the loss in energy
Accurate representation Can illustrate the amount of food available
Better to compare different eco systems Accurate representation of the ecosystem

Nutrient cycles and population

Carbon cycle

Nitrogen cycle

Done by nitrogen
fixing bacteria or
lightning

Microorganisms are used for decomposition, nitrification, nitrogen fixation and denitrification

A population is a group of organisms of one species living in the same area

A community is a population of different species

Factors affecting rate of population growth-

• Food supply
• Competition
• diseases
The face when the birth rate is equal to
the death rate. This is time when there
are limited resources
 The face when the death
rate is greater than the
birthrate (extinction of
species)

This is the face when

organisms are getting used
to the conditions The face when the birth rate
is greater than the deathrate.
Meaning the rate of
reproduction is high

Food supply and consequences of pollution

Ways to increase food production

• Agricultural machinery to improve efficiency

• Chemical fertilizers to improve yield
• Insecticides to improve the quality of yield
• Selective breeding to improve production of crops

Large-Scale Monoculture of crop plants

Advantages Disadvantages
Can focus on high market demand Soil degradation
More efficient Disease risk
More cost effective Reduced biodiversity

Intensive livestock production

Advantages Disadvantages
High yield Animal welfare concerns
Cost effective Can lead to antibiotic resistant bacteria
Consistent supply Requires a lot of resources like water

Biodiversity is the number of species living in that area

Reasons for habitat destruction

• Increased area for housing

• Extraction of natural resources
• Marine pollution

Habitat destruction would mean that the home of the animals is destroyed. Due to this a disrupt in
the food chain would be caused. A disrupt in the food chain can cause species to be endangered or
even extinction, reducing the biodiversity. Deforestation can cause loss of soil, flooding and high
carbon dioxide concentration in the atmosphere. Pollution in the air can have several
consequences like climate change and enhanced green house effect. Also, plants can provide
vulnerable resources to us that can be used to create medicines.
Eutrophication is caused when excess of fertilisers applied on plants ends up in the water. Due to
this plants inside the water grow making them increase in numbers. When these plants dies they
decomposed by decomposers. Due to aerobic respiration by the decomposers there in a reduction
in dissolved oxygen leading to the death of organisms present in the water.

How to reduce eutrophication

• Control the use of fertilisers, do not apply in excess

• Do not apply before it is about to rain

Conservation

A sustainable resources is one which is produced as rapidly as it is removed from the environment

How can endangered species be conserved

• Monitor ad protecting species

• Education
• Seed banks
• Captive breeding programs

How forest can be conserved

• Education
• Protected areas
• Replanting plants

How fish stocks can be conserved

• Education
• Closed seasons
• Mesh size
• Monitoring

In vitro fertilisation (IVF) Artificial insemination (AI)

Both the egg and the sperm is collected Semen collected form a male
The eggs are fertilised with sperm It is store for later use
The embryo formed is implanted into the Introduced to the female
uterus

Biotechnology and Genetic modification

Yeast can be used to make ethanol and bread Can be made due to the
ethanol produced and the co2
given out allowing the bread
Used as a fuel to rise
Used as a solvent

Pectinase is used in fruit juice production to make it clear

Biological washing powers contain enzymes which are used to remove different substances from
clothes like starch, proteins and fats

Lactase is used to produce lactose free milk

 A fermenter can be used to produce useful products such as insulin, penicillin and mycoprotein. A
fermenter has to be controlled, the temperature of it should be kept constant otherwise it can
affect enzyme activity. It is also important to maintain the pH of the fermenter as it can affect
enzyme activity. Other factors like oxygen and nutrition supply should be provided as it can be
important for product formation.

What are uses of Genetic modification

• To make human proteins

• To make crops resistant to herbicides
• To make crops resistant to insects
• To increase the nutritional value of the crops

The process of producing a human protein is to first isolated the DNA making the human gene by
cutting them using restriction enzyme. Using the same enzyme cut the plasmid DNA forming
complementary sticky ends. Combine both of the sticky ends to form a recombinant plasmid by
joining them using DNA ligase enzyme. The bacteria would be placed in the fermenter to duplicate.\

Genetically modified crops

Advantages Disadvantages
Increased yield Pest can develop a resistance against the crop
Can make them pest resistant Ethical and safety concerns
Can improve the nutritional content Economic issues

All about plants

Types of plants
Plants can be divided into several sections –

1) Mono and dicotyledons

Feature Monocots Dicots

Number of Cotyledons One Two

Leaf Venation Parallel veins Net-like veins

Flower Parts Multiples of three Multiples of four or five

Root System Fibrous roots Taproot system

Vascular Bundles Scattered Arranged in a ring

Pollen Structure Single pore or furrow Three pores or furrows

2) Ferns and flowering plants

Photosynthesis and structure of the leaf

Photosynthesis is a process by which plants synthesise carbohydrates from raw materials using the
energy from sunlight

The word equation of it - carbon dioxide + water → glucose + oxygen

The balanced chemical equation of it - 6CO2 + 6H2 O → C6 H12 O6 + 6O2

 The light is captured using a green pigment called chlorophyll

Uses of carbohydrates in plants –

• Starch as an energy source

• Cellulose to build cell walls
• Sucrose for transportation
• Nectar to attract insects

Plants require specific mineral ions like magnesium and nitrates. Magnesium is required for making
chlorophyll, deficiency of it would cause the leaf to look yellow. Nitrate are required for growth as
they make amino acids, deficiency of it would cause the plant to look short

A limiting factor is a substance that can cause a change in rate of something.

In this graph shown till point B light intensity is classified as a

limiting factor as when it increases the rate of photosynthesis
also in crease. After point B light intensity is no longer a
limiting factor as it does not affect the rate of photosynthesis
even though it is in creasing

A waxy layer helps

reduce water loss
Used to transfer
A transparent layer water till the leaves
allowing light too
enter the leaf

Many cells packed with chloroplast

to do maximum photosynthesis

This layer contains loosely

packed cells allowing
gases to move freely

Used for
translocation of
Contains the stomata Small pores that allow sucrose and
openings for gas exchange and amino acid from
transpiration source to the
sink
Controls the opening and closing of a stomata

More on vascular bundles

Vascular bundles consist of 2 tissues xylem and phloem
Characteristics of xylem –

• Thick walls with lignin

• No cell contents (just dead cells)
• Cells are joint end to end allowing continuous flow

The root hair cells taking in the water from the soil through the plant through the process of osmosis.
Then the water enters the roots through the root hair cells, then it moves towards root cortex cell and
then to the whole plant by the xylem vessels. Due
to the water lost by the plant in the form of
transpiration, the pressure at the top increases.
This would cause a pull that draws up a column of
water molecules, held together by forces of
attraction between water molecules.

Wilting of the plant occurs due to the high rate of water lost from the plant. This would cause the plant
to get less amount of water decreasing the rate of photosynthesis.

Factors affecting transpiration –

• Temperature (directly)
• Wind speed (directly)
• Humidity (inversely)

A portometer can be used to measure the rate of transpiration of a leaf in a plant

Translocation is the movement of sucrose and amino acid from sources to sink -

• sources as the parts of plants that release sucrose or amino acids

• sinks as the parts of plants that use or store sucrose or amino acids

Some plant parts act as both sources and sinks at different times depending on their growth stage
and function. Young leaves, roots, and developing fruits are sinks as they require sugars for growth,
while mature leaves serve as sources by producing sugars through photosynthesis. Storage organs
like tubers and roots act as sinks when storing carbohydrates and become sources when mobilizing
energy for new growth. Similarly, stems and seeds transition from sinks during development to
sources when supplying stored nutrients. This dynamic shift helps plants efficiently distribute energy
based on their needs.

Excretory system in humans

Carbon dioxide is excreted by lungs as it is a waste product

Kidney is used in the excretion of urea, bladder and urethra

The liver is the organ the produces urea. The excess amino acids are converted to protein by the
process of assimilation. The nitrogen containing part from the proteins is removed to form
carbohydrates. This process is known as deamination. Then the nitrogen containing part is converted
to urea as it is toxic. Urea is toxic as well but not as much as the nitrogen. That’s why it is important
to excrete urea.

The Blood enters through the renal artery. The blood then enters the glomerulus for the
filtration process, in this process water, glucose, urea and ions are removed from the
blood. Then the blood passes through the nephron, there reabsorption takes place. All
of the glucose, some ions and most of the water is taken back into the blood. Then the
water is mixed with urea to form urine and taken down the ureter to the bladder and then
out through the urethra. The blood after reabsorption goes out of the kidneys through the
renal vein.

All about living organisms and cells

Classification of organisms
movement as an action by an organism or part of an organism causing a change of position or place

respiration as the chemical reactions in cells that break down nutrient molecules and release
energy for metabolism

sensitivity as the ability to detect and respond to changes in the internal or external environment

growth as a permanent increase in size and dry mass

reproduction as the processes that make more of the same kind of organism

excretion as the removal of the waste products of metabolism and substances in excess of
requirements

nutrition as the taking in of materials for energy, growth and development

Organisms can be classified into group by the feature they share.

Species are a group of organisms that can reproduce to form a fertile offspring

The five kingdoms used to classify organisms

animal

plant
The general naming of organisms
fungus
Genus species
prokaryote

Protoctista

Animals that have a backbone are known as

vertebrates some of them include -

Mammals: • Have feathers

• Warm-blooded • Lay eggs with hard shells

• Have hair or fur • Have beaks and no teeth

• Give birth to live young (mostly) Reptiles:

• Produce milk to feed their young • Cold-blooded

Birds: • Have dry, scaly skin

• Warm-blooded • Lay eggs (mostly) with leathery shells

 • Breathe through lungs

Amphibians: Fish:

• Cold-blooded • Cold-blooded

• Have moist, permeable skin • Have scales

• Typically lay eggs in water • Breathe through gills

• Live in water

Animals that don’t have a back bone are

classified as invertebrates

Myriapods (e.g., centipedes, millipedes): Arachnids (e.g., spiders, scorpions):

• Many body segments • Two body segments (cephalothorax

and abdomen)
• One or two pairs of legs per segment
• Four pairs of legs
Insects (e.g., ants, butterflies, beetles):
• No antennae
• Three body segments (head, thorax,
abdomen) Crustaceans (e.g., crabs, lobsters, shrimp):

• Three pairs of legs • Multiple body segments

• One or two pairs of wings (most) • Five or more pairs of legs

• Two pairs of antennae

Virus are organisms that are dead but become active when they are in the hosts body

Cells

Structure of a
plant cells

Structure of an animal
cell
Structure Function

Cell Wall Provides structural support and protection.

Cell Membrane Controls the movement of substances in and out of the cell.

Nucleus Contains genetic material and controls cell activities.

Cytoplasm site of many metabolic activities.

Mitochondria Produces energy through cellular respiration.

Chloroplasts Conducts photosynthesis to produce food for the plant.

Vacuole Stores nutrients, waste products, and helps maintain turgor pressure.

Ribosomes Synthesizes proteins.

Bacterial cells

Cell → Tissue → Organ → Organ system (increasing in size)

Specialised Cell Function

Ciliated Cells Movement of mucus in the trachea and bronchi

Root Hair Cells Absorption

Palisade Mesophyll Cells Photosynthesis

Neurones Conduction of electrical impulses

Red Blood Cells Transport of oxygen

Sperm and Egg Cells (Gametes) Reproduction

Magnification = Image size / Actual size (note: magnification has no unit)

1mm = 1000 μm

Movement of substances into and out of the cell

Diffusion is the netmovent of particles form an area of higher concentration to an area of lower
concentration down the concentration gradient.

Rate of diffusion can be affected by several factors –

• Surface area (directly)

• Temperature (directly)
• Mass (inversely)
 • Concentration gradient (directly)

Osmosis is the net movement of water molecules form an area of

higher concentration to an area of lower concentration down the
concentration gradient. This process occurs through a partially
permeable membrane

When a plant cell is placed in distilled water, water particles will

move into the plant through osmosis causing the cell to become
turgid as the turgor pressure would increase (the cell wall would
prevent the plant cell form bursting). However, if the same plant
cell is placed in a high concentration of sugar solution it would become flaccid as plasmolysis
would occur. This would cause water to move out the cell.

Active transport is the net movement of ions from an area of lower concentration to an area of
higher concentration against the concentration gradient requiring energy

Active transport occurs in roots to take up important mineral ions for the plant.

Biological molecules and enzymes

Biological molecules
C H O for fats and carbohydrates

C H O N for proteins

Test Substance Initial Color Final Color

Iodine Solution Test Starch Brown/Yellow Blue/Black

Benedict’s Solution Test Reducing Sugars Blue Brick - Red

Biuret Test Proteins Blue Violet/Purple

Ethanol Emulsion Test Fats and Oils Colorless Cloudy White Emulsion

DCPIP Test Vitamin C Blue Colorless

DNA has a double helix structure where 2 strands coil together. Each strand contains a base. Where
base A pairs with base T and base G pairs with base C

Enzymes
A catalyst is a substance that increases the rate of reaction without being used up

Enzymes are classified as biological catalysts (they are proteins)

The shape of the substate is complimentary to the shape of the enzymes. The bonding of these 2
form an Enzyme-substate complex .

As and when the temperature of the mixture with the enzyme and substate in it
increases, the rate of product formation also increases. This would increase the rate
of product formation as there are more amount of collisions between the substrate
and the enzyme. When the enzymes reaches the optimum temperature, the
amount of collisions per seconds are the most. After the optimum temperature if
the temperature is increased, the number of collisions per second decreases and
soon the enzyme denatures due to high temperatures ( same for pH)
 Disease and immunity
A pathogen is a disease causing organism

A transmissible disease is a disease that can be transferred form one host to another. This can pass
through direct contact, form blood. Or it can pass indirectly from contaminated surfaces.

Some of the defenses of our body –

• Hair in nose
• Mucus
• Stomach acid
• Skin

How to control the spread of diseases

• Clean water supply

• Hygienic food preparation
• Good personal hygiene
• Waste disposal
• Sewage treatment

Condition Active immunity Passive immunity

Memory cells Produced Not produced
Gained by Vaccination of weakened Vaccination of antibodies or
pathogens Breast feeding
Time Long term Short term

When a vaccination with weakened pathogens are given to the person. The weakened pathogens
trigger an immune response where the lymphocytes produce antibodies. These antibodies would
have a complimentary shape to the antigen. This process also creates memory cells providing long
term memory

Vaccination can be used to control the spread of diseases

Breast feeding is important for a fetus as it would provide the fetus with antibodies. Initially the
lymphocytes cannot produce antibodies to specific pathogens. To support the immune system as it
is rich with nutrients. Along with that, it also provides hormones for growth of the fetus

The cholera bacterium produces a toxin that causes secretion of chloride ions into the small
intestine, causing osmotic movement of water into the gut, causing diarrhoea, dehydration and loss
of ions from the blood. This is mainly caused by contaminated water. To solve this issue oral
rehydration treatment is required