Download SA Biology Revision Notes

Module 1: Staying Alive
Learning Outcomes
1.1

Know food is the source of chemical energy in humans.

Respiration is a chemical reaction between food and oxygen, releasing energy.

Know respiration occurs in every living cell.

Respiration Equation: Glucose + Oxygen → Carbon dioxide + Water + Energy

Energy in food is measured in Kilojoules (kJ)

Know how to compare the energy content of different foods, by experiment.

Know why individuals require different amounts of nutrients – age, gender, activity.

Know we need fats for heat and energy and are obtained from butter, cheese.

Know we need proteins for growth and repair, for enzymes and are obtained from
1.2
red meat and milk.

Know we need carbohydrates for energy and are obtained from bread, pasta,
potatoes.

Know we need Vitamin C for healthy skin, prevents scurvy and is obtained from
fresh fruit.

Know we need Vitamin D for strong bones and teeth, prevents rickets and is
obtained from milk, butter, eggs.

Know we need Calcium for strong teeth and bones and is obtained from milk, eggs.

Know we need Iron to make red blood cells and is obtained from spinach, liver.

Know we need Water for chemical reactions, for transport system, regulates body
temperature and it is a solvent.

Know that fibre prevents constipation and reduces bowel cancer.

Know how to test for:

Fats – blotting paper. (Observe grease spot)

Proteins – Biuret. (Turns Blue)

Carbohydrates (starch) - Use Iodine. (Turns Black)

Sugars – Use Benedicts Solution and Place in water bath. (Turns brick red)
1.3

Know that a balanced diet is required in order to have a healthy lifestyle.

A balanced diet is eating the correct proportions of food.

Malnourishment occurs when you do not eat a balanced diet.
Module 1: Staying Alive

Obesity is a compulsive eating disorder. Obesity occurs when you take in more
energy than you use. Can cause arthritis, diabetes, high blood pressure, heart
disease.

Anorexia Nervosa occurs when you do not eat enough food to remain healthy.
People with anorexia nervosa are prone to illness.

Bulimia Nervosa is when someone eats large amounts of food, followed by selfinduced vomiting.
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Understand why people are slow to change their lifestyle.

Heart Disease is when your coronary arteries become blocked by cholesterol.

Heart Attack is when your heart stops beating.

Stroke is when blood vessels in the brain become completely blocked (thrombosis).

Heart Disease is caused by a fatty diet, no exercise, overweight, smoking,
consuming excess alcohol, a stressful life.

Can reduce heart disease by exercising, relaxing, stop smoking, steam food, less
fatty foods, more fruit and vegetables, less salt, less sugar, less alcohol.
1.4

Be aware of the costs of circulatory diseases – effects on family.

Pulse is where the arteries throb as waves of blood are pushed around the body.

Heart rate is the number of times your heart pumps in one minute.

Your heart rate increases during exercise.

After exercise your heart rate returns to normal.

High Fitness Level = return to resting heart rate very quickly.
1.5
Low Fitness Level = return to resting heart rate very slowly.
1.6
1.7

Photosynthesis is a key process which is essential to life.

Photosynthesis occurs in the green part (chloroplasts) of the plant.

Chlorophyll is the green pigment which traps light energy from the sun.

Photosynthesis Equation:
sunlight
Carbon dioxide + Water Chlorophyll GStarch + Oxygen + Energy

Can test a leaf for the presence of starch. 1. Boil leaf in water. 2. Place leaf in
boiling ethanol. 3. Wash ethanol off leaf. 4. Add Iodine. 5. Leaf turns black if
Starch is present.
Module 1: Staying Alive
1.8

Food chains: the arrow shows the transfer of energy.

Producers – make own food using sunlight (ALWAYS A PLANT!)
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Primary Consumer – the first eater – eats plants (Herbivore)
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Secondary Consumer – the second eater – eats animals (Carnivore)

Many food chains combined together make FOOD WEBS

Nucleus is the control centre of the cell. It contains chromosomes.

Chromosomes are made up of sections called Genes.

Genes give the instructions for characteristics.

DNA makes up the genes and chromosomes. It has a special shape – Double
1.9
Helix (twisted ladder).

DNA codes for proteins.
1.10

Humans have 23 pairs of chromosomes (46 chromosomes) in all cells.

Sex cells contain half the chromosomes (23) – 1 chromosome of each pair.
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2 sex cells combine to produce a baby with 23 pairs of chromosomes (1 from each
parent).
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The physical appearance of the baby is determined by these genes (Phenotype).
Blue eyes, brown hair.

If the genes on the chromosomes are different the dominant characteristic will
show. We say they are Heterozygous.

If the genes on the chromosomes are the same we say they are Homozygous.
These 2 genes could be both Dominant or both Recessive.

Must be able to use Punnett Squares
BB x BB
Bb x bb
B
B
b
b
B BB
BB
B Bb
Bb
B BB
BB
b
bb
bb

Inherited Diseases are passed on in our genes. E.g. Cystic Fibrosis

Be able to discuss ethical issues of diagnosing foetal abnormalities (Spina bifida)
and deciding to terminate a pregnancy.
1.11

Reproduction means producing new living things.
Module 1: Staying Alive

Asexual Reproduction involves only 1 parent. The offspring have the same genes
as their parents and the offspring are identical (no variation).

Sexual Reproduction reproducing with 2 parents and the offspring vary from their
parents.
1.13

Nervous System helps us know what is happening in the world around us.

Receptors detect changes in our environment (Stimulus). (nose, eyes, ears, skin,
tongue).

Information passes along Sensory Neurones into the Central Nervous System
(CNS).

CNS = brain and spinal cord.

Motor Neurones send out the action to the Effector Organ.

2 types of action:
Voluntary – we can control using our brain (walking).
Reflex (Involuntary) – it is controlled by the spinal cord (touching hot object).
1.14

Phototropism is how a plant responds to light.

Hormone AUXIN increases growth when in darkness.
1.15

Fertilisation is when an ovum and sperm meet and join together.

Fertilisation occurs in the oviduct.

Fertilised egg implants on the wall of the uterus.

Can label the male and female reproductive system.
1.16

Contraception is removing the possibility of becoming pregnant.
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Contraceptive Pill changes hormone levels and prevents the release of egg.

Condom acts as a barrier, preventing the passage of sperm.

Vasectomy – sperm ducts are surgically cut.

Female Sterilisation – oviducts are surgically cut.
1.17

Insulin is a hormone produced in the pancreas. It converts glucose into glycogen
in the liver.

Diabetes is a disease where the pancreas does not produce enough insulin.

Type 1 Diabetes – the body cannot make insulin.

Type 2 Diabetes – the insulin that the body produces doesn’t work properly.
Module 1: Staying Alive

Symptoms: very tired; extremely thirsty; pass large amounts of urine; weight loss;
genital itching / thrush; slow healing of cuts / wounds.

Treatment – Type 1- injections of insulin, avoid high glucose diet, physical exercise
to use glucose.
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Treatment – Type 2- avoid high glucose diet; tablets to help body make insulin;
physical exercise to use glucose.