1] Characteristics and classification of living organisms

2] Movement in and out of cells

3] Biomolecules

4] Enzymes

5] Plant Nutrition

Nitrate ions

Magnesium ions

Required for amino acid synthesis.

· Reduced/stunted growth

· Upper leaves turn pale green.

· Lower leaves turn yellow

· Thin stems and smaller roots

Required for chlorophyll synthesis.

· Yellowing between veins of leaves.

· Lower leaves turn green

· Upper leaves turn yellow.


6] Human Nutrition


Contained in:

Required for:

Deficiency effects


Milk and other dairy products; bread

For bones and teeth; blood clotting

Rickets: brittle and deformed bones.


Red meat; egg yolk; dark green vegetables.

For making haemoglobin

Anaemia: not enough RBCs so less oxygen delivered to organs.


Contained in:

Required for:

Deficiency effects

Vitamin C

Citrus fruits

Making stretchy protein- collagen.

Scurvy: pain in joints and bleeding in gums.

Vitamin D

Butter; egg yolk

Helps calcium get absorbed; for making bones and teeth

· Rickets: bones become soft and deformed;

· Muscle cramps

· Stunted growth

· Fatigue

· Reduced ability to absorb calcium ions.

  1. Mouth
    • food is ingested using the teeth.
    • teeth crush and grind to increase surface area[mechanical digestion].
      • Tooth Decay:
        • Process:
          • bacteria use sugar / AW (on teeth as a food source) ;
          • bacteria anaerobically respire ;
          • lactic acid is produced ;
          • corrodes through enamel and dentine
          • reaches nerves in pulp cavity causing pain
          • tooth falls out or needs removal.
        • Prevention:
          • regular, brushing / mouthwash / flossing / wash / clean, teeth
          • avoid sugary foods / diet described
          • dental check-ups
        • saliva contains salivary amylase which breaks down starch to maltose[chemical digestion]
  1. Oesophagus
    • mechanical digestion: peristalsis [using outer longitudinal and inner circular muscles]
  2. Stomach:
    • sphincter muscles are present at both the entrance and the exit to prevent acid reflux and keep the food in the stomach.
    • muscles contract and relax to churn food in order to increase surface area[mechanical digestion]
    • pepsin secreted that breaks down proteins to polypeptides[chemical digestion]
    • HCL secreted, to make the pH acidic as:
      • the optimum pH for pepsin is acidic
      • it kills any bacteria.
  1. Small intestine:
    • pancreatic juice is secreted from the pancreas through the pancreatic duct [chemical digestion], containing:
      • pancreatic amylase
      • trypsin
      • lipase
    • bile is secreted by the gall bladder. Functions:
      • neutralises the acidic chyme from the stomach to give suitable pH for enzyme action.
      • emulsification: breaks up large fat globules into smaller ones to increase surface area for enzyme action of lipase.[mechanical digestion]
      • Also contains bile pigments made of old RBCs. It is egested along with faeces.
      • Also denatures enzymes from the stomach such as
    • villi: secrete enzymes for digestion of food.
      • The cells of the villi secrete the following enzymes:
        • maltase
        • sucrase
        • lactase
        • peptidase
        • lipase
      • Adaptations of the villus:
        • capillaries in close proximity: to allow faster diffusion and active transport; good blood supply.
        • lacteals in close proximity: to allow for faster diffusion and active transport, to absorb and carry fats and cholesterol.
        • lots of mitochondria: to provide energy for active transport by respiration.
        • villi wall is one cell thick: faster diffusion.
        • microvilli:to increase surface area for absorption, faster diffusion and active transport.
        • goblet cells present: secrete mucus to protect the villus from:
          • enzymes such as proteases and lipases.
          • physical damage.
          • acid from the stomach.
        • Most of water is absorbed in the colon.
  1. Large intestine:
    • absorbs any leftover nutrients and water.

7] Transport in plants



Made up of many dead cells joined end to end, where the end walls are dissolved.

Made up of many cells joined end to end, however they are not completely dissolved. They have perforations.

Transport water and mineral ions.

Translocate sucrose and amino acids.

No cytoplasm or nucleus.

No nucleus [cytoplasm is present]

Lignin present.

Lignin absent.

Unidirectional movement.

Bidirectional movement.







All organs

Plant leaves photosynthesise to produce glucose which gets converted to sucrose and translocated to all parts of the plant.

End of winter/spring

Storage organs[vegetable]

New shoots

Storage organs contain starch which is used for respiration and energy for the shoot. It is converted to sucrose and translocated to the shoots for energy and development.


Germinating seeds


Leaves have not yet developed to photosynthesise so energy is needed for the growth of the plumule and radicle. Glucose is stored in the form of starch, converted to sucrose and translocated to the plumule and radicle for growth.

8] Transport in animals

Pulmonary circulation

Systemic circulation

Between heart and lungs

Between heart and rest of the body

Involves pulmonary artery[de-oxygenated blood] and pulmonary vein[oxygenated blood]

Involves vena cava[de-oxygenated blood] and aorta[oxygenated blood]

Faster, because it involves a smaller circuit.

Slower, because it involves a bigger circuit.

Low pressure circulation: because of thinner walls of right ventricle

High pressure circulation: due to thicker walls of left ventricle.

  1. Arteries:
  1. Veins:
    • carry de-oxygenated blood from the tissue/muscle to the heart[except for the pulmonary artery].
    • transport blood at low pressure.
    • Adaptations:
      • valves: prevent backflow of blood.
      • wide lumen: allows blood to flow with minimum resistance.
      • thin wall: allows contraction of muscles outside the veinto be felt inside the lumen, which allows blood to flow.
  1. Capillaries:
    • exchange of substances between the blood and tissue/cells by diffusion occurs in capillaries.
    • Adaptations:
      • pores in capillary walls:
        1. allows filtration/movement of small molecules and nutrients between blood to tissue.
        2. allows WBCs to squeeze
      • one-cell thick:faster
      • very narrow:
        1. blood moves slowly in order to facilitate exchange of substances.
        2. ensures RBCs are closer to wall to facilitate diffusion of oxygen.
      • large number of capillaries/capillary bed: to increase surface area for faster




Red blood cells

Transporting oxygen. Haemoglobin absorbs oxygen and transports it.

White blood cells

Phagocytosis and antibody production.




Transport of blood cells, ions, soluble nutrients, hormones, proteins and carbon dioxide.

9] Diseases and Immunity

  1. chemical barriers:
    • mucus is present, produced by goblet cells, to trap dust and bacteria.
    • HCL produced by the stomach kills any bacteria present in the food.
    • pathogens are also killed by:
      • phagocytes:
      • lymphocytes:antibody production.
    • WBCs can be enhanced by vaccines.

Active immunity

Passive immunity

Antibodies produced by organism’s body.

Antibodies produced and acquired from another individual.

Memory cells produced.

Memory cells not produced.

Long-lived immunity.

Short-lived immunity.

Response in subsequent infection is faster.

Response in subsequent infection is slower.

10] Respiration and Gas Exchange

Aerobic respiration

Anaerobic respiration

Presence of oxygen.

Absence of oxygen.

More energy released.

Less energy released.

Complete breakdown of glucose.

Incomplete breakdown of glucose.

Carbon dioxide and water produced.

In human muscle cells:lactic acid produced. In yeast:carbon dioxide and ethanol produced.

All living cells.

Only specific cells[muscle, yeast, etc.]



Mechanical process.

Chemical process.

Inhaling and exhaling.

Involves the breakdown of glucose to release energy.

Involves lungs, diaphragm, and ribcage muscles.

Takes place in every cell of the body.

11] Excretion



The removal of toxic materials, waste products of metabolism and excess materials.

Removal of undigested or unabsorbed food, and fibre.

Excreted through the lungs, skin, kidneys and liver.

Egested through the anus.

  1. Reabsorption:
    • takes place in all parts of the kidney tubule except for the renal capsule.
    • all glucose, almost all water and salts get reabsorbed by diffusion and osmosis.
    • they move into the capillaries which join up to form the renal vein.
    • the solution left in the kidney tubule after reabsorption:
      • excess salts.
      • excess water.
    • this solution is called urine.
    • this flows into the collecting duct and goes to the ureter.

Renal artery

Renal vein

Oxygenated blood.

De-oxygenated blood.


No urea.

More water.

Less water.

More salts.

Less salts.


No toxins.

12] Coordination & Response

Voluntary action

Involuntary action

Not a rapid response.

Rapid response.

Requires conscious thought.

Does not require conscious thought.

Requires learning/not present from birth.

Does not require learning/present from birth.

Not protective in nature.

Protective in nature.

  1. vesicles containing chemicals called neurotransmitters.
  2. synaptic cleft [minute gap].
  3. receptor molecules.
  • Process:
    1. in the pre-synaptic neurone, an impulse triggers the vesicles containing neurotransmitters to move towards the cell membrane.
    2. vesicles fuse with the cell membrane.
    3. neurotransmitters are released.
    4. neurotransmitters diffuseacross the synaptic cleft.
    5. neurotransmitters bind with receptor molecules on the cell surface of the post-synaptic neurone.
    6. neurotransmitter and receptor molecules are complementary to each other.
    7. binding results in an electrical impulse in the post-synaptic neurone.
  • Advantage of a synapse: ensures that impulses travel in one direction only.
  • Disadvantage of a synapse:drugs can act upon synapses.
  • sense organs as groups of receptor cells responding to specific stimuli: light, sound, touch, temperature and chemicals.
    1. cornea:refracts light.
    2. iris:controls how much light enters the pupil.
    3. lens:focuses light onto the retina.
    4. retina: contains light receptors, some sensitive to light of different colours.
    5. optic nerve:carries impulses from the eye to the brain.
  • Pupil reflex:
    1. In bright light:
  • In dim light:
  • Accommodation:
    1. When the object is near:
  • When the object is far:
  • Rods


    Sensitive to dim light.

    Sensitive to bright light. [R, G, B]

    Distributed throughout the retina.[except for the fovea and the blind spot.]

    Concentrated mainly in the fovea.

    Responsible for black and white vision.

    Responsible for colouredvision and sharpimages.



    Target organs

    Increases breathing and pulse rate.

    Oxygen and glucose supplied to muscle cells for energy.

    Lungs and heart.

    Widens pupils.

    More light enters the eye, leading to clearer vision.

    Iris muscles [radial and circular muscles]

    Increases blood concentration

    More glucose supplied to muscles for energy.


    Blood vessels in skin and digestive system constrict.

    Blood vessels in leg muscles dilate.

    Diverting blood[which contains oxygen and glucose] to leg muscles.

    Artery and arteriole muscles.

    Nervous system

    Endocrine system

    Made of neurones.

    Made of secretory cells and hormones.

    Impulses transmitted along nerve fibres.

    Chemicals carried dissolved in plasma.

    Information transmitted in the form of electrical impulses.

    Information carried in chemicals called hormones.

    Impulses travel quickly.

    Hormones travel more slowly.

    Effect of a nerve impulse is short-lived.

    Effect of a hormone lasts long.

    Plant growth substances

    13] Homeostasis

    14] Drugs

    1. carbon monoxide:
      • poisonous/toxic gas.
      • combines with haemoglobin permanently and decreases the volume of oxygen it can carry.
      • puts strain on the heart, leading to exhaustion and tiredness.
    2. nicotine:
      • stimulant: leads to hypertension and makes the user feel more alert by narrowing arterioles and increasing heart rate.
      • increases stickiness of blood platelets.
      • decreases appetite.
    3. tar:
      • contains chemicals called carcinogens.
      • these can cause cells in the respiratory passage to divide, leading to a tumour and lung cancer.
      • it can cause irritation in the airways, leading to more mucus being produced by goblet cells.
      • carcinogens can also stick to alveoli and damage them. Leading to reduced surface for gas exchange.
    4. smoke particles:
      • get trapped in the lungs.
      • WBCs try to remove them but end up damaging the alveoli.
      • leads to COPD and emphysema.

    15] Reproduction in plants:


    Insect pollinated flower

    Wind pollinated flower


    Large/conspicuous and brightly to attract insects.

    Inconspicuous and dull.


    Have strong, attractive scent.

    No scent.





    Sticky, have ridges and grooves.


    Quantity of pollen.

    Large amounts

    Larger amounts.


    Inside the flower.

    Hanging out/pendulous.


    Inside flower; sticky.

    Sticking out/pendulous; feathery.







    Capacity to respond to changes to environment.

    Less compared to cross-pollinated because there is no variation. However, if parent plant is well adapted, offspring will adapt well also.

    Variation leads to adaptability, disease resistance, more chances of evolution.

    Reliance of pollinators.

    Pollinators are not always required.

    Requires pollinators. Energy needs to be invested in petals and nectaries.

    16] Reproduction in humans


    Egg cell



    Motile, uses tale for movement.

    Not motile, moved by cilia.

    500,000 produced.

    One produced once a month.

    Less amount of food store.

    Lots of food store.



    Follicle stimulating hormone[FSH]

    Stimulates the maturing of eggs in the ovary and the production of oestrogen by ovaries.

    Luteinising hormone[LH]

    Stimulates the release of a mature egg cell from one of the ovaries in a process known as ovulation.


    Stimulates the thickening of the walls of the uterus and inhibits the production of FSH. Stimulates pituitary gland to produce LH.


    Increases the thickening of the uterus wall. Prevents menstruation. Inhibits the production of LH.

    17] Inheritance

    18] Variation and Selection

    Continuous variation

    Discontinuous variation

    Results in a range of phenotypes between two extremes.

    Results in a limited number of distinct phenotypes and no intermediates.

    Caused by genes and environment. [phenotypic variation]

    Caused by genes only.[genotypic variation]



    HbA HbA [homozygous: normal RBCs]

    Individuals are highly susceptible to malaria, which is fatal. The malarial parasite passes a few stages of its life cycle in RBCs, so it is a breeding ground.

    HbS HbS [homozygous: all RBCs sickle shaped]

    Individuals are not susceptible to malaria[because the parasite cannot survive], but seriously affected by sickle-cell anaemia, leading to death.

    HbA HbA [heterozygous: 50% RBCs are sickle shaped]

    These individuals are less likely to suffer from a fatal attack of malaria and are resistant, and are not seriously affected by sickle cell anaemia. They therefore have a selective advantage. They are able to survive and pass on this allele to the next generation.

    Natural selection

    Artificial selection

    Organisms are selected by nature.

    Organisms are selected by humans.

    Results are unpredicted.

    Results are predicted and planned.

    Species are more adapted to the environment.

    Species are more useful to humans.

    19] Organisms and their environment

    20] Biotechnology