Diagram Bank and Quick Revision

What to remember

• Learn each diagram by its parts in order and by the one function of each part; draw with a sharp pencil, label with straight lines on the right side, and give a heading.
• Most questions at this level test a few fixed pairs: organelle and function, gland and hormone, vitamin and deficiency disease, pathogen and disease, scientist and discovery.
• Always link a diagram to its function and to a daily-life example; this is also the way to teach it in class.

Diagram bank: what to label

Tips for drawing: draw large and neat; do not shade or colour unless asked; label parts, not the processes; keep the labelling lines parallel and not crossing; always write a title. For the heart, show the right side (deoxygenated blood) and left side (oxygenated blood) with arrows. For the eye, the retina is at the back and the lens is behind the pupil.

Cell and tissue quick facts

Robert Hooke saw the cell in cork (1665). Schleiden and Schwann gave the cell theory (cells are the basic units of all living things); Virchow said new cells come from old cells. Robert Brown discovered the nucleus. Plant cells have a cell wall of cellulose, chloroplasts and large vacuoles; animal cells have none of these, but have centrioles.

Cell division: mitosis gives two identical daughter cells (growth, repair); meiosis gives four cells with half the chromosomes (gametes). Plant tissues: meristematic (division), permanent (xylem carries water, phloem carries food). Animal tissues: epithelial, connective, muscular, nervous.

Plants and life processes

• Photosynthesis: carbon dioxide + water → glucose + oxygen, in the presence of sunlight and chlorophyll (6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂). It takes place in chloroplasts; starch is stored.
• Transpiration: loss of water vapour from leaves through stomata; it pulls water upward and cools the plant. Xylem carries water and minerals up; phloem carries food (translocation).
• Respiration: glucose is broken down to release energy; aerobic respiration needs oxygen; anaerobic respiration (yeast) gives alcohol and carbon dioxide; in muscles it gives lactic acid.
• Plant hormones: auxin (growth and bending towards light), gibberellin (stem growth), cytokinin (cell division), abscisic acid (stops growth, closes stomata in stress), ethylene (ripens fruit).
• Tropism: growth movement in response to a stimulus; phototropism (light), geotropism (gravity), hydrotropism (water).

Human body quick facts

• Digestion: salivary amylase (mouth) starts starch digestion; pepsin (stomach, with hydrochloric acid) acts on proteins; bile (made in the liver, stored in the gall bladder) emulsifies fat; pancreatic juice has trypsin, amylase and lipase; digestion ends and absorption takes place in the small intestine through villi; water is absorbed in the large intestine.
• Blood: plasma, red blood cells (haemoglobin carries oxygen), white blood cells (fight germs), platelets (clotting). Blood groups were found by Karl Landsteiner; group O can donate to all (universal donor) and group AB can receive from all (universal recipient). Normal blood pressure is about 120/80 mm Hg.
• Heart: four chambers; the right side pumps blood to the lungs and the left side pumps blood to the body. Arteries carry blood away from the heart; veins bring blood to the heart (the pulmonary artery carries deoxygenated blood).
• Respiration: gas exchange takes place in alveoli; the diaphragm and rib muscles help breathing.
• Excretion: the nephron is the unit of the kidney; it filters blood and forms urine.
• Nervous system: the cerebrum controls thinking and memory; the cerebellum controls balance; the medulla controls involuntary actions such as heartbeat and breathing. A reflex action is a quick automatic response (the reflex arc passes through the spinal cord).
• Eye: rods work in dim light; cones see colour. Short sight (myopia) is corrected with a concave lens; long sight (hypermetropia) with a convex lens.

Hormones, vitamins and diseases

Diseases and pathogens: malaria (Plasmodium, spread by female Anopheles); dengue (virus, spread by Aedes); cholera (Vibrio, water-borne); typhoid (Salmonella); tuberculosis (Mycobacterium); polio (virus); AIDS (HIV). Vaccination: Edward Jenner developed the smallpox vaccine; Louis Pasteur developed the rabies vaccine; Alexander Fleming discovered penicillin, the first antibiotic.

Reproduction, heredity, ecology in one view

• Asexual: fission, budding, spores, fragmentation, regeneration, vegetative propagation. Sexual: pollination, then fertilisation, then seed and fruit in plants; internal fertilisation in humans, implantation in the uterus, placenta.
• Mendel: 3:1 and 9:3:3:1. Father decides the sex of a child (XY).
• Ecology: energy flows one way and follows the ten percent law; nitrogen fixation by Rhizobium and nitrification by Nitrosomonas and Nitrobacter.
• Environment: ozone depletion by CFCs; greenhouse gases cause global warming; in situ and ex situ conservation.

Teaching angle: introduce a diagram first as a simple outline on the board, then add the parts one at a time. Ask students to label a blank diagram, and use models, charts and a microscope slide of onion peel and a cheek cell where possible.

Scientists and discoveries (quick list)

Hooke: cell. Leeuwenhoek: first to see bacteria and protozoa with a simple microscope. Mendel: laws of inheritance. Darwin: natural selection. Jenner: smallpox vaccine. Pasteur: rabies vaccine and germ theory. Fleming: penicillin. Landsteiner: blood groups. Watson and Crick: DNA double helix. Harvey: circulation of blood. Ronald Ross: malaria parasite carried by mosquitoes. Jagadish Chandra Bose: showed that plants respond to stimuli and invented the crescograph. Salim Ali: the Birdman of India. Use this list for quick revision in the last week.

Classification and nutrition quick facts

Living things are grouped into kingdoms such as Monera (bacteria), Protista (Amoeba), Fungi (yeast, mushroom), Plantae and Animalia. Animals are divided into those without a backbone (invertebrates: sponges, cnidarians, worms, arthropods, molluscs, echinoderms) and those with a backbone (vertebrates: fish, amphibians, reptiles, birds, mammals). Insects have three pairs of legs and a body in three parts (head, thorax, abdomen). A balanced diet has carbohydrates and fats for energy, proteins for growth and repair, and vitamins, minerals, water and roughage for protection and regulation.

Exam traps

• Mitochondria release energy; they do not "make" energy.
• Rough ER has ribosomes; Golgi body packs and secretes.
• Xylem carries water up; phloem carries food up and down.
• Pulmonary artery carries deoxygenated blood; pulmonary vein carries oxygenated blood.
• Myopia needs a concave lens; hypermetropia needs a convex lens.
• Rickets (vitamin D) is not scurvy (vitamin C); beri-beri is vitamin B1.
• Malaria is spread by female Anopheles; dengue by Aedes.
• Mitosis keeps the number of chromosomes the same; meiosis halves it.

One-liners

• 1. Robert Hooke first observed cells in cork.
• 2. The pituitary is the master gland.
• 3. Insulin is made in the pancreas.
• 4. Goitre is caused by lack of iodine.
• 5. Night blindness is caused by lack of vitamin A.
• 6. Haemoglobin is the oxygen-carrying pigment of red blood cells.
• 7. Stomata are surrounded by guard cells.
• 8. Cerebellum controls body balance.
• 9. Alveoli are the site of gas exchange.
• 10. Blood group O is the universal donor.
• 11. Fleming discovered penicillin.
• 12. Photosynthesis takes place in chloroplasts.

Practice questions

1. The powerhouse of the cell is the

   1. Golgi body
   2. lysosome
   3. ribosome
   4. mitochondrion
   Answer

   D. mitochondrion

   Mitochondria release energy from food.

2. Photosynthesis takes place in the

   1. mitochondrion
   2. chloroplast
   3. nucleus
   4. vacuole
   Answer

   B. chloroplast

   Chloroplasts contain chlorophyll.

3. Protein synthesis takes place on the

   1. lysosomes
   2. vacuoles
   3. centrioles
   4. ribosomes
   Answer

   D. ribosomes

   Ribosomes are the protein factories of the cell.

4. Who first observed cells in a slice of cork?

   1. Virchow
   2. Schleiden
   3. Robert Hooke
   4. Robert Brown
   Answer

   C. Robert Hooke

   Hooke used a simple microscope in the seventeenth century.

5. Which gland is known as the master gland?

   1. Adrenal
   2. Pituitary
   3. Thyroid
   4. Pancreas
   Answer

   B. Pituitary

   It controls many other glands.

6. Insulin is produced by the

   1. thyroid
   2. pituitary
   3. liver
   4. pancreas
   Answer

   D. pancreas

   Insulin lowers blood sugar.

7. Lack of iodine in the diet causes

   1. rickets
   2. night blindness
   3. goitre
   4. scurvy
   Answer

   C. goitre

   Iodine is needed for thyroxine.

8. Scurvy is caused by deficiency of vitamin

   1. A
   2. C
   3. D
   4. K
   Answer

   B. C

   Vitamin C keeps gums and skin healthy.

9. Rickets in children is due to lack of vitamin

   1. A
   2. B1
   3. C
   4. D
   Answer

   D. D

   Vitamin D helps absorb calcium.

10. Night blindness is caused by lack of vitamin

    1. B1
    2. C
    3. D
    4. A
    Answer

    D. A

    Vitamin A is needed for vision in dim light.

11. The malaria parasite is transmitted by the female

    1. tsetse fly
    2. Anopheles mosquito
    3. Aedes mosquito
    4. housefly
    Answer

    B. Anopheles mosquito

    Plasmodium is spread by Anopheles.

12. The first antibiotic, penicillin, was discovered by

    1. Louis Pasteur
    2. Robert Koch
    3. Alexander Fleming
    4. Edward Jenner
    Answer

    C. Alexander Fleming

    Fleming found it in a mould.

13. The vaccine for smallpox was developed by

    1. Ronald Ross
    2. Karl Landsteiner
    3. Alexander Fleming
    4. Edward Jenner
    Answer

    D. Edward Jenner

    Jenner used cowpox material.

14. Blood groups were discovered by

    1. Gregor Mendel
    2. Louis Pasteur
    3. Karl Landsteiner
    4. William Harvey
    Answer

    C. Karl Landsteiner

    Landsteiner found the ABO system.

15. Which blood group is called the universal donor?

    1. O
    2. AB
    3. B
    4. A
    Answer

    A. O

    Group O red cells carry neither A nor B antigens.

16. Gas exchange in the lungs takes place in the

    1. pharynx
    2. alveoli
    3. bronchi
    4. trachea
    Answer

    B. alveoli

    Alveoli are tiny, thin-walled air sacs.

17. Which part of the brain controls balance of the body?

    1. Cerebellum
    2. Spinal cord
    3. Cerebrum
    4. Medulla
    Answer

    A. Cerebellum

    The cerebellum coordinates posture and balance.

18. Rods in the retina are responsible for vision in

    1. bright light
    2. colour
    3. near objects only
    4. dim light
    Answer

    D. dim light

    Cones are for bright light and colour.

19. Myopia (short sight) is corrected by using a

    1. concave lens
    2. convex lens
    3. bifocal lens only
    4. plane mirror
    Answer

    A. concave lens

    A concave lens diverges rays so that the image falls on the retina.

20. Water and minerals are carried upward in plants by the

    1. phloem
    2. xylem
    3. epidermis
    4. cambium
    Answer

    B. xylem

    Phloem carries food.

21. The hormone that causes ripening of fruits is

    1. cytokinin
    2. gibberellin
    3. ethylene
    4. auxin
    Answer

    C. ethylene

    Ethylene is a gaseous plant hormone.

22. The enzyme that starts starch digestion in the mouth is

    1. trypsin
    2. pepsin
    3. salivary amylase
    4. lipase
    Answer

    C. salivary amylase

    Pepsin acts on proteins in the stomach.

23. Bile helps in the

    1. absorption of water
    2. emulsification of fats
    3. breakdown of starch
    4. digestion of proteins
    Answer

    B. emulsification of fats

    Bile is made in the liver and stored in the gall bladder.

24. The unit of structure and function of the kidney is the

    1. neuron
    2. alveolus
    3. villus
    4. nephron
    Answer

    D. nephron

    Each kidney has many nephrons that filter blood.

25. The pulmonary artery carries

    1. deoxygenated blood from the body to the heart
    2. deoxygenated blood from the heart to the lungs
    3. oxygenated blood to the body
    4. oxygenated blood from the lungs to the heart
    Answer

    B. deoxygenated blood from the heart to the lungs

    It is the only artery that carries deoxygenated blood.

26. Mitosis results in the formation of

    1. four cells with half the chromosomes
    2. one cell with double chromosomes
    3. gametes only
    4. two identical daughter cells
    Answer

    D. two identical daughter cells

    Meiosis gives four cells with half the chromosomes.

27. Which of the following is a vertebrate?

    1. Prawn
    2. Earthworm
    3. Frog
    4. Starfish
    Answer

    C. Frog

    Frogs belong to amphibians, which have a backbone.

28. Insects have how many pairs of legs?

    1. 2
    2. 4
    3. 3
    4. 5
    Answer

    C. 3

    They have a head, thorax and abdomen with three pairs of legs on the thorax.

29. Plants bend towards light because of the hormone

    1. auxin
    2. abscisic acid
    3. ethylene
    4. insulin
    Answer

    A. auxin

    Auxin collects on the shaded side and makes it grow faster.

30. The reflex arc passes through the

    1. spinal cord
    2. cerebrum only
    3. cerebellum only
    4. heart
    Answer

    A. spinal cord

    A reflex action is quick and does not need the brain's thinking.

31. A person with low haemoglobin and tiredness most likely lacks

    1. iodine
    2. calcium
    3. sodium
    4. iron
    Answer

    D. iron

    Iron is needed to make haemoglobin.

32. Which of the following pairs is correctly matched?

    1. Typhoid — Anopheles
    2. Dengue — Aedes mosquito
    3. Cholera — Plasmodium
    4. Tuberculosis — Vibrio
    Answer

    B. Dengue — Aedes mosquito

    Cholera is caused by Vibrio, typhoid by Salmonella and TB by Mycobacterium.

33. Which organelle digests worn-out cell parts and is called the 'suicide bag'?

    1. Centriole
    2. Ribosome
    3. Chloroplast
    4. Lysosome
    Answer

    D. Lysosome

    It contains digestive enzymes.

34. The equation 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ represents

    1. photosynthesis
    2. respiration
    3. transpiration
    4. fermentation
    Answer

    A. photosynthesis

    It needs light and chlorophyll.

35. Statements: 1. Xylem carries food in plants. 2. Phloem carries water and minerals from the roots.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    D. Neither 1 nor 2

    Xylem carries water and minerals; phloem carries food, so both are wrong.

36. Statements: 1. Mitosis is for growth and repair. 2. Meiosis forms gametes.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    C. Both 1 and 2

    Both are correct.

37. Statements: 1. Veins carry blood towards the heart. 2. Arteries always carry oxygenated blood.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    A. 1 only

    The pulmonary artery carries deoxygenated blood.

38. Statements: 1. Thyroxine contains iodine. 2. Insulin is secreted by the adrenal gland.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    A. 1 only

    Insulin is secreted by the pancreas.

39. Statements: 1. Plant cells have a cell wall. 2. Animal cells have chloroplasts.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    A. 1 only

    Animal cells have no chloroplasts.

40. Statements: 1. Rough ER carries ribosomes. 2. Golgi body is the site of photosynthesis.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    A. 1 only

    Photosynthesis is in chloroplasts; Golgi body packs and secretes materials.

41. Statements: 1. Beri-beri is caused by lack of vitamin B1. 2. Scurvy is caused by lack of vitamin D.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    A. 1 only

    Scurvy is due to vitamin C deficiency.

42. Statements: 1. Hypermetropia is corrected by a convex lens. 2. Cones are responsible for colour vision.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    C. Both 1 and 2

    Both are correct.

43. Statements: 1. Pasteur developed the rabies vaccine. 2. Ronald Ross showed that mosquitoes spread malaria.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    C. Both 1 and 2

    Both statements are correct.

44. Statements: 1. Transpiration pulls water upward in plants. 2. It takes place mainly through stomata.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    C. Both 1 and 2

    Both are correct.

45. Statements: 1. HIV spreads by shaking hands. 2. Aedes mosquito spreads dengue.

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    B. 2 only

    HIV does not spread by handshake.