All 26 questions from the West African Examinations Council (WAEC) Biology 2021 Theory paper, with the correct answer and a full explanation for each. Free, no signup needed.
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1(a). A sample of human blood was put in a test tube and allowed to spin in a centrifuge. The components of the blood sample were clearly separated. List the four main components of blood that would be in the test tube.
Model answer
Blood plasma; red blood cells; white blood cells; blood platelets.
1(b). Name the component of the blood that: (i) would form the top layer in the test tube; (ii) destroys pathogens; (iii) is biconcave in shape; (iv) would be relatively low in a haemophilic condition; (v) is produced in the bone marrow; (vi) is a thrombocyte; (vii) is nucleated.
Model answer
(i) Blood plasma. (ii) White blood cells. (iii) Red blood cells. (iv) Blood platelets. (v) Red blood cells (also produced in bone marrow along with white cells and platelets). (vi) Blood platelets. (vii) White blood cells.
1(c). Mention three chemical substances transported by the blood component named in 1(b) above (plasma).
Model answer
Any three of: hormones; nutrients; oxygen (dissolved/carried); waste products (e.g. urea, carbon dioxide).
1(d). List four diseases associated with blood.
Model answer
Any four of: anaemia; leukaemia (blood cancer); haemophilia; sickle cell anaemia; malaria.
1(e). Explain briefly why a disease of the blood could be dangerous.
Model answer
Blood circulates throughout the entire body, transporting oxygen, nutrients, hormones and removing waste for every organ and tissue — so a disease affecting the blood can disrupt these vital functions everywhere in the body, potentially causing widespread organ damage or death.
2(a). What is dentition in animals?
Model answer
Dentition refers to the number, type, and arrangement of teeth in the jaw of an animal.
2(b). Describe briefly the generalised structure of a tooth in animals.
Model answer
A tooth consists of enamel, dentine, cementum, and pulp tissue. The portion of the tooth exposed above the gum (in the oral cavity) is the crown, while the portion below the crown, embedded in the jaw, is the root.
2(c). List three food substances that plants manufacture from glucose.
Model answer
Cellulose; starch; protein (also fats/oils).
2(d). Make a diagram, 6 cm to 8 cm long, of an experimental set-up to show that oxygen is produced during photosynthesis.
Model answer
The set-up consists of an inverted funnel over a sprig of an aquatic plant (e.g. Hydrilla/Elodea) submerged in water inside a beaker, with a water-filled test tube inverted over the funnel stem to collect the gas (oxygen/test gas) given off as bubbles from the plant's cut stem, supported by a stand. As photosynthesis proceeds, oxygen bubbles collect at the top of the submerged test tube, which can then be tested with a glowing splint to confirm it relights (indicating oxygen).
3(a). Complete the table below by placing each of the following organisms under the appropriate heading: Algae, Bacteria, Dog, Water lettuce, Tadpole, Cat, Lemna, Waterleaf, Mucor, Mushroom.
Model answer
Decomposer: Bacteria, Mucor, Mushroom. Producer: Algae, Water lettuce, Waterleaf, Lemna. Consumer: Dog, Tadpole, Cat.
3(b). (i) Name four products of decomposition. (ii) Mention three roles of decomposers on a refuse dump.
Model answer
(i) Carbon dioxide; water; heat; nutrients (mineral salts). (ii) They help in cleaning the environment; they help in nutrient recycling; they help in creating space for new organisms/further waste breakdown.
3(c). List three materials in a dump which would not be affected by the action of decomposers.
Model answer
Bottle (glass); plastic; nylon (materials that are non-biodegradable).
4(a). Complete the table below by naming five wildlife animals in West Africa and one body part each that makes them endangered because of the activities of humans.
Model answer
Monkey — Skull. Lynx — Furs. Lion — Whiskers. Dolphin — Skeletons. Zebra — Hides.
4(b). State three effects each of the following factors on the conservation of natural resources: (i) Poor economy of a nation; (ii) poaching.
Model answer
(i) A poor national economy negatively impacts conservation efforts because necessary facilities and funding won't be available; it also becomes difficult to limit/monitor how people exploit natural resources; and enforcement of conservation laws becomes weaker. (ii) Poaching has a detrimental effect on conservation as it directly leads to a decline in wildlife populations; it disturbs the ecosystem and its functioning; and it can drive species toward extinction.
4(c). State four roles played by the Government in conservation of natural resources.
Model answer
Establishment of game reserves; enactment of appropriate laws/regulations; imposing necessary punitive measures on defaulters; educating the public on the need for conservation.
5(a). Complete the table below by naming the nutrient cycle that involves each of the given processes (Combustion, Precipitation, Lightning) and give three other processes involved in that nutrient cycle.
Model answer
Combustion → Carbon cycle (other processes: putrefaction, respiration, photosynthesis). Precipitation → Water cycle (other processes: evaporation, condensation, transpiration). Lightning → Nitrogen cycle (other processes: ammonification, nitrification, denitrification).
5(b). (i) What is irritability? (ii) Complete the table below by stating the type of response elicited by each of the given actions: Euglena moving towards light; opening/closing of Mimosa leaves; mosquitoes avoiding repellants; earthworm moving away from light; sperm cell moving towards chemical substances of an ovum; four o'clock plant opening at 4:00pm; shoot of bean seedling growing towards sunlight.
Model answer
(i) Irritability is that characteristic of living organisms by which they are aware of, and able to respond to, stimuli. (ii) Euglena moving towards light — positive phototaxis. Opening/closing of Mimosa leaves — nastism. Mosquitoes avoiding repellants — negative chemotaxis. Earthworm moving away from light — negative phototaxis. Sperm cell moving towards chemical substances of an ovum — positive chemotaxis. Four o'clock plant opening at 4:00pm — nastism. Shoot of bean seedling growing towards sunlight — positive phototaxis (phototropism).
5(c). Name three animals each that exhibit: (i) territoriality; (ii) seasonal migration; (iii) display.
Model answer
(i) Birds, wolf, monkeys (any three territorial animals). (ii) Dragonflies, reindeer, monarch butterflies. (iii) Birds, beetles, mammals (any three animals known for display behaviour).
Practical 1(a). Study the specimens A, B and C and answer questions (i)–(ii). (i) Name the part of the body where specimens A, B and C would be found in a mammal. (ii) State the function of specimens A, B and C.
Model answer
(i) A: Neck region. B: Chest (thoracic) region. C: Upper abdominal region. (ii) A (cervical vertebra): supports the head, protects blood vessels and the spinal cord, provides a passage for the spinal cord/blood vessels, and a surface for neck muscle attachment. B (thoracic vertebra): provides a point of attachment for chest muscles and articulates with the rib bones, and protects the spinal cord. C (lumbar vertebra): bears the weight of the body, permits bending/rotation of the body, provides a surface for muscle attachment, and protects the spinal cord.
Practical 1(b). (i) Make a drawing, 6 cm to 8 cm long, of the anterior view of specimen C (lumbar vertebra) and label fully. (ii) State four observable similarities between specimens L and M.
Model answer
(i) The drawing should show and label: Neural spine; Prezygapophysis; Metaphysis; Neural Arch; Neural Canal; Transverse Process; Centrum. (ii) Similarities between L and M would typically include shared structural features appropriate to their common classification group (e.g. both possess a similar body plan, segmentation, or symmetry) — specific to the organisms provided in the practical exam.
Practical 1(c). (i) Name one habitat each of specimens L and M. (ii) State one function of four of the parts labelled in 1(b)(i). (iii) Mention the total number of each of specimens A, B and C found in adult humans. (iv) Name two other vertebrae in humans.
Model answer
(ii) Transverse process — for attachment of (abdominal and back) muscles. Neural arch — for muscle attachment/protection of the spinal cord. Centrum — provides mechanical support. Neural canal — encloses/houses the spinal cord and provides its passage. (iii) A/Cervical vertebra: 7. B/Thoracic vertebra: 12. C/Lumbar vertebra: 5. (iv) Sacral (sacrum) and caudal (coccyx) vertebrae.
Practical 2(a). Beakers D, E, F and G contain seeds that have been sown for seven days. Carefully remove one seed/seedling from each of the beakers labelled D, E, F and G and place each on the corresponding white tile. Study them and record two observations and the result for each.
Model answer
D: Cotyledons split open; emergence of radicle; presence of epicotyl; foliage leaves/stem present; moist soil — Result: Germination occurred. E: Seeds/cotyledons are separate/split, brown, and decaying; no testa; no embryo/plumule/radicle; moist soil — Result: No germination. F: Seeds are brown; testa intact; seeds smooth and soft; moist soil/oil present — Result: No germination. G: Seeds are intact, with brown/white testa, hard, and the soil is dry (OR radicle/root present, cotyledon split, plumule present, but soil is dry) — Result: Delayed/slow germination.
Practical 2(b). (i) Name one condition for germination that was likely absent in the beakers labelled E, F and G. (ii) Give two reasons for the result in beaker D.
Model answer
(i) E: viable seed was absent. F: oxygen/viable seed was absent. G: moisture/water was absent. (ii) All the conditions necessary for germination — oxygen/air, warmth/suitable temperature, a viable seed, and moisture/water — were present in beaker D.
Practical 2(c). Make a drawing, 8 cm to 10 cm long, of one seed/seedling obtained from the beaker D and label fully.
Model answer
The drawing should clearly show and label the key germinating seedling structures observed in beaker D, such as the radicle, plumule, cotyledons, epicotyl, and hypocotyl, drawn to the specified 8–10 cm size with neat, ruled label lines.
Practical 3(a). Classify each of specimens L and M into its: (i) Phylum; (ii) Class.
Model answer
Students identify the phylum and class of each specimen provided in the practical exam based on observable features (e.g. body symmetry, segmentation, presence of an exoskeleton or shell, etc.).
Practical 3(b). (i) State three observable features of members of the class of specimen L. (ii) Name three other classes of the phylum to which specimen L belongs.
Model answer
(i) Three observable features consistent with the identified class of specimen L (e.g. body covering, symmetry, limbs/appendages, or other diagnostic features specific to that class). (ii) Three other classes within the same phylum as specimen L (e.g. if specimen L is a member of Phylum Arthropoda, other classes could include Insecta, Arachnida, and Crustacea).
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