All 19 questions from the West African Examinations Council (WAEC) Biology 2018 Theory paper, with the correct answer and a full explanation for each. Free, no signup needed.
1.(a) Explain briefly how the structure of each of the following cells relate to their functions:
(i) Sperm cell
(ii) Palisade cell
Model answer
(i) Sperm cell: has a tail (flagellum) to propel it forward; mitochondria in the mid-piece supply the energy needed for swimming; the acrosome on its head releases enzymes that help penetrate the egg.
(ii) Palisade cell: has a thin wall allowing easy penetration of light, and contains numerous chloroplasts to absorb light for photosynthesis.
1.(b) Make a drawing, 8cm to 10cm long, of the front view of the female reproductive system in humans and label fully.
Model answer
The drawing should show and label: the ovary, fallopian tube, uterus, endometrium, cervix and vagina, arranged as a front view of the female reproductive tract.
1.(c) State two differences between reproduction in mammals and in amphibians.
Model answer
Mammals do not lay eggs (except a few, e.g. egg-laying mammals) while amphibians lay eggs.
Fertilization in mammals is internal, while fertilization in amphibians is external.
2.(c)(i) What is a variegated leaf?
(ii) Which part of the variegated leaf would test positive when treated with iodine solution?
(iii) State two reasons for the answer in 2(c)(i).
(iv) Name one mineral element required by plants for the formation of the part that would test positive in 2(c)(i).
Model answer
(i) A variegated leaf is a leaf with different coloured patches (green and non-green areas).
(ii) Only the green part of the leaf will test positive for starch.
(iii) The green parts contain chlorophyll, which they use to manufacture carbohydrates (starch); the non-green parts lack chlorophyll and so cannot photosynthesise or produce starch.
(iv) Magnesium (iron and nitrogen are also needed for chlorophyll formation).
2.(d) The table below indicates different methods by which organisms obtain food. Place the following organism under the heading in the table below: Human, Mushroom, Venus flytrap, Waterleaf plant, Tapeworm, Elephant grass, Housefly, Lichen, Spirogyra, Rhizopus.
3.(a) Explain briefly the following terms:
(i) Renewable natural resources;
(ii) Non-renewable natural resources.
3.(b) Give two examples each of:
(i) Renewable natural resources;
(ii) Non-renewable natural resources.
3.(c) State five ways of conserving forests.
Model answer
(a)(i) Renewable natural resources are natural resources that can be regenerated/replaced after they have been used up.
(ii) Non-renewable natural resources are those that cannot be regenerated once used up.
(b)(i) Air and vegetation are examples of renewable resources.
(ii) Coal and petroleum are examples of non-renewable resources.
(c) Ways to conserve forests: encouraging afforestation; discouraging deforestation; discouraging bush fires; enacting appropriate forest laws; educating the public about the importance of conserving forests.
3.(d) State four effects of adding animal manure to garden soil.
Model answer
Replenishes the nitrate content of the soil; helps bind soil particles together; improves the water-holding properties of the soil; prevents the soil from being blown away by erosion.
4.(a)(i) Explain briefly the terms: (i) gene; (ii) Hybrid; (iii) Trait.
Model answer
A gene is defined as the basic unit of inheritance.
A hybrid is an offspring resulting from a cross between two genetically different parents of the same species.
A trait refers to a feature or characteristic possessed by an organism.
6.(a)(i) Explain briefly chemosynthesis as a mode of nutrition.
(ii) Give two examples of organisms that carry out chemosynthesis.
Model answer
(i) Chemosynthesis is a mode of nutrition in which organisms manufacture organic food using energy obtained from the oxidation of simple inorganic substances (such as ammonia), rather than from sunlight.
(ii) Examples: Nitrobacter and Nitrosomonas (nitrifying bacteria); sulphur bacteria.
6.(c)(i) State four characteristics of a salt marsh habitat.
(ii) Explain briefly how plants are modified for anchorage in a salt marsh habitat.
Model answer
(i) A salt marsh habitat is characterized by: a high level of salinity; domination by halophytes; formation on depositional coasts; plants having varying levels of salt tolerance.
(ii) Plants are modified by possessing silt roots for anchorage and possessing long/numerous roots to grip the loose, waterlogged substrate.
6.(d)(i) List four bacterial diseases associated with poor food hygiene.
(ii) State three effects of poor food hygiene.
Model answer
(i) Cholera, dysentery, typhoid and staphylococcal food poisoning.
(ii) Poor food hygiene may cause: food poisoning; pest infestation; disease outbreaks; general discomfort.
6.(e) A person was involved in a car accident and became unconscious due to excessive blood loss. Explain briefly how the blood lost could be restored.
Model answer
The person should be given an appropriate blood transfusion. The person's blood group must first be tested/matched, and the donor blood must be screened to ensure it does not carry any transmissible disease before transfusion.
Advertisement
Sign up free to unlock
Score tracking
Practice history
Saved questions
Progress dashboard
Personalized sessions
Weak-topic breakdown
…and/or go further with premium services and No Ads.