All 23 questions from the West African Examinations Council (WAEC) Biology 2014 Theory paper, with the correct answer and a full explanation for each. Free, no signup needed.
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SECTION B — Answer two questions only from this section. 1(a)(i). List three characteristics of living organisms. (3 marks)
Model answer
Three characteristics of living organisms: Movement, Respiration, Nutrition (other acceptable answers: Growth, Reproduction, Excretion, Irritability/Sensitivity — any three).
1(a)(ii). Explain briefly the characteristics listed in 1(a)(i) above. (6 marks)
Model answer
Movement: the ability of an organism (or part of it) to change its position or location in response to a stimulus. Respiration: the breakdown of food substances within cells to release energy for life processes. Nutrition: the process by which an organism obtains and utilizes food materials for energy, growth, and repair.
1(b). In a tabular form, state four differences between plants and animals. (4 marks)
Model answer
Plants | Animals 1. Autotrophic (manufacture their own food) | 1. Heterotrophic (depend on other organisms for food) 2. Store food as starch | 2. Store food as glycogen 3. Possess a cell wall made of cellulose | 3. Do not possess a cell wall 4. Show little or no movement of the whole body | 4. The whole body is generally capable of movement
1(c)(i). Name one organism that exhibits both plant and animal features. (1 mark) 1(c)(ii). State four animal features and two plant features possessed by the organism named in 1(c)(i) above. (6 marks)
Model answer
(i) Euglena. (ii) Animal features: possession of an eye spot; possession of a gullet for feeding; possession of a flagellum for movement; possession of a contractile vacuole for osmoregulation. Plant features: possession of chloroplasts for photosynthesis; possession of pyrenoids/paramylum granules for starch storage.
2(a). Define the following terms: (i) Elimination; (ii) Excretion; (iii) Secretion. (6 marks)
Model answer
(i) Elimination: the removal of undigested food substances (waste) from the body, also called egestion. (ii) Excretion: the removal of the waste products of metabolism from the body of an organism. (iii) Secretion: the release of useful substances (such as enzymes or hormones) by specialized cells or glands.
2(b). Describe the digestion of boiled fish in the gut of humans.
Model answer
In the stomach: the enzyme pepsin, in the acidic gastric juice, converts the protein in the fish to peptones. In the duodenum: the enzyme trypsin (released into the duodenum in the pancreatic juice) converts the peptones to polypeptides. In the ileum: the enzyme peptidase (erepsin), in the intestinal juice, converts the polypeptides to amino acids, which are then absorbed into the bloodstream through the villi.
2(c). Make a diagram 8cm–10cm long of a longitudinal section of a villus and label fully. (8 marks)
Model answer
The diagram should show, fully labelled: the columnar epithelium (outer covering), a central lacteal (lymph vessel), a network of blood capillaries, goblet cells (mucus-secreting), and the muscle layer at the base of the villus. (A hand-drawn diagram is required in the exam; the labelled parts listed above are the key features to include.)
3(a). Explain briefly the following ecological terms: (i) Biosphere; (ii) Habitat. (4 marks)
Model answer
(i) Biosphere: the part of the Earth (including land, water, and atmosphere) within which living organisms exist. (ii) Habitat: the natural environment or specific place where an organism normally lives.
3(b). Describe the mode of nutrition in a named carnivorous plant. (7 marks)
Model answer
Venus flytrap: The plant has modified leaves forming a hinged trap lined with sensitive trigger hairs. When an insect touches the trigger hairs, the trap snaps shut, enclosing the prey. The plant then secretes digestive enzymes that break down the insect's soft tissues, and the resulting nutrients (particularly nitrogen compounds) are absorbed by the leaf, supplementing the plant's nutrition since it typically grows in nitrogen-poor soils.
3(c). State three reasons why the dispersal of fruits and seeds are important. (3 marks)
Model answer
1. To prevent overcrowding and competition with the parent plant for light, water, and nutrients. 2. To enable the colonization of new habitats, spreading the species over a wider area. 3. To reduce the chances of diseases and pests spreading to all the offspring at once.
3(d). State six methods of conserving soil.
Model answer
1. Terracing 2. Contour ploughing 3. Crop rotation 4. Afforestation (planting of trees/wind breaks) 5. Mulching 6. Strip cropping
4. A survey to determine blood groups was carried out on 250 people living in a community (Blood group A: 8.0%, B: 14.0%, AB: 32.8%, O: 45.2%). 4(a)(i). Explain the term co-dominance. (2 marks)
Model answer
Co-dominance is a genetic condition in which two different alleles of a gene are both fully and separately expressed in the phenotype of a heterozygous individual, with neither allele being dominant or recessive over the other.
4(a)(ii). Calculate the number of individuals with the co-dominance blood group. (3 marks)
Model answer
The co-dominant blood group is AB (32.8%). Number of individuals = 32.8% × 250 = 82 individuals.
4(a)(iii). What is the total number of individuals in the table that are able to donate blood to an accident victim with blood group B? (6 marks)
Model answer
Blood group O is the universal donor (can donate to all groups); blood group B can also donate to a group B recipient. Total % = O(45.2%) + B(14.0%) = 59.2% Number of individuals = 59.2% × 250 = 148 individuals.
4(b). A man whose blood group is heterozygous A is married to a woman whose blood group is AB. With the aid of a genetic diagram, suggest the possible blood groups of their children.
Model answer
Father's genotype: IᴬIᵒ (heterozygous A). Mother's genotype: IᴬIᴮ (AB). Father's gametes: Iᴬ, Iᵒ. Mother's gametes: Iᴬ, Iᴮ. Punnett square: Iᴬ×Iᴬ = IᴬIᴬ (Group A) Iᴬ×Iᴮ = IᴬIᴮ (Group AB) Iᵒ×Iᴬ = IᴬIᵒ (Group A) Iᵒ×Iᴮ = IᴮIᵒ (Group B) Possible blood groups of the children: A, AB, and B (in the ratio 2 A : 1 AB : 1 B).
6(a). State five reasons why animals move from place to place. (5 marks)
Model answer
1. To search for food. 2. To search for water. 3. To escape from predators or danger. 4. To search for mates for reproduction. 5. To find suitable shelter or escape unfavourable environmental/climatic conditions.
6(b). State one function each of the following structures found in plants: (i) epidermis; (ii) phloem; (iii) sclerenchyma. (3 marks)
Model answer
(i) Epidermis: protects the underlying plant tissues from water loss, mechanical injury, and entry of pathogens. (ii) Phloem: transports (translocates) manufactured food from the leaves to other parts of the plant. (iii) Sclerenchyma: provides mechanical support and strength to the plant.
6(c). Give two examples each of the following types of organisms: (i) parasitic plants; (ii) saprophytes. (4 marks)
Model answer
(i) Parasitic plants: Mistletoe, Dodder (Cuscuta) — (Witchweed/Striga also acceptable) (ii) Saprophytes: Mushroom, Mucor (Rhizopus/bread mould also acceptable)
6(d). State two adaptive features of plants which inhabit salt water swamp.
Model answer
1. Presence of pneumatophores (breathing/aerial roots) for gaseous exchange in waterlogged, oxygen-poor soil. 2. Vivipary — seeds germinate while still attached to the parent plant, giving seedlings a head start before dropping into the mud.
6(e). State two factors each which result in: (i) increase; (ii) decrease, in population density.
Model answer
(i) Increase: immigration into the area; high birth rate (natality). (ii) Decrease: emigration from the area; high death rate (mortality) — e.g. due to disease, predation, or famine.
6(f). Mention four ways in which modern agricultural activities may threaten the survival of species.
Model answer
1. Use of pesticides and herbicides that harm non-target species. 2. Deforestation/clearing of land for farming, destroying natural habitats. 3. Monocropping, which reduces biodiversity. 4. Use of inorganic fertilizers that cause water pollution and eutrophication, harming aquatic life.
6(g). State three reasons why mitosis is important to living organisms.
Model answer
1. It enables growth through an increase in cell number. 2. It enables the repair of damaged or worn-out tissues. 3. It enables asexual reproduction in some organisms.
6(h). State three causes of food spoilage.
Model answer
1. Action of microorganisms (bacteria and fungi). 2. Enzymatic action (natural ripening/decay processes). 3. Poor storage conditions (excess moisture, heat exposure, or pest infestation).
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