53 questions. Try each one, then open the answer to check yourself and read the explanation.
The excretory product in protozoans is
Answer: C (ammonia.)
Protozoans live in water and get rid of nitrogen as ammonia, which diffuses out easily and is diluted by the water.
Which of the following is a living organism?
Answer: C (Yeast)
Yeast is a complete single-celled fungus that can live on its own; the others are only parts of organisms.
Which of the following organisms is the most specialized?
Answer: D (Rhizopus.)
Rhizopus has different parts for different jobs: rhizoids for anchorage and feeding, stolons for spreading and sporangia for making spores.
Active transport can be defined as the movement of
Answer: B (substances from a region of low concentration to a region of high concentration across a living cell membrane.)
Active transport moves substances against the concentration gradient (low to high) across a living membrane, which needs energy from respiration.
Which of the following cell inclusions can destroy other cell organelles?
Answer: C (Lysosome)
Lysosomes contain digestive enzymes that break down worn-out organelles.
In which of the following yam tissues will osmosis occur?
Answer: B (Raw and peeled)
Osmosis needs living cells with working membranes; boiling or roasting kills the cells.
The line XZ in the diagram represents an actual distance of 10.0 cm and the length of the diagram is 5.0 cm. What is the magnification of the diagram?
Answer: B (x 0.5)
Magnification = length of drawing ÷ actual length = 5.0 cm ÷ 10.0 cm = ×0.5.
The following events occur during mitosis in a cell:
I. Chromatids separate;
II. Chromosomes become visible;
III. Chromosomes align at the equator;
IV. Cytoplasm divides (Cytokinesis).
The correct sequence of the events is
Answer: B (II, III, I, IV.)
Prophase (chromosomes appear), metaphase (line up at the equator), anaphase (chromatids separate), then cytokinesis.
Which of the following statements about asexual reproduction is correct? It
Answer: C (always involves one parent and the offspring is genetically identical to the parent.)
Asexual reproduction needs only one parent and, being by mitosis, gives offspring identical to it.
The diagram is an illustration of a mammalian bone.
The bone illustrated is the
Answer: A (femur.)
The book identifies this long limb bone, with a rounded head at one end and condyles at the other, as the femur (thigh bone).
The diagram is an illustration of a mammalian bone.
The function of the part labelled I is to
Answer: B (fit into the acetabulum of the pelvic girdle.)
I is the rounded head of the femur, which fits into the acetabulum (socket) of the pelvic girdle to form the hip ball-and-socket joint.
Which of the following processes is not a function of the mammalian skin?
Answer: D (Gaseous exchange.)
Mammalian skin is too thick and dry for gaseous exchange; that happens in the lungs. It does control temperature, sense stimuli and excrete sweat.
The legs of an accident victim with a fractured vertebral column and injured spinal cord could not be raised because
Answer: B (impulses from the brain cannot travel to the legs.)
To move the legs, impulses must go from the brain down the spinal cord to the leg muscles; a break in the cord stops them, so the legs are paralysed.
Which of the following conditions in flowering plants enhance self-pollination?
Answer: A (Cleistogamy)
In cleistogamy the flower never opens, so it can only pollinate itself; the other conditions favour cross-pollination.
The diagram is an illustration of the left side of the human cerebrum.
The part labelled X controls
Answer: A (general memory.)
X points to the upper part of the cerebral hemisphere, the area the book links with memory and intelligence; sight is at the back and breathing is controlled by the medulla.
The diagram is an illustration of
Answer: C (correction of long sightedness.)
The upper eye focuses light behind the retina (long sight); the lower one shows a convex lens in front of the eye bringing the focus onto the retina.
The inability to maintain proper balance of the body in humans may be due to a defect in the
Answer: C (semi-circular canals.)
The semicircular canals in the inner ear detect movement of the head and help keep balance.
An inferior ovary of a flower is situated
Answer: A (below the floral parts.)
An inferior ovary lies below the point where the sepals, petals and stamens are attached.
Older parts of plant roots do not normally absorb water because
Answer: D (they lack root hairs.)
Water is absorbed mainly through root hairs near the tip; older parts have no root hairs and are covered with cork.
The amount of starch in a germinating seed decreases because the starch is used up
Answer: A (for respiration and building up of cells.)
Stored starch is turned to sugar, which is respired for energy and used to make new cells for the growing seedling.
The purpose of treating poor soil with lime is to increase the quantity of
Answer: C (calcium.)
Lime is calcium carbonate or calcium oxide; it adds calcium and reduces soil acidity.
A meal consisting of yam and a lot of vegetables is not balanced because it does not contain
Answer: B (proteins.)
Yam supplies carbohydrate and vegetables supply vitamins and minerals, but there is no good source of protein.
A characteristic feature of plant parasites is the
Answer: D (development of haustoria.)
Haustoria are special suckers that parasitic plants push into the host's vascular tissue to absorb food and water.
The part of a leguminous plant where bacteria like Azotobacter can be found is
Answer: C (in the root nodules.)
Nitrogen-fixing bacteria associated with legumes live in the root nodules (strictly, the nodule bacterium is Rhizobium; Azotobacter lives free in the soil).
The following adaptations are associated with the flight of birds except
Answer: D (clawed digits.)
Light hollow bones, a streamlined body and strong flight muscles help flight; claws are for perching and grasping.
The following habitats can be found in West Africa except
Answer: D (temperate grassland.)
Temperate grasslands occur in cool regions such as North America and Asia, not in tropical West Africa.
The difference between a community and population is
Answer: B (a community is made up of populations of living organisms while a population is made up of organisms of the same species.)
A population is one species in an area; a community is all the populations of different species living there together.
Which of the following statements about the circulation of water in nature is not correct? Water
Answer: C (removed from oceans is permanently lost.)
Water evaporated from oceans returns as rain; in the water cycle nothing is permanently lost.
The diagram illustrates an ecological instrument.
The instrument is
Answer: D (a wind vane.)
An arrow that turns on a pole above fixed N, S, E and W arms is a wind vane.
The diagram illustrates an ecological instrument.
The instrument is used to measure the
Answer: A (direction of wind.)
A wind vane shows the direction the wind is blowing from; wind speed needs an anemometer.
The following organisms are consumers except
Answer: B (Spirogyra.)
Spirogyra is a green alga that photosynthesises, so it is a producer.
Use the substances listed below to answer this question.
I. Fertilizer II. Insecticides III. Sewage IV. Crude oil V. Sulphur dioxide.
The atmosphere can be polluted by
Answer: D (II and V only.)
Insecticide sprays and sulphur dioxide (from burning fuels) are released into the air; the others mainly pollute land and water.
Use the substances listed below to answer this question.
I. Fertilizer II. Insecticides III. Sewage IV. Crude oil V. Sulphur dioxide.
Which of the substances constitute domestic waste?
Answer: B (III only)
Sewage comes from homes (toilets, kitchens, bathrooms), so it is domestic waste.
The table below shows the oxygen level, number of green plants and fish in rivers flowing through four towns.
Town A: oxygen level high, green plants few, fish many.
Town B: oxygen level low, green plants many, fish many.
Town C: oxygen level high, green plants few, fish few.
Town D: oxygen level low, green plants many, fish few.
Which of the towns is likely to be discharging untreated sewage in their river?
Answer: D (D.)
Sewage adds nutrients, so plants grow a lot; bacteria decomposing the sewage use up oxygen, so fish die. Low oxygen, many plants and few fish fit town D.
Which of the following natural resources is non-renewable?
Answer: B (Coal)
Coal took millions of years to form and cannot be replaced once used.
Which of the following statements is not a reason for banning bush burning? It
Answer: A (allows for quick regrowth of grasses.)
Quick regrowth of grass is a supposed benefit of burning, not a reason to ban it; the other options are harms.
Which of the statements below explains why fertilizers are added to soils?
Answer: C (Increasing the nutrient level of the soil)
Fertilizers add mineral nutrients such as nitrogen, phosphorus and potassium that crops need.
Characteristics that exhibit continuous variation are generally controlled by
Answer: D (multiple genes.)
Continuous traits like height are controlled by many genes (polygenes) acting together.
Differences in characteristics that exist among individuals of the same species is referred to as
Answer: D (variation.)
Variation means the differences between members of the same species.
Which of the following traits is not a morphological variation in humans?
Answer: A (Ability to taste PTC)
Morphological variations are differences in outward form, such as size, colour and fingerprints. Being able to taste PTC depends on body chemistry, so it is physiological.
Which of the following statements about chromosomes is correct?
Answer: B (The number present in a species is constant)
Each species has a fixed chromosome number (e.g. 46 in human body cells); chromosomes differ in shape and are in the nucleus.
A small stem from a hibiscus plant was placed in a nutrient medium, and it developed into a new plant. The new plant was reproduced
Answer: C (asexually with the same genotype as the parent plant.)
Growing a plant from a stem piece is vegetative (asexual) propagation, so the new plant is genetically identical to the parent.
The F1 generation of a cross between a red cock and white hen were all red because the gene for the
Answer: B (red colour was dominant.)
When all F1 offspring show one parent's trait, that trait is dominant.
Which of the following diseases can be inherited?
Answer: C (Sickle cell anaemia)
Sickle cell anaemia is caused by an inherited gene; the others are caused by germs or diet.
In dihybrid inheritance, Mendel considered
Answer: B (two pairs of contrasting characters.)
'Di' means two: a dihybrid cross follows two pairs of contrasting characters at once, e.g. seed shape and seed colour.
The main reason for nuptial flight in termites is to
Answer: C (form new colonies.)
Winged reproductive termites fly out, mate, shed their wings and start new colonies.
Which of the following organisms is not a social insect?
Answer: C (Grasshoppers)
Termites, ants and bees live in organised colonies with castes; grasshoppers live alone.
Lamarck's theory of evolution is based on the fact that
Answer: B (organisms pass on acquired characters to their offspring.)
Lamarck said that features gained during an organism's life through use or disuse are passed on to its offspring.
(a)(i) List three characteristics of living organisms. (ii) Explain briefly the characteristics listed in 1(a)(i) above.
(b) In a tabular form, state four differences between plants and animals.
(c)(i) Name one organism that exhibits both plant and animal features. (ii) State four animal features and two plant features possessed by the organism named in 1(c)(i) above.
(a)(i) Any three: nutrition; respiration; excretion; growth; reproduction; irritability (sensitivity); movement.
(ii) Each explained, e.g. Nutrition — obtaining or making food for energy and growth; Respiration — breaking down food to release energy; Excretion — removing waste products of metabolism; Growth — permanent increase in size/dry mass; Reproduction — producing new individuals of the same kind; Irritability — responding to changes (stimuli) in the environment; Movement — changing position of the body or its parts.
(b) Table (any four) — Plants: autotrophic (make food by photosynthesis) / Animals: heterotrophic; have chlorophyll / no chlorophyll; cellulose cell wall / no cell wall; usually fixed, move only parts / move whole body; growth at tips, indefinite / growth all over, definite; store starch / store glycogen; no special sense or excretory organs / have them; respond slowly / respond quickly.
(c)(i) Euglena (or Chlamydomonas).
(ii) Animal features (Euglena): moves with a flagellum; has a gullet; has a pellicle and no cellulose wall; has a contractile vacuole; has an eyespot; can feed heterotrophically in the dark. Plant features: has chloroplasts/chlorophyll; makes food by photosynthesis; stores paramylon (starch-like).
In (b) set each plant feature against the matching animal feature.
(a) Define the following terms: (i) elimination; (ii) excretion; (iii) secretion.
(b) Describe the digestion of boiled fish in the gut of humans.
(c) Make a diagram 8 cm – 10 cm long of a longitudinal section of a villus and label fully.
(a)(i) Elimination (egestion): removal of undigested food (faeces) from the alimentary canal through the anus.
(ii) Excretion: removal of waste products of metabolism (e.g. urea, CO2) from the body.
(iii) Secretion: release of useful substances (e.g. enzymes, hormones, mucus) made by cells or glands.
(b) Fish is mainly protein (and some fat). Mouth: chewed and moistened with saliva (no protein digestion). Stomach: HCl kills germs and gives acid pH; pepsin breaks proteins into polypeptides/peptones. Duodenum: bile emulsifies fats; pancreatic trypsin breaks proteins/polypeptides into peptides; lipase breaks fats into fatty acids and glycerol. Ileum: erepsin (peptidase) breaks peptides into amino acids; intestinal lipase completes fat digestion. Amino acids are absorbed into blood capillaries of the villi; fatty acids and glycerol into the lacteals.
(c) Diagram of correct size with title, labels: epithelium (single layer of cells); microvilli; blood capillaries; arteriole and venule; lacteal (lymph vessel); goblet cells; connective tissue.
Follow the protein from mouth to ileum, naming the enzyme and product at each stage.
(a) Explain briefly the following ecological terms: (i) biosphere; (ii) habitat.
(b) Describe the mode of nutrition in a named carnivorous plant.
(c) State three reasons why the dispersal of fruits and seeds are important.
(d) State six methods of conserving soil.
(a)(i) Biosphere: the zone of the earth (land, water and lower atmosphere) where living things are found.
(ii) Habitat: the particular place where an organism or a population lives, e.g. a pond or forest floor.
(b) e.g. Sundew (Drosera) or pitcher plant / bladderwort: it grows in nitrogen-poor soil; it makes carbohydrates by photosynthesis; insects are attracted by colour, scent or nectar; they are trapped (sticky glandular hairs fold over them in sundew; slippery walls into a fluid-filled pitcher); glands secrete protein-digesting enzymes; the digested products (amino acids, nitrogen compounds) are absorbed to supply nitrogen.
(c) Any three: prevents overcrowding of seedlings; reduces competition for light, water and nutrients with the parent and each other; allows colonisation of new areas; increases survival of the species; reduces spread of disease.
(d) Any six: crop rotation; cover cropping; mulching; contour ploughing/terracing; planting windbreaks/afforestation; avoiding bush burning; avoiding overgrazing; adding manure/fertilisers; strip cropping; bush fallowing.
In (b) name the plant and say why it traps insects (to get nitrogen).
A survey to determine blood groups was carried out on 250 people living in a community. The results are represented in the table below.
Blood group A: 8.0%; Blood group B: 14.0%; Blood group AB: 32.8%; Blood group O: 45.2%.
(a)(i) Explain the term co-dominance. (ii) Calculate the number of individuals with co-dominant blood group.
(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?
(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.
(a)(i) Co-dominance is when both alleles in a heterozygote are fully expressed in the phenotype, neither being dominant over the other, e.g. blood group AB.
(ii) Co-dominant group is AB: 32.8/100 × 250 = 82 individuals.
(iii) A group B person can receive from groups B and O: (14.0 + 45.2)/100 × 250 = 59.2% × 250 = 148 individuals.
(b) Man IAIO × woman IAIB; gametes IA, IO and IA, IB; offspring IAIA, IAIB, IAIO, IBIO; blood groups: A (IAIA and IAIO), AB and B, in the ratio 2 A : 1 AB : 1 B.
Convert each percentage to a number of people by multiplying by 250 and dividing by 100.
(For candidates in Nigeria only)
(a) State five reasons why animals move from place to place.
(b) State one function each of the following structures found in plants: (i) epidermis; (ii) phloem; (iii) sclerenchyma.
(c) Give two examples each of the following types of organisms: (i) parasitic plants; (ii) saprophytes.
(d) State two adaptive features of plants which inhabit salt water swamp.
(e) State two factors each which result in: (i) increase; (ii) decrease, in population density.
(f) Mention four ways in which modern agricultural activities may threaten the survival of species.
(g) State three reasons why mitosis is important to living organisms.
(h) State three causes of food spoilage.
(a) Any five: search for food; search for water; find mates; escape predators/danger; find shelter; avoid unfavourable conditions (heat, cold, drought); find breeding sites; avoid overcrowding/competition.
(b)(i) Epidermis: protects inner tissues / reduces water loss / gas exchange through stomata. (ii) Phloem: transports manufactured food (translocation). (iii) Sclerenchyma: gives mechanical support and strength.
(c)(i) Dodder (Cuscuta), mistletoe (Loranthus), Striga. (ii) Mushroom, Rhizopus/Mucor (bread mould), bacteria of decay.
(d) Any two: breathing roots (pneumatophores) for air; stilt/prop roots for support in soft mud; salt glands/succulent leaves to deal with salt; viviparous seeds (germinate on the parent); thick cuticle.
(e)(i) Increase: high birth rate (natality); immigration; abundant food; absence of predators/disease. (ii) Decrease: high death rate; emigration; food shortage; predation; disease; natural disasters.
(f) Any four: clearing forests (habitat destruction); use of pesticides and herbicides that kill non-target species; bush burning; monoculture reducing variety; fertiliser run-off polluting water; draining of wetlands; overgrazing.
(g) Any three: growth of the organism; repair and replacement of worn-out or damaged cells; asexual reproduction; keeps the chromosome number constant in body cells (identical daughter cells).
(h) Any three: microorganisms (bacteria, fungi); enzymes within the food; insects and rodents; moisture; warm temperature; exposure to air (oxidation).
Many short parts: give exactly the number of points asked for each.