46 questions. Try each one, then open the answer to check yourself and read the explanation.
The scientist who introduced binomial nomenclature in the classification of organisms was
Answer: B (Carolus Linnaeus.)
Carolus Linnaeus gave every organism a two-part Latin name (genus and species), e.g. Homo sapiens.
Which of the following statements is true about arthropods?
Answer: A (Prothorax bears only legs)
An insect's thorax has three segments, each with a pair of legs. The first (prothorax) has legs only; the second and third (mesothorax and metathorax) carry both legs and wings.
The streaming movement of cytoplasm within Paramecium is known as
Answer: C (cyclosis.)
Cyclosis is the circular flowing of cytoplasm inside a cell, which carries food vacuoles and materials around.
Which of the following cell organelles is found only in plant cells?
Answer: D (Plastids)
Plastids, such as chloroplasts and leucoplasts, are found only in plant cells. Mitochondria and ribosomes occur in both plant and animal cells.
Active transport differs from diffusion in that active transport
Answer: B (allows the movement of substances against concentration gradient.)
Active transport uses energy (ATP) to move substances from a low to a high concentration. Diffusion only moves them down the gradient, from high to low.
The diagrams below are illustrations of an experimental set-up to demonstrate a type of tropic response in plants. The type of response demonstrated is
Answer: C (hydrotropism.)
The roots in dry soil grow towards the water seeping from the porous clay pot. A growth response towards water is hydrotropism.
The diagrams below are illustrations of an experimental set-up to demonstrate a type of tropic response in plants. The conclusion drawn from the experiment is that
Answer: D (roots of plants are positively hydrotropic.)
The roots bend and grow towards the water source, so roots are positively hydrotropic.
The odontoid process is found on the
Answer: A (axis vertebra.)
The axis (second neck vertebra) has a peg, the odontoid process, that fits into the atlas and lets the head turn from side to side.
A seedling was made to stand in a solution of red ink for three hours and a transverse section of the stem was examined under the microscope. The process being investigated was
Answer: B (ascent of water through the xylem.)
The dye travels with the water and stains only the xylem vessels. This shows that water rises up the stem through the xylem.
Which of the following structures would carry out respiration?
Answer: A (germinating cowpea.)
Only living cells respire. A germinating seed is alive and very active, while decolourised, dry or boiled material is dead.
Which of the following substances is not an excretory product of animals?
Answer: D (Oxygen)
Animals take in oxygen for respiration; they do not produce it as a waste. Carbon dioxide, urea and sweat are all excreted.
An example of homeostasis in living organisms is
Answer: A (cooling effect resulting from evaporation of water from the body surface.)
Sweating cools the body as the sweat evaporates, which keeps body temperature steady. Keeping internal conditions constant is homeostasis.
Ultrafiltration in the kidney takes place in the
Answer: D (Bowman's capsule.)
Blood under high pressure in the glomerulus is filtered into the Bowman's capsule. This pressure filtration is ultrafiltration.
The thyroid gland is located at the base of the
Answer: C (neck.)
The thyroid gland lies in the neck, at the front of the windpipe below the larynx.
Which of the following statements about the response of neurones to stimulus is correct?
Answer: D (Intensity of stimulus must reach a threshold value before the neurones can be excited)
A neurone fires only when the stimulus reaches a minimum strength, the threshold. Weaker stimuli give no impulse, and during the refractory period it cannot fire at all.
Which of the following practices may lead to infection of the eye? Use of
Answer: A (contact lenses.)
Contact lenses sit directly on the eye. If they are not cleaned properly or are worn too long, they can carry germs that infect the eye.
The structures for gaseous exchange in breathing roots are
Answer: B (lenticels.)
Breathing roots, such as those of mangroves, stick up out of the mud. Air enters them through lenticels, small pores in their bark.
The diagram below is an illustration of the life cycle of an insect. The adult insect in this life cycle is
Answer: B (butterfly.)
The life cycle has a caterpillar larva and a pupa hanging in a pod (chrysalis), which is complete metamorphosis of a butterfly.
The diagram below is an illustration of the life cycle of an insect. The larva is also known as
Answer: C (caterpillar.)
The larva of a butterfly or moth is called a caterpillar. A maggot is a fly larva and a nymph is the young of insects such as cockroaches.
The source of energy required by plants during food production is
Answer: C (sunlight.)
Plants make food by photosynthesis using light energy from the sun, which chlorophyll absorbs.
One major difference between plant and animal nutrition is the ability of plants to synthesize
Answer: A (food for plants and animals.)
Green plants make their own food by photosynthesis, and this food passes on to animals that eat them. Animals cannot make their own food.
By what process is starch converted into maltose?
Answer: A (Hydrolysis)
Amylase breaks starch into maltose by adding water to the bonds between sugar units. This splitting with water is hydrolysis.
The ascent of water in tall trees is mainly due to
Answer: B (transpiration pull.)
Water evaporating from the leaves pulls the column of water up the xylem from the roots. This transpiration pull is the main force in tall trees.
The duodenum of a person was surgically removed. Which of the following food substances would have their digestion affected?
Answer: D (Starch, protein and lipids)
Pancreatic juice and bile enter the duodenum. Pancreatic amylase, trypsin and lipase digest starch, protein and fat, so all three would be affected.
Which of the following dental formulae represents the dentition in rabbits?
Answer: A (I 2/1, C 0/0, P 3/2, M 3/3)
A rabbit has 2 upper and 1 lower incisor on each side, no canines (leaving a gap, the diastema), 3 upper and 2 lower premolars, and 3 molars above and below.
The diagram below is an illustration of an experimental set-up to demonstrate a property of soil. The property of soil demonstrated is
Answer: B (capillarity.)
The tubes of soil stand in water and the water rises up through them. This upward movement of water through soil pores is capillarity.
The diagram below is an illustration of an experimental set-up to demonstrate a property of soil. Which of the following statements would be a correct observation at the end of the experiment? Water moves
Answer: D (highest in clayey soil.)
Clay has the smallest particles and the narrowest pore spaces, so water rises highest in it by capillarity. Water rises least in sandy soil.
The most important factor(s) that influence(s) the ecological niche of an organism is/are the
Answer: B (food and water availability.)
An organism's niche is its role in the habitat, mainly decided by what it feeds on and the resources (food and water) it can get.
The diagram below is an illustration of organisms in an air-tight aquarium. The most important factor needed by the organisms is
Answer: A (light energy.)
The aquarium is sealed, so nothing comes in from outside except light. With light, the water plants photosynthesise and produce the oxygen and food that the fish, snail and insects need.
Xerophytes have the following characteristics aimed at conserving water except
Answer: B (broad leaf surfaces.)
Broad leaves lose a lot of water by transpiration. Xerophytes have small, narrow or spiny leaves instead, along with thick waxy cuticles and sunken stomata.
Two unconscious patients X and Y whose blood group genotypes are AO and AB respectively were transfused with blood from the same donor. Patient X immediately showed signs of difficulty in breathing while patient Y showed no negative reaction. Patients X and Y were likely transfused with blood of genotype
Answer: C (BO.)
Patient X is group A and has anti-B antibodies, so X reacted to blood carrying the B antigen. Patient Y is AB and accepts any group. A donor of genotype BO (group B) explains both results.
Two unconscious patients X and Y whose blood group genotypes are AO and AB respectively were transfused with blood from the same donor. Patient X immediately showed signs of difficulty in breathing while patient Y showed no negative reaction. What should the hospital have done to prevent patient X from showing the symptom described above? Patient X should have
Answer: A (undergone an agglutination test.)
Before transfusion, the donor's and patient's blood should be mixed and checked for clumping (agglutination test, or cross-matching). This would have shown the blood was incompatible.
The diagrams below are illustrations of the inheritance of coat colour in mice. J, K, L, M and N are parents. The cross between two parent mice gave rise to offspring P, Q, R and S. Which parent mouse is heterozygous for coat colour?
Answer: D (L)
L is black but, crossed with the white mouse M, gives both black and white young. So L must carry a hidden white allele: it is heterozygous.
The diagrams below are illustrations of the inheritance of coat colour in mice. J, K, L, M and N are parents. The cross between two parent mice gave rise to offspring P, Q, R and S. Which of the offspring are all homozygous?
Answer: C (S)
White is recessive. M and N are both white (homozygous recessive), so all their young S are white and homozygous too.
Genes that remain linked are those
Answer: A (close to each other on the chromosomes.)
Genes that sit close together on the same chromosome are seldom separated by crossing over, so they are inherited together: they stay linked.
A plant cell has 14 chromosomes prior to mitosis. What is the number of chromosomes in the daughter cells?
Answer: A (14)
Mitosis produces two daughter cells, each with exactly the same number of chromosomes as the parent: 14.
The chemical bond that holds the bases of the two strands of DNA together is
Answer: B (hydrogen bond.)
The two strands of DNA are joined by weak hydrogen bonds between paired bases (A with T, G with C). This lets the strands separate when DNA is copied.
The diagram below is an illustration of one of the theories of evolution. Who proposed the theory in the illustration?
Answer: D (Jean Lamarck)
The giraffes' necks get longer over time as they stretch to reach the leaves. This is Jean Lamarck's idea that organs grow with use and are passed on.
The diagram below is an illustration of one of the theories of evolution. The theory supports
Answer: D (the use and disuse of body parts.)
Lamarck's theory says that body parts that are used a lot grow bigger and those not used shrink, and these changes are inherited. This is the theory of use and disuse.
In evolution, fossils are naturally preserved in
Answer: A (rocks.)
Fossils are the remains or traces of ancient organisms preserved in sedimentary rocks.
Which of the following insects is not a social insect?
Answer: B (Housefly)
Termites, honeybees and ants live in organised colonies with castes. Houseflies live on their own.
(a) Explain briefly how the structure of each of the following cells relate to their functions: (i) sperm cell; (ii) palisade cell. (b) Make a drawing 8 cm – 10 cm long of the front view of the female reproductive system in humans and label fully. (c) State two differences between reproduction in mammals and in amphibians. (d) State two methods of birth control in humans.
(a)(i) Sperm cell: long tail (flagellum) lets it swim to the ovum; acrosome in the head holds enzymes that digest a way into the egg; head has a nucleus with half the chromosomes (haploid) to fuse with the egg nucleus; middle piece packed with mitochondria supplies energy for swimming; small and streamlined.
(ii) Palisade cell: many chloroplasts to trap light; long, column-shaped and packed close together just under the upper epidermis, at right angles to the surface, so many cells receive light; thin cell wall lets light and gases pass; chloroplasts can move towards the light; large vacuole holds water.
(b) Front view drawing, 8–10 cm, with title and labels: ovaries, oviducts (Fallopian tubes) with funnels/fimbriae, uterus (with its wall/endometrium), cervix, vagina, (vulva). Symmetrical, clear lines, ruled label lines.
(c) Any two: mammals have internal fertilisation / most amphibians have external fertilisation (in water); mammal embryo develops inside the uterus with a placenta / amphibian eggs develop outside in water; mammals produce few eggs / amphibians produce many eggs; mammals give birth to live young / amphibians lay eggs; mammals show much parental care and feed young on milk / amphibians show little or none; amphibians have a larval (tadpole) stage and metamorphosis / mammals do not.
(d) Any two: condom; diaphragm/cap; contraceptive pill or injection; IUD (loop); spermicides; rhythm (safe period) method; withdrawal; abstinence; vasectomy or tubal ligation.
Link every structural feature to its function with 'so that' or 'for'.
(a) Name the gases involved in the photosynthesis of a plant. (b) State one role each of the gases named in 2(a). (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)(ii). (v) Name one mineral element required by plants for the formation of the part that would test positive in 2(c)(ii). (d) The table below indicates different methods by which organisms obtain food. Place the following organisms under the headings in the table below: Human, Mushroom, Venus flytrap, Waterleaf plant, Tapeworm, Elephant grass, Housefly, Lichen, Spirogyra, Rhizopus.
Mode of Nutrition: Holozoic | Parasitic | Symbiotic | Saprophytic | Autotrophic
(a) Carbon (IV) oxide (CO2) and oxygen (O2).
(b) CO2: raw material, its carbon is built into glucose. O2: by-product given off (released into the air for respiration).
(c)(i) A variegated leaf has green parts (with chlorophyll) and white or yellow parts (without chlorophyll).
(ii) The green parts.
(iii) The green parts contain chlorophyll, which traps light for photosynthesis; so only they make glucose, which is stored as starch; the white parts lack chlorophyll and make no starch.
(v) Magnesium (or nitrogen, or iron needed to make chlorophyll).
(d) Holozoic: Human, Housefly.
Parasitic: Tapeworm.
Symbiotic: Lichen.
Saprophytic: Mushroom, Rhizopus.
Autotrophic: Waterleaf plant, Elephant grass, Spirogyra, Venus flytrap (it photosynthesises; it also traps insects, so it may be accepted as holozoic too).
The part numbered (iv) is missing in the book; answer the parts as printed.
(a) Explain briefly the following terms: (i) renewable natural resources; (ii) non-renewable natural resources. (b) Give two examples each of: (i) renewable natural resources; (ii) non-renewable natural resources. (c) State five ways of conserving forests. (d) State four effects of adding animal manure to garden soil. (e) Give the possible genotypes in humans.
(a)(i) Renewable resources are natural resources that can be replaced naturally (or by people) after use, so they need not run out if managed well.
(ii) Non-renewable resources exist in fixed amounts and cannot be replaced once used up, or take millions of years to form.
(b)(i) Any two: water, soil, forests/plants, wildlife/animals, air, sunlight.
(ii) Any two: petroleum (crude oil), coal, natural gas, minerals such as iron ore, tin, gold, limestone.
(c) Any five: afforestation and reforestation; forest reserves; controlled/selective felling; ban on bush burning and control of forest fires; laws against illegal logging; use of alternative fuels instead of firewood; taungya system; education of the public; fire belts.
(d) Any four: adds nutrients (nitrogen, phosphorus, potassium); adds humus, which improves soil structure; increases water-holding capacity; improves aeration; increases soil organisms; reduces erosion; buffers soil pH.
(e) The question is unclear as printed. Likely meaning: haemoglobin genotypes AA, AS, SS (and AC, SC); or blood group genotypes AA, AO, BB, BO, AB, OO.
Part (e) seems out of place in the paper; give the common human genotypes.
(a) Explain briefly the following terms: (i) gene; (ii) hybrid; (iii) trait. (b) Two heterozygous yellow flowers are crossed. Using a genetic diagram; state the phenotypic and genotypic ratios of the first filial generation. (c) State four transmittable characters in plants.
(a)(i) A gene is a unit of heredity, a section of DNA on a chromosome that controls one characteristic.
(ii) A hybrid is the offspring of parents that differ genetically (e.g. of two different varieties or species); a heterozygous individual.
(iii) A trait is a characteristic or feature of an organism that can be inherited, e.g. flower colour.
(b) Let Y = yellow (dominant), y = other colour (e.g. white). Parents: Yy × Yy; gametes: Y, y and Y, y; F1: YY, Yy, Yy, yy.
Genotypic ratio 1 YY : 2 Yy : 1 yy.
Phenotypic ratio 3 yellow : 1 non-yellow (white).
(c) Any four: height (tall/dwarf); flower colour; seed colour; seed shape (round/wrinkled); pod shape or colour; position of flowers; leaf shape; fruit colour; disease resistance.
Show parents, gametes, fusion and offspring in the genetic diagram.
(a)(i) Explain briefly chemosynthesis as a mode of nutrition. (ii) Give two examples of organisms that carry out chemosynthesis. (b) List three gases in the atmosphere with their percentage composition.
Gases in the atmosphere | Percentage composition
(c)(i) State four characteristics of a salt marsh habitat. (ii) Explain briefly how plants are modified for anchorage in a salt marsh habitat. (d)(i) List four bacterial diseases associated with poor food hygiene. (ii) State three effects of poor food hygiene. (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. (f) State three differences between tillage and bush burning as farming practices.
Tillage | Bush burning
(a)(i) Chemosynthesis is a type of autotrophic nutrition in which some bacteria make their own food from simple inorganic substances using energy released by oxidising chemicals (e.g. ammonia, nitrites, iron or sulphur compounds) instead of light.
(ii) Any two: Nitrosomonas; Nitrobacter; iron bacteria; sulphur bacteria (e.g. Thiobacillus).
(b) Any three: nitrogen about 78%; oxygen about 21%; argon (noble gases) about 0.9%; carbon (IV) oxide about 0.03%; water vapour variable.
(c)(i) Any four: water is salty/brackish and its salt level changes; flooded at high tide and exposed at low tide; soft, muddy, waterlogged soil; mud poor in oxygen; strong sunlight and high evaporation; tidal currents.
(ii) Mangrove plants have stilt (prop) roots growing from the stem and spreading into the mud, which hold them firmly against tides; extensive branching roots; breathing roots (pneumatophores) also help.
(d)(i) Any four: cholera; typhoid fever; bacillary dysentery; food poisoning (Salmonella, Staphylococcus); botulism; tuberculosis (from milk); diarrhoea caused by E. coli.
(ii) Any three: spread of food-borne diseases; diarrhoea, vomiting and dehydration; death; food spoilage and waste; loss of working/school days and money.
(e) He should be given a blood transfusion of matched (compatible) blood after cross-matching; meanwhile intravenous fluids (saline/plasma) restore volume; later the body replaces lost blood: bone marrow makes new red cells, liver makes plasma proteins; a diet rich in iron, protein and vitamins helps.
(f) Any three: tillage loosens and turns the soil / bush burning clears vegetation by fire; tillage improves aeration and drainage / bush burning does not; tillage keeps organic matter, which can be turned in / burning destroys organic matter and soil organisms; tillage does not pollute the air / burning releases smoke and CO2; burning exposes soil to erosion / tillage (done properly) causes less erosion; burning quickly releases potash (ash) / tillage does not.
Section C (candidates in Nigeria only). Use the tables for (b) and (f).