52 questions. Try each one, then open the answer to check yourself and read the explanation.
The major function of the cell membrane is that it
Answer: A (delimits the cytoplasm)
The cell membrane forms the boundary around the cytoplasm and controls what enters and leaves the cell.
Display is a phenomenon which occurs when an animal is
Answer: A (ready for mating)
Display (showing bright colours or special movements) is mainly courtship behaviour by an animal ready to mate, to attract a partner.
The advantages of sexual reproduction include the following except
Answer: D (it provides means for the variation of chromosome number from generation to generation)
Sexual reproduction (with meiosis and fertilisation) keeps the chromosome number constant from generation to generation; it does not vary it.
Which of the following groups contains a non-supporting structure in animals?
Answer: A (Cartilage, bone and pseudopodia)
Pseudopodia are temporary outgrowths used by Amoeba for movement and feeding, not for support.
Which of the following statements is true about blood groupings?
Answer: D (Group O has no antigen.)
Group O red cells carry neither antigen A nor antigen B; AB is the universal recipient and antigens are on the red cells, not in the plasma.
Which of the following is not a constituent of blood plasma?
Answer: D (Platelets)
Platelets are cell fragments carried in the blood, not dissolved in the plasma like proteins and salts.
The process by which plants convey food material to different parts of the body is called
Answer: D (translocation)
Translocation is the movement of manufactured food through the phloem to other parts of the plant.
Which part of the gill of fish is involved in gaseous exchange?
Answer: D (Gill filaments)
The thin, blood-filled gill filaments have a large surface where oxygen and carbon dioxide are exchanged.
Which of the following is not a product of fermentation of glucose?
Answer: C (Lactic acid)
Fermentation by yeast gives alcohol, carbon dioxide and energy; lactic acid is made by anaerobic respiration in muscle.
Which of the following pairs of structures does not perform similar functions?
Answer: B (Root hair and mammalian hair)
Root hairs absorb water and salts, while mammalian hair keeps the body warm, so their functions differ.
The effect of the contraction of the muscles of the diaphram is that
Answer: A (the volume of the thoracic cavity increases.)
When the diaphragm contracts it flattens, making the chest cavity bigger, so air is drawn in.
Which of the following is an excretory product of Amoeba?
Answer: B (Ammonia)
Amoeba excretes ammonia, which diffuses out easily into the surrounding water.
Which of the following processes occurs when the body temperature of a mammal rises above the normal?
I. The arterioles in the skin dilate. II. Sweat production is reduced. III. The erector muscles contract.
Answer: A (I only)
When the body is too hot, skin arterioles dilate to lose heat; sweating increases (not reduces) and the erector muscles relax.
The following functions are associated with the liver except
Answer: D (production of vitamin D)
The liver controls blood sugar, makes fibrinogen and produces heat; vitamin D is made in the skin in sunlight (the liver only stores it).
Short-sight could be corrected with the use of
Answer: C (concave lens)
In short sight images fall in front of the retina; a diverging (concave) lens moves them back onto it.
Which of the following statements about the maize grain is not correct? It
Answer: C (is non-endospermous)
The maize grain stores its food in a large endosperm, so it is endospermous.
In mammals, fertilization usually occurs in the
Answer: D (oviduct)
Sperm meet the egg in the oviduct (Fallopian tube); the embryo then moves to the uterus.
Which of the following vertebrates incubate their eggs?
Answer: B (Birds)
Birds sit on their eggs to keep them warm until they hatch.
Which of the following is an agent of pollination of grasses?
Answer: C (Wind)
Grasses have small dull flowers with feathery stigmas and light pollen carried by wind.
The spinneret found in the caterpillar of butterfly is used for
Answer: D (production of silk thread)
The spinneret releases silk, which the caterpillar uses to spin threads and make its cocoon.
Carbon dioxide enters the leaf through the structure labelled
Answer: C (IX)
Carbon dioxide diffuses in through the stoma on the lower epidermis, which is labelled IX.
Manufactured food is transported from the leaves through the structure labelled
Answer: B (V)
V is the phloem on the lower side of the vascular bundle; phloem carries manufactured food.
The pallisade cells are the structures labelled
Answer: A (III)
III marks the tall, closely packed cells just below the upper epidermis: the palisade layer.
Which of the groups of structures listed below contains chloroplast?
Answer: D (III, VIII and XI)
Chloroplasts are found in the palisade (III) and spongy mesophyll (VIII) cells and in the guard cells (XI); the cuticle, epidermis and air spaces have none.
In which of the following processes is light energy converted to ATP?
Answer: D (Photosynthesis)
In the light stage of photosynthesis, chlorophyll traps light energy and uses it to make ATP.
The correct equation for photosynthesis is
Answer: C (6CO2 + 6H2O → (sunlight, chlorophyll) C6H12O6 + 6O2)
Six molecules of carbon dioxide and six of water make one glucose molecule and six of oxygen; this is the only balanced option.
Which of the following is an evidence of photosynthesis?
Answer: B (Formation of starch)
A leaf that has photosynthesised contains starch, which can be shown with iodine.
Which of the following organisms is a chemo-autotroph?
Answer: B (Bacteria)
Some bacteria, such as nitrifying bacteria, make food using energy from chemical reactions (chemosynthesis).
Turgidity in the cell of plant does not easily lead to bursting of the cell because the
Answer: C (cellulose cell wall can resist the turgidity)
The strong cellulose wall pushes back against the swelling contents, so the cell does not burst.
Magnesium is needed by plants for
Answer: D (formation of chlorophyll)
Magnesium is a part of the chlorophyll molecule.
Which of the following is not a micronutrient?
Answer: C (Potassium)
Potassium is needed in large amounts (a macro-nutrient); manganese, copper and zinc are trace elements.
The mineral needed for the formation of haemoglobin is
Answer: B (iron)
Each haemoglobin molecule contains iron, which binds oxygen; lack of iron causes anaemia.
A person who fails to detect the bitter taste of a substance swallowed, is more likely to have
Answer: B (avoided the substance from contacting the back of his/her tongue.)
Bitter taste is detected mainly at the back of the tongue; if the substance does not touch that area, the bitterness is not noticed.
Which of the following solutions is suitable for removing chlorophyll in a green leaf?
Answer: B (Methylated spirit)
Chlorophyll dissolves in hot alcohol such as methylated spirit; the other solutions are food-test reagents.
Micro-organisms which break down dead organisms and absorb their contents are called
Answer: A (decomposers)
Decomposers such as bacteria and fungi break down dead matter and absorb the products.
The substances recycled in the soil by the activities of micro-organisms during the decay of dead organisms are first utilised by the
Answer: D (autotrophs)
Decay releases mineral salts into the soil, and these are first taken up by green plants (autotrophs).
Which of the following associations can upset the balance of nature?
Answer: B (Parasitism)
Parasites harm and can kill their hosts, which can upset population balance; the other associations do no harm.
Which of the following groups of factors do the Agama lizards compete for? I. Space II. Food III. Mates
Answer: D (Space, food and mates)
Agama lizards compete for territory (space), food and females (mates).
Which of the following structures in a housefly aids in the transmission of diseases in man?
Answer: A (Hairs)
Germs stick to the hairs on the housefly's body and legs and are left on food it lands on.
Which of these is not correct about the tse-tsefly and mosquito? They
Answer: C (have intermediate hosts.)
The tsetse fly and mosquito are themselves the vectors (intermediate hosts) of protozoa; they do not have intermediate hosts.
Which of these is a vector of malaria fever?
Answer: A (Female anopheles mosquito)
Only the female Anopheles mosquito sucks blood and carries the malaria parasite, Plasmodium.
Fresh milk is often kept in refrigerated vehicles, for distribution to customers in order to
Answer: D (ensure that the milk is preserved for a longer period.)
Cold slows the growth of bacteria that sour milk, so it stays fresh longer.
In medicine, bacteria have proved very useful due to the production of
Answer: B (antibiotics)
Some bacteria (such as Streptomyces) produce antibiotics like streptomycin used to treat infections.
Use the following human characteristics to answer this question.
I. Complexion II. Height III. Blood Rh factor IV. Colour blindness
Which of the above human characteristics are discontinuous variations?
Answer: D (III and IV only)
Rh factor and colour blindness fall into clear-cut groups (you either have it or not); complexion and height vary continuously.
The character that expresses itself in the presence of the contrasting character is
Answer: D (dominant)
A dominant character shows even when the allele for the contrasting (recessive) character is present.
Which of the following animals exhibits territoriality?
Answer: C (Lizards)
Male lizards such as Agama defend a territory, nodding their heads and chasing other males away.
(a) (i) Draw and label the human sperm cell. (ii) State where the sperm cell is produced and where it is stored.
(b) Explain how the structure of the sperm cell enables it to function effectively in fertilization.
(c) Mention four advantages of sexual reproduction.
(a)(i) Drawing of the sperm cell with oval head, short middle piece and long tail; labels: acrosome, nucleus, head, middle piece, mitochondria, centriole, tail (flagellum); title.
(ii) Produced in the seminiferous tubules of the testes; stored in the epididymis.
(b) The acrosome at the tip contains enzymes that dissolve the egg membrane so the sperm can enter; the middle piece has many mitochondria to supply energy for swimming; the long tail (flagellum) lashes to move the sperm towards the egg; the nucleus carries the father's genetic material (haploid) that fuses with the egg nucleus; the small, streamlined shape helps it swim.
(c) Any four: produces variation among offspring; new varieties/better adapted offspring; allows production of hybrids with desirable traits; offspring can survive in changing environments; leads to formation of new species (evolution); keeps the chromosome number constant through meiosis and fertilisation.
Link each part of the sperm to its job.
(a) (i) Draw and label the mammalian heart. (ii) Explain briefly pulmonary circulation in mammals.
(b) State five processes by which the mammalian body reduces its temperature.
(a)(i) Drawing of the vertical section of the heart with labels: right and left auricles, right and left ventricles, septum, tricuspid valve, bicuspid valve, semilunar valves, chordae tendineae, anterior and posterior vena cava, pulmonary artery, pulmonary vein, aorta (aortic arch).
(ii) The right ventricle contracts and pumps deoxygenated blood through the pulmonary artery to the lungs; in the lung capillaries carbon dioxide is given out and oxygen taken in; the oxygenated blood returns through the pulmonary veins to the left auricle.
(b) Any five: more sweating (evaporation cools the skin); vasodilation of skin arterioles; relaxation of hair erector muscles so hair lies flat; panting (in dogs); reduced metabolic rate; less muscular activity; seeking shade/cool places; taking cold drinks; licking fur (in some animals).
Pulmonary circulation: right ventricle → lungs → left auricle.
(a) State eight human activities that may pollute water bodies.
(b) Explain the measures that may be used to prevent pollution of water bodies.
(c) Mention four methods of purifying water.
(a) Any eight: dumping refuse into water; discharging untreated sewage; oil spills from drilling and tankers; run-off of fertilisers and pesticides; discharging industrial chemicals, dyes and detergents; hot water from factories (thermal pollution); radioactive waste; using chemicals (e.g. gammalin) or explosives for fishing; washing and bathing in drinking water sources; mining waste.
(b) Treat sewage before discharge; dispose of refuse properly (burn, bury, recycle) and not in water; treat industrial waste and cool hot water before release; use fertilisers and pesticides in correct amounts; use biodegradable detergents; clean up oil spills (detergents/booms); laws and penalties against polluters and against chemical fishing; educate the public.
(c) Any four: boiling; filtration; sedimentation (settling) with alum; chlorination; distillation; use of ultraviolet light; aeration.
List distinct activities, not the same one in different words.
(a) (i) Define tropic and nastic movements. (ii) List four differences between tropic and nastic movements.
(b) Describe an experiment to show that auxins are produced in the apical cells of a shoot.
(c) (i) Name two plant hormones, other than auxins. (ii) Give two examples of tropism.
(a)(i) A tropic movement (tropism) is a growth movement of part of a plant in response to a stimulus coming from one direction. A nastic movement is a non-directional movement of part of a plant in response to a stimulus, not related to the direction the stimulus comes from.
(ii) Tropic vs nastic: direction of response related to the stimulus vs not related; growth movement vs often turgor (non-growth) movement; slow vs usually fast; usually irreversible vs reversible; involves auxins vs usually changes in turgor; e.g. stems bending to light vs closing of Mimosa leaves.
(b) Use three similar seedlings (e.g. maize coleoptiles) A, B and C. Leave A intact (control). Cut off the tip of B and leave it. Cut off the tip of C, place it on an agar block for some hours, then put the agar block on the cut stump of C. After a few days A and C grow, B does not. So a growth substance (auxin) made in the tip passed into the agar and caused growth.
(c)(i) Any two: gibberellins; cytokinins; abscisic acid; ethylene.
(ii) Any two: phototropism; geotropism; hydrotropism; thigmotropism (haptotropism); chemotropism.
Tropic = direction matters; nastic = direction does not matter.
(a) What is an ecosystem?
(b) Name two abiotic factors each which affect plants and animals in a terrestrial habitat.
(c) Describe the effects of three abiotic factors on a named plant and an animal in the habitat mentioned in (b) above.
(a) An ecosystem is a natural unit made up of a community of living organisms interacting with one another and with their non-living environment.
(b) Any two for each: temperature; rainfall/water; light; wind; relative humidity; soil (edaphic) factors such as pH and texture; topography.
(c) Name a plant and an animal (e.g. maize and the grasshopper/lizard) and give three factors, e.g. Temperature: high temperature increases transpiration and may wilt the plant; animals become more active up to a point, very high heat makes them seek shade or aestivate. Rainfall/water: enough rain allows germination and growth; drought causes wilting/death; animals need water and breed in the rainy season. Light: plants need light for photosynthesis and flowering; animals use light for vision and their activity follows day length (e.g. lizards bask in sunlight). Wind: spreads pollen and seeds and increases transpiration; may damage plants; affects flight of insects.
Always name the plant and animal you are describing.
(a) (i) Name two types of competition (ii) State four factors that bring about competition among organisms.
(b) Outline the relationship between competition and succession.
(c) (i) Explain briefly Darwin's Theory of Natural Selection. (ii) List five evidences to support the occurrence of evolution.
(a)(i) Intraspecific competition (between members of the same species) and interspecific competition (between different species).
(ii) Any four: limited food/nutrients; space; light; water; mates; shelter/breeding sites; oxygen.
(b) During succession new species invade an area and compete with those already there for light, water and nutrients; stronger competitors replace weaker ones, changing the community step by step until a stable climax community is reached; so competition drives the replacement of species in succession.
(c)(i) Organisms produce many more offspring than can survive; so there is a struggle for existence; offspring vary; those with variations that suit the environment survive (survival of the fittest) and reproduce, passing these variations to their young; over many generations this gives rise to new species.
(ii) Any five: fossil records; comparative anatomy (homologous organs); vestigial organs; comparative embryology; geographical distribution; comparative biochemistry/molecular evidence; adaptive radiation; observed changes such as industrial melanism and drug/pesticide resistance.
Struggle, variation, survival of the fittest, inheritance: the four steps of natural selection.