63 questions. Try each one, then open the answer to check yourself and read the explanation.
In the binomial system of naming organisms, the second name is called the
Answer: D (specific name)
In binomial naming the first name is the genus (generic name) and the second is the species (specific name), e.g. Homo sapiens.
Which of the following features does not necessarily place Paramecium at a higher level of organization over Amoeba?
Answer: D (Presence of more than one food vacuole)
Amoeba can also have several food vacuoles, so this feature does not show that Paramecium is more advanced; cilia and two kinds of nuclei do.
The living material of the cell consists of
Answer: A (nucleus and cytoplasm)
Protoplasm, the living substance of a cell, is the nucleus together with the cytoplasm.
A pupil accidentally "watered" a potted plant with concentrated salt solution. After sometime the plant began to wilt.
The wilting of the plant is due to the fact that
Answer: C (the salt solution has caused water to be lost from the plant cells leading to loss of turgor)
The salt solution is more concentrated than the cell sap, so water leaves the root cells by osmosis and the cells lose turgor.
A pupil accidentally "watered" a potted plant with concentrated salt solution. After sometime the plant began to wilt.
Which of the following activities would revive the plant?
Answer: D (Adding more water to the soil.)
Adding plenty of water dilutes the salt in the soil, so water can again enter the root cells by osmosis and the cells regain turgor.
Primary growth in plants is brought about by the activity of the
Answer: A (meristem)
Apical meristems at root and shoot tips divide to give primary growth in length.
Study the diagram and use it to answer the question.
To form a ball and socket joint, the structure labelled I fits into another structure in the scapula called the
Answer: B (glenoid cavity)
The bone is the humerus; its rounded head (I) fits into the glenoid cavity of the scapula to form the shoulder joint.
Study the diagram and use it to answer the question.
The structure labelled II is called
Answer: C (shaft)
II points to the long middle part of the humerus, which is the shaft.
Which of the following parts of the skeleton does not have a protective function?
Answer: B (Carpals)
Carpals are wrist bones that allow movement; ribs, skull and pelvis protect organs.
Carbon dioxide is carried in the plasma
Answer: D (as bicarbonate ion.)
Most carbon dioxide is carried in the plasma as hydrogencarbonate (bicarbonate) ions; haemoglobin is in the red cells, not the plasma.
The process of regulating the amount of water and solutes in the body fluids is called
Answer: C (osmoregulation)
Osmoregulation is the control of water and salt balance in the body.
The presence of glucose in the urine of a patient is an indication of malfunctioning of the
Answer: A (pancreas)
Glucose in urine is a sign of diabetes, caused by the pancreas making too little insulin.
Which of the following statements is not true about hormones?
Answer: C (Hormonal responses are usually swift, instant and electrical)
Hormones are chemical messages and their effects are usually slow and long-lasting; swift electrical responses are nervous.
Plant hormones include the following except
Answer: A (insulin)
Insulin is an animal hormone from the pancreas; auxins, cytokinins and gibberellins are plant hormones.
The passage of nerve impulse across a synapse is facilitated by the secretion of
Answer: A (acetylcholine)
The nerve ending releases acetylcholine, which crosses the synaptic gap and starts an impulse in the next neurone.
The part of the brain which controls and coordinates body posture is the
Answer: A (cerebellum)
The cerebellum controls balance, posture and muscle co-ordination.
Which of the following processes is not an example of a reflex action?
Answer: B (Reading)
Reading is learned and done under conscious control, so it is a voluntary action, not a reflex.
The eyes can properly focus images of objects of various distances on the retina by a process called
Answer: C (accommodation)
Accommodation is the change in the shape of the lens that keeps near and far objects in focus on the retina.
Which of the following sensations may not be detected by the skin?
Answer: C (Stress)
The skin has receptors for touch, pressure, pain, heat and cold, but not for 'stress'.
The process by which flowers produce fruit without the process of fertilization is called
Answer: B (parthenocarpy)
Parthenocarpy is fruit formation without fertilization, which gives seedless fruits such as some bananas.
The part of the young root that pushes its way through the soil is the
Answer: C (root cap)
The root cap covers and protects the root tip as it pushes through the soil.
An example of a dehiscent fruit is
Answer: A (crotolaria)
Crotalaria pods split open when dry to release their seeds; tomato, mango and orange are fleshy fruits that do not split.
Which of the following food substances gives the least amount of calories?
Answer: C (Cabbage)
Cabbage is mostly water and fibre, so it gives very little energy compared with rice, groundnuts or egg yolk.
Analysis of the gut content of an animal showed that it contained small pieces of bone, seeds, roughage and insects. The animal is likely to be a/an.
Answer: D (omnivore.)
It eats both animal food (bones, insects) and plant food (seeds, roughage), so it is an omnivore.
Filaments of Spirogyra placed in a beaker of tap water in a dark cupboard died because
Answer: A (the filaments could not photosynthesize)
Without light Spirogyra cannot photosynthesise, so it runs out of food and dies.
The importance of the concentration of chloroplast in the palisade layer of the leaf is for maximum exposure to
Answer: B (light)
The palisade layer lies just under the upper surface, so its many chloroplasts receive the most sunlight.
A community is best defined as
Answer: C (populations of different species living together and interacting with each other in one habitat)
A community is made up of the populations of different species living and interacting in one habitat; A describes an ecosystem.
Which of the following physical factors is likely to affect the distribution of plants in a pond?
Answer: A (Light)
Light gets weaker with depth, so plants that need light are found mainly near the surface and edges of a pond.
Which of the following instruments is used to measure wind speed?
Answer: D (Anemometer.)
An anemometer measures wind speed.
Study the food web and use it to answer the question.
Tertiary consumers within the web are
Answer: A (cat and lion only)
Tertiary consumers eat secondary consumers. The cat eats the lizard (a secondary consumer), and the lion eats man, who is a secondary consumer when he eats rabbits or snails. Man himself eats only primary consumers or the cat, so he is not a tertiary consumer.
Study the food web and use it to answer the question.
What would be the effect of taking the lion out of the web?
Answer: B (Man would occupy the apex of the web)
Nothing in the web eats man except the lion, so without the lion man becomes the top (apex) consumer.
Which of the following statements about the transfer of energy in an ecosystem is correct?
Answer: D (Energy is lost at each trophic level.)
At every step energy is lost as heat in respiration and in uneaten or undigested parts, so less passes on.
Pond weeds normally lack thick layers of cuticle because
Answer: B (there is no danger of becoming desiccated)
Plants living in water never risk drying out, so they do not need a thick waxy cuticle to save water.
Shrubs do not survive on newly weathered soils because
Answer: C (humus is absent from the soil)
Newly weathered soil is just broken rock with no humus, so it holds little water and nutrients; pioneer plants must add humus before shrubs can grow.
The speed of the flow of water in a river is faster in the middle than along the banks due to
Answer: D (resistance offered by the wall of the banks.)
Water along the banks is slowed by friction with the banks and bed, while water in the middle meets little resistance.
The effects of environmental degradation caused by human activities can be controlled by the following measures except
Answer: C (resettling indigenous inhabitants)
Moving local people elsewhere does not repair damaged land, while turning mining pits into fish ponds is a form of land reclamation.
The following observations concerning succession are true except that the
Answer: C (climax community has the greatest number of species)
Species diversity usually peaks in the middle stages and falls slightly at the climax, so the climax does not have the most species.
A vaccine is introduced into a person's body to
Answer: B (stimulate the body to produce antibodies)
A vaccine contains weakened or dead germs (or their parts) that make the body produce antibodies, giving immunity.
Which of the following activities constitutes biological control?
Answer: C (Tilapia feeding on the larvae and pupae of mosquito)
Using a living predator such as tilapia to reduce mosquito numbers is biological control.
Many diseases caused by bacteria can be treated and cured by using
Answer: B (antibiotics)
Antibiotics, such as penicillin, kill bacteria or stop them multiplying inside the body.
To avoid over-fishing in a lake, the following measures may be helpful except
Answer: C (fishing throughout the year)
Fishing all year round gives fish no chance to breed and recover, so it leads to over-fishing.
Conservation may be promoted by
Answer: A (encouraging tree planting)
Planting trees (afforestation) replaces cut forests and protects soil and wildlife.
Which of the following substances is not recycled in an ecosystem?
Answer: B (Energy)
Matter such as carbon, water and nitrogen is recycled, but energy flows one way and is lost as heat.
Which of the following statements about phenylthiocarbamide (PTC) is not correct?
Answer: D (Ability to taste the chemical is not heritable.)
PTC tasting is controlled by a gene and is inherited, so saying it is not heritable is wrong.
Which of the following characters is not an example of discontinuous variation?
Answer: A (Skin colour)
Skin colour shows a smooth range of shades, so it is continuous variation; the others fall into distinct groups.
Which of the following human traits in a class of school children may give an approximate normal distribution curve when the variation is plotted?
Answer: D (Heights.)
Height varies continuously, so a plot gives a bell-shaped normal curve.
The observable characteristics of an individual usually resulting from the interaction between the gene composition and the environment is referred to as
Answer: C (phenotype)
The phenotype is what an organism looks like or how it functions, produced by its genes acting together with its environment.
The sudden change in a gene structure or chromosome number in an organism likely to cause an inheritable change in the phenotype is known as
Answer: B (mutation)
A mutation is a sudden heritable change in a gene or in chromosome number.
The defective cells involved in sickle-cell anaemia disease are
Answer: C (erythrocytes)
Sickle-cell anaemia affects haemoglobin, so the red blood cells (erythrocytes) become sickle-shaped.
What does the chemical composition of the genetic material of all living organisms consist of?
Answer: A (Deoxyribonucleic acid)
Genes are made of DNA, deoxyribonucleic acid.
What of the following occurrences is not a feature of meiosis?
Answer: D (Formation of two diploid cells.)
Two diploid daughter cells are the result of mitosis; meiosis gives four haploid cells.
Which of the following diseases is commonly observed in human males and is sex-linked?
Answer: D (Colour blindness.)
The gene for colour blindness is on the X chromosome, so males, with one X, show it more often.
If red is dominant to white and homozygous red pea-plants are crossed with homozygous white pea-plants, the first filial generation will have
Answer: B (4 red flowers)
RR × rr gives only Rr offspring, and red is dominant, so all are red.
The resemblance of a palatable insect to a poisonous insect is an example of
Answer: C (an escape from the predator by mimicry)
A harmless insect that copies the look of a harmful one is showing mimicry, so predators avoid it.
Which of the following statements in not true of the worker termites? They
Answer: B (produce enzymes to digest cellulose)
Termites digest wood with the help of protozoa (and bacteria) living in their gut that make the cellulose-digesting enzyme; the termite itself does not.
The accepted concepts for the theory of Natural Selection does not include
Answer: D (use and disuse of body parts.)
Use and disuse was Lamarck's idea; overproduction, struggle for existence and survival of the fittest are parts of Darwin's natural selection.
The order of evolutionary trend in plants is
Answer: B (Thallophyta, Bryophyta, Pteridophyta and Spermatophyta)
Plants evolved from simple thallophytes (algae) to bryophytes (mosses), then pteridophytes (ferns), then seed plants.
(a) State one function of each of the following structures: (i) Arteries; (ii) Capillaries; (iii) Veins; (iv) Xylem; (v) Phloem
(b) Describe the changes that take place in the composition of human blood as it passes through the:
(i) Lungs; (ii) Liver; (iii) Kidneys; (iv) Small intestine. (c) List the cellular components of blood.
(a)(i) Arteries carry blood away from the heart (oxygenated, except the pulmonary artery).
(ii) Capillaries allow exchange of materials between blood and tissues; link arteries and veins.
(iii) Veins carry blood back to the heart (deoxygenated, except the pulmonary vein).
(iv) Xylem carries water and mineral salts from roots upwards; gives support.
(v) Phloem carries manufactured food (sugars) from leaves to other parts.
(b)(i) Lungs: oxygen added; carbon(IV) oxide and some water removed.
(ii) Liver: excess glucose removed (stored as glycogen) or added when low; amino acids removed and urea added; worn-out red cells and toxins removed; plasma proteins added.
(iii) Kidneys: urea, excess water and salts removed; blood leaving is purer.
(iv) Small intestine: digested food added – glucose, amino acids, vitamins, minerals and water (fats into lacteals); oxygen used up.
(c) Red blood cells (erythrocytes); white blood cells (leucocytes); platelets (thrombocytes).
One function per vessel/tissue in (a).
(a) What is transpiration?
(b) (i) Name two types of transpiration (ii) List four factors which affect the rate of transpiration
(c) Describe the mechanisms of opening and closing of the stomata. (d) State:
(i) two similarities and (ii) two differences between transpiration and sweating
(a) Transpiration is the loss of water in the form of vapour from the aerial parts of a plant, mainly through the stomata of the leaves.
(b)(i) Any two: stomatal; cuticular; lenticular.
(ii) Any four: light intensity; temperature; humidity; wind; availability of soil water; leaf surface area; thickness of cuticle; number/position of stomata (sunken, hairy leaves).
(c) Opening: in light the guard cells photosynthesise (and take in K+ ions/convert starch to sugar), so their solute concentration rises; water enters them from neighbouring cells by osmosis; they become turgid; the thin outer walls stretch more than the thick inner walls, so the cells curve apart and the pore opens.
Closing: in darkness or water shortage the solute concentration of the guard cells falls; water leaves by osmosis; the guard cells become flaccid and straighten, closing the pore.
(d)(i) Both lose water from the body; both cool the organism; water passes out through pores.
(ii) Transpiration occurs in plants through stomata/lenticels vs sweating occurs in mammals through sweat pores; transpiration loses only water vs sweat contains water, salts and urea; water lost as vapour vs lost as liquid; transpiration mainly by day vs sweating day and night.
Explain stomatal movement through osmosis and turgor.
(a) Explain the following terms:
(i) Population; (ii) Competition; (iii) Succession. (b)(i) State three sources of noise pollution
(ii) List two ways by which noise pollution can be reduced. (c) State three effects each of the following pollutants on humans: (i) smoke; (ii) sewage.
(a)(i) Population: a group of organisms of the same species living in a particular area at a particular time.
(ii) Competition: the struggle between organisms of the same species (intraspecific) or different species (interspecific) for resources in short supply, such as food, light, water, space or mates.
(iii) Succession: the gradual, orderly replacement of one community by another in an area over time, from pioneer to a stable climax community.
(b)(i) Any three: generators; motor vehicles; aircraft; loudspeakers/music systems; factory machines; sirens; gunfire/explosions; construction and quarry work.
(ii) Any two: laws to control noise; siting airports, factories and military bases away from homes; using silencers and soundproof or low-noise machines; public education.
(c)(i) Smoke: breathing difficulties and respiratory diseases (bronchitis, asthma); irritates and damages eyes; carbon monoxide poisoning; reduces visibility, causing accidents; may cause lung cancer.
(ii) Sewage: spreads water-borne diseases (cholera, typhoid, dysentery); makes water unsafe for drinking and domestic use; offensive smell; kills fish by using up oxygen, reducing food for man; breeding site for flies and mosquitoes.
Give three effects each for smoke and sewage.
(a) Describe the main stages of mitotic division. (b) State four ways in which mitosis is important to living organisms.
(a) Interphase (preparation): chromosomes replicate.
Prophase: chromosomes shorten and thicken and become visible as two chromatids joined at a centromere; nuclear membrane and nucleolus disappear; spindle forms.
Metaphase: chromosomes line up on the equator of the spindle, attached by their centromeres.
Anaphase: centromeres split and the chromatids are pulled to opposite poles.
Telophase: chromosomes reach the poles; nuclear membranes re-form round each set; cytoplasm divides (cleavage furrow in animals, cell plate in plants), giving two identical daughter cells.
(b) Any four: growth of the organism; repair of damaged tissues and replacement of worn-out cells; asexual reproduction; keeps chromosome number constant; daughter cells are genetically identical, maintaining characteristics; regeneration of lost parts.
Name the stages in order: prophase, metaphase, anaphase, telophase.
(a) What are hormones?
(b) In a tabular form, state four differences between nervous coordination and hormonal coordination in humans.
(c) State three effects each of: (i) Over-secretion; (ii) Under-secretion of thyroxin on mammals. (d) Make a diagram 10-12 cm long of the reflex arc and label fully.
(a) Hormones are chemical messengers produced by ductless (endocrine) glands and carried in the blood to target organs, where they bring about responses.
(b) Nervous vs hormonal: electrical impulses vs chemical substances; carried by neurones vs carried in blood; fast vs slow; short-lived vs long-lasting effect; localised vs widespread effect; can be voluntary vs always involuntary.
(c)(i) Over-secretion (hyperthyroidism): high metabolic rate; weight loss; nervousness and restlessness; fast heartbeat; protruding eyes (exophthalmic goitre); sweating and intolerance of heat.
(ii) Under-secretion: in children – cretinism (stunted growth, mental retardation); in adults – myxoedema (low metabolism, weight gain, sluggishness, puffy skin); goitre; feeling cold.
(d) Diagram 10–12 cm, title, labels: receptor (e.g. skin), sensory neurone, dorsal root and dorsal root ganglion, spinal cord with grey and white matter, relay neurone, motor neurone, ventral root, effector (muscle); arrows showing the direction of the impulse.
Label the direction of the impulse on the reflex arc.
(a) Explain the following modes of nutrition which occur in plants: (i) Autotrophic; (ii) Chemosynthetic; (iii) Carnivorous
(b) Give one example each of a plant which undergoes the modes of nutrition listed in 8(a) above.
(c) (i) Describe three ways by which nitrogen is added to the soil for plant use.
(ii) State two ways by which nitrogen is lost from the soil.
(a)(i) Autotrophic: the organism makes its own organic food from simple inorganic substances (carbon(IV) oxide and water) using light energy trapped by chlorophyll (photosynthesis).
(ii) Chemosynthetic: the organism makes its own food using energy from oxidising inorganic chemicals (e.g. ammonia, nitrites, iron or sulphur compounds) instead of light.
(iii) Carnivorous: green plants that photosynthesise but also trap and digest insects to obtain nitrogen, usually because they grow in nitrogen-poor soil.
(b) Autotrophic – any green plant, e.g. maize, hibiscus; chemosynthetic – nitrifying bacteria such as Nitrosomonas or Nitrobacter (sulphur bacteria); carnivorous – sundew (Drosera), pitcher plant (Nepenthes), bladderwort (Utricularia), Venus flytrap.
(c)(i) Any three: Rhizobium in root nodules of legumes fixes atmospheric nitrogen; free-living bacteria (Azotobacter, Clostridium) and blue-green algae fix nitrogen; lightning makes nitrogen oxides that dissolve in rain to form nitrates; decay of dead organisms and wastes releases ammonia, which nitrifying bacteria change to nitrates; adding fertilizers and manure.
(ii) Any two: denitrification by bacteria; leaching of nitrates by rain; uptake by crops that are then harvested; soil erosion; burning of vegetation.
Chemosynthesis uses chemical energy, not light.