49 questions. Try each one, then open the answer to check yourself and read the explanation.
In terms of the number of individuals, which of the following taxa is most inclusive?
Answer: C (Class)
The hierarchy runs class → order → family → genus → species. Class is the highest of these, so it contains the most individuals.
A characteristic that can possibly be shared by both living and non-living organisms is
Answer: D (increase in size.)
Non-living things like a growing crystal or a snowball can get bigger by adding material to the outside. Biomass means mass of living tissue, which non-living things do not have.
The cell of an onion bulb can be differentiated from a cheek cell by the presence of
Answer: C (cell wall)
Plant cells have a cellulose cell wall but animal cells do not. Onion bulb cells grow underground, so they have no chloroplasts, and both cells have a membrane and nucleus.
Use the diagram to answer: Which of the organisms is characterized by the possession of a chitinous exoskeleton?
Answer: A (I)
I is an arthropod with jointed legs. Arthropods have an exoskeleton made of chitin; the fish, bird and Hydra do not.
Use the diagram to answer: The type of reproduction illustrated in IV is
Answer: D (budding.)
IV is Hydra with a small outgrowth on its side. A new individual growing out of the parent like this is budding, an asexual method.
In plants, the structure that performs a similar function with the testis is in mammals is the
Answer: C (anther)
The testis makes male gametes (sperm). In a flower the anther makes pollen grains, which carry the male gametes.
The bacteria type that are arranged in chains are the
Answer: C (Streptococci)
'Strepto-' means chain: streptococci are round bacteria joined in chains. Staphylococci form grape-like clusters.
The most abundant group of organisms in the animal kingdom is
Answer: D (Insecta.)
Insects have more known species and individuals than any other animal group, far more than mammals, birds or worms.
Radial symmetry is a feature common to the
Answer: C (coelenterates)
Coelenterates such as Hydra and jellyfish have body parts arranged around a central axis (radial symmetry). Flatworms, roundworms and arthropods are bilaterally symmetrical.
Which of the following is used mainly for balancing in fish?
Answer: D (The dorsal fin.)
The dorsal fin on the back stops the fish from rolling over and keeps it upright. The caudal fin drives it forward and the pectoral fins steer and brake.
The beak of a duck is structurally adapted for
Answer: A (scooping and sieving food)
A duck's broad flat beak has comb-like edges. It scoops up mud and water and strains out small plants and animals.
The most important characteristic that makes reptiles to conquer terrestrial habitats is the possession of
Answer: D (amniotic egg.)
The amniotic egg has a shell and membranes that keep the embryo moist, so reptiles can breed on dry land without returning to water as amphibians must.
In a dicotyledonous stem, the zone between the epidermis and the pericycle is the
Answer: A (cortex)
Going inwards from the epidermis you meet the cortex, then the endodermis and pericycle, which mark the start of the stele.
The order of passage of food in the digestive system is
Answer: A (ileum → caecum → large intestine → rectum)
Food leaves the ileum (small intestine) into the caecum at the start of the large intestine, moves along the colon and ends in the rectum.
Insectivorous plants trap and kill their prey to derive
Answer: C (nitrogen)
Insect-eating plants grow in soils poor in nitrogen. They digest insects to get nitrogen compounds for making proteins.
Use the diagram to answer: Water reabsorption takes place in
Answer: B (III and IV)
III is the alimentary canal, where the large intestine absorbs water, and IV is the nephron of the kidney, where water is reabsorbed from the filtrate.
Use the diagram to answer: The vessel that carries blood from I to II is the
Answer: A (pulmonary artery)
I is the heart and II the lungs. The pulmonary artery carries deoxygenated blood from the right ventricle to the lungs.
In the alimentary system of a bird, the function of teeth is carried out by the
Answer: C (gizzard)
Birds have no teeth. The muscular gizzard, often holding small stones, grinds the food as teeth would.
What will happen when two equal sized pieces of unripe pawpaw labelled X and Y are dropped into equal volumes of concentrated salt solution and distilled water respectively?
Answer: C (pawpaw Y will become turgid)
Y is in distilled water, so water enters its cells by osmosis and they become turgid. X loses water to the salt solution and becomes flaccid.
Exhaled air differs from inhaled air in that it
Answer: D (usually has more water vapour.)
Air breathed out has been warmed and moistened in the lungs, so it has more water vapour, more carbon (IV) oxide and less oxygen than inhaled air.
In the mammalian kidney, the Bowman's capsule is located in the
Answer: C (cortex)
Bowman's capsules and glomeruli lie in the outer cortex of the kidney; the loops of Henle and collecting ducts run into the medulla.
A plant parenchyma cell also acts as a supporting tissue when it
Answer: C (becomes turgid)
When parenchyma cells are full of water they press firmly against each other, and this turgor pressure holds up soft stems and leaves.
Use the diagram to answer: The illustration is a typical example of a plant pollinated by
Answer: A (wind)
The plant is maize. Its male tassel hangs high in the air and releases light pollen that the wind carries to the silky female styles.
Use the diagram to answer: The male inflorescence is labelled
Answer: A (I)
I points to the tassel at the top of the maize plant, which is the male inflorescence. The female cob grows lower down on the stem.
During ovulation an egg is released from the
Answer: C (Graafian follicle)
The ripe Graafian follicle in the ovary bursts and releases the egg. The empty follicle then becomes the corpus luteum.
Use the diagram to answer: The part labelled I represents the
Answer: B (lag phase)
At the start of the curve the yeast numbers hardly rise while the cells adjust to the new medium. This slow start is the lag phase.
Use the diagram to answer: The part labelled IV indicates that the yeast population has
Answer: A (reached its maximum size)
At IV the curve levels off: births equal deaths because food and space are limited, so the population has reached its maximum size (stationary phase).
The transmission of impulses along a nerve fibre is characterized by
Answer: B (electrical and ionic changes)
A nerve impulse is a wave of electrical change caused by sodium and potassium ions moving across the nerve membrane.
The major consequence of bush burning in an ecosystem is
Answer: B (the loss of biological diversity)
Bush burning kills many kinds of plants, animals and soil organisms at once, so the main result is loss of biodiversity.
Which of the following associations is an example of mutualism?
Answer: A (Hydra viridis and zoochlorellae)
The green algae (zoochlorellae) living in Hydra viridis give it food and oxygen from photosynthesis, and the Hydra gives them shelter and carbon (IV) oxide. Both benefit.
In a typical freshwater habitat, the edge of the stream or pond constitutes the
Answer: C (littoral zone)
The shallow edge of a pond or stream, where rooted plants grow, is the littoral zone. Tidal and intertidal zones are found on the seashore.
The main ecological problem facing intertidal organisms is
Answer: A (desiccation)
The intertidal zone is covered by sea at high tide and exposed to sun and wind at low tide. Organisms there must avoid drying out.
Stomata of some plants are sunken and protected by hairs. These are features of
Answer: D (xerophytes.)
Sunken, hairy stomata trap moist air and cut water loss by transpiration. These are adaptations of xerophytes, plants of dry places.
An ecological factor that will have the most limiting effect on the abundance of phytoplankton in a turbid pond is
Answer: C (light)
Turbid water is cloudy with suspended particles, which block light. Phytoplankton need light to photosynthesise, so light limits them most.
Use the graph to answer: If species I, II and III interact in a community, which of the following statements is true?
Answer: C (The population of species I has become extinct)
The curve for species I rises, then falls to zero at about day 48, so that species has died out. Species II rises steadily and species III is still changing.
In an experiment to determine the percentage of air in a soil sample, the following readings were recorded:
Volume of water in a measuring cylinder = 500cm3
Volume of soil added to water = 350cm3
Volume of water and soil after stirring = 800cm3
The percentage of air in the soil sample is
Answer: C (14.28%)
Air driven out = (500 + 350) − 800 = 50 cm³. Percentage of air in the soil = 50/350 × 100 = 14.28%.
A boy who is fond of swimming in a pond finds himself passing urine with traces of blood. He is likely to have contracted
Answer: A (schistosomiasis)
Larvae of the blood fluke Schistosoma live in snail-infested ponds and enter through the skin. The adult worms damage the bladder, causing blood in the urine.
The easiest way to establish the level of pollution in a local stream is to measure the level of
Answer: A (oxygen)
Sewage and organic waste feed decomposers, which use up the dissolved oxygen. The lower the oxygen level, the more polluted the stream.
Which of the following is a major cause of variation among organisms?
Answer: C (Sexual reproduction)
In sexual reproduction genes from two parents are shuffled and combined in new ways, so offspring differ from each other and from their parents.
The Rhesus factor of blood was first identified in a category of
Answer: A (monkeys)
Landsteiner and Wiener discovered the factor in 1940 using the blood of rhesus monkeys, which is why it is called the Rhesus (Rh) factor.
Use the diagram to answer: Which of the four offspring of the cross will be short if T the gene for tallness is dominant to t?
Answer: D (IV.)
Only IV receives t from both parents, giving tt. With no dominant T it is short; I, II and III all carry at least one T.
Use the diagram to answer: The genotypic ratio of the offspring of the cross is
Answer: B (1:2:1)
The offspring are TT (I), Tt (II and III) and tt (IV), giving 1 TT : 2 Tt : 1 tt.
Genetically modified food products have not become universally accepted because
Answer: C (their effects on human consumers is not yet fully understood)
Many people worry that the long-term health and environmental effects of GM foods are not yet fully known, so some countries limit them.
A major adaptive feature of endoparasites is the
Answer: A (loss of the organ of movement)
Endoparasites like tapeworms live inside the host's gut, where they are carried along and surrounded by food, so they have lost organs of movement.
Use the graph to answer: From the graph above, it can be appropriately deduced that
Answer: B (the body temperature in I is independent of external temperature)
Line I stays flat at about 37–40 °C whatever the external temperature, while line II rises with it. So I's body temperature does not depend on its surroundings.
Use the graph to answer: The animal represented by I is a
Answer: B (homoiotherm)
An animal that keeps a constant body temperature, like a bird or mammal, is a homoiotherm (warm-blooded). II, whose temperature follows the surroundings, is a poikilotherm.
The ability of a chameleon to change its colour is an adaptive feature for
Answer: B (defence)
By matching its colour to its background the chameleon is camouflaged and hidden from predators, which is a means of defence.
Which of the following is the most advanced evolutionary development in plants?
Answer: B (Development of flowers)
Flowers appear only in angiosperms, the most recently evolved and most advanced plant group. Spores and unicellular forms belong to simpler plants, and conifers also have secondary thickening.
The natural process that produces adaptive evolutionary changes is
Answer: D (natural selection)
Natural selection lets individuals with useful variations survive and breed more, so over generations the population becomes better adapted. Mutation, drift and gene flow change genes at random.