47 questions. Try each one, then open the answer to check yourself and read the explanation.
Use the diagram of the cell to answer: The endoplasmic reticulum is represented by the part labelled
Answer: D (IV)
IV points to the stack of folded membranes near the edge of the cell. This network of membranes is the endoplasmic reticulum.
Use the diagram of the cell to answer: The part labelled II is responsible for
Answer: B (respiration)
II is a mitochondrion, recognised by its folded inner membrane. Mitochondria carry out aerobic respiration to release energy.
The rods in the retina of the eye are examples of
Answer: A (cells)
Each rod is a single light-sensitive cell. Many rods and cones together form the retina tissue.
The absence of special food and water-conducting systems restricts the body size in
Answer: A (algae, liverworts and mosses)
Algae, liverworts and mosses have no xylem or phloem, so they stay small and rely on diffusion. Ferns (pteridophytes) do have vascular tissue.
The most common characteristic of the fungal hyphae is the possession of
Answer: B (cell walls that are both rigid and chitinous)
All fungal hyphae have rigid walls made of chitin. Many hyphae, as in Rhizopus, have no cross-walls, so they are not divided into one-nucleus compartments.
Insects are considered the most successful among the invertebrates because they
Answer: B (survive in various environmental conditions)
Insects live almost everywhere: on land, in fresh water, in deserts and in the cold. Surviving in so many conditions is what makes them so successful.
The larval stage of a mosquito is called
Answer: A (wriggler)
Mosquito larvae wriggle through the water, so they are called wrigglers. Maggots are housefly larvae and caterpillars are butterfly or moth larvae.
The function of the long-winged reproductives in a termite colony is to
Answer: A (disperse the population)
The winged reproductives fly out of the nest, pair up and start new colonies elsewhere. This spreads (disperses) the termite population.
A peculiar characteristic of mammals is that they
Answer: D (have sebaceous glands)
Sebaceous (oil) glands in the skin are found only in mammals. Birds are also warm-blooded, and reptiles also have lungs and teeth.
In the internal structure of plants, a wide pith in the centre is common to
Answer: B (dicot stems and monocot roots)
Dicot stems have a ring of bundles around a central pith, and monocot roots have a ring of xylem and phloem around a large pith. Dicot roots have xylem in the centre and monocot stems have scattered bundles.
All living cells require water because it
Answer: A (is a medium for all metabolic reactions)
The chemical reactions of the cell take place in water. Water dissolves the substances so that they can react.
The breakdown of fats and oils into simpler absorbable compounds is catalyzed by the group of enzymes called
Answer: A (lipases)
Lipases break fats and oils into fatty acids and glycerol, which can be absorbed. Amylases digest starch and peptidases digest proteins.
Use the diagram of the yam set-up to answer: Yam is used in this set-up because it
Answer: D (acts as a semi-permeable membrane)
The living yam tissue lets water pass through but holds back the dissolved salt. It works as a semi-permeable membrane for osmosis.
Use the diagram of the yam set-up to answer: Which of the following results is to be expected if the set-up is left for several hours?
Answer: C (decrease in the volume of water inside the yam)
The water inside the hollow yam is more dilute than the salt solution outside. Water moves out through the yam by osmosis, so the water inside goes down.
The surface of an alveolus in a mammal is well supplied with tiny blood vessels known as
Answer: D (capillaries)
Each alveolus is covered with a network of capillaries. Their thin walls let oxygen and carbon(IV) oxide diffuse quickly.
The anaerobic fermentation of a glucose molecule yields
Answer: B (2 ATP molecules and alcohol)
Yeast fermentation turns one glucose molecule into alcohol and carbon(IV) oxide, with a net gain of only 2 ATP. Aerobic respiration gives about 38 ATP, water and carbon(IV) oxide.
The opening of the stoma is controlled by the
Answer: B (increase in solute concentration in the guard cells)
When solutes build up in the guard cells, water enters them by osmosis. The guard cells swell and curve apart, opening the stoma.
Use the diagram of the skin to answer: The sweat gland is the structure labelled
Answer: D (IV)
IV points to the coiled tube deep in the dermis. That coiled tube is the sweat gland.
Use the diagram of the vertebral column to answer: The bones labelled II are called
Answer: D (lumbar vertebrae)
Region II lies between the thoracic vertebrae (with long spines) and the tail end. These large vertebrae of the lower back are the lumbar vertebrae.
Use the diagram of the vertebral column to answer: The type of joint between adjacent bones in the part labelled II is the
Answer: B (sliding joint)
Neighbouring vertebrae glide slightly over each other at their joint surfaces. These are sliding (gliding) joints, which give the backbone some flexibility.
The type of reproduction that is common to both Hydra and yeast is
Answer: D (budding)
Both Hydra and yeast grow small outgrowths (buds) that develop into new individuals. This is budding.
Use the diagram of the flower to answer: The part labelled II is the
Answer: D (anther)
II points to the knob at the top of a stamen. This is the anther, which makes pollen.
Use the diagram of the flower to answer: The process of pollination involves the transfer of pollens from
Answer: B (II to III)
Pollination is the transfer of pollen from the anther (II) to the stigma (III).
The eggs of birds contain relatively larger quantities of yolk than those of amphibians and reptiles because
Answer: B (embryonic development is longer in birds)
A bird embryo develops for a long time inside the egg until it hatches as a well-formed chick. It needs a large food store, the yolk, to last that long.
Epigeal germination of a seed is characterized by
Answer: A (more rapid elongation of the hypocotyl than the epicotyl)
In epigeal germination (e.g. bean) the hypocotyl lengthens quickly and carries the cotyledons above the ground. In hypogeal germination the epicotyl grows more and the cotyledons stay below.
Nervous control differs from hormonal control in that the former
Answer: C (produces short-term changes)
Nerve impulses act quickly and their effects end quickly. Hormones act more slowly but their effects last longer.
If a nursing mother is not producing enough milk, her hormonal system is probably deficient in
Answer: A (prolactin)
Prolactin from the pituitary gland stimulates the mammary glands to produce milk.
The two key cations involved in the action potential of nervous transmissions are
Answer: C (Na+ and K+)
A nerve impulse happens when sodium ions rush into the nerve fibre and potassium ions then move out. So Na+ and K+ are the key ions.
A caterpillar and an aphid living in different parts of the same plant can be said to
Answer: C (occupy different ecological niches)
A niche is an organism's role and way of life. The caterpillar chews leaves while the aphid sucks sap from another part, so they share a habitat but have different niches.
Use the table to answer:
Ecological zone | Temperature (°C) | Rainfall (mm)
I | 45 | 300
II | 32 | 2000
III | 30 | 2200
IV | 15 | 800
High relative humidity will be expected in zones
Answer: C (II and III)
Zones II and III have the highest rainfall (2000 mm and 2200 mm). Places with heavy rain have moist air, so high relative humidity.
Use the table to answer:
Ecological zone | Temperature (°C) | Rainfall (mm)
I | 45 | 300
II | 32 | 2000
III | 30 | 2200
IV | 15 | 800
Which of the zones is likely to be a desert?
Answer: A (I)
Zone I is the hottest (45 °C) and has the least rain (300 mm). Hot and dry conditions describe a desert.
The association between termites and the cellulose-digesting protozoans in their guts is an example of
Answer: B (mutualism)
The protozoa digest cellulose for the termite and get food and shelter in return. Both benefit, so it is mutualism.
The progressive loss of energy at each level in a food chain leads to
Answer: B (a decrease in biomass at each successive level)
Energy is lost as heat at each feeding level, so less is left to build new living matter. Biomass gets smaller at each higher level.
One adaptation of reptiles to water loss is the presence of
Answer: A (keratinous scales)
Reptiles have dry skin covered in horny (keratin) scales. These scales are waterproof and reduce water loss on land.
A state in Nigeria that is most susceptible to desert encroachment is
Answer: D (Katsina)
Katsina is in the far north, on the edge of the Sahara, where rainfall is lowest. The desert is spreading south into such states.
The scarcity of food causes a sudden decrease in population size by
Answer: C (raising the mortality rate)
When food runs short, many organisms starve and die. A higher death rate quickly reduces the population.
The soil type that will be most difficult to plough in a wet season is one that is
Answer: B (clayey)
Wet clay soil is sticky and heavy because its fine particles hold a lot of water. This makes it very hard to plough.
A farm practice that results in the loss of soil fertility is
Answer: D (continuous cropping)
Growing crops on the same land year after year removes nutrients without giving the soil time to recover. Bush fallowing and shifting cultivation let the soil rest.
Paternity disputes can most accurately be resolved through the use of
Answer: C (DNA analysis)
A child gets half of its DNA from each parent. Comparing DNA can show who the father is with great accuracy; blood groups can only rule people out.
In a Mendelian cross of red and white varieties of the four o'clock plant, the F1 generation expresses incomplete dominance by having flowers which are
Answer: C (pink)
With incomplete dominance neither allele fully masks the other. Red × white gives pink flowers in between.
Identical twins inherit their genes from
Answer: B (the same egg and sperm)
Identical twins come from one fertilised egg (one egg and one sperm) that splits into two embryos. So they have the same genes.
Sex-linked genes are located on
Answer: D (X-chromosome)
Sex-linked traits such as colour-blindness and haemophilia are carried on the X chromosome. The Y chromosome carries very few genes.
Which of the following is an example of intraspecific competition?
Answer: B (a worker termite and a soldier in a limited space)
Intraspecific competition is between members of the same species. A worker and a soldier termite are both termites; the other pairs are different species.
Plants survive hot dry conditions by
Answer: A (storing water in large parenchyma cells)
Desert plants such as cacti store water in large parenchyma cells in their stems or leaves. Many leaves or stomata would lose more water.
Rodents gnaw on food with their
Answer: D (chisel-like front teeth)
Rodents such as rats have long, chisel-shaped front teeth (incisors) that keep growing. They use them to gnaw hard food.
The spots and stripes of the leopard and tiger are examples of
Answer: C (disruptive colouration)
Spots and stripes break up the outline of the animal's body. In grass or shade this disruptive pattern makes it hard to see.
An evidence of the relationship between living organisms and their extinct relatives can best be obtained from
Answer: D (palaeontology)
Extinct organisms survive only as fossils. Palaeontology, the study of fossils, links them to living organisms.