49 questions. Try each one, then open the answer to check yourself and read the explanation.
Night-blindness results from a deficiency of
Answer: B (vitamin A)
Vitamin A is needed to make the light-sensitive pigment in the rods of the retina. Without it, a person cannot see well in dim light.
The product of excretion common to the mammalian kidney, lung and skin is
Answer: C (water)
The kidneys remove water in urine, the lungs breathe out water vapour and the skin loses water in sweat. Only water is excreted by all three.
Use the diagram to answer: Sexual reproduction is illustrated in
Answer: B (I)
I shows two cells joined side by side and exchanging nuclear material (conjugation), which is a sexual process. II, III and IV show asexual methods: sprouting, fission and leaf plantlets.
Use the diagram to answer: A plant that exhibits the type of reproduction shown in IV is
Answer: C (Bryophyllum)
IV shows small plantlets growing from the notches at the edge of a leaf. This is how Bryophyllum reproduces vegetatively.
An increase in air pressure in the lungs is due to the
Answer: C (relaxation of the diaphragm)
When the diaphragm relaxes it domes upward and the chest gets smaller. The smaller volume raises the air pressure in the lungs, pushing air out.
One basic similarity between nervous and endocrine system is that they both
Answer: C (involve the use of chemical substances)
Nerves pass messages across synapses using chemical transmitters, and the endocrine system uses hormones, which are chemicals. Widespread, slow effects are typical only of hormones.
The organ situated in the pericardial cavity of a mammal is the
Answer: A (heart)
The pericardium is the bag that encloses the heart. The space inside it is the pericardial cavity.
A unique characteristic of the cervical vertebrae is the presence of
Answer: D (vertebrarterial canal)
Cervical (neck) vertebrae have small holes in their transverse processes, the vertebrarterial canals, through which arteries pass to the head. No other vertebrae have them.
In rabbits, the chamber of the heart that receives oxygenated blood from the lungs is the
Answer: B (left auricle)
The pulmonary veins bring oxygenated blood from the lungs into the left auricle (atrium). It then passes to the left ventricle.
Use the diagram of the pregnant uterus to answer: The part labelled IV is for
Answer: C (protection)
IV points to the fluid-filled amniotic sac around the foetus. The amniotic fluid cushions the foetus against shocks and so protects it.
Use the diagram of the pregnant uterus to answer: The organ through which the embryo receives food, water and oxygen is labelled
Answer: C (II)
II points to the placenta, where the mother's blood and the embryo's blood come very close. Food, water and oxygen pass across it to the embryo.
The formation of water in the tissue respiration results from the
Answer: B (reduction of oxygen by hydrogen)
At the end of aerobic respiration, hydrogen removed from food combines with oxygen. This reduces the oxygen to water.
Water is necessary for a germinating seed because it
Answer: B (activates the enzymes)
Water entering the seed switches on its enzymes. They then break down the stored food for the growing embryo.
Which of the following produces both hormones and enzymes?
Answer: B (Pancreas)
The pancreas makes digestive enzymes (amylase, lipase, trypsin) for the duodenum, and its islets make the hormones insulin and glucagon.
Mammals are capable of producing hypertonic urine mainly because of reabsorption in the
Answer: D (loop of Henle)
The loop of Henle creates a salty region deep in the kidney. Water is drawn back from the urine there, making the urine concentrated (hypertonic).
The mammalian vein which starts with and ends in a capillary network is the
Answer: D (hepatic portal vein)
The hepatic portal vein starts in the capillaries of the intestine and ends in the capillaries of the liver. Most veins end at the heart.
In the transverse section of a dicot stem, the region lying between the endodermis and the vascular bundle is the
Answer: B (pericycle)
Just inside the endodermis, before the vascular bundles, is the pericycle. The hypodermis is near the outside of the stem.
Hassan and Hussain are identical twins but Hassan grows taller and fatter than Hussain. This is probably because
Answer: D (they are raised in different environments)
Identical twins have the same genes. Any difference between them must come from their environment, such as food and exercise.
The two normal types of sex chromosomes are
Answer: D (XX and XY)
Normal females are XX and normal males are XY. XXY and XYY are abnormal conditions.
Use the diagram to answer: The diagram represents the structure of
Answer: D (DNA)
The diagram shows two strands twisted into a double helix joined by rungs. This is the shape of DNA; RNA is single-stranded.
Use the diagram of the double helix to answer: The part labelled I represents the
Answer: A (base pairs)
I points to a rung across the middle of the helix. The rungs are pairs of bases (A–T and C–G) holding the two strands together.
Mendel's second law of inheritance states that
Answer: B (alleles segregate independently)
Mendel's second law (independent assortment) says that the alleles of different genes separate into gametes independently of each other.
Use the diagram of the giraffes to answer: The change in the length of the necks of the giraffes shown was brought about by
Answer: D (natural selection)
Giraffes with longer necks could reach more leaves, so they survived and bred more. Over many generations this natural selection made long necks common.
Use the diagram of the giraffes to answer: The variation illustrated is
Answer: B (morphological)
Neck length is a difference in body form and structure that can be seen. Such visible differences are morphological variation.
The intensity of competition among animals in a given area will increase with
Answer: B (an increase in population size)
More animals in the same area means more of them need the same food, space and mates. So competition gets stronger as the population grows.
Use the diagram to answer: The economic importance of the larva is that it
Answer: D (feeds on the leaves of crops)
Economic importance means how it affects people. Caterpillars eat the leaves of crop plants, reducing yields.
Use the diagram to answer: The type of adaptation shown by the larva is
Answer: A (mimicry)
The larva looks like a leaf or twig of the plant it lives on. Resembling an object this way to fool predators is mimicry.
The part of the mammalian skin involved in temperature regulation is the
Answer: A (sweat gland)
Sweat glands release sweat onto the skin. As the sweat evaporates it takes heat away and cools the body.
The role of the Golgi complex in a eukaryotic cell is to
Answer: D (transport organic materials in and out of the cell)
The Golgi complex packages proteins and other substances into vesicles. These carry the materials to the cell surface for secretion.
Use the diagram of the insect head to answer: The maxillary palp is labelled
Answer: B (IV)
The maxillary palps are the long jointed feelers that hang from the mouthparts at the sides of the head. IV points to one of them.
Use the diagram of the insect head to answer: The structure labelled I is sensitive to
Answer: D (chemicals and touch)
I is an antenna. Antennae detect smells (chemicals) and touch. Light is detected by the compound eyes.
The dominant phase in the life cycle of a bryophyte is the
Answer: C (gametophyte)
In mosses and liverworts, the green plant you see is the gametophyte. The sporophyte is small and grows on it.
The evidence that supports the advancement of ferns over mosses is derived from
Answer: A (comparative anatomy)
Comparing their structure shows that ferns have true roots, stems, leaves and vascular tissue, which mosses lack. This comparative anatomy shows ferns are more advanced.
Which of the following vertebrates has the most simple structured heart?
Answer: B (Fish)
A fish heart has only two chambers (one atrium and one ventricle). Amphibians and reptiles have three and mammals have four.
Use the diagram of the cock to answer: A unique characteristic that distinguishes the class of vertebrates represented from other vertebrates is the presence of
Answer: D (a covering of feathers)
Only birds have feathers. Other animals can have wings (bats), scales (reptiles) or two pairs of limbs.
Use the diagram of the cock to answer: The structures used for offence and defence are labelled
Answer: B (I and II)
The cock fights with its claws and spurs on the feet (I) and its beak (II). The comb (III) and tail (IV) are for display.
One primitive feature of the coelenterates is the possession of
Answer: B (radial symmetry)
Coelenterates such as Hydra have radial symmetry, with body parts arranged around a centre. More advanced animals are bilaterally symmetrical.
A characteristic that best exemplifies the evolutionary advancement of mammals over other vertebrates is the
Answer: A (viviparous mode of reproduction)
Most mammals give birth to live young that develop inside the mother and are fed through a placenta. Other vertebrates mostly lay eggs.
An organism which exhibits extracellular digestion is
Answer: D (Rhizopus)
Rhizopus releases digestive enzymes onto its food and absorbs the products, so digestion happens outside its cells. Amoeba and Paramecium digest food inside food vacuoles, and Spirogyra makes its own food.
The causative agent of typhoid fever is
Answer: A (Salmonella)
Typhoid fever is caused by the bacterium Salmonella typhi, spread through dirty food and water.
Grasses recover quickly from bush fires in the savanna because of their
Answer: A (perennating organs)
Savanna grasses keep underground stems (rhizomes) and buds that the fire does not reach. New shoots grow from these perennating organs soon after the fire.
Climax communities in a biotic succession are usually characterized by
Answer: C (a stable composition of plant and animal species)
A climax community is the final stage of succession. Its mix of plant and animal species stays stable over time.
Use the graph to answer: Which of the following can be deduced from the distribution?
Answer: D (Species I thrives under conditions of moderate to high rainfall)
Species I is scarce at low rainfall but rises above 200 per km² once rainfall is moderate and stays high as rainfall increases. Species III falls as rainfall rises, and species IV is found only within a narrow rainfall range.
Use the graph to answer: The species whose distribution is not affected by rainfall is
Answer: A (II)
The line for species II stays flat at 200 per km² at every rainfall level. So rainfall does not affect it.
The soil type that contains nutrients which are not readily available for plants is
Answer: B (clayey)
Clay soil is rich in minerals, but its tiny particles hold them tightly and it is badly aerated and waterlogged. So the nutrients are hard for roots to take up.
Use the diagram of the lichen to answer: The importance of the association to the fungus is that it obtains
Answer: C (oxygen and carbohydrates from the algae)
The alga has chloroplasts and makes carbohydrates by photosynthesis, giving off oxygen. The fungus takes these from the alga, while the fungus gives water and shelter.
Use the diagram of the lichen to answer: The association illustrated demonstrates
Answer: D (mutualism)
In a lichen, the alga feeds the fungus and the fungus shelters the alga and keeps it moist. Both benefit, so it is mutualism.
A population that doubles in size at constant intervals is an indication of
Answer: B (exponential growth)
Doubling in equal time steps (2, 4, 8, 16…) is exponential growth. Sigmoid growth slows down and levels off.
The main purpose of establishing shelter belts in the Sahel region is to
Answer: A (check desert encroachment)
Rows of trees planted across the Sahel slow the wind, hold the soil and stop sand from spreading. Their main purpose is to check the advance of the desert.