49 questions. Try each one, then open the answer to check yourself and read the explanation.
Which of the following does a virus have in common with animal cells?
Answer: B (DNA)
A virus is just nucleic acid (DNA or RNA) in a protein coat; it has no nucleus, cytoplasm or stored glycogen, so DNA is what it shares with animal cells.
Which of the following organelles are likely to be present in cells that are actively respiring and photosynthesizing?
Answer: B (Mitochondria and chloroplasts)
Mitochondria carry out aerobic respiration and chloroplasts carry out photosynthesis.
One common characteristic of fungi, algae, mosses and ferns is that they
Answer: C (produce spores that are dispersed)
Fungi, algae, mosses and ferns all reproduce by spores that are scattered to new places. Fungi lack chlorophyll and only some algae and fungi conjugate.
Protein-like bodies are borne on the part labelled
Answer: A (II)
The diagram is a Spirogyra filament. The protein-like pyrenoids sit on the spiral chloroplast, labelled II.
The sexual reproductive function is performed by the part labelled
Answer: D (V)
V is the nucleus; in conjugation the nuclei of the two gametes fuse to form the zygote, so the nucleus carries out the sexual function.
Which of the following is transmitted through mosquito bite?
Answer: A (Filariasis)
Filariasis (elephantiasis) worms are spread by Culex mosquitoes. Typhus is spread by lice, plague by fleas and schistosomiasis through water snails.
Which of the following insects lays its eggs in horny, purse-like cases?
Answer: D (Cockroach.)
The female cockroach lays her eggs inside a hard, purse-shaped case called an ootheca.
In which of the following vertebrates does the skin function as a respiratory surface?
Answer: D (Frog.)
A frog's skin is thin, moist and full of blood vessels, so oxygen diffuses through it.
Birds maintain their body temperature with the help of their
Answer: B (feathers which cover the body)
Feathers trap a layer of air that insulates the bird's body and reduces heat loss.
Secondary thickening in dicotyledonous stem is controlled by the
Answer: C (cambium)
The cambium divides to add new xylem inside and new phloem outside, making the stem thicker.
2H2O → 2H2 + O2(g). The equation above represents a part of the light stage of photosynthesis. Which of the following must be present for this reaction to occur?
Answer: C (Light energy and chlorophyll)
Splitting water (photolysis) needs light energy trapped by chlorophyll; carbon dioxide is used later, in the dark stage.
In an experiment to investigate the effect of nitrogen on the growth of plants, the substrate should be a medium of
Answer: A (washed sand)
The medium must contain no nitrogen of its own so the effect of adding it can be seen; washed sand is nearly free of nutrients. Cow dung and clay soil already contain nitrogen.
Which vitamin plays an important role in blood clotting?
Answer: B (Vitamin K)
Vitamin K is needed by the liver to make prothrombin and other clotting factors.
The mammalian organ which acts both as a digestive and as an endocrine organ is the
Answer: C (pancreas)
The pancreas releases digestive enzymes into the duodenum and also makes the hormones insulin and glucagon.
Which of the following is NOT involved in the transport of substances in the body?
Answer: C (Leucocytes)
Leucocytes (white blood cells) defend the body against germs. Plasma, lymph and red cells carry food, wastes and gases.
The end product of glycolysis in plants and animals is
Answer: A (pyruvic acid)
Glycolysis splits glucose into two molecules of pyruvic acid in the cytoplasm.
During respiration, air circulates round plant tissues via the
Answer: D (intercellular spaces.)
Air enters through stomata and lenticels but then moves around the inner tissues through the intercellular air spaces.
The excretory structure in the earthworm is the
Answer: C (nephridium)
Earthworms excrete with nephridia, tubes found in nearly every body segment.
During the bending of the arm, the biceps muscle
Answer: A (contracts and the triceps muscle relaxes)
Biceps and triceps are an antagonistic pair: to bend the arm the biceps contracts while the triceps relaxes.
When a healthy shoot of a flowering plant is illuminated from one side, auxins, accumulate on the
Answer: A (non-illuminated side of the shoot)
Auxin moves to the shaded side, making those cells grow faster so the shoot bends towards the light.
The type of placentation shown is
Answer: B (marginal)
The ovules are attached along one edge (margin) of a single carpel, which is marginal placentation.
An example of a plant having the placentation shown is
Answer: D (pride of Barbados.)
Pride of Barbados is a legume; legume pods have marginal placentation with seeds along one edge.
The term caryopsis is used to describe a fruit in which the
Answer: C (testa and pericarp are fused)
A caryopsis, such as a maize grain, is a dry one-seeded fruit in which the seed coat (testa) is fused to the fruit wall (pericarp).
The sex of a foetus is determined during
Answer: C (fertilization)
Sex depends on whether an X or a Y sperm fuses with the egg, so it is fixed at fertilisation.
The process of walking is under the control of the part of the brain called
Answer: C (cerebellum)
The cerebellum coordinates muscle movements and balance, which walking needs.
The gland directly affecting metabolic rate, growth and development is known as
Answer: B (thyroid gland)
The thyroid gland produces thyroxine, which controls the rate of metabolism and normal growth and development.
The diagram represents
Answer: D (motor neurone)
The neurone has its cell body at one end and its axon ending on muscle fibres, so it carries impulses to a muscle: a motor neurone.
The part labelled X is the
Answer: B (cell body)
X points to the swollen part near the dendrites and nucleus, which is the cell body of the neurone.
Which of the following ions is involved in the conduction of the nerve impulse?
Answer: B (K+)
A nerve impulse depends on the movement of sodium and potassium (K+) ions across the nerve cell membrane.
The depth of illumination in a water body can be measured with a
Answer: B (secchi disc)
A Secchi disc is lowered into water until it disappears; the depth shows how far light gets through.
In a food chain involving a primary producer, a primary consumer as well as a secondary consumer, the sharing of trophic energy is in the form that the
Answer: D (secondary consumer gets only a small portion of the energy contained in the primary producer.)
Only about a tenth of the energy passes from one level to the next; the rest is lost as heat and waste, so the secondary consumer gets only a small share of what the producer trapped.
In spite of the removal of carbondioxide from the atmosphere, its amount remains more or less constant because
Answer: B (it is produced during respiration by animals)
Respiration by animals (and plants and decomposers) puts carbon dioxide back into the air, balancing what photosynthesis removes.
In a tropical rain forest, non-epiphytic ferns and allies occur as
Answer: C (shade-loving species)
Ferns on the forest floor live in deep shade under the tree layers, so they are shade-loving plants.
Colonization of a bare rock surface is termed
Answer: C (primary succession)
Succession that starts on bare ground with no soil, such as rock, is primary succession.
Which of the following is a measure for the control of bilharzia?
Answer: B (Application of molluscicides in water bodies)
Bilharzia worms pass part of their life in water snails, so killing the snails with molluscicides breaks the cycle.
Some of the diseases caused by bacteria are
Answer: A (tuberculosis, gonorrhoea and syphilis)
Tuberculosis, gonorrhoea and syphilis are all bacterial. AIDS and poliomyelitis are caused by viruses.
Environmental pollutants which can work through the media of water, soil and air include
Answer: C (sulphur (IV) oxide)
Sulphur(IV) oxide pollutes the air and dissolves in rain to form acid rain, which then harms soil and water.
Human height is an example of a feature which depends on both
Answer: B (genetic and environmental factors)
Genes set a person's possible height, but food and health (the environment) affect how tall they actually grow.
A person with type O blood can donate to a patient with type A because the donor's blood
Answer: A (lacks antigens)
Group O red cells carry no A or B antigens, so the patient's antibodies have nothing to clump; that is why O is the universal donor.
The DNA molecule is a chain of repeating
Answer: D (nucleotides.)
DNA is a polymer of nucleotides, each made of a sugar, a phosphate and a nitrogenous base.
The specific number of chromosomes in each somatic cell is represented by
Answer: C (2N)
Body (somatic) cells are diploid, with two sets of chromosomes, written 2N; gametes have N.
A man with blood group A is married to a woman with blood group A. Which of the followng group combinations is possible if the family has three children?
Answer: D (A, O, A.)
If both parents are AO, their children can be A (AA or AO) or O (OO); B and AB are impossible as neither parent has a B allele.
The F1 of a cross between a tall and a dwarf plant was tall. The F1 was advanced to F2. How many of 120 F2 plants will be dwarf?
Answer: A (30)
F1 plants are Tt; crossing Tt × Tt gives 3 tall : 1 dwarf, so a quarter of 120 = 30 are dwarf.
All the sons of a colour-blind woman will be colour blind regardless of the state of the father because
Answer: B (sons inherit the sex chromosomes of their mothers)
A son receives his X chromosome from his mother and his Y from his father. A colour-blind mother has the gene on both X chromosomes, so every son gets it.
The slender, long and slightly curved beak of the sun-bird is an adaptation for feeding on
Answer: A (nectar)
A long, thin, curved beak can reach deep into flowers to suck nectar.
Scales on reptiles are a feature for
Answer: A (conserving water)
The dry, horny scales of reptiles form a waterproof covering that stops the body drying out on land.
The colour of the ventral surface of a fish is lighter than that of the dorsal. This is mainly
Answer: B (an adaptation for camouflage)
Seen from below, the pale belly blends with the bright water surface; seen from above, the dark back blends with the deep water. This countershading hides the fish.
The least evidence in support of the theory of evolution is provided by the study of
Answer: B (ecology)
Comparative anatomy, embryology and fossils in rocks (geology) give direct evidence of evolution; ecology studies organisms and their surroundings and gives the least.
From which group of animals are the mammals generally believed to have most recently evolved?
Answer: A (Reptiles)
Fossils show mammals arose from a group of reptiles called mammal-like reptiles; fish came much earlier in the line.