49 questions. Try each one, then open the answer to check yourself and read the explanation.
An Amoeba and an unlaid chicken egg are
Answer: C (single cells)
An Amoeba is a one-celled organism, and the unfertilised egg (the yolk with its germinal disc) is one very large cell. So both are single cells.
In corms, food is usually stored in the
Answer: B (stems)
A corm is a short, swollen underground stem, as in cocoyam. The food is stored in this stem.
The animals that move by means of flagella include
Answer: A (Chlamydomonas and Euglena)
Chlamydomonas and Euglena both swim with whip-like flagella. Amoeba uses pseudopodia, Paramecium uses cilia, and Planaria and Hydra are many-celled animals.
The structures found only in the plant cells are
Answer: C (cell wall and chloroplast)
Animal cells have a cell membrane, cytoplasm and nucleus too, but only plant cells have a cellulose cell wall and chloroplasts.
A flower that has both stamens and pistil is said to be
Answer: C (perfect)
A perfect (bisexual) flower has both male parts (stamens) and female parts (pistil). Staminate or pistillate flowers have only one of them.
When oil is poured into the breeding site of mosquitoes, it
Answer: C (suffocates the pupae)
Mosquito larvae and pupae breathe air through tubes at the water surface. A film of oil blocks these tubes, so the pupae (and larvae) suffocate.
Use the diagram to answer: The correct evolutionary sequence of the organisms represented is
Answer: D (IV II III I)
The pictures show a mammal (I), a frog (II), a bird (III) and a fish (IV). Fishes came first, then amphibians, then birds, then mammals: IV, II, III, I.
Use the food web diagram to answer: In the diagram, the hawk is
Answer: C (a tertiary consumer)
The hawk eats the snake and the lizard, which themselves eat other animals (mouse, grasshopper). Being third in line after the plant eaters makes it a tertiary consumer.
Use the food web diagram to answer: Examples of competitors are
Answer: C (grasshopper and mouse)
Competitors need the same resource. The grasshopper and the mouse both feed on the vegetation.
One of the adaptations to life on trees by a monkey is its possession of digits which are
Answer: C (opposable)
An opposable thumb (or toe) can press against the other digits. This lets the monkey grasp branches firmly while climbing.
The community of plants in which the same species occur from year to year is the
Answer: D (climax vegetation)
A climax community is the final, stable stage of succession. Its species stay the same from year to year unless something disturbs it.
The most common means of transmitting the Acquired Immune Deficiency Syndrome (AIDS) is
Answer: C (through sexual intercourse)
HIV, which causes AIDS, can spread in all these ways, but most infections come from unprotected sexual intercourse.
Plants tend to prevent overcrowding by means of efficient
Answer: D (seed dispersal)
Seed dispersal carries seeds away from the parent plant. This stops the young plants from crowding and competing with the parent and each other.
The physical and climatic factors of a region primarily determine the
Answer: D (community of organisms in the region)
Rainfall, temperature, light and soil decide which plants can grow, and the plants in turn decide which animals can live there. So these factors shape the whole community of organisms.
A step in the movement of energy through an ecosystem is a description that best fits the term
Answer: B (trophic level)
Each feeding level (producer, primary consumer, secondary consumer, and so on) is a trophic level. Energy passes from one level to the next, step by step.
In a field experiment, the frequency of water leaf was observed to be 48 after 20 tosses of a 2m2 quadrat. What is the density of the plant in the field?
Answer: A (1.2per m2)
Total area sampled = 20 × 2 m² = 40 m². Density = 48 plants ÷ 40 m² = 1.2 per m².
The supporting tissue in xylem is most poorly developed in
Answer: C (submerged water plants)
Water holds up submerged plants, so they need very little woody supporting tissue. Their xylem is poorly developed.
The addition of lime to clayey soil serves to
Answer: C (prevent water-logging)
Lime makes the fine clay particles stick together into larger crumbs. The soil gets bigger air spaces, drains better and does not become water-logged.
The excessive use of agro-chemicals could lead to the pollution of
Answer: C (fresh water)
Rain washes fertilisers and pesticides from farms into streams, rivers and lakes. This pollutes fresh water and can cause algal blooms and fish deaths.
In a population study using the transect method, a student is likely to record the highest number of species in
Answer: A (a tropical rain forest)
The tropical rain forest has plenty of rain and warmth all year. It has more different species than any other Nigerian habitat.
In his theory of evolution, Darwin implied that
Answer: B (the most successful organisms are those that best adapt to their environment)
Darwin's natural selection says the organisms best suited to their environment survive and reproduce most. Use and disuse and passing on acquired traits are Lamarck's ideas.
The carnassial teeth of a carnivorous animal consist of the
Answer: A (last upper premolar and the first lower molar)
In carnivores such as dogs, the last upper premolar and the first lower molar are large and blade-like. They slide past each other like scissors to cut flesh.
A feature of the caste systems of bees and termites is that
Answer: A (the workers are sterile)
In both bees and termites the workers cannot reproduce. Only the queen (and the drones or king) breed.
The structure that is common in the embryos of mammals, amphibians, birds, fishes and reptiles and which is an evidence of their common ancestry is the
Answer: D (gill-slits)
All vertebrate embryos develop gill slits (pharyngeal clefts) at an early stage. This shared feature points to a common fish-like ancestor.
Animals aestivate when the environment in which they live becomes
Answer: A (hot and dry)
Aestivation is a dormant state during hot, dry periods, as in lungfish and snails. Hibernation is the winter (cold) version.
Birds which are large with long straight pointed beaks, long necks and long legs are likely to be
Answer: B (fish catchers)
Long legs let the bird wade in water, and a long neck with a straight, pointed beak lets it spear fish, as herons and egrets do.
Examples of organisms in which extracellular digestion occurs are
Answer: D (rhizopus, housefly and hydra)
Extracellular digestion happens outside the cells. Rhizopus and the housefly release enzymes onto their food, and Hydra digests prey in its body cavity. A tapeworm does not digest at all, and sponges digest inside their cells.
The mammalian erythrocytes differ from the leucocytes at maturity because the erythrocytes are
Answer: B (discoid and enucleated)
Mature red blood cells are disc-shaped (biconcave) and have no nucleus, which leaves more room for haemoglobin. White blood cells keep their nucleus and can change shape like an amoeba.
The presence of endoskeleton is characteristic of
Answer: B (vertebrata)
Vertebrates have an internal skeleton of bone or cartilage. Insects have an exoskeleton, and coelenterates have no hard skeleton.
The capture and digestion of insects by a pitcher plant is a special form of nutrition termed
Answer: B (heterotrophic)
The pitcher plant makes food by photosynthesis, but it also traps and digests insects to get nitrogen. Feeding on other organisms is heterotrophic nutrition.
Use the diagram of the experiment to answer: Which of the following statements is correct about the experiment?
Answer: D (The leaves outside the flask serve as control.)
The leaf in the flask gets no carbon(IV) oxide because caustic soda absorbs it. The leaves outside the flask get normal air, so they are the comparison (control).
Use the diagram of the experiment to answer: The experimental set-up can be used to demonstrate that
Answer: D (carbon(IV) oxide is necessary for photosynthesis.)
Caustic soda (sodium hydroxide) absorbs carbon(IV) oxide from the air in the flask. The leaf inside does not make starch, which shows carbon(IV) oxide is needed for photosynthesis.
When a marine fish was taken from the ocean and put in a tank of fresh water, it died after a short period because
Answer: B (the body cells of the fish swelled and burst as a result of the hypotonic fresh water)
Fresh water is hypotonic (more dilute) compared with the fish's body fluids. Water enters the cells by osmosis until they swell and burst.
Which of the following pairs of organs is located in the anterior half of the mammalian body cavity?
Answer: C (Lungs and heart)
The chest (thorax) forms the front part of the body cavity, and it holds the heart and lungs. The kidneys and ovaries are in the abdomen.
The mode of nutrition exhibited by a tapeworm is
Answer: C (parasitic)
A tapeworm lives in the intestine of its host and absorbs the host's digested food, harming the host. That is parasitic nutrition.
The organ located within the duodenal loop in the mammal is the
Answer: B (pancreas)
The duodenum curves into a U-shaped loop, and the pancreas lies inside this loop. Its duct opens into the duodenum.
In which of the following groups of fruits is the pericarp inseparable from the seed coat?
Answer: D (Caryopsis.)
A caryopsis, such as a maize or rice grain, is a one-seeded fruit in which the fruit wall is fused to the seed coat.
A person that is obese must avoid meals containing
Answer: B (margarine and butter)
Margarine and butter are almost pure fat, the most energy-rich food. An obese person should cut down on fatty foods.
Tissue respiration is important for the
Answer: C (release of energy for the body use)
Tissue (cellular) respiration breaks down food in the cells to release energy for life processes. The other options describe breathing and gas exchange.
Use the diagram of the root to answer: The function of absorption is performed by the structure labelled
Answer: B (II)
II points to the outer layer with root hairs. Root hairs absorb water and mineral salts from the soil.
Use the diagram of the root to answer: The structure labelled I represents the
Answer: D (pericycle.)
I points to the outer edge of the central vascular cylinder (stele). That outermost layer of the stele is the pericycle.
Use the diagram to answer: The gland usually found in the position labelled I is the
Answer: D (pituitary.)
Position I is in the head. The pituitary gland sits at the base of the brain.
Use the diagram to answer: The hormone secreted at IV serves to
Answer: A (facilitate the development of facial hairs)
Position IV is the lower abdomen, where the gonads (testes) are. Testosterone from the testes causes male features such as facial hair.
To select and retain the desirable trait of large body size which a farmer has observed in his herd, the farmer needs to
Answer: C (inbreed the animals in his herd)
Breeding animals that already have the trait with each other (inbreeding) keeps and fixes that trait in the herd. Crossing with another herd would mix in other genes.
In a population of living things, the parameters of size, height, weight and colour are examples of
Answer: B (continuous variations)
Traits like height and weight vary gradually over a range, with many in-between values. This is continuous variation.
If XN is the dominant allele for normal vision and Xn the recessive allele for colour-blindness, a boy with the genotype YXn will
Answer: B (be colour-blind)
A boy has only one X chromosome, so there is no second allele to mask the recessive one. With Xn he is colour-blind.
The first four children of a couple were all girls. The probability that the fifth will also be a girl is
Answer: D (1/2.)
Each child's sex depends only on whether an X or a Y sperm fertilises the egg. Earlier births make no difference, so the chance is always 1/2.
Genetic counselling is important when a marriage is planned between a
Answer: A (Rh− woman and Rh+ man)
If an Rh-negative mother carries an Rh-positive baby, her body can make antibodies that attack the red blood cells of a later Rh-positive baby. So this couple needs counselling.
What proportion of the offspring of a cross between two heterozygous parents will exhibit the recessive condition phenotypically
Answer: A (1/4)
Aa × Aa gives AA, Aa, Aa and aa. Only aa (1 in 4) shows the recessive trait.