48 questions. Try each one, then open the answer to check yourself and read the explanation.
The membrane surrounding the vacuole in a plant cell is called the
Answer: B (tonoplast)
The tonoplast is the membrane that encloses the large sap vacuole of a plant cell. The plasmalemma surrounds the whole cytoplasm.
The smallest living organisms which share the characteristics of both living and non-living matter are
Answer: C (viruses)
Viruses can be crystallised like non-living matter but reproduce inside living cells, so they are on the border between living and non-living.
Green plants are distinguished from other living organisms by their ability to
Answer: D (manufacture their own food.)
Using chlorophyll, green plants make their own food by photosynthesis; all organisms use water and most use oxygen.
The soil swallowed by the earthworm to form the worm cast is ground up in the
Answer: D (gizzard.)
The earthworm's muscular gizzard grinds the soil and food it swallows. The clitellum is used in reproduction.
Which is the correct order in an evolutionary sequence for the following plant groups?
Answer: C (Bacteria → algae → mosses → ferns → seed plants)
Plants became more complex in this order: bacteria, algae, mosses (no vascular tissue), ferns (vascular, no seeds), then seed plants.
In Amoeba, osmoregulation is carried out by the
Answer: C (contractile vacuole)
The contractile vacuole collects the excess water that enters Amoeba by osmosis and pumps it out.
The part used for feeling is labelled
Answer: A (I)
I marks the antenna, which the cockroach uses to touch and smell its surroundings.
The mouth part of the insect is adapted for
Answer: A (biting and chewing)
The cockroach has strong mandibles and maxillae for biting and chewing solid food.
Which of the following combinations differentiates a bony fish from a cartilaginous fish? I. Presence of gills II. Absence of gill slits III. Possession of bony skeleton IV. Possession of laterally compressed body V. Possession of dorso-ventrally compressed body
Answer: C (II, III and IV)
Bony fish have their gills covered by an operculum (no visible gill slits), a skeleton of bone and a body flattened from side to side. Cartilaginous fish such as rays are flattened top to bottom.
Which is the most important adaptation of a bony fish to life in water?
Answer: A (The possession of a streamlined shape)
A streamlined (spindle-shaped) body cuts down water resistance, so the fish can swim easily. Scales and slime protect the body, and the tail fin gives push.
Which of the labelled parts allows for efficient absorption of water and mineral?
Answer: A (I)
Part I is the outer layer bearing root hairs, which greatly increase the surface area for taking in water and mineral salts.
Starch is usually stored in the part labelled
Answer: B (II)
II is the wide cortex of the root, made of parenchyma cells that store starch.
The failure of transport and respiratory systems in plants as well as the presence of reddish colour in stems and leaves result from the deficiency of
Answer: D (phosphorus.)
Phosphorus is part of ATP, so lack of it upsets respiration and transport, and the leaves and stems turn dull purplish-red.
The dental formula i 3/3 c 1/1 pm 4/4 m 2/3 is that of a
Answer: D (dog)
Three pairs of incisors, one canine, four premolars and 2/3 molars in each half jaw (42 teeth) is the dog's formula. Goats and rabbits have no upper incisors or no canines; man has i 2/2.
The nitrifying bacteria, Nitrosomonas, convert ammonia to
Answer: A (nitrites)
Nitrosomonas oxidises ammonia (ammonium compounds) to nitrites; Nitrobacter then changes nitrites to nitrates.
The activity of ptyalin is likely to decrease with an increase in the concentration of
Answer: D (acid.)
Ptyalin (salivary amylase) works best in neutral or slightly alkaline conditions; acid slows it down, which is why it stops working in the stomach.
The phloem parenchyma is sometimes used for
Answer: A (food storage)
Phloem parenchyma cells are living, unspecialised cells that can store food such as starch.
The process by which a red blood cell placed in distilled water absorbs water until it bursts and releases its contents into the surrounding is known as
Answer: D (haemolysis)
Water enters the red cell by osmosis and, with no cell wall to stop it, the cell bursts; this bursting is called haemolysis.
The most appropriate title for the set up is
Answer: D (comparison of respiratory rates in plants and animals.)
One flask holds a living animal and the other a living plant, each with NaOH to absorb CO2, joined to a water manometer, so the set-up compares their rates of respiration.
The part labelled J is called
Answer: C (manometer)
The U-tube of water joining the two flasks shows pressure changes as oxygen is used up; a tube used to measure gas pressure is a manometer.
A circulatory system that does not allow mixing of oxygenated and de-oxygenated blood in mammalian heart is referred to as
Answer: D (closed.)
In mammals blood stays inside vessels and the heart is fully divided, so oxygenated and deoxygenated blood are kept apart. Of the options, this matches a closed system.
Which of the following waste products in plant is excreted through the stomata and lenticels?
Answer: A (Carbondioxide)
Gaseous wastes such as carbon dioxide (and oxygen) leave the plant by diffusion through stomata and lenticels. The others are stored in tissues.
The vertebra illustrated is
Answer: B (thoracic)
The long, single neural spine pointing upward is typical of a thoracic vertebra, where back muscles and ribs attach.
The neural arch is labelled
Answer: B (II)
II marks the arch of bone above the centrum that encloses the neural canal (spinal cord). I is the neural spine, III the transverse process, IV the centrum.
In animals, meiosis comes
Answer: C (before fertilization)
Animals make sperm and eggs by meiosis, halving the chromosome number; fertilisation then restores it. So meiosis comes before fertilisation.
The fleshy base of a flower to which the different floral parts are attached is known as
Answer: C (thalamus)
The thalamus (receptacle) is the swollen tip of the flower stalk that bears the sepals, petals, stamens and carpels.
When a short-sighted person views a distant object without spectacles, the image is formed
Answer: B (in front of the retina)
In short sight (myopia) the eyeball is too long or the lens too strong, so light from far objects focuses in front of the retina.
The graph above shows the relationship between the body and atmospheric temperatures for dog and lizard. What is the most appropriate deduction that could be made from the graph?
Answer: C (The dog's body temperature is independent of the external temperature)
The dog's line stays flat near 40 °C whatever the outside temperature, so it is independent of it; the lizard's body temperature rises with the surroundings.
The part of the brain that controls heart beat and breathing is the
Answer: D (medulla oblongata.)
The medulla oblongata controls automatic activities such as heartbeat, breathing and swallowing.
Use the list of ecological constituents: 1 Mango 2. Spear grass 3. Goat 4. Sheep 5. Temperature 6. Beans 7. Rock 8. Water. Items 1-4 can be regarded as
Answer: B (a community)
Items 1–4 are different species of living things sharing an area, which is a community. A population would be one species only.
Use the list of ecological constituents: 1 Mango 2. Spear grass 3. Goat 4. Sheep 5. Temperature 6. Beans 7. Rock 8. Water. The physical factors are represented by
Answer: C (5, 7, 8)
Temperature (5), rock (7) and water (8) are non-living (physical) factors; the others are living things.
Which of the following sets is made up of decomposers?
Answer: B (Mushroom, rhizopus and bacteria)
Fungi (mushroom, Rhizopus) and bacteria break down dead matter and release nutrients; they are the true decomposers.
The correct order in a food chain involving the organisms (1) Grasses, (2) Hawks, (3) Snakes, (4) Grasshopper, (5) Lizards is
Answer: C (1 4 5 3 2)
Grass is eaten by grasshoppers, grasshoppers by lizards, lizards by snakes and snakes by hawks: 1 → 4 → 5 → 3 → 2.
The organisms with the least number of individuals in a pyramid of numbers are the
Answer: B (tertiary consumers)
Energy is lost at each level, so the top (tertiary) consumers are the fewest.
Use the list of biomes: 1. Desert 2 Rain forest 3 Southern Guinea savannah 4 Northern Guinea savannah. A biome with a low annual rainfall, few scattered trees within dense layer of grasses and found in Kano and Katsina States is
Answer: D (4)
The drier northern savannah, with tall grasses and few scattered trees, covers the far north of Nigeria; of the options this is the Northern Guinea savannah.
Use the list of biomes: 1. Desert 2 Rain forest 3 Southern Guinea savannah 4 Northern Guinea savannah. A biome where there are many cacti and the small mammals undergo aestivation for long periods is
Answer: A (1)
Cacti and long periods of summer sleep (aestivation) to escape heat and drought are features of the desert.
Ecological succession ends with the formation of a stable
Answer: D (climax community.)
Succession goes from pioneer communities through several stages and ends in a stable climax community.
In a drought situation, plants suffer from water stress which could result in
Answer: A (reduced biochemical activities)
Water is the medium for all cell reactions; when plants lack water their stomata close and photosynthesis and other biochemical activities slow down.
The water-retention capacity of a soil indicates its
Answer: B (capillarity)
How much water a soil holds depends on its fine pores, through which water is held and rises by capillarity.
People who suck petrol with their mouths run the risk of increasing in their blood the concentration of
Answer: B (lead)
Leaded petrol contains lead compounds, and sucking it lets lead into the body, where it is poisonous.
The differences and similarities among living things account for
Answer: D (evolution.)
Similarities show that organisms share common ancestors, and differences show how they have changed over time; together they are evidence for evolution.
People with sickle-cell anaemia have haemoglobin
Answer: A (S and are homozygous recessive)
Sickle-cell sufferers have two copies of the recessive allele for haemoglobin S (genotype SS), so they are homozygous recessive.
In the gene locus for eye colour in humans, the allele for brown eyes is dominant over the allele for blue eyes. If a homozygous brown-eyed girl has a brother with blue eyes, what are the likely phenotypes of their parents' eye colour? (Eye colour is not a sex-linked trait)
Answer: C (Both parents have brown eyes)
The girl (BB) got a B from each parent and the blue-eyed boy (bb) got a b from each, so both parents are Bb and have brown eyes.
The sex-linked defect in which very slight cut produces severe bleeding is known as
Answer: C (haemophilia)
In haemophilia the blood does not clot properly, so a small cut bleeds for a long time; the gene is on the X chromosome.
Breathing root is an adaptation for survival in the
Answer: A (mangrove swamp)
Mangrove mud is waterlogged and short of oxygen, so mangroves send up breathing roots (pneumatophores) to take in air.
Red coloration on the head of a male lizard helps it to
Answer: C (secure its mate)
The bright red head of the male agama is shown off in courtship display to attract females.
A phenomenon by which an animal goes into a state of dormancy during the dry season is called
Answer: B (aestivation)
Aestivation is a resting state some animals (e.g. lungfish, snails) enter to survive heat and drought. Hibernation is the winter (cold) equivalent.
The anatomical evidence usually used in support of the evolutionary relationship among whales, human, birds, and dogs is the possession of
Answer: B (pentadactyl limb)
Whales, humans, birds and dogs all have limbs built on the same five-digit plan, showing they share a common ancestor.