54 questions. Try each one, then open the answer to check yourself and read the explanation.
An organism that carries out both intracellular and extracellular digestion is
Answer: C (hydra)
Hydra begins digesting prey in its gut cavity (extracellular) and finishes inside the cells lining the cavity (intracellular).
A sample of urine from a patient was tested with Benedict's solution, and the observation was an orange precipitate. This could be an indication of
Answer: B (diabetes)
An orange precipitate shows reducing sugar (glucose) in the urine, a sign of diabetes mellitus.
The mode of nutrition of an organism that digests its food externally is
Answer: B (saprophytic)
Saprophytes pour enzymes onto dead matter outside their bodies and absorb the digested products.
The primary hydrogen acceptor in photosynthesis is
Answer: D (NADP)
In the light stage, hydrogen from split water is picked up by NADP, forming NADPH, which is used to reduce carbon (IV) oxide.
A potted plant was placed in an experimental setup to measure the rate of water loss in plants. The instrument in the experimental setup that would be used to measure the rate of water loss is
Answer: A (potometer)
A potometer measures the rate at which a shoot takes up water, which is used to estimate the rate of transpiration.
A potted plant was placed in an experimental setup to measure the rate of water loss in plants. A structure in the plant that is primarily responsible for water loss is
Answer: C (stomata)
Most water vapour leaves the plant through the stomata in the leaves.
The diagram below is an illustration of an ecological pyramid.
4th level: 10
3rd level: 1,000
2nd level: 8 000
1st level: 20
The illustrated diagram is a pyramid of
Answer: B (numbers)
The values are counts of individuals at each feeding level, and a pyramid of numbers can have a narrow base when the producers are few large trees.
The diagram below is an illustration of an ecological pyramid.
4th level: 10
3rd level: 1,000
2nd level: 8 000
1st level: 20
Organisms that would occupy the first level are
Answer: B (trees)
Only 20 producers support 8,000 primary consumers, so each producer must be very large, like a tree.
During an ecological survey, it was observed that the following factors were prevalent in a community with limited resources.
I. High birth rate; II. Low mortality; III. High immigration.
The likely implication of the factors on the community would be
Answer: C (increased competition and food shortage)
All three factors increase the population; with limited resources this leads to more competition and food shortage.
During an ecological survey, it was observed that the following factors were prevalent in a community with limited resources.
I. High birth rate; II. Low mortality; III. High immigration.
A measure that could be introduced by the government to control the implication of the factors on the community is
Answer: A (encourage birth control measures)
Birth control lowers the birth rate and slows population growth; the other options would make the population larger.
Which of the following pairs of structures perform the same function in their organisms?
Answer: B (Contractile vacuole and kidney)
Both the contractile vacuole (in protozoa) and the kidney remove excess water and wastes, i.e. osmoregulation and excretion.
The tentacles in a hydra were cut off and they could not be regenerated. The functions that would be impaired in the hydra are
Answer: B (movement and nutrition)
Hydra uses its tentacles to catch food and to move (by looping and somersaulting), so feeding and movement would suffer.
The diagram below is an illustration of a unicellular organism. Which of the labelled parts qualify the organism as an animal?
Answer: B (II, IV and V)
The organism is Euglena. Its flagellum (V), gullet (IV) and flexible pellicle (II), with no cellulose wall, are animal-like features; the chloroplasts (III) are plant-like.
The diagram below is an illustration of a unicellular organism. The part labelled III in the illustrated organism is used for
Answer: D (photosynthesis)
III points to a chloroplast, which carries out photosynthesis.
An organism possesses cell wall in its cell. Another structure that would be unique to the cell of the organism is
Answer: B (chloroplast)
A cell wall shows a plant cell; chloroplasts are found in plant cells but not in animal cells. Mitochondria and nuclei are in both.
The organism that is the smallest in size is
Answer: A (a virus)
Viruses are far smaller than bacteria and can only be seen with an electron microscope.
Use the following organisms: Cycad, Spirogyra, Fern, Tridax. The correct order of complexity of the organisms in the evolutionary trend would be
Answer: B (Spirogyra → fern → cycad → Tridax)
Plants become more complex from algae (Spirogyra) to ferns (pteridophytes) to gymnosperms (cycad) to flowering plants (Tridax).
Use the following organisms: Cycad, Spirogyra, Fern, Tridax. A characteristic that is common to all the organisms is that they
Answer: C (possess chlorophyll)
All four are green plants with chlorophyll. Spirogyra has no true roots or stems, and only the cycad has naked seeds.
An organelle that is found in large number in the muscles of the heart is
Answer: B (mitochondrion)
Heart muscle works non-stop and needs much energy, so its cells contain many mitochondria, where respiration releases energy.
In a practical class, baker's yeast was added to a bread dough that rose after 30 minutes. The gas responsible for the rise observed in the dough is
Answer: A (carbon(IV) oxide)
Yeast ferments the sugar in dough and releases carbon (IV) oxide, whose bubbles make the dough rise.
DNA replication occurs in a cell during
Answer: A (interphase of mitosis)
DNA is copied in interphase, before the cell starts dividing, so each chromosome has two chromatids.
If the chromosome number of the root tip of an onion species is 16, what would be the chromosome number of the leaf?
Answer: B (16)
Root tip and leaf cells are both body cells made by mitosis, so they have the same diploid number, 16.
The following conditions are sex-linked except
Answer: C (diabetes)
Haemophilia, colour blindness and (Duchenne) muscular dystrophy are carried on the X chromosome; diabetes is not sex-linked.
Evolution by natural selection is most likely to occur when there is
Answer: D (more variation in a population)
Natural selection acts on variation: the more differences there are, the more there is for selection to favour.
The term used to describe the extinction of dinosaurs and the rise in number of birds is
Answer: B (evolution)
The gradual change in the kinds of living things over long periods, with some dying out and others appearing, is evolution.
An example of physiological variation is
Answer: D (blood group)
Blood group depends on chemicals in the blood, not on visible structure, so it is a physiological variation; height, leaf shape and hair colour are morphological.
The correct pair of organism with its type of skeleton is
Answer: B (earthworm and hydrostatic skeleton)
An earthworm is supported by fluid under pressure in its body cavity (hydrostatic skeleton). Grasshoppers and spiders have exoskeletons, rats endoskeletons.
The diagram below is an illustration of the percentage of tongue rollers and non-tongue rollers in a human population. The type of variation in the illustrated diagram is
Answer: C (discontinuous)
People are either rollers or non-rollers, with no in-between groups, so the variation is discontinuous.
The diagram below shows the appearance of chromosomes during a cell division. The appearance shown is
Answer: C (chiasma formation)
The paired chromosomes are crossing over each other; the cross-over points are chiasmata, formed in prophase I of meiosis.
The genotypes of both parents of four children are AS. What is the likely percentage of the offspring that would be sicklers?
Answer: A (25%)
AS x AS gives AA, AS, AS and SS; only SS (one in four, 25%) is a sickler.
Fossils are usually found in
Answer: B (sedimentary rocks)
Fossils form when remains are buried in layers of sediment that harden into sedimentary rock.
The component of the blood in mammals which is circular, biconcave and non-nucleated is
Answer: A (erythrocyte)
Mammalian red blood cells (erythrocytes) are biconcave discs without a nucleus, which gives more room for haemoglobin.
Organisms that excrete uric acid do so because uric acid
Answer: C (is excreted with minimal water loss)
Uric acid is almost insoluble and can be passed out as a paste, so birds, reptiles and insects lose very little water excreting it.
Absorption of water by seeds during germination is by
Answer: C (imbibition)
A dry seed soaks up water into its seed coat and stored food (proteins, starch); this swelling uptake is imbibition.
A hormone responsible for the development of secondary sexual characters in females is
Answer: A (oestrogen)
Oestrogen from the ovaries causes breast development, widening of hips and other female secondary sexual characters.
Homeostasis refers to
Answer: C (maintenance of a steady internal environment of the body)
Homeostasis is keeping conditions inside the body (temperature, water, glucose) constant.
A teacher made a drawing of the brain and asked students to label the part responsible for regulation of heartbeat and respiration. The part that should be labelled is
Answer: D (medulla oblongata)
The medulla oblongata controls involuntary actions such as heartbeat and breathing.
The diagram below is an illustration of a biological process that occurs in the body of a mature female mammal. The process illustrated in the diagram is
Answer: B (fertilization)
Many sperms surround an ovum, one of which is entering it: this is fertilisation.
The diagram below is an illustration of a biological process that occurs in the body of a mature female mammal. The product resulting from the illustrated process will
Answer: A (undergo mitotic division)
Fertilisation forms a zygote, which divides repeatedly by mitosis to form the embryo.
Plant tissues that make up the bulk of young herbaceous plants are
Answer: C (parenchyma)
Parenchyma, made of thin-walled packing cells, forms most of the cortex and pith of young herbaceous plants.
An activity that encourages conservation is
Answer: B (using old newspapers to make tissue papers)
Recycling old newspapers into tissue paper reduces the number of trees cut down.
Examples of non-renewable resources are
Answer: D (petroleum, coal, tin and copper)
Petroleum, coal and metal ores such as tin and copper cannot be replaced once used up. Water, air, plants and animals are renewable.
A dodder plant is a parasite because it
Answer: D (possesses haustoria)
Dodder sends haustoria (sucking roots) into the host's vascular tissue to take water and food, which makes it a parasite.
Commensalism is a relationship in which
Answer: C (one partner benefits and the other neither loses nor benefits)
In commensalism one organism gains while the other is neither helped nor harmed.
The following measures are adequate for conserving crude oil except
Answer: D (exploiting new crude oil reserves)
Exploiting new reserves uses up more crude oil instead of saving it; the other measures reduce oil use.
Which of the following factors is responsible for phenotypic variation in organisms? I - Genetic factors; II - Environmental factors; III - A-B-O blood group system
Answer: C (I and II only)
Phenotype results from genes acting together with the environment. The ABO blood group system is itself a trait, not a cause of variation.
The following substances are products of decomposition except
Answer: D (faeces)
Decomposition releases carbon (IV) oxide, hydrogen sulphide and heat. Faeces are a waste that is decomposed, not a product of decomposition.
Which of the following statements is correct about ecdysis? It is the
Answer: D (periodic shedding of exoskeleton for growth)
Ecdysis (moulting) is the shedding of the hard exoskeleton by arthropods so that they can grow.
An ecosystem comprises abundance of grasses, 120 antelopes and 20 hyenas. What would likely happen to the ecosystem if 15 of the hyenas were killed by a disease?
Answer: B (Increase in number of antelopes)
With fewer predators, fewer antelopes are eaten, so the antelope population rises.
Section A
A gardener that cultivates ornamental plants observed a delay in the flowering of the plants on the garden and then introduced bees to encourage a biological interaction between the bees and the plants, and also stimulate flowering.
Use the information to answer questions 1(a) to 1(c).
(a)(i) Name the biological process resulting from the interaction that led to the flowering of the plants. (ii) Explain briefly the process named in 1(a)(i).
(b) Mention two features each in the bees and the plants that encouraged the interaction. (i) Bees (ii) Plants
(c) Give one advantage of the plants to the bees.
(d) Mention two. (i) essential parts of a hibiscus flower; (ii) non-essential parts of a hibiscus flower.
(e) Explain briefly double fertilization in flowering plants.
(f) Give two features of the fruit of pride of Barbados that promotes its dispersal.
(g) Complete the table below.
Table columns: Fruit | Type of placentation
Rows: Cowpea; Okra; Pawpaw
(a)(i) Pollination (insect pollination).
(ii) Pollination is the transfer of pollen grains from the anther to the stigma of a flower of the same species; bees visiting flowers for nectar carry pollen on their hairy bodies from flower to flower.
(b)(i) Bees, any two: hairy body to which pollen sticks; pollen baskets on the hind legs; long proboscis for sucking nectar; good colour vision/sense of smell.
(ii) Plants, any two: large, brightly coloured petals; scent; nectar and nectar guides; sticky or rough pollen; sticky stigma inside the flower.
(c) Any one: nectar as food (energy); pollen as protein food for larvae; resins/wax materials for the hive.
(d)(i) Stamens (androecium) and pistil/carpels (gynoecium).
(ii) Sepals (calyx), petals (corolla), epicalyx.
(e) The pollen tube carries two male nuclei into the embryo sac. One fuses with the egg cell to form the zygote (which becomes the embryo); the other fuses with the two polar nuclei (or definitive nucleus) to form the triploid endosperm nucleus. Two fusions occur, hence double fertilisation.
(f) Any two: the pod is dry and dehiscent; the pod walls dry unevenly and split along two lines (sutures), twisting and throwing the seeds out (explosive mechanism); seeds are small and smooth.
(g) Cowpea - marginal; Okra - axile; Pawpaw - parietal.
Name the essential parts in (d) as the reproductive organs.
(a) Explain briefly the process of translocation of food in plants.
(b) A student obtained a green leaf from a plant that has been exposed to sunlight for six hours and wants to test it for starch in the laboratory. Complete the table below by stating four steps that would be involved in the experiment and give one reason for each of the steps.
Table columns: Four steps involved in the experiment | One reason for the step
(c) Complete the table below on enzymes
Table columns: Enzyme | Organ/gland where enzyme is produced | Site of action | Substrate that enzyme acts on
Rows: Ptyalin; Trypsin; Sucrase
(a) Translocation is the movement of manufactured food (mainly sucrose and amino acids) from the leaves where it is made to other parts (growing points, storage organs, fruits) through the phloem sieve tubes, in both directions.
(b) 1. Boil the leaf in water for a few minutes - to kill the cells and stop enzyme action, and make the cells permeable.
2. Put the leaf in alcohol (methylated spirit) in a test tube heated in a water bath - to remove the chlorophyll (decolourise the leaf).
3. Dip the leaf in warm water - to soften it, as alcohol makes it brittle.
4. Spread the leaf on a white tile and add iodine solution - a blue-black colour shows starch is present.
(c) Ptyalin - salivary glands - mouth - starch (cooked starch) to maltose.
Trypsin - pancreas - duodenum (small intestine) - proteins/peptones to polypeptides.
Sucrase - wall of small intestine (intestinal glands) - small intestine (ileum) - sucrose to glucose and fructose.
Never heat alcohol over a direct flame; use a water bath.
The population of some plant species found in a rainforest is presented on the table below.
Plant species | Population of plant species
Mahogany | 10
Iroko | 25
Obeche | 15
Hevea sp. | 5
Delonix sp. | 10
Use the information to answer questions 3(a) to 3(c).
(a) On the graph below, draw a bar chart with plant species on the x-axis and the population of plant species on the y-axis, using a scale of 2cm to five plants on the y-axis.
(b)(i) Identify the most dominant plant species in the habitat. (ii) Name one method of population studies that could be used to collect the data on the table.
(c) If the area of the rainforest is 1000m2, calculate the population density of Hevea sp.
(d) State four: (i) Ways of conserving endangered species (ii) benefits of conserving forests to humans
(a) A bar chart with a title, labelled axes (plant species on x, population on y), the stated scale (2 cm = 5 plants, so Iroko's bar is 10 cm tall), five separate bars of equal width: Mahogany 10, Iroko 25, Obeche 15, Hevea 5, Delonix 10.
(b)(i) Iroko (largest population, 25).
(ii) Quadrat method (or line/belt transect, direct counting).
(c) Population density = number ÷ area = 5 ÷ 1000 m2 = 0.005 per m2.
(d)(i) Any four: protect their habitats in game reserves and national parks; enforce laws against poaching and illegal trade; breed them in captivity (zoos, botanical gardens) and release them; control deforestation and bush burning; public education; seed and gene banks.
(ii) Any four: supply timber, fuel wood and other products; give food and medicinal plants; protect the soil from erosion; take in carbon (IV) oxide and give out oxygen (control climate); habitat for wildlife; protect water catchments; tourism and recreation.
In the bar chart, keep gaps between the bars and label every axis.
A group of insects living together have each member performing different tasks in the community.
(a) Give a term to describe the group of insects with the kind of behaviour.
(b) Complete the table below
Table columns: Four likely members of the insect community | One role of the member | One structure for performing the role
(c) Give two likely examples of the group of insects.
(d) State: (i) three advantages of the type of behaviour named in 4(a) to the community. (ii) two methods of communication among the group of insects with the behaviour named in 4(a).
(a) Social insects (social behaviour / division of labour in a caste system).
(b) For termites, four of: Queen - lays eggs - very large abdomen/ovaries; King - fertilises the queen - testes/reproductive organs; Workers - build the nest, find food, feed others - strong biting mandibles; Soldiers - defend the colony - large head with powerful mandibles (or nozzle). (For bees: queen - lays eggs - ovaries; drone - mates with queen - reproductive organs; worker - collects nectar and pollen - proboscis and pollen basket; worker as guard - stings - sting.)
(c) Any two: termites; honeybees; ants; wasps.
(d)(i) Any three: division of labour makes work efficient; better defence against enemies; better food gathering and storage; care of the young; building of protective nests; continuity of the colony.
(ii) Any two: chemicals (pheromones); touch/antennae contact; dancing (in bees); sounds/vibrations (head banging in termites).
Each member in (b) needs its role and the body part used for it.
Section B
(a) Explain briefly the reason why energy flow in an ecosystem is non-cyclic.
(b) Make a drawing of a pyramid of energy using the information below.
Primary consumer - 1000kJ
Tertiary consumer - 200kJ
Secondary consumer - 500kJ
Producer - 3000 kJ
(c) State three differences between pyramid of energy and pyramid of numbers.
Table columns: Pyramid of energy | Pyramid of numbers
(d) State the: (i) first law of thermodynamics (ii) second law of thermodynamics
(e) State three adaptations of a tapeworm to its mode of feeding.
(f) Two organisms A and B live in different habitats within a rural area. Organism A possesses gills while organism B possesses lungs for gaseous exchange.
(i) Name the habitats of each of organisms A and B
(ii) Give two abiotic factors that are unique to the habitats of each of organisms A and B.
(a) Energy enters as sunlight, passes one way from producers to consumers, and at each level some is lost as heat (respiration, movement) and cannot be reused by producers, so it does not cycle back.
(b) A pyramid of four stacked bars, widest at the base: Producer 3000 kJ (bottom), Primary consumer 1000 kJ, Secondary consumer 500 kJ, Tertiary consumer 200 kJ (top); bar widths in proportion, each level labelled, with a title.
(c) Any three: pyramid of energy is always upright, pyramid of numbers may be inverted; energy pyramid shows energy (kJ) at each level, numbers pyramid shows the count of organisms; energy pyramid takes account of the size of organisms and time, numbers pyramid does not; energy pyramid allows comparison between ecosystems, numbers pyramid does not.
(d)(i) Energy can neither be created nor destroyed, but can be changed from one form to another.
(ii) In every energy change some energy is lost as heat (unusable energy), so no transfer is 100% efficient.
(e) Any three: hooks and suckers on the scolex for attachment to the host's gut; thick cuticle resistant to digestive enzymes; secretes anti-enzymes; no mouth or gut - absorbs digested food over its whole body surface; flat body with large surface area; can respire anaerobically; produces very many eggs.
(f)(i) A - aquatic habitat (e.g. pond, stream, river); B - terrestrial habitat (land).
(ii) A, any two: turbidity; salinity; dissolved oxygen; water current/waves; depth/pressure of water. B, any two: relative humidity; wind; soil/edaphic factors; topography/altitude; rainfall.
In (b) the bars must decrease in width from the producer to the tertiary consumer.