WAEC Biology 2022 past questions and answers

51 questions. Try each one, then open the answer to check yourself and read the explanation.

Question 1

Characteristics and Classification of Living Things

Which of the following statements about living things is correct?

  1. A.Animals respire using carbon (IV) oxide as a raw material
  2. B.Growth in plants is limited after some time
  3. C.Most plants respond to stimulus slowly
  4. D.Higher animals can reproduce asexually
Show the answer and explanation

Answer: C (Most plants respond to stimulus slowly)

Explanation

Plants usually respond to stimuli slowly, by growing towards or away from them. Animals use oxygen (not CO2) in respiration, plant growth is unlimited, and higher animals reproduce sexually.

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Question 2

Cell Structure and Organisation

Organ level of organization in living things is found in

  1. A.waterleaf plant
  2. B.virus particle
  3. C.kidney
  4. D.spermatozoon
Show the answer and explanation

Answer: C (kidney)

Explanation

The kidney is an organ made of several tissues working together; a spermatozoon is a cell and a waterleaf plant is a whole organism.

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Question 4

Structure of Flowering Plants

Diagrams X and Y are illustrations of transverse sections of a part of plants.
The part responsible for conducting water and dissolved mineral salts from the soil to the leaves is labelled

Diagram for this question
  1. A.I
  2. B.II
  3. C.III
  4. D.IV
Show the answer and explanation

Answer: A (I)

Explanation

Water is carried from the roots to the leaves in the xylem, the star-shaped central tissue labelled I. Root hairs (IV) only absorb it from the soil.

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Question 5

Structure of Flowering Plants

Diagrams X and Y are illustrations of transverse sections of a part of plants.
The part labelled II is the

Diagram for this question
  1. A.pith
  2. B.xylem
  3. C.phloem
  4. D.endodermis
Show the answer and explanation

Answer: A (pith)

Explanation

II is the large central region of Y inside the ring of vascular tissue: the pith.

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Question 6

Cell Structure and Organisation

The organelles in cells which are also referred to as suicidal bags are the

  1. A.mitochondria
  2. B.lysosomes
  3. C.ribosomes
  4. D.nuclei
Show the answer and explanation

Answer: B (lysosomes)

Explanation

Lysosomes hold digestive enzymes; if they burst they digest the cell itself, hence 'suicide bags'.

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Question 7

Cell and Its Environment

The process that brings about the shrinking of a Spirogyra cell when placed in a strong solution is

  1. A.osmosis
  2. B.autolysis
  3. C.plasmolysis
  4. D.diffusion
Show the answer and explanation

Answer: C (plasmolysis)

Explanation

In a strong solution water leaves the cell and the cytoplasm pulls away from the wall: plasmolysis.

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Question 8

Structure of Flowering Plants

The region of a plant stem in which cells divide to increase its diameter is the

  1. A.cambium
  2. B.phloem
  3. C.xylem
  4. D.collenchyma
Show the answer and explanation

Answer: A (cambium)

Explanation

The cambium is a meristem whose divisions add new xylem and phloem, making the stem thicker.

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Question 9

Support and Movement

The total number of caudal vertebrae in animals X and Y is 4 and 27 respectively. The animals are likely to be

  1. A.fish and human
  2. B.toad and rat
  3. C.toad and fish
  4. D.humans and rat
Show the answer and explanation

Answer: D (humans and rat)

Explanation

Humans have about 4 fused tail vertebrae (coccyx), while a rat's long tail has many caudal vertebrae.

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Question 11

Respiration

Use the following processes to answer this question.
I. Ribs move upward and outward
II. Diaphragm relaxes
III. Volume of thorax increases
IV. Air is forced out of the lungs
Which of the processes take place during inspiration?

  1. A.I and III only
  2. B.II and III only
  3. C.II and IV only
  4. D.III and IV only
Show the answer and explanation

Answer: A (I and III only)

Explanation

Breathing in: ribs move up and out and the diaphragm contracts, so the thorax gets bigger. Diaphragm relaxing and air forced out happen in expiration.

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Question 12

Respiration

Use the following processes to answer this question.
I. Ribs move upward and outward
II. Diaphragm relaxes
III. Volume of thorax increases
IV. Air is forced out of the lungs
Which of the processes is a direct result of contraction of the intercostal muscles?

  1. A.I
  2. B.II
  3. C.III
  4. D.IV
Show the answer and explanation

Answer: A (I)

Explanation

The intercostal muscles lie between the ribs; when they contract they lift the ribs up and out, which then enlarges the chest.

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Question 13

Homeostasis

The process by which the amount of water and solutes in the blood are controlled is known as

  1. A.haemolysis
  2. B.diffusion
  3. C.turgidity
  4. D.osmoregulation
Show the answer and explanation

Answer: D (osmoregulation)

Explanation

Osmoregulation keeps the water and salt balance of body fluids steady.

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Question 14

Hormonal Coordination

The table shows the effect of hormones I, II, III and IV on some parts of the human body (✓ = effect, X = no effect):
Hormone I: heart ✓, digestive system ✓, kidney ✓, uterus ✓
Hormone II: heart X, digestive system X, kidney ✓, uterus X
Hormone III: heart X, digestive system X, kidney X, uterus ✓
Hormone IV: heart X, digestive system ✓, kidney X, uterus X
Which of the following hormones are I, II, III and IV respectively?

  1. A.ADH, Glucagon, Oestrogen, Adrenaline
  2. B.Adrenaline, Glucagon, Oestrogen, ADH
  3. C.Glucagon, ADH, Oestrogen, Adrenaline
  4. D.Adrenaline, ADH, Oestrogen, Glucagon
Show the answer and explanation

Answer: D (Adrenaline, ADH, Oestrogen, Glucagon)

Explanation

Adrenaline affects many organs (I); ADH acts only on the kidney (II); oestrogen acts on the uterus (III); glucagon acts on the liver, part of the digestive system (IV).

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Question 15

Hormonal Coordination

The table shows the effect of hormones I, II, III and IV on some parts of the human body (✓ = effect, X = no effect):
Hormone I: heart ✓, digestive system ✓, kidney ✓, uterus ✓
Hormone II: heart X, digestive system X, kidney ✓, uterus X
Hormone III: heart X, digestive system X, kidney X, uterus ✓
Hormone IV: heart X, digestive system ✓, kidney X, uterus X
The hormone responsible for anxiety is

  1. A.I
  2. B.II
  3. C.III
  4. D.IV
Show the answer and explanation

Answer: A (I)

Explanation

Hormone I acts on many organs at once, like adrenaline, the hormone released in fear and anxiety.

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Question 16

Sense Organs

The diagram is an illustration of some parts of a mammalian ear.
The parts labelled I are the

Diagram for this question
  1. A.semi circular canals
  2. B.ossicles
  3. C.cochlea
  4. D.external auditory meatus
Show the answer and explanation

Answer: B (ossicles)

Explanation

I points to the three tiny bones in the middle ear (malleus, incus, stapes): the ossicles.

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Question 17

Sense Organs

The diagram is an illustration of some parts of a mammalian ear.
Which of the parts are correctly grouped?
A. Inner ear: I, IV; Middle ear: III; Outer ear: II
B. Inner ear: III; Middle ear: II, IV; Outer ear: I
C. Inner ear: I; Middle ear: II; Outer ear: III, IV
D. Inner ear: II; Middle ear: I, III; Outer ear: IV

Diagram for this question
  1. A.A
  2. B.B
  3. C.C
  4. D.D
Show the answer and explanation

Answer: D (D)

Explanation

II (semicircular canals) is inner ear; I (ossicles) and III (Eustachian tube) belong to the middle ear; IV (ear canal) is outer ear.

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Question 18

Sense Organs

The diagram is an illustration of some parts of a mammalian ear.
The middle ear is connected to the pharynx by the part labelled

Diagram for this question
  1. A.I
  2. B.II
  3. C.III
  4. D.IV
Show the answer and explanation

Answer: C (III)

Explanation

The Eustachian tube runs from the middle ear down to the pharynx and equalises air pressure on both sides of the eardrum.

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Question 19

Reproduction in Animals

The diagrams are illustrations of two different cells (P and Q) involved in a biological process in mammals.
Which parts of P and Q fuse to complete the biological process?

Diagram for this question
  1. A.III and I
  2. B.IV and I
  3. C.III and II
  4. D.IV and II
Show the answer and explanation

Answer: A (III and I)

Explanation

At fertilisation the nucleus in the sperm head (III) fuses with the egg nucleus (I).

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Question 20

Reproduction in Animals

The diagrams are illustrations of two different cells (P and Q) involved in a biological process in mammals.
Which of the following statements about P and Q is correct?

Diagram for this question
  1. A.Both cells are structures for asexual reproduction
  2. B.Both cells normally belong to the same individual
  3. C.Both cells are found in plants
  4. D.The union of both cells gives rise to a new mammal
Show the answer and explanation

Answer: D (The union of both cells gives rise to a new mammal)

Explanation

A sperm and an egg fuse at fertilisation to form a zygote, which develops into a new individual.

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Question 21

Reproduction in Animals

The diagrams are illustrations of two different cells (P and Q) involved in a biological process in mammals.
If the number of chromosomes in the skin cells of mammals is 46, how many chromosomes would be found in P and Q respectively?

Diagram for this question
  1. A.23 and 23
  2. B.23 and 46
  3. C.46 and 23
  4. D.46 and 46
Show the answer and explanation

Answer: A (23 and 23)

Explanation

Gametes are haploid, so both sperm and ovum carry half the body-cell number: 23 each.

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Question 22

Photosynthesis and Plant Nutrition

In which of the following structures is simple sugar produced?

  1. A.Vacuole
  2. B.Cytoplasm
  3. C.Chloroplast
  4. D.Cell wall
Show the answer and explanation

Answer: C (Chloroplast)

Explanation

Photosynthesis, which makes glucose, takes place in the chloroplasts.

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Question 23

Photosynthesis and Plant Nutrition

An evidence of the occurrence of photosynthesis in an experiment is the

  1. A.release of carbon(IV) oxide
  2. B.release of oxygen
  3. C.formation of water molecules
  4. D.formation and release of fructose
Show the answer and explanation

Answer: B (release of oxygen)

Explanation

Oxygen is a by-product of photosynthesis, so oxygen given off shows it is taking place.

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Question 24

Food Substances and Enzymes

The major sources of vitamin A are

  1. A.egg yolk, carrot and palm oil
  2. B.mango, pawpaw and eggs
  3. C.sorghum, soya bean and liver
  4. D.rice bran, green vegetables and milk
Show the answer and explanation

Answer: A (egg yolk, carrot and palm oil)

Explanation

Egg yolk, carrots and red palm oil are rich in vitamin A (or carotene, which the body turns into vitamin A).

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Question 25

Food Substances and Enzymes

Diagram J is a protease while diagrams K, L, M and N are food substances.
Which of the illustrated food substances would form a reaction with protease J?

Diagram for this question
  1. A.K
  2. B.L
  3. C.M
  4. D.N
Show the answer and explanation

Answer: B (L)

Explanation

L has a square projection that fits exactly into the square notch (active site) of J, like a key in a lock.

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Question 26

Food Substances and Enzymes

Diagram J is a protease while diagrams K, L, M and N are food substances.
Protease J would react with the particular illustrated substance because enzymes

Diagram for this question
  1. A.are denatured at a high frequency
  2. B.are specific in their action
  3. C.remain unchanged after a reaction
  4. D.speed up the rate of chemical reaction
Show the answer and explanation

Answer: B (are specific in their action)

Explanation

Each enzyme's active site fits only one substrate shape, so it acts only on that substance (lock-and-key).

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Question 27

Food Substances and Enzymes

Diagram J is a protease while diagrams K, L, M and N are food substances.
After a reaction between protease J and the food substance, the end-product would be

  1. A.fatty acids
  2. B.glucose
  3. C.amino acids
  4. D.water
Show the answer and explanation

Answer: C (amino acids)

Explanation

Proteases digest proteins, and the final products of protein digestion are amino acids.

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Question 28

Soil

The property of clayey soil that prevents it from supporting thick vegetation is its

  1. A.composition of chemically weathered granite rocks
  2. B.inability to retain much water
  3. C.tendency of becoming waterlogged
  4. D.porosity and low water-retention ability
Show the answer and explanation

Answer: C (tendency of becoming waterlogged)

Explanation

Clay particles are tiny with small pores, so clay holds water and easily becomes waterlogged, leaving roots short of air.

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Question 29

Soil

Which of the following practices will not maintain soil fertility?

  1. A.Preventing soil erosion
  2. B.Bush fallowing
  3. C.Leaving the land bare
  4. D.Planting cover crops
Show the answer and explanation

Answer: C (Leaving the land bare)

Explanation

Bare land is exposed to erosion and leaching, which strip away fertile topsoil and nutrients.

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Question 30

Population Ecology

A group of organisms of the same species living in a particular place is known as

  1. A.colony
  2. B.community
  3. C.ecosystem
  4. D.population
Show the answer and explanation

Answer: D (population)

Explanation

A population is all the individuals of one species living in an area at a given time.

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Question 31

Soil

The diagram is an illustration of an experiment on sedimentation of soil.
The organic component of the soil is labelled

Diagram for this question
  1. A.I
  2. B.II
  3. C.III
  4. D.IV
Show the answer and explanation

Answer: A (I)

Explanation

Humus (organic matter) is light and floats on the water surface, at I.

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Question 32

Soil

The diagram is an illustration of an experiment on sedimentation of soil.
The part labelled IV is

Diagram for this question
  1. A.silt
  2. B.sand
  3. C.humus
  4. D.clay
Show the answer and explanation

Answer: B (sand)

Explanation

The heaviest, coarsest particles settle first at the bottom; IV is the bottom layer of sand (above any gravel), with silt and clay above it.

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Question 33

Feeding Relationships and Energy Flow

Which of the following pyramids is not used in ecology? Pyramid of

  1. A.energy
  2. B.numbers
  3. C.biomass
  4. D.organisms
Show the answer and explanation

Answer: D (organisms)

Explanation

Ecologists use pyramids of numbers, biomass and energy; there is no 'pyramid of organisms'.

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Question 34

Feeding Relationships and Energy Flow

Study the food chain J → K → L → M → N.
Organism J is normally sustained by energy from

  1. A.green plants
  2. B.carbohydrates
  3. C.organism K
  4. D.sunlight
Show the answer and explanation

Answer: D (sunlight)

Explanation

J is the producer at the start of the chain; it gets its energy from sunlight.

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Question 35

Feeding Relationships and Energy Flow

Study the food chain J → K → L → M → N.
Which of the following statements about organism L is correct? It

  1. A.feeds on organism M
  2. B.is a primary consumer
  3. C.is the producer
  4. D.is a secondary consumer
Show the answer and explanation

Answer: D (is a secondary consumer)

Explanation

J is the producer, K the primary consumer, so L, which eats K, is the secondary consumer.

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Question 36

Feeding Relationships and Energy Flow

Study the food chain J → K → L → M → N.
The position occupied by each of organisms J, K, L, M and N in the food chain is known as the

  1. A.energy level
  2. B.trophic level
  3. C.food web
  4. D.pyramid of numbers
Show the answer and explanation

Answer: B (trophic level)

Explanation

Each feeding step in a food chain is called a trophic level.

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Question 39

Conservation of Natural Resources

The conservation of natural resources is enhanced by the following practices except

  1. A.controlling farming activities
  2. B.protecting endangered species
  3. C.poaching in game reserves
  4. D.establishing parks and gardens
Show the answer and explanation

Answer: C (poaching in game reserves)

Explanation

Poaching is illegal hunting, which destroys wildlife instead of conserving it.

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Question 40

Conservation of Natural Resources

The burning of farmlands should be discouraged because it

  1. A.destroys the organic components of the soil
  2. B.increases the population of wild animals on the farm
  3. C.increases the dormancy period of some seeds
  4. D.destroys some plant pests
Show the answer and explanation

Answer: A (destroys the organic components of the soil)

Explanation

Fire burns off humus and kills soil organisms, lowering soil fertility.

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Question 41

Conservation of Natural Resources

The use of a lighter instead of match sticks is a way of conserving

  1. A.petroleum
  2. B.forest
  3. C.water
  4. D.wildlife
Show the answer and explanation

Answer: B (forest)

Explanation

Match sticks are made of wood; using fewer of them means fewer trees are cut down.

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Question 42

Transport in Animals

An accident victim was successfully transfused with blood from the father whose blood group is AB. The blood group of the accident victim is

  1. A.B
  2. B.O
  3. C.AB
  4. D.A
Show the answer and explanation

Answer: C (AB)

Explanation

AB blood carries both A and B antigens, so only a group AB person (the universal recipient) can safely receive it.

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Question 43

Variation

Which of the following traits in humans is an example of physiological variation?

  1. A.Skin colour
  2. B.Fingerprint
  3. C.Tongue rolling
  4. D.Height
Show the answer and explanation

Answer: C (Tongue rolling)

Explanation

Tongue rolling is an ability (how the body works), while skin colour, fingerprints and height are features of form (morphological).

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Question 44

Transport in Animals

Individuals belonging to blood group O are universal donors because

  1. A.antigens are absent in their blood cells
  2. B.members of the group constitute the highest number of humans
  3. C.there are no antibodies in their blood plasma
  4. D.the antigens in their blood cells are easily destroyed
Show the answer and explanation

Answer: A (antigens are absent in their blood cells)

Explanation

Group O red cells carry no A or B antigens, so the recipient's antibodies have nothing to react with.

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Question 45

Mendelian Inheritance

Two tall plants were crossed and all the F1 plants were tall. When the F1 plants were selfed, some of the F2 plants were tall while others were short. What are the possible genotypes of the original plants?

  1. A.Tt and tt
  2. B.TT and TT
  3. C.tt and tt
  4. D.TT and Tt
Show the answer and explanation

Answer: D (TT and Tt)

Explanation

Both parents are tall and all F1 are tall, so at least one parent is TT; short F2 plants mean some F1 were Tt, so the other parent carried t: TT × Tt.

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Question 46

Mendelian Inheritance

Which of the following statements best describes a test cross? It is

  1. A.to determine the genotype of an individual whose phenotype is known
  2. B.to determine the phenotype of an individual whose genotype is known
  3. C.between the progeny of parents to ascertain their external expressions
  4. D.between two homozygous recessive individuals to confirm the genotypes of the offspring
Show the answer and explanation

Answer: A (to determine the genotype of an individual whose phenotype is known)

Explanation

An organism showing a dominant trait is crossed with a homozygous recessive one; the offspring reveal whether it is homozygous or heterozygous.

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Question 47

Chromosomes, DNA and Sex Linkage

Which of the following statements about sex-linked traits is not correct?

  1. A.Males inherit sex-linked traits from their fathers
  2. B.Sex-linked traits are more common in males
  3. C.Females can be carriers because they can be heterozygous for the trait
  4. D.Males are never carriers since they only receive one sex chromosome
Show the answer and explanation

Answer: A (Males inherit sex-linked traits from their fathers)

Explanation

A son receives the Y chromosome from his father and his X from his mother, so X-linked traits pass to sons from their mothers.

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Question 48

Mendelian Inheritance

When two carriers of sickle cell anaemia produce an offspring, the probability of the offspring being a Sickler is

  1. A.¾
  2. B.¼
  3. C.½
  4. D.⅔
Show the answer and explanation

Answer: B (¼)

Explanation

AS × AS gives AA, AS, AS and SS; one in four (¼) is SS, a sickler.

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Question 49

Adaptation

Which of the following organisms exhibits adaptive colouration?

  1. A.Rabbit
  2. B.Chameleon
  3. C.Mouse
  4. D.Dog
Show the answer and explanation

Answer: B (Chameleon)

Explanation

A chameleon changes its skin colour to match its background, hiding it from enemies and prey.

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Question 50

Evolution

Which of the following sequences is the correct evolutionary trend in organisms?

  1. A.Algae → Liverwort → Ferns → Angiosperms
  2. B.Liverwort → Angiosperms → Ferns → Algae
  3. C.Angiosperms → Algae → Ferns → Liverwort
  4. D.Ferns → Liverwort → Angiosperms → Algae
Show the answer and explanation

Answer: A (Algae → Liverwort → Ferns → Angiosperms)

Explanation

Plants evolved from simple algae to liverworts, then ferns with vascular tissue, and finally flowering plants (angiosperms).

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Theory question 101

Cell Structure and Organisation

(a)(i) What is a cell? (ii) Name three scientists that are associated with the discovery of the cell.
(b)(i) Make a diagram, 6 cm to 8 cm long of a plant cell and label only the organelle responsible for cell reproduction.
(ii) Name one blood cell in humans that does not have the organelle labelled in 1(b)(i).
(iii) What is the biological implication of the cell named in 1(b)(ii) not possessing the organelle responsible for cell reproduction?
(c) List six organelles found in a plant cell.

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Model answer

(a)(i) A cell is the basic structural and functional unit of life; the smallest unit that can carry out all life processes.
(ii) Any three: Robert Hooke; Anton van Leeuwenhoek; Matthias Schleiden; Theodor Schwann; Rudolf Virchow; Felix Dujardin.
(b)(i) Diagram of correct size, roughly rectangular plant cell with cell wall, cell membrane, cytoplasm, large vacuole and chloroplasts drawn; only the nucleus labelled; title.
(ii) Red blood cell (erythrocyte).
(iii) It cannot divide/reproduce or repair itself, so it has a short life (about 120 days) and must be constantly replaced by the bone marrow; (lack of nucleus gives more room for haemoglobin to carry oxygen).
(c) Any six: nucleus; chloroplast; mitochondrion; vacuole; endoplasmic reticulum; ribosome; Golgi body; cell membrane; (lysosome).

Explanation

Label only the nucleus in (b)(i), as the question asks.

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Theory question 102

Photosynthesis and Plant Nutrition

(a) Complete the table below by ticking (✓) the appropriate group to which each of the listed elements required by plants belongs.
Elements: Hydrogen, Copper, Magnesium, Zinc, Phosphorus, Manganese, Boron, Nitrogen, Carbon, Oxygen
Groups: Microelement | Macroelement
(b) State: (i) three differences between the dentition of a herbivore and a carnivore; (ii) four differences between the dentition of a human and a goat.
(c) What are milk teeth?

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Model answer

(a) Macroelements: hydrogen, magnesium, phosphorus, nitrogen, carbon, oxygen. Microelements: copper, zinc, manganese, boron.
(b)(i) Any three — Herbivore: has a diastema / carnivore: no diastema; canines absent or reduced / long, pointed canines; no carnassial teeth / carnassial teeth present; molars with flat, ridged grinding surfaces / molars with sharp cusps; incisors absent in upper jaw (horny pad) / incisors in both jaws.
(ii) Any four — Human: incisors in both jaws / goat: no upper incisors (horny pad); canines present / no canines; no diastema / diastema present; molars and premolars with cusps / with ridges for grinding; dental formula i2/2 c1/1 pm2/2 m3/3 / i0/3 c0/1 pm3/3 m3/3; jaws move up and down / jaws move side to side.
(c) Milk teeth are the first (deciduous) set of teeth in young mammals, which fall out and are replaced by permanent teeth.

Explanation

Use paired, ruled columns for the differences.

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Theory question 103

Ecosystem and Ecological Factors

(a)(i) What is an ecological niche? (ii) State five roles played by a mango tree in its ecological niche.
(b)(i) State two reasons why ecologists use sampling techniques in population studies. (ii) State four examples of sampling techniques used in the population studies.
(c) Name four types of fingerprints in humans.
(d)(i) Name the plant used by Gregor Mendel in his experiment. (ii) State two reasons why the plant named in 3(d)(i) was used.

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Model answer

(a)(i) An ecological niche is the role or functional position of an organism in its habitat: where it lives, what it feeds on, what feeds on it and how it affects the environment.
(ii) Any five: producer — makes food by photosynthesis; provides fruits as food for animals and humans; provides shelter/nesting sites for birds, insects; gives shade; releases oxygen and absorbs CO2; adds leaf litter/humus to the soil; roots hold the soil and prevent erosion; host to epiphytes and parasites; transpiration adds water vapour to the air.
(b)(i) It is impossible or too time-consuming to count every organism in a large area; sampling saves time, labour and cost; it gives a good estimate of the whole population; avoids destroying the habitat.
(ii) Any four: quadrat; line transect; belt transect; capture–mark–recapture; pitfall trap; sweep net; pooter.
(c) Arch; loop; whorl; compound (composite).
(d)(i) Garden pea (Pisum sativum).
(ii) Any two: it has many clear contrasting characters; it is normally self-pollinating, so pure lines are easy to keep; it can be cross-pollinated by hand; short life cycle; produces many seeds; easy to grow.

Explanation

For (a)(ii) think of what the tree does for other organisms and the environment.

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Theory question 104

Conservation of Natural Resources

(a)(i) What are conservation laws? (ii) State three conservation laws.
(b)(i) State two reasons why animals are poached. (ii) Name five animals that are commonly poached.
(c) State four effects of excessive use of the forest.
(d) Explain briefly the following terms: (i) blood transfusion; (ii) antigen.

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Model answer

(a)(i) Conservation laws are rules made by government to protect and regulate the use of natural resources so that they are not wasted or destroyed.
(ii) Any three: laws against hunting endangered species; ban on bush burning; laws against illegal felling of trees/requiring permits; closed seasons for hunting/fishing; laws against trade in wildlife products; laws against pollution; laws setting up game reserves and national parks.
(b)(i) For meat (bushmeat); for skins, tusks, horns, scales to sell for money; for traditional medicine; for pets/trade.
(ii) Any five: elephant; leopard; pangolin; crocodile; gorilla/chimpanzee; antelope; python; grasscutter; rhinoceros; parrot.
(c) Any four: deforestation and loss of habitats; extinction of plant and animal species; soil erosion and desertification; reduced rainfall/climate change; flooding; loss of timber and medicinal plants; increased CO2 in the air.
(d)(i) Blood transfusion is the transfer of blood from a healthy donor into the blood vessels of a recipient who needs it, after matching blood groups.
(ii) An antigen is a foreign substance (usually a protein, e.g. on red cells or germs) that stimulates the body to produce antibodies.

Explanation

Give named animals, not general groups, in (b)(ii).

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Theory question 105

Animal Nutrition

(a)(i) State three differences between the alimentary canals of earthworm and cockroach. (ii) State three similarities between the alimentary canals of earthworm and cockroach.
(b) The diagram is an illustration of a biological cycle. Study it and answer questions 5(b)(i) to 5(b)(iii).
(i) Name the biological cycle. (ii) Explain briefly three roles played by plants and animals in the cycle. (iii) Name the processes that occur in X, Y and Z.
(c) Complete the table below:
Organ associated with excretion in humans | Three diseases each that affect the organ
(i) ________ | ________
(ii) ________ | ________
(d)(i) What is decay of organic matter? (ii) Name two groups of organisms that cause decay of organic matter. (iii) State one other factor that causes decay. (iv) Name the biological cycle that involves decay.
(e) Explain briefly the mode of nutrition in carnivorous plants.

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Model answer

(a)(i) Any three — Earthworm: gizzard grinds soil and food / cockroach: gizzard with chitinous teeth; earthworm has a typhlosole in the intestine / cockroach has none; earthworm has calciferous glands / cockroach has salivary glands with reservoirs; earthworm has no hepatic caeca / cockroach has hepatic (gastric) caeca; earthworm gut is a straight tube / cockroach gut is coiled; earthworm feeds on soil and organic matter / cockroach on many kinds of food with mouthparts.
(ii) Any three: both have a mouth and anus; both have a crop for storage; both have a gizzard for grinding; both have an intestine for digestion and absorption; both have a pharynx/oesophagus.
(b)(i) The water cycle (hydrological cycle).
(ii) Plants take in water through roots and lose it as vapour by transpiration; plants and animals release water vapour in respiration; animals lose water by sweating and excretion (urine); animals drink water; decay of dead plants and animals releases water.
(iii) X: evaporation (of water vapour into the air); Y: transpiration/respiration (and sweating) by plants and animals; Z: evaporation from streams, lakes and oceans.
(c) Any two organs with three diseases each, e.g. kidney — kidney stones, nephritis, kidney failure; liver — hepatitis, cirrhosis, liver cancer; lungs — tuberculosis, pneumonia, lung cancer, asthma; skin — ringworm, scabies, eczema, skin cancer.
(d)(i) Decay is the breakdown of dead plants, animals and their wastes into simpler substances.
(ii) Bacteria and fungi (saprophytes).
(iii) Any one: warmth; moisture; oxygen; detritivores such as earthworms.
(iv) Carbon cycle (or nitrogen cycle).
(e) Carnivorous plants (e.g. pitcher plant, sundew, Venus flytrap) grow in nitrogen-poor soil; they make carbohydrates by photosynthesis; they attract insects by colour, scent or nectar and trap them with special leaves; glands secrete enzymes that digest the insect's proteins; the plant absorbs the amino acids/nitrogen compounds.

Explanation

In the water cycle X and Y lie on the path from plants and animals to the clouds, and Z on the path from open water.

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