WAEC Biology 2015 Objective Past Questions

All 50 questions from the West African Examinations Council (WAEC) Biology 2015 Objective paper, with the correct answer and a full explanation for each. Free, no signup needed.

Biology 2015 Objective — Question 1

Which of the following organisms is not a protozoan?

• A. Amoeba
• B. AscarisCorrect
• C. Plasmodium
• D. Paramecium

Explanation

Amoeba, Plasmodium and Paramecium are protozoans, while Ascaris is a worm (nematode).

Biology 2015 Objective — Question 2

The structure of the cell membrane is a

• A. double layer and a double protein layer
• B. middle bi-layer of protein with a lipid layer on either surfaceCorrect
• C. middle bi-layer of lipid with a protein layer on either surface
• D. protein layer with two inner lipid layers

Explanation

The cell membrane is made up of proteins and lipids held together by non-covalent interactions - the protein part is sandwiched between two lipid layers, i.e. a middle bi-layer of protein with a lipid layer on either surface.

Biology 2015 Objective — Question 3

Which of the following cells is a specialized cell?

• A. amoeba
• B. Plasmodium
• C. guard cellCorrect
• D. meristematic cell

Explanation

The guard cell is a specialized cell which controls the opening and closing of stomata.

Biology 2015 Objective — Question 4

The following organisms have structures for movement except

• A. amoeba
• B. spirogyraCorrect
• C. volvox
• D. Paramecium

Explanation

Amoeba, Volvox and Paramecium are motile (have structures for movement), while Spirogyra is non-motile.

Biology 2015 Objective — Question 5

Which of the following statements about protoplasm of a cell is not correct? It

• A. is a gelatinous mass
• B. consists of cytoplasm and nucleus
• C. is the liquid part of the nucleusCorrect
• D. contains cellular organelles

Explanation

Protoplasm is the entire living part of the cell, not merely the liquid part of the nucleus.

Biology 2015 Objective — Question 6

When a spirogyra filament is placed in a concentrated salt solution for 30 minutes, the cell would become

• A. plasmolysedCorrect
• B. turgid
• C. shortened
• D. elongated

Explanation

Since the salt solution is hypertonic to the cell content of Spirogyra, the organism loses water to the solution by osmosis and eventually becomes plasmolysed.

Biology 2015 Objective — Question 7

The diagram below is an illustration of a crocodile. Use it to answer questions 7 and 8. Which of the labelled parts enable the animal to stay underwater most of the time?

• A. I, IV and V
• B. I, II and VCorrect
• C. I, III and IV
• D. III, IV and V

Explanation

The possession of a transparent eyelid (I), eyes located at the top of the head (II), and a nostril at the tip of the nose (V) adapts the crocodile to staying underwater for long periods.

Biology 2015 Objective — Question 8

Two characteristic features of the class to which the crocodile belongs are labelled

• A. I and II
• B. III and IVCorrect
• C. II and IV
• D. II and V

Explanation

The possession of scaly skin (III) and homodont teeth (IV) qualifies the crocodile as a reptile.

Biology 2015 Objective — Question 9

Water and salts are both lost from the human body in

• A. breath and sweat
• B. breath, urine and sweat
• C. sweat and urine
• D. urine and sweatCorrect

Explanation

Water and salts are both lost from the human body in urine and sweat; note that water (but not salts) is also lost through breathing (exhalation) as water vapour.

Biology 2015 Objective — Question 10

Which of the following features could be used to determine the growth of a seedling?

• A. number of flowers
• B. number of leaves
• C. length of flowers
• D. length of radicleCorrect

Explanation

The growth of a seedling can be evaluated by measuring the length of its radicle (or plumule).

Biology 2015 Objective — Question 11

The following diagram shows the sequence of events in early cell division. Study the diagram and answer question 11. In which of the following cells is the division likely to take place?

• A. sperm cellCorrect
• B. blood cell
• C. muscle cell
• D. uterine cell

Explanation

The diagram represents meiosis, which occurs only in reproductive cells, such as the sperm cell (used to produce sperms/eggs).

Biology 2015 Objective — Question 12

A plant that commonly undergoes vegetative propagation by means of leaves is

• A. Hibiscus
• B. BryophyllumCorrect
• C. Crotalaria
• D. spirogyra

Explanation

Bryophyllum is a plant that commonly undergoes vegetative propagation by means of its leaves.

Biology 2015 Objective — Question 13

The diagram below illustrates a part of the mammalian skeleton. Use it to answer questions 13 and 14. The part of the mammalian skeleton illustrated in the diagram is the

• A. atlas vertebrae
• B. axis vertebrae
• C. cervical vertebraeCorrect
• D. thoracic vertebrae

Explanation

This is the diagram of a typical cervical vertebra.

Biology 2015 Objective — Question 14

The function of the part I is to

• A. provide support to the spinal cordCorrect
• B. provide surface for attachment of the muscle
• C. carry the spinal cord
• D. articulate with adjacent vertebrae

Explanation

The part labelled 'I' is the neural canal, which is for the passage of (i.e. supports/protects) the spinal cord.

Biology 2015 Objective — Question 15

Blood pressure is higher in the arteries as a result of

• A. stress
• B. contraction and relaxationCorrect
• C. blockage in the arteries
• D. pressure of valves

Explanation

The contraction and relaxation of the heart (and arterial walls) are responsible for the higher blood pressure found in the arteries.

Biology 2015 Objective — Question 16

A farmer who wants to keep seeds for three years before planting and wants to prevent them from sprouting out uses

• A. auxin
• B. gibberellins
• C. abscisinCorrect
• D. cytokinins

Explanation

Abscisin (abscisic acid) promotes/induces seed dormancy, suppressing sprouting/germination until the farmer is ready to plant.

Biology 2015 Objective — Question 17

A person had an accident that affected the skull but not the nose and later lost the sense of smell. The accident must have affected the

• A. nose by extension
• B. olfactory lobes of the brainCorrect
• C. passages from the nose to the brain
• D. part of the skull near the nose

Explanation

The olfactory lobes of the brain are the part connected with the perception of smell; damage to them (rather than the nose itself) would cause loss of smell.

Biology 2015 Objective — Question 18

Ability of the human eye to focus images accurately on the retina is called

• A. astigmatism
• B. myopia
• C. adjustment
• D. accommodationCorrect

Explanation

The ability of the human eye to focus images accurately on the retina is called accommodation.

Biology 2015 Objective — Question 19

Which of the following characteristic features is not associated with monocotyledonous plants?

• A. well differentiated sepals and petalsCorrect
• B. presence of fibrous root system
• C. presence of narrow leaves
• D. floral parts are in multiples of three

Explanation

Monocots typically have an undifferentiated perianth (not clearly differentiated sepals and petals), unlike dicots; they do have a fibrous root system, narrow (parallel-veined) leaves, and floral parts in multiples of three.

Biology 2015 Objective — Question 20

The main difference between a seed and a fruit is that a fruit

• A. is large while a seed is small
• B. has two scars while a seed has oneCorrect
• C. is pigmented while a seed is not
• D. can be dispersed by animals while a seed cannot

Explanation

A fruit bears remains of the style/stalk, giving it two scars, while a seed has only one scar (the hilum), formed by the attachment of the funicle to the placenta.

Biology 2015 Objective — Question 21

Which of the following processes removes carbon (IV) oxide from the atmosphere?

• A. Burning fuels
• B. Putrefaction
• C. PhotosynthesisCorrect
• D. Respiration in Plants

Explanation

Burning of fuels, putrefaction and respiration all release CO₂ into the atmosphere; photosynthesis, on the other hand, removes CO₂ from the atmosphere.

Biology 2015 Objective — Question 22

A student used the following steps in testing for non-reducing sugar: (i) added Benedict's solution to the sugar solution (ii) added dilute hydrochloric acid to the sugar solution and boiled it (iii) added sodium hydroxide solution to the solution in II and boiled it (iv) added Benedict's solution to the cooled solution in III. Why did the student add dilute hydrochloric acid to the sugar solution in step II?

• A. to oxidize the sugar solution
• B. to hydrolyse the sugar solutionCorrect
• C. to dry the sugar solution
• D. to increase the volume of the sugar solution

Explanation

Dilute hydrochloric acid is added and boiled to hydrolyse the (non-reducing) sugar solution, breaking it down into reducing sugars.

Biology 2015 Objective — Question 23

What is the importance of step II [addition of sodium hydroxide] in the testing process?

• A. to neutralize the sugar solutionCorrect
• B. to soften the sugar solution
• C. to change the colour of the sugar solution
• D. to increase the acid content of the sugar solution

Explanation

Sodium hydroxide is added to neutralize the acid that was added earlier (in the hydrolysis step).

Biology 2015 Objective — Question 24

The colour change to be observed in step IV is

• A. blue-black
• B. brick redCorrect
• C. purple
• D. violet

Explanation

After the hydrolysis and neutralization, Benedict's test on the resulting reducing sugar gives a colour change to brick-red.

Biology 2015 Objective — Question 25

Which of the following organs of the alimentary canal is not correctly matched with its function?

• A. Gall bladder - stores bile
• B. Liver - stores glycogen
• C. Appendix - releases enzymesCorrect
• D. Teeth - grind food

Explanation

The appendix does not produce any enzyme; it is believed to have no active digestive function in humans.

Biology 2015 Objective — Question 26

A person suffering from obstruction of the bile duct is advised not to eat fats and oil because

• A. bile digests fats and oil
• B. fats and oil can only be absorbed when bile is absent
• C. bile emulsifies fats and oilCorrect
• D. bile adds water to digesting food

Explanation

Emulsification of fats and oils cannot be done without bile; without bile (due to the obstruction), fats and oils cannot be properly broken down/absorbed.

Biology 2015 Objective — Question 27

A community reaches a climax when

• A. only pioneer organisms are present
• B. new habitats are constantly being formed
• C. there is an introduction of new plants and animal species within the community
• D. the composition and size of a community remains constant over a long periodCorrect

Explanation

A community is said to reach a climax when its composition and size remain fairly constant over a long period of time.

Biology 2015 Objective — Question 28

Which of the following components make up an ecosystem?

• A. Decomposers, animals and non-living factors
• B. Living and non-living factorsCorrect
• C. Plants and non-living factors
• D. Plants, decomposers and non-living factors

Explanation

An ecosystem comprises the living component (biotic) and the non-living component (abiotic).

Biology 2015 Objective — Question 29

The major problem experienced by organisms living in small water bodies is

• A. drying upCorrect
• B. oxygen deficiency
• C. scarcity of food
• D. wave action

Explanation

The major problem experienced by organisms living in small water bodies is desiccation (drying up).

Biology 2015 Objective — Question 30

The capillarity of a soil refers to

• A. the particle size of soil
• B. how easily water passes through soil
• C. how well water rises up in soilCorrect
• D. proportion of water a soil holds

Explanation

The capillarity of a soil refers to how well water rises up through the soil.

Biology 2015 Objective — Question 31

An organism at the start of a food chain which provides the total input of energy into an ecosystem is the

• A. sun
• B. producerCorrect
• C. consumer
• D. decomposer

Explanation

The organism at the start of a food chain is the producer (green plant), which captures energy (originally from the sun) and introduces it into the ecosystem.

Biology 2015 Objective — Question 32

Study the diagram (a pitcher plant) below and use it to answer questions 32-34. The mode of nutrition of the plant in the diagram is

• A. photosynthetic and chemosynthetic
• B. saprophytic and carnivorous
• C. photosynthetic and carnivorousCorrect
• D. chemosynthetic and saprophytic

Explanation

This is a pitcher plant - a carnivorous plant that is still capable of photosynthesis; it is therefore simultaneously photosynthetic and carnivorous.

Biology 2015 Objective — Question 33

The structure labelled I is a

• A. pitcherCorrect
• B. an onion
• C. a flower
• D. a tendril

Explanation

The part labelled 'I' is known as the pitcher, the actual device with which the plant traps insects.

Biology 2015 Objective — Question 34

In which type of soil is the plant found? Soil that is

• A. poorly aerated
• B. water logged
• C. exposed
• D. nitrogen deficientCorrect

Explanation

Carnivorous (pitcher) plants are typically found in nitrogen-deficient soils, and trap insects to obtain the nitrogen they need.

Biology 2015 Objective — Question 35

Which of the following organisms is an endo-parasite?

• A. TapewormCorrect
• B. Flea
• C. Tick
• D. Aphid

Explanation

Tapeworm is an endo-parasite (lives inside its host), while flea, tick and aphid are ecto-parasites (live on the outside of their hosts).

Biology 2015 Objective — Question 36

Oil applied to the surface of water kills the larvae of mosquitoes through

• A. dehydration
• B. poisoning
• C. starvation
• D. suffocationCorrect

Explanation

The oil layer prevents air from entering the water, so the mosquito larvae, which need to breathe atmospheric air, die of suffocation.

Biology 2015 Objective — Question 37

Which of the following natural resources is most readily available to all organisms?

• A. Oil
• B. Water
• C. AirCorrect
• D. Food

Explanation

Air is the natural resource most readily available to all organisms.

Biology 2015 Objective — Question 38

Which of the following resources is non-renewable?

• A. Forest reserve
• B. Mineral depositCorrect
• C. Water
• D. Wild life

Explanation

Mineral deposits are non-renewable resources, unlike forest reserves, water and wildlife, which can regenerate/replenish over time.

Biology 2015 Objective — Question 39

Soil erosion could be prevented by

• A. flooding a farmland
• B. cover-croppingCorrect
• C. deforestation
• D. leaving the soil bare

Explanation

Cover-cropping is an effective way of preventing soil erosion, as plant cover protects the soil surface from being washed or blown away.

Biology 2015 Objective — Question 40

Which of the following statements about human blood groups is not true?

• A. A is dominant over BCorrect
• B. O is recessive
• C. B is dominant over O
• D. A and B are co-dominant

Explanation

Neither A nor B is dominant over the other (they are co-dominant); this is why blood group AB exists. O is recessive (OA=A, OB=B).

Biology 2015 Objective — Question 41

Which of the following traits is not inheritable?

• A. Ability to taste PTCCorrect
• B. Ability to roll the tongue
• C. Ability to move the ear
• D. Ability to rotate the eyeball

Explanation

The ability to taste phenylthiocarbamide (PTC) is not an inheritable trait.

Biology 2015 Objective — Question 42

A woman with blood group A gives birth to a child with blood group O. Which of the following blood groups cannot belong to the father?

• A. A
• B. B
• C. ABCorrect
• D. O

Explanation

The father cannot be AB, since a cross involving AB can never yield an offspring with blood group O (AB always contributes either A or B, never O).

Biology 2015 Objective — Question 43

How many chromosomes will be in a gamete if the normal (somatic) cell has 4 chromosomes?

• A. 2Correct
• B. 4
• C. 6
• D. 8

Explanation

A gamete cell has half the number of chromosomes present in a normal (somatic) cell; if a normal cell has 4 chromosomes, a gamete will have 2 chromosomes.

Biology 2015 Objective — Question 44

Use the diagram below (cross between a spotted leopard and a black panther, giving F₁ and F₂) to answer questions 44 and 45. Which of the following statements about the cross is correct?

• A. The gene for the spotted coat is recessive to the gene for the black coat
• B. Black coat and spotted coat are co-dominant
• C. The gene for the spotted coat is dominant over the gene for the black coatCorrect
• D. The genotype for the F₁ are Homozygous dominant

Explanation

The gene for the spotted coat is dominant over the gene for the black coat, which is why the F₁ generation is made up entirely of the spotted coat pattern.

Biology 2015 Objective — Question 45

What are the genotypes of the parents if the gene for skin colour is H?

• A. HH ; hhCorrect
• B. HH ; Hh
• C. Hh ; Hh
• D. Hh ; hh

Explanation

The genotype of the spot-coated leopard (dominant, homozygous) is HH, while that of the black-coated panther (recessive, homozygous) is hh.

Biology 2015 Objective — Question 46

According to Mendel's first law of inheritance, segregation of genes occur when

• A. tall plants are crossbred
• B. short plants are crossbred
• C. tall plants and short plants are crossbredCorrect
• D. plants are crossbred

Explanation

Mendel derived his first law of inheritance (the Law of Segregation) from crosses between tall pea plants and short pea plants.

Biology 2015 Objective — Question 47

Which of the following statements about sex-linked characters is not true?

• A. They are usually borne of the X-chromosome
• B. They are more common in males
• C. Males are usually carriersCorrect
• D. They are not usually carried on the Y chromosome

Explanation

Males are either free from a particular sex-linked character or they suffer from it directly; since males have only one X-chromosome, they cannot be carriers (a carrier state requires two X-chromosomes, one normal and one affected).

Biology 2015 Objective — Question 48

In explaining the term camouflage to a class, the diagram below showing four varieties, P, Q, R and S, of the same species of fish living amongst water plants in a river were used. Use the diagram to answer questions 48 to 50. Which of the varieties is likely to decrease most in number if a predatory fish is introduced into the river?

• A. P
• B. Q
• C. RCorrect
• D. S

Explanation

The fish variety R is susceptible to the greatest predation since it does not blend with its environment, making it easy for predators to locate.

Biology 2015 Objective — Question 49

Which of the varieties is most likely to outlive the others?

• A. P
• B. Q
• C. R
• D. SCorrect

Explanation

Fish variety S blends the most with its environment, making it the most likely to outlive the others, as predators would find it difficult to locate.

Biology 2015 Objective — Question 50

The variety selected in question 49 will outlive the others because the

• A. variety does not have markings
• B. variety is the most beautiful
• C. markings of the variety are similar to those of the environmentCorrect
• D. predator does not like eating the variety

Explanation

As already explained, variety S will outlive the others because its markings are similar to those of the environment (effective camouflage).