WAEC Biology 2012 Objective Past Questions

All 60 questions from the West African Examinations Council (WAEC) Biology 2012 Objective paper, with the correct answer and a full explanation for each. Free, no signup needed.

Biology 2012 Objective — Question 1

The science of life is referred to as

• A. anatomy
• B. biologyCorrect
• C. ecology
• D. phylogeny

Explanation

Biology is the science of life.

Biology 2012 Objective — Question 2

The epidermis of a leaf is considered an example of a tissue because the cells

• A. allow sunlight to pass through
• B. are covered by a waxy cuticle
• C. possess a similar structure and functionCorrect
• D. allow water to enter them by osmosis

Explanation

The epidermis of a leaf is considered an example of a tissue because the cells possess a similar structure and function.

Biology 2012 Objective — Question 3

The organism at the organ level of organisation of life is a

• A. Euglena
• B. Spirogyra
• C. GingerCorrect
• D. Tapeworm

Explanation

Ginger exists at the organ level of organization of life.

Biology 2012 Objective — Question 4

The disadvantage of complexity of organisation in the higher organisms is that it leads to

• A. mutual interdependence between component cells
• B. internal structural specialization
• C. increased adaptation to environment
• D. slower rate of diffusion of oxygen to individual cellsCorrect

Explanation

Complexity, which is noted in higher organisms, makes diffusion an inefficient means of transport, hence the slower rate of diffusion of oxygen to individual cells.

Biology 2012 Objective — Question 5

In which of the following multicellular organisms is interdependence of cells maintained?

• A. Spirogyra
• B. VolvoxCorrect
• C. Eudorina
• D. Pandorina

Explanation

Volvox, Eudorina and Pandorina are all colonial organisms. In Eudorina and Pandorina, the cells forming the colony are independent. In Volvox, each cell cannot live independently; the cells have become specialized — some for reproduction, others for photosynthesis and locomotion.

Biology 2012 Objective — Question 6

Which of the following processes occurs in the second phase of meiosis?

• A. Homologous chromosomes separate
• B. Two daughter cells are formedCorrect
• C. Fertilization occurs
• D. Segregation of genes occurs

Explanation

At the metaphase of the second meiotic division, nuclear membrane gets dissolved in the cytoplasm; chromosomes are attached to the spindle by their centromeres. The two chromatids of the chromosomes become more distinct, and two daughter cells are formed.

Biology 2012 Objective — Question 7

The muscle cell fluid of an athlete was tested immediately after a 100m race and was found to contain a high concentration of lactic acid. Explain what could have caused this.

• A. The athlete must have eaten food containing lactic acid just before the race
• B. The athlete must have injected lactic acid into his blood just before the race
• C. The athlete's muscle cell must have carried out anaerobic respiration during the raceCorrect
• D. The athlete must have inhaled lactic acid from the environment during the race

Explanation

The athlete's muscle must have carried out anaerobic respiration. In plants, the products of anaerobic respiration are alcohol and CO2, whereas in animals, the products are CO2 and lactic acid.

Biology 2012 Objective — Question 8

The graph below represents the growth pattern of an animal. Which of the following groups of animal shows this pattern of growth?

• A. Cestoda
• B. Reptilia
• C. Amphibia
• D. InsectaCorrect

Explanation

This is the pattern of growth of insects, which grow in a stepwise manner corresponding to periods of moulting.

Biology 2012 Objective — Question 9

The pulmonary circulation involves movement of the blood to and from the

• A. brain
• B. kidneys
• C. liver
• D. lungsCorrect

Explanation

Pulmonary circulation involves movement of blood between the heart and the lungs. The table below shows the blood composition of four individuals. Use the table to answer questions 10 and 11: Blood Composition | Plasma | Red blood cells | White blood cells | Platelets Individual I: Normal, Normal, High, Normal Individual II: Normal, Normal, Normal, Normal Individual III: Normal, Normal, Low, Normal Individual IV: Normal, Normal, Normal, Low

Biology 2012 Objective — Question 10

Which of the individuals is likely to be suffering from haemophilia?

• A. I
• B. II
• C. III
• D. IVCorrect

Explanation

Low level of platelets (thrombocytes) in the blood causes haemophilia. Individual IV shows low platelets.

Biology 2012 Objective — Question 11

Which of the individuals is likely to have HIV?

• A. I
• B. II
• C. IIICorrect
• D. IV

Explanation

The blood of a person having HIV must be deficient of white blood cells — they are being continually destroyed. Individual III shows low white blood cells.

Biology 2012 Objective — Question 12

A student dissecting an animal specimen discovered that it has two auricles and one ventricle. The animal is likely to be a/an

• A. fish
• B. reptile
• C. amphibianCorrect
• D. bird

Explanation

Amphibians have a three-chambered heart — two auricles and one ventricle. (Fishes have a two-chambered heart — one auricle, one ventricle; reptiles have two auricles and a partially divided ventricle; birds and mammals have four-chambered hearts.)

Biology 2012 Objective — Question 13

The diagrams above are parts of a human lung. Which of the labeled parts is diagram Z taken from?

• A. IICorrect
• B. III
• C. IV
• D. V

Explanation

The structure given in the diagram is extracted from the left lung (labelled II in the source figure).

Biology 2012 Objective — Question 14

The diagram above is an illustration of the human excretory system. Which of the labeled parts contains the highest amount of nitrogenous wastes?

• A. ICorrect
• B. II
• C. IV
• D. VI

Explanation

The part labeled 'I' is the urinary bladder. It stores urine (which contains huge amounts of nitrogenous wastes) before it is finally expelled via the urethra.

Biology 2012 Objective — Question 15

Increasing adrenaline content of the blood would be expected to decrease the flow of blood to the

• A. Liver
• B. heartCorrect
• C. lungs
• D. brain

Explanation

Increasing adrenaline content increases the rate of heart contraction, which leads to increase in blood pressure. This means blood flowing back to the heart is limited as the amount of blood leaving the heart is increased.

Biology 2012 Objective — Question 16

The following are all examples of a simple reflex action, except

• A. swallowing
• B. sneezing
• C. walkingCorrect
• D. blinking

Explanation

Sneezing, swallowing and blinking are reflex actions while walking is a voluntary action.

Biology 2012 Objective — Question 17

Impulses are conducted towards the nerve cell through the

• A. myelin sheath
• B. dendronsCorrect
• C. axons
• D. synaptic nodes

Explanation

Dendrons/Dendrites are branched projections of the neuron cytoplasm and are the receptive surface of a neuron. Dendrons conduct impulses towards the cell body while axons carry impulses away from the cell body.

Biology 2012 Objective — Question 18

The function of the convex lens in the correction of eye defects is to

• A. diverge light rays from far objects to focus image on the retina
• B. converge light rays to focus image behind the retina
• C. converge light rays to focus the image before the retina
• D. converge light rays from far objects to focus their image on the retinaCorrect

Explanation

The convex lens is used for correcting long sightedness (hypermetropia). It does this by converging light rays from far objects to focus their image on the retina.

Biology 2012 Objective — Question 19

Which of the following parts of the eye contains light sensitive cells?

• A. Choroid
• B. Iris
• C. RetinaCorrect
• D. Lens

Explanation

The retina contains light-sensitive cells called rods and cones. Rods are sensitive to dim light; cones detect colour and are sensitive to bright light.

Biology 2012 Objective — Question 20

The hair on the human skin will stand erect when the person is

• A. in an air-conditioned roomCorrect
• B. strolling in the sun
• C. taking a hot drink
• D. doing strenuous exercise

Explanation

When cold, the hair on human skin stands erect to trap air around the skin and conserve body heat. An air-conditioned room is cold.

Biology 2012 Objective — Question 21

When fertilization occurs that leads to formation of a zygote, which of the following processes takes place?

• A. The tail of the sperm fuses with the egg cell
• B. Both tail and head of the sperm fuse with the egg cell
• C. The nucleus of the sperm fuses with the egg cellCorrect
• D. The egg cell develops on its own without the sperm

Explanation

During fertilization, the tail of the sperm disintegrates after entering the oocyte cytoplasm, and the nucleus of the sperm fuses with the ovum, forming the zygote.

Biology 2012 Objective — Question 22

Which of the following structures in a flower develops into the seed?

• A. Testa
• B. Integument
• C. OvuleCorrect
• D. Ovary

Explanation

The ovule develops into a seed while the ovary develops into a fruit.

Biology 2012 Objective — Question 23

An illustration of a human male reproductive system is shown above. Which of the labelled parts can be cut to ensure permanent sterility?

• A. I
• B. IICorrect
• C. III
• D. IV

Explanation

Sterilization of a man is done by cutting the sperm duct (vasectomy). The part labeled 'II' is the sperm duct.

Biology 2012 Objective — Question 24

The brightly coloured petals in some plants is an adaptive colouration for

• A. feeding
• B. pollinationCorrect
• C. dispersal
• D. shedding

Explanation

It is to attract insects for pollination.

Biology 2012 Objective — Question 25

Squirrels easily kill some trees because

• A. they inject poisonous substances into the trees
• B. most trees are susceptible to squirrel bites
• C. they feed voraciously on the roots
• D. they gnaw the bark and destroy the phloemCorrect

Explanation

It is because the phloem may get destroyed as squirrels gnaw the bark of those trees.

Biology 2012 Objective — Question 26

The major role played by accessory pigments during photosynthesis is to

• A. add colour to plants but not to trap light energy
• B. trap light energy that chlorophyll cannot absorbCorrect
• C. transfer energy from chlorophyll to other pigments
• D. prevent chlorophyll from absorbing unnecessary light

Explanation

The major role played by accessory pigments during photosynthesis is to trap light energy that chlorophyll cannot absorb, e.g. carotenes.

Biology 2012 Objective — Question 27

The main raw materials required for photosynthesis are

• A. oxygen and water
• B. oxygen and carbon dioxide
• C. oxygen and chlorophyll
• D. carbon dioxide and waterCorrect

Explanation

The main raw materials required for photosynthesis are carbon dioxide and water.

Biology 2012 Objective — Question 28

What is the benefit of thunder and lightning to farmers?

• A. Addition of nitrates to the soilCorrect
• B. Aeration of the soil
• C. Removal of harmful bacteria from the soil
• D. Addition of rain water to the soil

Explanation

Thunder and lightning cause nitrogen in air to combine with oxygen to form nitrogen oxide, which dissolves in rain water to form a nitrate solution added to the soil.

Biology 2012 Objective — Question 29

Which of the following substances must be present in the soil for growth of a healthy green plant?

• A. Amino acids
• B. Carbon
• C. Glucose salts
• D. Magnesium ionsCorrect

Explanation

A plant can only be green if it has sufficient chlorophyll. The elements required for chlorophyll formation include magnesium, iron and nitrogen.

Biology 2012 Objective — Question 30

The appropriate food to be given to the child in the picture above is a

• A. garri
• B. bread
• C. avocado pear
• D. beanCorrect

Explanation

Protein is a body-building food, needed by a child (e.g. one with a protein-deficiency condition).

Biology 2012 Objective — Question 31

Which of the following food substances will have little or no calorific value?

• A. Proteins
• B. Carbohydrates
• C. Lipids
• D. WaterCorrect

Explanation

Water contains no calories.

Biology 2012 Objective — Question 32

The purpose of proteins in the diet of a mammal is to

• A. promote growth and repair worn out tissuesCorrect
• B. provide energy primarily
• C. add colour to food
• D. aid digestion of fats only

Explanation

The purpose of proteins in the diet of a mammal is to promote growth and repair worn out tissues, and to serve as body-building material.

Biology 2012 Objective — Question 33

The child in a given picture suffers from kwashiorkor, caused by deficiency of protein. The bones of the legs of a six-year old boy were observed to be weak and crooked. Which of the following elements were deficient in his mother's diet at pregnancy?

• A. Sodium and manganese
• B. Iron and manganese
• C. Calcium and phosphorusCorrect
• D. Magnesium and sulphur

Explanation

Calcium and phosphorus are essential for strong and healthy teeth and bones. A child with weak and crooked legs suggests these elements were deficient in the mother's diet during pregnancy.

Biology 2012 Objective — Question 34

Which of the following processes acts anaerobically to release alcohol and carbon (IV) oxide?

• A. Yeast respirationCorrect
• B. Bile action
• C. Pepsin action
• D. Lipase action

Explanation

Yeast respires anaerobically to release alcohol and carbon (IV) oxide, a gas known to turn lime water milky.

Biology 2012 Objective — Question 35

Fats and oils are also known as lipids. Thus, the enzymes acting on fats and oils are collectively known as

• A. amylase
• B. protease
• C. lipaseCorrect
• D. cellulase

Explanation

Bile is known to emulsify fat. Fats and oils are lipids, and the enzymes acting on them are collectively known as lipase.

Biology 2012 Objective — Question 36

Of all the given food classes, water has the

• A. highest calorific value
• B. moderate calorific value
• C. least calorific valueCorrect
• D. no measurable value

Explanation

Of all the given food classes, water has the least calorific value.

Biology 2012 Objective — Question 37

A space containing a group of interactive organisms is referred to as a

• A. communityCorrect
• B. population
• C. biome
• D. habitat

Explanation

A space containing a group of interactive organisms is referred to as a community.

Biology 2012 Objective — Question 38

The area around the earth where all life activities go on is known as the

• A. biosphereCorrect
• B. ecosystem
• C. habitat
• D. population

Explanation

The area around the earth where life activities go on is known as the biosphere. Its liquid, solid and gaseous parts are respectively the hydrosphere, lithosphere and atmosphere.

Biology 2012 Objective — Question 39

The following are abiotic components of an ecosystem except

• A. water
• B. temperature
• C. bacteriaCorrect
• D. wind

Explanation

Biotic components of an ecosystem are the living components; bacteria, being living organisms, are biotic, not abiotic.

Biology 2012 Objective — Question 40

Which of the following instruments is used for measuring wind?

• A. hygrometer
• B. barometer
• C. thermometer
• D. anemometerCorrect

Explanation

The anemometer is the instrument with which wind speed is measured. (Note: per the printed answer key the labelled correct option is D.)

Biology 2012 Objective — Question 41

Study the diagram below of a food web and use it to answer questions 41 and 42. The best title for the above diagram is

• A. terrestrial food chainCorrect
• B. terrestrial food web
• C. aquatic food chain
• D. aquatic food web

Explanation

This is a food web since it contains many food chains, and all the organisms involved are terrestrial organisms. Thus, it is a terrestrial food web.

Biology 2012 Objective — Question 42

(Using the same diagram as Q41) How many food chains are in the diagram?

• A. Three
• B. Four
• C. FiveCorrect
• D. Six

Explanation

The food web contains a total of five food chains.

Biology 2012 Objective — Question 43

Plants with breathing roots are characteristic features of vegetation in

• A. tropical grassland
• B. temperate grassland
• C. tropical rain forest
• D. salt water swampCorrect

Explanation

Plants with breathing roots (pneumatopores) are characteristic features of vegetation in salt water swamp.

Biology 2012 Objective — Question 44

Study the diagram below to answer questions 44 to 45. In which of the zones can very few or living organisms be found?

• A. I
• B. II
• C. III
• D. IVCorrect

Explanation

The zone receiving the least amount of light is where the fewest organisms are found, since light is a major factor governing the distribution of organisms in a marine habitat.

Biology 2012 Objective — Question 45

Which of the following factors exerts a major effect on the distribution of living organisms in the habitat?

• A. Salt
• B. pH
• C. LightCorrect
• D. Rainfall

Explanation

Light is the major factor affecting the distribution of organisms found in a marine or aquatic habitat, as it decreases with depth.

Biology 2012 Objective — Question 46

The use of water closet and septic tanks is preferred to the use of pit, bucket and pail latrines because it is

• A. the most efficient
• B. most cost effective
• C. least likely to spread diseasesCorrect
• D. most convenient

Explanation

The use of water closet and septic tanks ensure contaminated faeces are completely kept away from flies, reducing the incidence of cholera.

Biology 2012 Objective — Question 47

Which organism is the causative agent of cholera, contamination of drinking water by which unequivocally leads to a cholera outbreak?

• A. Plasmodium
• B. Escherichia coli
• C. Vibrio choleraeCorrect
• D. Trypanosoma

Explanation

Vibrio cholerae is the causative organism of cholera. A water sample containing vibrio cholerae has unequivocally been contaminated by faecal matter.

Biology 2012 Objective — Question 48

Which of the following factors is likely to increase the incidence of cholera?

• A. Access to clean water
• B. Buildup of waste products, predation and parasitism as density-dependent factors while unfavourable climate is notCorrect
• C. Effective sanitation
• D. Vaccination programmes

Explanation

Buildup of waste products, predation and parasitism are density-dependent factors while unfavourable climate is a density-independent factor — these buildups increase disease incidence including cholera.

Biology 2012 Objective — Question 49

Which of the following habitats does not favour continuous existence of a species?

• A. One with abundant food and shelter
• B. One with stable climatic conditions
• C. One with disappearing habitats due to human activityCorrect
• D. One with balanced predator-prey relationships

Explanation

Disappearing habitats due to human activity are regarded as a primary cause of species endangerment.

Biology 2012 Objective — Question 50

Which of the following traits are continuous variations in man?

• A. Body weight, height, skin colour and eye colourCorrect
• B. Blood group
• C. Tongue rolling
• D. Fingerprints

Explanation

Body weight, height, skin colour and eye colour are continuous variations, while tongue rolling, blood group and fingerprints are discontinuous.

Biology 2012 Objective — Question 51

Which of the following statements about the ABO blood group system is true?

• A. Antigens are located on the surface of red blood cells while antibodies are located in the blood plasma
• B. Antigens are found in plasmaCorrect
• C. Antibodies are found on red cells
• D. Both antigens and antibodies are found on red cells

Explanation

Antigens are located on the surface of red blood cells while antibodies are located in the blood plasma.

Biology 2012 Objective — Question 52

The main classes of fingerprints in man are

• A. whorl, arch, compound and loop
• B. line, dot, spiral and curve
• C. arch, compound, whorl and simpleCorrect
• D. compound, arch, whorl and simple

Explanation

The main classes of fingerprints in man are whorl, arch, compound and loop.

Biology 2012 Objective — Question 53

Which of the following diseases are transmissible through genes?

• A. AIDS and malaria
• B. Sickle-cell anaemia; HIV/AIDS, diabetes and presbyopia are acquiredCorrect
• C. Cholera and typhoid
• D. Tuberculosis and pneumonia

Explanation

Sickle-cell anaemia is transmitted through genes while HIV/AIDS, diabetes and presbyopia are acquired conditions.

Biology 2012 Objective — Question 54

Two plants with red flowers were test crossed. Which of the following results indicate that the plants are heterozygous for red flowers?

• A. If the two plants are homozygous red, all the offspring will also be redCorrect
• B. 25% white, 75% red and 50% white
• C. 100% white
• D. 100% red

Explanation

If the two plants are homozygous red, all offspring will also be red. Since the two are heterozygous for red flower colour, the ratio of red flower to white flower will be 3:1 (75% red; 25% white).

Biology 2012 Objective — Question 55

In the structure of DNA, which of the following statements is true?

• A. Guanine and cytosine are complementary; thymine and adenosine are complementaryCorrect
• B. Adenine pairs with guanine
• C. Cytosine pairs with thymine
• D. All bases pair randomly

Explanation

Guanine and cytosine are complementary bases; thymine and adenosine are complementary bases.

Biology 2012 Objective — Question 56

In a case of complete dominance, what is the phenotype ratio of the cross Bb (where B=black and b=white) x Bb?

• A. 1 black : 1 grey : 2 white
• B. 1 black : 3 white
• C. 1 black : 2 blues : 1 white
• D. 3 black : 1 whiteCorrect

Explanation

Bb x Bb will be black since black colour is dominant over white colour. 3 out of every 4 will be black while the remaining one will be white.

Biology 2012 Objective — Question 57

Two yellow-flowered hybrid plants each carrying a recessive factor for flowers with green colour were crossed. Which of the following ratios shows the correct proportion of offspring that have green flowers?

• A. 2 in 2
• B. 1 in 4Correct
• C. 1 in 3
• D. 1 in 5

Explanation

The correct proportion of offspring with the recessive (green) phenotype in a heterozygote x heterozygote cross is 1 in 4.

Biology 2012 Objective — Question 58

What name is given to a sudden change in a gene or chromosome?

• A. Allele
• B. Genotype
• C. MutationCorrect
• D. Phenotype

Explanation

Mutation is the name given to a sudden change in the genetic constituent of an organism.

Biology 2012 Objective — Question 59

Bees are of great importance to the farmer because they

• A. provide him with honey
• B. pollinate flowersCorrect
• C. sting crop pests to death
• D. destroy flowers by sucking nectar from them

Explanation

Bees are of great importance to farmers because they are good pollinators.

Biology 2012 Objective — Question 60

Which of the following sequences is the correct evolutionary trend?

• A. Algae → liverworts → mosses → fernsCorrect
• B. Ferns → mosses → liverworts → algae
• C. Mosses → algae → liverworts → ferns
• D. Liverworts → algae → mosses → ferns

Explanation

The correct sequence of the organisms according to their evolutionary advancement is: Algae → liverworts → mosses → ferns.