All 60 questions from the West African Examinations Council (WAEC) Biology 2009 Objective paper, with the correct answer and a full explanation for each. Free, no signup needed.
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Which of the following organisms is not classified as an animal?
Euglena occurs at the boundary of plants and animals - it shows some plant features (chloroplast) as well as some animal features, so it is not classified strictly as an animal.
An organism that operates at the cellular level of organisation, carries out its physiological activities by using its
A unicellular organism performs all its physiological activities with the use of organelles.
The organelle which eliminates water from the body of a protozoan is the
The organelle which eliminates water from the body of a protozoan is known as the contractile vacuole.
Which of the following cell types has the least number of mitochondria?
The more active a cell is, the higher the number of mitochondria it is expected to have. Cells of the cornified (dead, keratinised) layer are metabolically inactive and so have the fewest mitochondria.
A typical plant cell is mainly distinguished from an animal cell by the possession of
Chloroplast and cell wall are present in plant cells but absent in animal cells.
Which of the following characteristics do fungi share in common with animals?
Plants store carbohydrate as starch, while animals and fungi both store carbohydrate as glycogen.
Which of the following processes involves diffusion?
The absorption of digested food into the villi occurs via diffusion.
The mechanism of opening and closing of stomata in plants is based on
The stoma opens when the guard cell is turgid and closes when the guard cell is flaccid.
In cellular respiration, energy is made available to organism by
With the use of the enzyme ATPase, adenosine triphosphate (ATP) is broken down into adenosine diphosphate (ADP), and energy is released for use in the cell.
Excretion in Paramecium sp. is by diffusion because
Diffusion is an efficient means of transport in protozoans because these organisms have a large surface area to volume ratio.
The axial skeleton is composed of the
The axial skeleton comprises the skull, the vertebral column, the sternum and the ribs, while the appendicular skeleton comprises the limbs and the limb girdles.
The inorganic components of bone consist of
The inorganic components of bone consist of magnesium, phosphorus and calcium.
A pulse is best described as A. contraction of arteries to allow blood into them B. constriction of veins to allow blood into them C. dilation of arteries to accommodate blood D. pumping action of the heart to move blood round the body
Since the heart pumps blood at high force, the arteries have to dilate sufficiently to accommodate the blood rushing through - the sound produced by this is known as the pulse.
The following characteristics are associated with the mammalian lungs except
A respiratory surface has the following features: a thin surface to enhance diffusion, moist, well vascularised (supplied with enough blood vessels), and a large surface area. (Note: the exact option text for this item was not fully legible in the source scan; the answer is based on the properties of a good respiratory surface described in the key.)
The excretory system in mammals consists of the following parts except
The excretory system in mammals comprises two kidneys, two ureters, one bladder and one urethra - so 'two bladders' is not correct.
The organ that receives reduced flow of blood during vigorous exercise except
During exercise, the heart rate increases, which increases the flow of blood to the brain. The brain is the one organ whose blood flow cannot be reduced, since there must be a constant supply of blood to it to provide sufficient oxygen; blood flow to the limbs, lungs and skin is adjusted to support increased muscular activity.
The ear pinna is strengthened by
The ear pinna is strengthened by cartilage.
The relationship between the retina and the brain is similar to that between the
The retina is a sensory receptor that relays visual signals; similarly, the cochlea is a sensory receptor that relays auditory signals to the auditory nerve. (Note: the official answer key text for this specific item was not clearly legible in the source scan; this answer follows the typical structure-function analogy used in such questions.)
Which of the following statements about the development of the foetus is not correct?
The statement that the circulatory system of the foetus is totally separate from that of the mother is NOT correct - although the foetal and maternal blood do not mix directly, they are closely connected via the placenta, across which food and oxygen are exchanged.
[Diagram of an egg, labelled I-VI] The parts that supply food and water to the developing embryo are labelled
The embryo is nourished by the yolk (labelled VI) and the albumen (labelled V), which supply food and water to the developing embryo.
[Same diagram as above] The part labelled III is the
The part labelled 'III' is known as the chalaza. The chalaza holds the yolk in place.
Transpiration refers to the loss of water in the form of water vapour. It can occur via
Transpiration refers to the loss of water in the form of water vapour. It can occur via the stomata (stomatal transpiration), the lenticels (lenticular transpiration), or the cuticle (cuticular transpiration).
Translocation is connected with the transport of
Translocation is connected with the transport of manufactured (organic) material, and not the transport of water (which is the function of xylem via transpiration pull).
Butterfly lays its egg under the surface of a leaf for the sole purpose of
The butterfly lays its egg under the surface of a leaf for the sole purpose of protection.
Carbohydrates are organic compounds containing carbon, hydrogen and oxygen with the hydrogen and oxygen occurring in the ratio of
Carbohydrates are organic compounds containing carbon, hydrogen and oxygen, with the hydrogen and oxygen occurring in the ratio of 2:1 (as in water).
A person suffering from obesity must avoid
A person suffering from obesity must avoid fatty foods.
In testing for starch in a leaf, the leaf is first boiled in water for about a minute so that the
In testing for starch in a leaf, the leaf is first boiled in water for about a minute so that the cells are killed (this stops enzyme activity and helps in subsequent steps of the test).
Pepsin does not act on
Pepsin does not act on sucrose. It acts on protein, converting it to peptone.
The enzymes in the stomach require which condition to function optimally?
The enzymes in the stomach (such as pepsin) require acidic conditions to function optimally.
Legumes hold a symbiotic relationship with the bacteria known as
Legumes hold a symbiotic relationship with the bacteria known as Rhizobium leguminosarium, which lives inside the root nodules of the legumes. These bacteria convert nitrogen gas from the air into ammonia, which is used by the legumes for optimum growth.
A herbivore cannot feed on a piece of meat because
A herbivore cannot feed on a piece of meat since it lacks canines, which are adapted for tearing meat.
In a particular habitat, the role of an organism is referred to as its A. habitat B. biomass C. niche D. space
The part of a habitat where an organism is found, along with its role, is known as its ecological niche.
The distribution of organisms in a fresh water habitat like a stream or pond is determined by the following factors except
Aquatic organisms are not affected by edaphic (soil) factors, so pH of the soil is the exception among the listed factors affecting distribution of organisms in a fresh water habitat.
The speed of wind is measured using
The direction of the wind is measured by a wind vane, while the speed of wind is measured by the anemometer.
Which of the following is a biotic component of an ecosystem?
Soil, rainfall and light constitute the abiotic component of an ecosystem since they are non-living, while fungi constitute the biotic component as they are living organisms.
A moss plant can withstand drought by means of its
The spores of a moss plant can withstand very dry conditions and will germinate when conditions become favourable.
Which of the following factors does the main problem facing xerophytic plants relate to?
Xerophytes are plants that grow in regions with low supply of water; the main problem they face is lack of adequate water.
The following gases are greenhouse gases except
Oxygen does not cause the greenhouse effect in any way. The greenhouse gases are CO2, H2O (water vapour), methane, nitrogen oxides and chlorofluorocarbons.
Bones are attached to other bones by ___ while muscles are attached to bones by ___
Bones are attached to other bones with the aid of ligaments, while muscles are attached to bones with the aid of tendons.
Rural-urban migration in developing countries can be prevented by
Rural-urban migration in developing countries can be prevented by even distribution of facilities in both rural and urban regions.
Shortage of food may trigger
Shortage of food may trigger competition among organisms for the limited resource.
Deforestation does not cause an increase in
Deforestation does not cause an increase in rainfall in any way; rather it tends to reduce rainfall and cause soil erosion, desertification and loss of biodiversity.
The main reason for the conservation of wildlife is to
The main reason for the conservation of wildlife is to save endangered species from extinction.
Which of the following is an example of variation?
Tongue rolling is an example of variation (discontinuous variation) - some people can do it while others cannot.
The parameters of size, height, weight and colour in a population of living things are examples of
Size, weight, height and colour are all examples of continuous variations.
Fingerprints are useful in crime detection because
Although there are just four main types of fingerprints - arch, loop, whorl and compound - no two individuals have exactly the same fingerprint, making them useful in crime detection.
A person with blood group O can be given blood from persons who have blood belonging to
It is only a person of blood group AB that can receive blood from any of the other groups. A person of group O can only receive blood from group O.
A man heterozygous for albino gene marries a woman who is also heterozygous for the gene. Both are normal for skin colour. The probability that they will have an albino child is
Since both parents are heterozygous carriers (Nn x Nn), the expected ratio of offspring is 1 NN : 2 Nn : 1 nn, so the probability of an albino child (nn) is 1/4.
Which of the following statements about heredity is not true? In heredity, the traits are
Traits are not always transmitted by only one parent - they are transmitted from both parents to offspring via genes contained in the ovum and sperm; so the statement that they are 'always transmitted by one parent' is not true.
An example of a saprophytic relationship is a/an
An example of a saprophytic relationship is a mushroom growing on decaying vegetation - a saprophyte obtains nutrients by decomposing dead organic matter.
In artificial selection, individuals without desirable traits may be prevented from
In artificial selection, individuals without desirable traits may be prevented from reproducing by sterilization.
In a family of eight (8), all the children are girls. Which of the following reasons correctly explains this?
The reason is that the Y chromosome of the man has never participated (in these conceptions) while the X chromosome was always involved, resulting in only female children.
Which of the following statements is correct about the structure of a chromosome? A chromosome consists of
A chromosome consists of two chromatids joined at the centromere.
Mr. Andrew, his wife and child belong to blood groups A, B and O respectively. The genotypes of both parents are
Blood group A can be genotype AA or AO; blood group B can be BB or BO. For two parents of blood groups A and B to produce a child of blood group O (OO), each parent must carry an O allele, so the parents must be AO and BO, i.e. IAIO and IBIO.
What would be the phenotypic ratio of the offspring of a cross between a heterozygous dominant parent and a double recessive parent?
A cross between a heterozygous dominant parent (Aa) and a double (homozygous) recessive parent (aa) produces offspring in a 1:1 ratio of dominant to recessive phenotypes.
The percentage probability a normal male married to a carrier woman would have a haemophilic male child is
The man is XY (normal) and the woman is XhX (carrier). Since males can never be carriers of a sex-linked disease - they are either fully affected or fully free - the cross produces two male children, of whom one will be haemophilic (XhY) and one will be normal (XY), giving a 50% probability.
The importance of courtship in animals includes the following except
Courtship is aimed at ensuring compatibility between intending couples, ensuring the female chooses the right species, protecting territory, and synchronising with the ovulation period to ensure fertilization; simply 'arousing both partners' is not, by itself, a distinct core function - it is the exception among the listed options.
Analogous structures are significant because they show
Analogous structures are significant because they show functional diversity - structures that are not related by common ancestry but perform similar functions.
Which of the following statements reflects the mechanism of natural selection?
Natural selection is predicated on the fact that there are variations within every species - individuals with advantageous variations are more likely to survive and reproduce.
Which of the following animals exhibits territoriality?
Territoriality is widely exhibited by lizards.
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