All 50 questions from the West African Examinations Council (WAEC) Biology 2020 Objective paper, with the correct answer and a full explanation for each. Free, no signup needed.
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The cell as the basic unit of life consist of
The cell is divided into the nucleus and the cytoplasm, where other cell organelles are found.
Which members of the classes live mainly in an aquatic habitat? (I-Crustacea; II-Insecta; III-Arachinda; IV-Chilopoda)
Class Crustacea comprises mainly aquatic organisms. Examples are crabs, crayfish, prawn, shrimps.
Which of the classes is characterized by the possession of two pairs of antennae? (I-Crustacea; II-Insecta; III-Arachinda; IV-Chilopoda)
Crustaceans are the only arthropods that have two pairs of antennae.
The organism with spiral chloroplasts and nucleus suspended by cytoplasmic strands is
The organism with spiral chloroplasts and nucleus suspended by cytoplasmic strands is spirogyra; spirogyra is an unbranched multicellular filamentous alga.
The network of double membrane that conveys materials through the cytoplasm is the
The network of double membrane that conveys material through the cytoplasm is the endoplasmic reticulum. It may be rough or smooth; rough endoplasmic reticulum has ribosomes on its outer membrane while the smooth type does not.
Food is stored in the part labelled (using the plant organ longitudinal section diagram, labels I-IV)
Food is stored in the part labelled II of the diagram (this illustrates an onion bulb).
The plant is a
The diagram represents an onion bulb.
The part labelled I is the
The part labelled I is the membranous or scale leaf of the bulb.
Which of the following materials is not a living semi-permeable membrane?
Pig's bladder, unripe pawpaw fruit and yam tuber can function as living semi-permeable membranes; a sheet of cellophane is a non-living (artificial) semi-permeable membrane.
In an experiment, mould and yeast cells were transferred into an environment with low oxygen concentration. After a few days, the mould died while the yeast cells did not. Which of the following statements best explains the above observation?
This shows that respiration can take place in yeast cells in the absence of oxygen (anaerobic respiration/fermentation), unlike the mould which requires oxygen.
Which of the following tissue does not provide support in flowering plants?
Collenchyma, parenchyma and xylem all provide mechanical/structural support in plants; phloem's main function is the transport of manufactured food (translocation), not support.
The set-up directly measures
The experimental set-up (photometer/potometer, with syringe, capillary tubing and air bubble) directly measures the rate of water transpired/absorbed by the shoot, indicated by the movement of the air bubble.
The set-up measure comparatively the rate of
The set-up is used to comparatively measure the rate of transpiration of a single shoot of a plant under different experimental conditions (e.g. varying humidity, light, wind).
The respiratory organ of a cockroach is the
Trachea is the respiratory organ in cockroach and other insects.
The excretory product of some reptile, birds and insects is
Mammals such as humans excrete urea, while birds, reptiles and some terrestrial invertebrates (like insects) produce uric acid as their nitrogenous excretory product.
The part of the mammalian kidney that stores urine is the
Urine is produced by the mammalian kidney and stored in the urinary bladder.
The properties of endocrine system include the following except
Endocrine glands are ductless glands; they do not release their secretions into ducts (that is a property of exocrine glands). Their hormones are secreted directly into the bloodstream to target organs.
The part of the central nervous system that controls unconsciousness actions in humans is the
Reflex actions (unconscious/involuntary actions) are not controlled by the brain but by the spinal cord.
What happens when the ciliary muscles of the eye contract?
When the ciliary muscles contract, the suspensory ligaments loosen and the lens becomes more spherical/convex, increasing its refractive power for near vision.
The function of the part labelled I is
The style is the tube-like structure which connects the ovary and the stigma, through which the pollen grain enters the ovary.
The part labelled II is the
The part labelled I is the style while the part labelled II is the ovary.
The part labelled II is the
The style provides the passage through which the male gamete (pollen tube) travels to reach the ovary for fertilization.
The reagent used in testing for carbon (IV) oxide is
The reagent used in testing for carbon (IV) oxide is lime water. Carbon (IV) oxide is known to turn lime water milky.
Oxygen comes out of the stomata during photosynthesis through the process known as
Oxygen comes out of the stomata during photosynthesis through the process of diffusion.
The first stable product of photosynthesis is
The first stable product of photosynthesis is glucose.
An example of a trace element is
Copper is a trace element. Trace elements are those nutrients required in very small quantities.
Which of the following statements about a mixture of a protein-digesting enzyme and starch solution would be correct?
Since enzymes are specific in their actions, a protein-digesting enzyme will show no effect on starch solution.
A mutualism type of relationship is different from a parasitic relationship because in mutualism, A. both organisms benefit B. none of the organisms benefit or harm each other C. both organism harm each other D. only one of the organism is harmed
In mutualism, both organisms benefit. In parasitism, one organism benefits while the other organism suffers harm.
What type of habitat is W? (using the given habitat table of organisms)
This type of organism present indicates that the habitat is not likely to be terrestrial. Therefore, the correct choice is pond (a freshwater habitat where plankton, tilapia, and waterflea can live comfortably).
The number of lions and antelopes in habitat Y shows that the lion
Lion is the predator while the antelope is the prey (lions typically have a much lower population than their prey in a food chain/web).
A disadvantage of the abiotic factor measured by the instrument is that it
The instrument is known as a rain gauge; it measures the amount of rainfall. Excessive rain (measured by this instrument) may lead to flooding.
When the instrument is in use, it is usually
When the rain gauge is in use, it is usually placed slightly above soil level.
Soil with the finest texture is
Clay is the soil type with the finest texture, while sandy soil is the coarsest form of soil.
The position occupied by an organism in a food chain is the
The position occupied by an organism in a food chain/habitat is the trophic level. In an ecosystem/habitat, the role and location of an organism is its ecological niche.
The depletion of the ozone layer will result in the earth surface receiving more
The ozone layer protects the earth surface from receiving excessive ultraviolet rays. Thus, the depletion of ozone layer exposes the earth surface to excessive ultraviolet rays.
The insects whose activities are both beneficial and harmful to humans are (using the list: I-cotton stainer, II-honeybee, III-termite, IV-weevil)
Honeybee and termite are both beneficial and harmful to humans. For instance, honeybees sting but also provide honey; termites are decomposers but also eat/destroy wood.
Which of the insects destroys grains? (using the list: I-cotton stainer, II-honeybee, III-termite, IV-weevil)
Weevils are known to destroy grains.
Conservation of natural resources does not
The purpose of conservation of natural resources is to enhance the survival of species, not threaten it.
A company was prohibited from producing bags made from natural leopard skin. This is an attempt to conserve
Prohibiting a company from producing bags from natural leopard skin is an adaptation to conserve wildlife.
Which of the following natural resources is not conservable?
Mineral, soil and water are conservable natural resources; air is generally considered non-conservable/inexhaustible in this context.
A child that can receive blood donation from anybody belongs to the blood group
A child from blood group AB can receive blood donation from anybody. This is why AB is known as the universal recipient.
Variation which exhibits a wide range from one extreme to the other is
Variation which exhibits a wide range from one extreme to the other is said to be continuous. That which does not is said to be discontinuous.
Measurements of height and weight of students in a class show A. discontinuous variation B. continuous variation C. shortness is more prevalent D. fatness is less prevalent
Measurements of height and weight of students in a class show continuous variation since these variations exhibit a wide range from one extreme to the other.
Which of the following statements about chromosomes is correct?
All members of a given species have a fixed chromosome number. For instance, the diploid chromosome number in humans is 46.
Which of the following disease can be inherited?
Sickle cell anaemia can be inherited, while pneumonia, whooping cough and malaria cannot be inherited (they are caused by pathogens/environmental factors).
If the F1 generation are plants with high yield and resistance, the genotype of the F1 generation plants would be
Given the parent genotypes YYrr (high yield, low resistance) and yyRR (low yield, high resistance), the F1 generation (crossing these) would have the genotype YyRr.
The process that gave rise to the F1 generation is
The F1 generation is obtained from the parent generation through cross fertilization.
Replication of DNA molecules is catalysed by an enzyme called
Replication of DNA molecules is catalysed by an enzyme called polymerase.
Who proposed the theory of evolution by natural selection?
The theory of evolution by natural selection was propounded by Charles Darwin.
Which of the following statement best explains the reason why termites swarm at night?
Termites swarm after their colony has reached a certain capacity level and is ready to expand; swarming at night helps them avoid day-flying birds (predators).
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