Biology 2021 Past Questions | WAEC
46. In humans, pointed eyebrows (B) is a dominant trait over smooth eyebrows (b). A student and the mother have smooth eyebrows while the father has pointed eyebrows. What is the genotype of the father?
- A. BB
- B. Bb
- C. bb
- D. BBbb
Correct Option: Answer is A
47. A woman with Rhesus negative blood group was advised not to marry a man with Rhesus positive blood group because
- A. it will hinder her from having blood transfusion from her husband
- B. it will result in sickness and probably death of the offspring
- C. her children may all resemble her husband
- D. it may affect her childbearing ability
Correct Option: Answer is B
48. Which of the following organisms exhibits division of labour?
- A. butterfly
- B. cockroach
- C. termite
- D. housefly
Correct Option: Answer is C
49. Natural selection arises as a result of?
- A. gene mutation
- B. change of habitat
- C. reduction in population
- D. climate change
Correct Option: Answer is D
50. Which of the following statements is not Lamarck’s postulate on evolution?
- A. great changes in the environment result in corresponding changes in species
- B. frequently used organs become well developed while the ones not used become vestigial
- C. well developed acquired characters are inheritable
- D. survivors in a competitive community must have inherited useful traits
Correct Option: Answer is D
BIOLOGY 2021 THEORY PAST QUESTIONS
1. A sample of human blood was put in a test tube and allowed to spin in a centrifuge. The components of the blood sample were clearly separated.
(a) List the four main components of blood that would be in the test tube.
(b) Name the component of the blood that: (i) would form the top layer in the test tube, (ii) destroys pathogens; (iii) is biconcave in shape (iv) would be relatively low in a haemophilic condition (v) is produced in the bone marrow: (vi) is a thrombocyte; (vii) is nucleated.
(c) Mention three chemical substances transported by the blood component named in 1(b)(i).
(d) List four diseases associated with blood.
(e) Explain briefly why a disease of the blood could be dangerous.
Solution & Explanation
- a)Components of Blood: -(Blood) Plasma-Platelets(Thrombocytes) – White blood cells/Leucocytes – Red blood cells/erythrocytes.
(b)Name or Component of Blood that: (i) forms top layer in the test tube: (Blood) Plasma. (ii) Destroys Pathogens: White Blood Cells/Leucocytes (iii) Is Biconcave in shape: Red Blood Cells/Erythrocytes (iv) Would be relatively low in a Haemophilic condition: Platelets(Thrombocytes) (v) is produced in the bone marrow: – platelets (thrombocytes); – white blood cells/Erythrocytes; – Red blood cells/leucocytes cells/erythrocytes. (vi) Is a Thrombocyte: Platelets (vii) Is Nucleated: White Blood Cells/Leucocytes.
(c) Chemical Substances Transported by the Blood Component Named in 1(b)(i) Blood Plasma: -Thyroxine/Adrenaline/Insulin/Progesterone/Hormones. (Digested) food substances/Nutrients/Glucose Amino acids/Any correctly named digested food substances.-Antibodies/Antigens. -Oxygen/carbon(IV) oxide/dissolved gases.-Toxins -Mineral salts/salt /magnesium/copper/potassium/zinc -Urea/uric acid -Water -Vitamins
(d) Diseases Associated with Blood: -Anaemia/Anemia -Hepatitis -Sickle cell anaemia leukemia Luekaemia/Blood cancer.
(e) Reason a Disease that Attacks the Blood is Deadly: -The blood circulates throughout the body/it is a medium of transportation in the body.-It makes contact with major organs of the body and makes it easy for a disease to be deadly. -Blood disease could attack any component of blood and threatens life.
2. (a) What is dentition in animals?
(b) Describe briefly the generalised structure of a tooth in animals.
(c) List three food substances that plants manufacture from glucose.
(d) Make a diagram, 6 cm to 8 cm long of an experimental set-up to show that oxygen is produced during photosynthesis.
Solution & Explanation
(a) Dentition In Animals: Is the type/shapes, number, and arrangement of teeth in the mouth/jaws of animals
(b) Description of the Generalised Structure of a Tooth in Animals: -The tooth is made up of a crown. neck and root. -The visible part of the tooth in the crown. -And is covered by the hardest substances/enamel -The neck of the tooth is surrounded by the gum. -While the root is embedded in the jawbone. -Beneath the enamel is the hard dentine. -Which forms the bulk of the tooth in the pulp cavity. -Containing sensory endings of nerves/blood capillaries. -The cement/periodontal membrane covers the root of the tooth in the jawbone.
(c) Food Substances that Plants Manufacture from Glucose:-Sucrose/maltose-Starch -Cellulose -Oil-Proteins
(d) Diagram of an Experiment that Shows that Oxygen is Produced During Photosynthesis
3. (a) Complete the table below by placing each of the following organisms under the appropriate heading: Algae, Bacteria, Dog, Water lettuce, Tadpole, Cat, Lemna, Waterleaf, Mucor, Mushroom
(b)(i) Name four products of decomposition (ii) Mention three roles of decomposers on a refuse dump
(c) List three materials found in a refuse dump which would not be affected by the action of decomposers.
Solution & Explanation
(a)
DECOMPOSER | PRODUCER | CONSUMER |
Bacteria | Water Lettuce | Dog |
Mucor | Waterleaf | Cat |
Mushroom | Algae | Tadpole |
| Lemna |
|
|
|
|
(b)(i) Products of Decomposition: Hydrogen sulphide;-Carbon(IV) oxide; -Methane; -Ammonia; -Water vapour/water;-Mineral salt/plant nutrients;-Heat/energy;-Humus.
(ii) Roles of Decomposer on Refuse Dump:-They feed on dead/decaying organisms, -They form a link in a food chain; -They form a link between biotic and abiotic factors in ecosystem; materials; -They release inorganic components from organic materials; – they facilitate the recycling of nutrients in the ecosystem; -They reduce the bulky nature of the debris/dump.
(c) Materials in a Refuse Dump that would not be Affected by the Action of Decomposers: -Plastics; -Metals/iron/tin/zinc/aluminium; -Glass/bottle -Nylon/polyethene; -Rubber/tyres,-Stones; Ceramics.
4. (a) Complete the table below by naming five wildlife animals in West Africa and one body part each that makes them endangered because of the activities of humans
(b) State three effects each of the following factors on conservation of natural resources: (i) poor economy of a nation (ii) poaching
(c) State four roles played by the Government in conservation of natural resources
Solution & Explanation
(a)
NAME OF ANIMALS | BODY PARTS |
Elephant | Tusk |
Rhinoceros | Horn |
Lion | Claws and Teeth |
Pangolin | Scales |
Tiger | Claws and Teeth |
(b) Effects of the Following Factors on the Conservation of Natural Resources:
- Poor economy of a nation: It leads to lack of funding in creating awareness /educating people on the importance of conservation. It leads to increase in poaching/forest encroachment/over fishing/illegal mining by locals,-Jt leads to inability to execute/enforce policies/strategies; It leads to poor implementation/enforcement of laws-It leads to inability to setup forest/game reserves: -It leads to inability to employ guards-lt affects the feeding of animal species in game reserves: -It affects the habitat of species;-t affects the maintenance/acquisition of enough land for game reserves.
- (ii) Poaching:-Leads to the death of endangered species, -Leads to recduced population/extinction of species; -It affects tourism/economy of a nation; -lt disrupts the natural food chain: -Leads to spread of disease from wildlife animals to humans.
(c) Roles Played by the Government in Conservation of Natural Resources: -Enactment/enforcement of laws for conservation:-Formulating policies against poaching/overgrazing/over fishing/for tree planting campaign/protecting soil from erosion. -Creating ranches to aviod overgrazing; -Training officials to guard game reserves/fish ponds; -Educating the general public on conservation of resources;-Setting up surveillance equipment for security officers in game reserves,-Setting up forest/game reserves/ Fish ponds; -Encouraging regeneration of endangered species.
5. (a) Complete the table below by naming the nutrient cycle that involves each of the given processes and give three other processes involved in the nutrient cycle.
(b)(i) What is irritability?
(ii) Complete the table below by stating the type of response elicited by each of the given actions.
(c) Name three animals each that exhibit: (i) territoriality (ii) seasonal migration (iii) display
Correct Option: Answer is B
Consumer’s Equilibrium means a state of maximum satisfaction. A situation where a consumer spends his given income purchasing one or more commodities so that he gets maximum satisfaction and has no urge to change this level of consumption, given the prices of commodities, is known as the consumer’s equilibrium.