WAEC GCE 2023 BIOLOGY ANSWERS

BIOLOGY SOLUTIONS 

BIOLOGY OBJ
01-10: BADACABCCC
11-20: DCACCBDABA
21-30: CBAACADBCD
31-40: DACCABBDDA
41-50: AADBDACDDC

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(2a)
TABULATE PLEASE

UNDER: X
– Food nutrients: Mineral salts, Vitamin
– End product of digestion: Mineral eg magnesium

UNDER: Y
– Food nutrients: Carbohydrates, fats and oil
– End product of digestion: Glucose

(2bi)
Constipation is the process of indigestion resulting from low water intake or roughage

(2bii)
X

(2biii)
The meal of contains water and roughage

(2c)
(i) It will supply energy.
(ii) It will replenish worn-out tissues.
(iii) It will refresh the skin

(2di)
(i) Lack of balanced diet.
(ii) Inadequate protein

(2dii)
(i) big head
(ii) Protruding stomach
(iii) Lean limbs
(iv) Presence of scurvy or wounds

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(4ai)
Iron

(4aii)
Vitamin K

(4aiii)
hemophilia

(4b)
(i) Spinach
(ii) Broccoli
(iii) Kale

(4c)
(i) Blood typing and crossmatching: To determine the patient’s blood type and match it with compatible donor blood.
(ii) Complete Blood Count (CBC): To assess the levels of red blood cells, white blood cells, and platelets.
(iii) Coagulation tests: Such as prothrombin time (PT) and activated partial thromboplastin time (APTT) to evaluate the blood clotting ability.

(4d)
(i) Two compatible blood group types for a person with blood group A are A positive (A+) and A negative (A-).
(ii) The likely blood groups of the patient’s parents could be A and O.

(4e)
(i) Hemophilia is an X-linked recessive disorder, meaning the gene responsible is located on the X chromosome. Males have only one X chromosome (XY), so if the X chromosome they inherit from their mother carries the hemophilia gene, they will manifest the disorder. Females have two X chromosomes (XX), so they need to inherit the hemophilia gene from both parents to manifest the disorder.

(ii) A condition that would result in a female offspring manifesting hemophilia is if she inherits an X chromosome with the hemophilia gene from her carrier mother and her father also carries the hemophilia gene on his X chromosome.

(iii)
– Down syndrome
– Cystic fibrosis

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(5ai)
Phototropism

(5aii)
Phototropism is a biological process where plants grow towards a light source. In this case, the dark box with a hole allowed light to enter from one side only. The seedlings detected the light and responded by growing and bending towards the direction of the hole. This directional growth is a result of differential cell elongation on the side of the seedling away from the light, causing it to bend towards the light source.

(5aiii)
Without a hole, the seedlings would not receive directional light cues, and their growth would likely be more random and not oriented towards a specific direction. The seedlings might exhibit a more upright and uniform growth pattern.

(5b)
The balance of carbon dioxide (CO₂) and oxygen (O₂) in an ecosystem is maintained through the processes of photosynthesis and respiration. During photosynthesis, plants and some microorganisms take in carbon dioxide and release oxygen, contributing to an increase in atmospheric oxygen. On the other hand, during respiration, organisms consume oxygen and release carbon dioxide. The overall balance between these processes helps to regulate the levels of carbon dioxide and oxygen in the ecosystem.

(5ci)
The Sun

(5cii)
Without a supply of energy, the ecosystem would be unable to sustain life. Energy is necessary for all biological processes, including growth, reproduction, and maintaining metabolic activities. If there is no supply of energy, the ecosystem’s organisms would not be able to function, leading to a collapse of the food chain and the ecosystem as a whole.

(5d)
(i) Lithosphere:
The lithosphere is the rigid outer layer of the Earth, consisting of the crust and the uppermost part of the mantle.

(ii) Hydrosphere:
The hydrosphere refers to all the water on Earth, including oceans, seas, lakes, rivers, groundwater, and water vapor in the atmosphere.

(iii) Ecological Niche:
An ecological niche is the role and position of a species within an ecosystem, including its interactions with the biotic and abiotic factors. It encompasses how a species obtains and uses resources and how it contributes to the structure and function of the ecosystem.

(5e)
(i) Interspecific competition is the competition for resources (such as food, water, and space) between different species in a community.

(ii) The likely reasons for the death of seedlings could include overcrowding, competition for nutrients, water, and sunlight among the maize plants. In a small piece of land, resources may be limited, leading to stress on the plants and increased susceptibility to diseases and pests. The lack of sufficient space for root expansion and the shading effect from nearby plants can also contribute to the mortality of seedlings.

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