WAEC 2021 - BIOLOGY ANSWER

Biology OBJ
1-10: CBABDABCDB
11-20: CDDACBBAAB
21-31: CBCCCBABAD
31-40: BCDCDDBDDA
41-50: BDADCABCDD


(1a)
(i) Plasma
(ii) Red blood cell
(iii) White blood cell
(iv) Platelets

1b)
(i) Plasma
(ii) White blood cells
(iii) Red blood cells
(iv) Platelets
(v) Red blood cells
(vi) Platelets
(vii) White blood cells

(1c)
(i) Amino acids
(ii) Glucose
(iii) Mineral salts and water

(1d)
(i) Anemia
(ii) Haemophilia
(iii) Blood clots
(iv) Leukemia

(1e)
Disease of the blood is dangerous because it can lead to other issues and consequently death.

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(2a)
Dentition refers to the development of teeth and their arrangement in the mouth of animals.

(2b)
The tooth consists of three main portions namely: The crown, neck and root. The crown is above the gym,covered with a white hard substance called enamel. The short neck is covered with gum. The root is embedded in the jaw bone by a substance called cement or cementum.

(2c)
(i) Proteins
(ii) Fats
(iii) Cellulose

(2d)


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(3a)
IN A TABULA FORM

DECOMPOSER:
-Bacteria
-Mushroom
-Mucor

PRODUCER:
-Water lettuce
-Water leaf
-Algae
-Lemna

CONSUMER:
-Dog
-Tadpole
-Cat

(3b)
(i) COâ‚‚
(ii) Water
(iii) Energy
(iv) Plant Nutrients

(3bii)
(i) Decomposer prevent accumulation of dead organisms
(ii) Increase soil fertility
(iii) Helps to break down biodegradable items

(3c)
(i) Non-biodegradable item
(ii) Metals
(iii) Bones

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(6a)
IN A TABULA FORM

PROCESS:
(i)Combustion
(ii)Precipitation
(iii)Lighting

NUTRIENT CYCLE:
(i)Carbon
(ii)Water
(iii)Nitrogen

OTHER PROCESSES:
(i)Decay, decomposition, respiration
(ii)Evaporation, transpiration, respiration
(iii)Artificial fertilizers, Nitrogen fixing, denitrification

(6bi)
Irritability is the ability of living things to respond to changes in external and internal stimuli such as light

(6bii)
TYPES OF RESPONSE
(i)Positive phototaxis
(ii)Thigmotropism
(iii)Negative phototaxis
(iv)Chemtropism (positive chemotaxis)
(v)Nastic
(vi)Phototropism

(6ci)
Territoriality:
(i) Birds
(ii) Agama lizards
(iii) Lion

(6cii)
Seasonal migration:
(i) Fish
(ii) Birds
(iii) Insects

(6ciii)
Display:
(i) Agama lizard
(ii) Peak cock
(iii) Human beings