WAEC 2018/19 MAY/JUNE BIOLOGY OBJECTIVE AND THEORY, QUESTIONS and ANSWERS

BIOLOGY OBJ:
1-10: BCDCDACDAB
11-20: ADADCBACBC
21-30: CABBDBAADC
31-40: AABCCBCDAA
41-50: AACBABDDAB

(1ai)
A sperm cell consists of a head, middle piece and a whip-like tail. At the anterior end of the head is a structure called Acrosome. This Acrosome contains a liquid which facilitates the entry of the sperm into an egg. The middle piece contains numerous mitochondria which are involved in producing energy needed for propelling the sperm after ejaculation. The tail is for movement.

(1aii)
A palisade cell contain chloroplasts which makes them a site of photosynthesis in the leaves of those that plants that contain them, converting the light to the chemical energy. Beneath the palisade mesophyll are the spongy mesophyll cells, which also perform photosynthesis. They allow the passage of gases through the intercellular spaces in them.

(1b)
Draw the Diagram

(1c)
In a tabular form:

Under mammals:
(i) Mammals give birth to their young ones alive
(ii) Mammals product amniotic eggs.

Under amphibians:
(i) Amphibians lay eggs
(ii) Amphibians do not produce amniotic eggs.

(1d)
(i)Use of condoms/pills.
(ii) Withdrawal method

(2a)
(i) carbon dioxide
(ii) Nitrogen

(2b)
(i) CO 2 is used by plants to photosynthesize carbohydrates (ii) Nitrogen is a major component of chhlorophyll

(2ci)
Variegated leaf is a leaf that has green parts (where the cells contain chlorophyll) and non green parts (where there is no chlorophyll).

(2cii)
The green parts

(2ciii)
(i) The parts without chlorophyll do not photosynthesise
(ii) The cells contain chlorophyll

(2civ) Nitrogen

(2d)
Holozoic:
Human

Parasitic:
Tapeworm; Venus flytrap

Symbiotic:
Lichen

Saorophytic:
Rhizopus; mushroom; housefly.

Autotropic:
Spirogyra; waterleaf plant; elephant grass.

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(3ai)
renewable resource is a resourcewhich can be used repeatedly and replaced naturally.

(3aii)
nonrenewable resource is a resource of economic value that cannot be readily replaced by natural means on a level equal to its consumption.

(3bi)
(i)oxygen
(ii)fresh water

(3bii)
(i)oil
(ii)natural gas

(3c)
(i)Regulated and Planned Cutting of Trees.
(ii)Control over Forest Fire.
(iii)Reforestation and Afforestation.
(v)Check over forest clearance for agricultural and habitation Purposes.
(iv)Proper Utilisation of Forest and Forests Products.

(3d)
(i) Increases soil nutrients
(ii) Improves soil structure.
(iii) Does not corrupt the soil.
(iv) Increases soil humus.

(3e)
Hb², Hb², I^a, I^o, I^o, T, t

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(4ai)
Gene is the discrete unit of inheritance which are found in the chromosomes of all cell.

(4aii)
A hybrid is an offspring obtained from the cross-breeding of the species that are not closely related.

(4aiii)
Trait is the characteristic factor of an individual which are hereditary.

(4b)
Draw the diagram
Phenotyoic ratio= 3:1
Genotypic ratio= 1:2:1

(4c)
The four transmittable characters in plants are:
-Height
-Colour
-Shape of fruit
-Size of Leaf

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(6ai)
Chemosynthesis is the biological conversion of one or more carbon-containing molecules (usually carbon dioxide or methane) and nutrients into organic matter using the oxidation of inorganic compounds (e.g., hydrogen gas, hydrogen sulfide) or methane as a source of energy, rather than sunlight

(6aii)
(i)Bacteria
(ii)methanogenic archaea

(6b)
Nitrogen — 78%
Oxygen — 21%
Carbon dioxide — 0.04%

(6ci)
(i) Too much clay deposit.
(ii) Too much salt deposit.
(iii) Eusterian vegetation.
(iv) Mangrove forests.

(6cii)
There roof are mainly buttress and prop up roots which may prop up and down, thus anchoring properly to the soil.

(6di)
(i) Typhoid fever.
(ii) Dysentery.
(iii) Cholera.

(6dii)
(i)Food poisoning
(ii) Food spillage.
(iii) Low market value of food.

(6e)
The person need plenty of rest and diet rich in protein, fruits and vegetables and take plenty of water.

(6f)
In a tabular form:

Under Tillage:
(i) The soil is prepared.
(ii) conserve soil nutrients.
(iii) Good for farm products.

Under Bush burning:
(i) Fire is used to remove plants.
(ii) Destroys soil nutrients.
(iii) A bad farm practice.