Waec 2018 Biology Obj AndTheory Answers




*2018 WAEC MAY/JUNE BIOLOGY OBJ AND THEORY*

_Biology-Obj_

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(1a) 

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

(ii) - A palisade cell contain chloroplasts which makes them a site of photosynthesis in the leaves at those 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 intracellular spaces in them. 

(1b) 
[DIAGRAM]

(1c) 
IN A TABULAR FORM MAMMALS AND AMPHIBIANS 

MAMMALS 

- Mammals give birth to their young ones alive. 

- Mammals produce amniotic eggs


AMPHIBIANS

- Amphibians lay eggs
- Amphibians do not produce amniotic eggs

(1d) 

- Use of condoms/pills
- withdrawal 


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(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)

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3 e )
i ) AA
ii) AO
iii ) BB
iv ) BO


(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

➖➖➖➖➖➖➖
(6a)

(i) - 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 percent.
Oxygen — 21 percent.
Argon — 0.93 percent.
Carbon dioxide — 0.04 percent.

(6c)

(i) - They are composed of relatively few species of plants

(ii) - The salt level of the habitat is high

(iii) - High flooding rate

(iv) - extreme temperature and salinity fluctuations.

(6cii)

Roots of salt marsh plants help stabilize the sandy substrate and trap and hold nutrients and detritus that flow through with each tidal cycle. This detritus trap helps feed bacteria, algae, and invertebrates. These root tangles also provide critical refuge for small fish and other animals.

(6dι) 
(ι) тypнoιd ғever.
(ιι) dyѕenтery. 
(ιιι) cнolera. 
        
(6dιι) 
(ι)ғood poιѕonιng 
(ιι) ғood ѕpιllage. 
(ιιι) low мarĸeт valυe oғ ғood. 

(6e) 
тнe perѕon need plenтy oғ reѕт and dιeт rιcн ιn proтeιn, ғrυιтѕ and vegeтaвleѕ and тaĸe plenтy oғ waтer. 

(6ғ) 
ιn a тaвυlar ғorм:
υnder тιllage:
(ι) тнe ѕoιl ιѕ prepared. 
(ιι) conѕerve ѕoιl nυтrιenтѕ. 
(ιιι) good ғor ғarм prodυcтѕ. 

υnder вυѕн вυrnιng:
(ι) ғιre ιѕ υѕed тo reмove planтѕ. 
(ιι) deѕтroyѕ ѕoιl nυтrιenтѕ. 
(ιιι) a вad ғarм pracтιce.

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