WAEC BIOLOGY (Essay & Obj) ANSWERS

waec

 

BIOLOGY OBJ:
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31BABCADCBDD
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(2a)
the leaf of a flowering plant is adapted for photosynthesis because carbon(iv) oxide, water, chlorophyll, sunlight, mineral, suitable temperature and enzymes are present.
carbon(iv) oxide is diffused into the intercellular spaces through stomata of the leaves and later diffuses into the mesophyll cells containing chloroplasts. menral salts derived from the soil pass into the roots of the plant by osmoisis and dissolved mineral salts are conducted by xylem from roofs of stem. the light from sunlight is trapped.
(2b)
the tapeworm is an endoparasite which carries out parasitic feeding on its host. food is absorbed though its entire body surface. the hooks and suckers are used for attachment to the intestine of the host to avoid dislogment. the entire body surface is used also for the absorption of food.
(2ci)
calcium
(2cii)
iodine
(2ciii)
iodine
(2di)
three benefits are:
-it eliminates constipation
-it helps to stimulate movement of bowel
-it helps to balance intestinal content
(2dii)
-for growth
-aids reproduction
-production of enzymes

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(3ai)Sewage can be defined as the domestic households, industrial and agricultural practices produce waste water that can cause pollution of many lakes and rivers

(3aii)
-Increased organic matter (from the sewage) breaking down in the river reduces the amount of dissolved oxygen in the water body as the decomposition process uses up the available dissolved oxygen. Fish and other aquatic life need that dissolved oxygen in the water to live.

-Sewage heightens the levels of nutrients, increasing the bioavailability of nutrients, which can increase productivity of plankton near the sewage outfall and increase the chance of algal blooms.

-Contaminants present in the sewage might be toxic for some already existing phytoplankton

-Sewage can increase the turbidity and amount of suspended sediments. This effect reduces light available for plant growth, can smother in-stream habitats, and damage fish gills and respiratory structures of other species

(3c)
An adaptation is a physical or behavioral characteristic that has developed to allow an organism to better survive in its environment. Adaptations are the result of evolution, and may occur when a gene mutates, or changes by accident. That mutation causes the organism to better survive and reproduce, and it passes on that trait to its offspring

 

(6a)
TABULATE

Disease->One effect->One remedy

-Kidney stones->Obstructs passage of urine->Nephrectomy must be done

-Nephritis->Inflamation of the kidney->Use of dialysis

-Deuresis->Loss of weight->Deuretic drugs must be used

(6b)
DRAW CARBON CYCLE

(6c)
(i)Estuarine habita is a body of water formed at the coast as a result of the action of tides which mix salt water from the sea with fresh water from the land

(ii)Detritus->Worms->Snails->Birds

(6d)
(i)Two pests are;-Stem borer andpod borer

Two diseases are;-Maize smut and rice blight

(ii)-Use of resistant varieties

-By seed treatment

(6e)
-It publishes medical journals
-it helps in maternal and child health care
-it sets and recommend safe standard for drugs
-it promotes measures for the control of world disease

(6f)
-Refuse disposal
-Sewage disposal
-Protection of water
-Protection of food

 

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