WAEC Biology anwers 2020 CONFIRMED

As wepromised, here is the answers to waec biology 2020. good luck

Theory

1a.
This is the structure of mammal that provides mechanical support for the body

1b

i. Exoskeleton eg..
ii. endoskeleton eg. Mammals
iii. Hydrostatic skeleton eg. Soft body animals

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(2a)
Vitamins are group of organic compounds which are essential for normal growth and nutrition and are required in small quantities in the diet because they cannot be synthesized by the body.

(2b)
Vitamin: C
One Function: Healing of wounds
One Deficiency: Scurvy
One Source: Citrus Fruits

Vitamin: D
One Function: Strong bones and teeth
One Deficiency: Rickets
One Source: Eggs

Vitamin: B
One Function: Releases energy from cabohydraes
One Deficiency: Beri-beri
One Source: Yeast

Vitamin: K
One Function: Clotting of blood
One Deficiency: Failure of blood to clot
One Source: Milk

(2c)
(i) Iron: Assists in nitrate and sulfate reduction and energy production within the plant

(ii) Nitrogen: For rapid growth

(iii) Calcium: It is responsible for holding together the cell walls of plants

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3a)
1) Food chain
Mango trees Caterpillars->
Producer) (Primary consumer)

-chicks of foul thank
secondary consumer) (Tertiary Consumer)

ii)Pyramid of numbers
Hawks 1o
chicks 30
Caterpillars 80
Mango trees 50

b) Benefits of
1) Water
– it serves as a medium of transportion
– it is useful for agricultural purposes eg earthworm
– it provides employment for people

ii) Soil
– it is the home of some organisms
– it the source of some mineral
resources

iii) Forest
-it supports forest and wildlife
– they are sources of raw materials
– They are sources of timber for
for Industries eg collon, nibber
– They provide medicinal herbs

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(6a)
(i) Rokert hoot
(ii) Felix Diyardin
(iii) Mathias Schleidon.
(iv) Theodor Schwom

(6b)
In a tabular form:
Classes of plants based on life cycle and Two examples

Classes | Examples
(i) Anual | Vegetable, Cotton
(ii) Biennials | Carrot, Ginger
(iii) Perennials | Cocoa/banana

(6c)
The amniotic fluid help to neutralize the effect of changes of external temperature

(6d)
(i) Rhizobium : It helps to fix atmospheric nitrogen directly into the plant.
(ii) Azotobacter: It can fix atmospheric nitrogen into the soil either aerobically or anaerobically.
(iii) Blue-green algae: They are mainly auto trophic plants; they can synthesize their own food.

(6e)
Draw the diagram

Theory completed………..

QUESTION 6 ANSWERS

6a) Recombinant DNA Technology is defined by the Encyclopedia Britannica as “the joining together of DNA molecules from different organisms and inserting it into a host organism to produce new genetic combinations that are of value to science, medicine, agriculture and industry.

B)Variation is the differences between individuals within a species.

C)continuous variation is where the different types of variations are distributed on a continuum, while discontinuous variation is where the different types of variations are placed into discrete, individual categories. Examples of continuous variation include things like a person’s height and weight

D)Lamarck’s two-factor theory involves 1) a complexifying force that drives animal body plans towards higher levels (orthogenesis) creating a ladder of phyla.

E) Sickle cell anaemia is A group of disorders that cause red blood cells to become misshapen and break down.

 

QUESTION 8

8a) I)Overgrazing leads to soil compaction.

Ii) It decreases water retention

III)It increases salinity of the soil.

B) Effects of high birth rate
I)economic benefits such as expansion of tax bases

Ii) Increase in labour

*Effects of lower death rate*
I)Increases in population of a country.

Ci)community is a group or association of populations of two or more different species occupying the same geographical area at the same time

Ii)ecological niche refers to the interrelationship of a species with all the biotic and abiotic factors affecting

III) Population is a group of individuals of the same species inhabiting the same area.

Di)Refer to notes.

 

QUESTION 4

4a) Antenatal care is a type of preventive healthcare. Its goal is to provide regular check-ups that allow doctors or midwives to treat and prevent potential health problems throughout the course of the pregnancy and to promote healthy lifestyles that benefit both mother and child.

B)I) it assists in screening
Ii) It helps in controlling the risk factors that might adversely affect the pregnant women and/or the pregnancy outcome.

C)Most exercises are safe to perform during pregnancy, as long as you exercise with caution and do not overdo it. The safest and most productive activities are swimming, brisk walking, indoor stationary cycling, step or elliptical machines, and low-impact aerobics.

 

Explain:
Community
Population
Ecological niche

Effect of :
high birth rate on population
Low death rate on population

effect of overgrazing on soil fertility

Why is the structure of DNA the same in all organisms

Draw a moss and fully label it.

Importance of mosses in the environment

How can mosses be prepared by extinction

Explain
Binary fusion
Conjugation
gutation
symbiotic relationship with examples

 

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