2020 BIOLOGY OBJ AND THEORY ANSWERS

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Tuesday, 25th August 2020

Biology 2 (Essay) 9:30 am. – 11:10am

Biology 1 (Objective) 11:10am – 12pm

(6ai)
External fertilization is a mode of reproduction in which a male organism’s sperm fertilizes a female organism’s egg outside of the female’s body.

(6aii)
Internal fertilization occurs most often in land-based animals, although some aquatic animals also use this method. There are three ways that offspring are produced following internal fertilization.

(6bi)
(i)Toad
(ii)Frog

(6bii)
(i)Goat
(ii)Cow

(6ci)
(i)the foetus will not get oxygen
(ii)the foetus will not get nutrients.
(iii)waste products from your baby’s blood will not be removed

(6cii)
[pick three]
(i)fundus
(ii)corpus
(iii)isthmus
(iv)cervix.

(6d)
Competition in feeding among organisms for scarce resources leads to the death of weaker members of the species and the reproduction of the stronger members, leading to a dynamic equilibrium that balances the rate of death to the rate of birth.

(6e)
(i) Problem of Wave
(ii) Effects of temperature
(iii) Salinity of the Marine
(iv) Humidity

(6fi)
Moisture helps in the germination of seeds by helping to activate the metabolic activities needed for germination, dissolved oxygen content in moisture acts is very beneficial to the biochemical process involved in germination.

(6fii)
Viable seeds are healthy and contain the organic requirements for a healthy germination, and is most times resistant to harsh weather conditions, and lack of nutrients.

(6g)
Light energy is considered a limiting factor in production of food by autotrophs because, photosynthesis which is the main process by which autotrophs produce food cannot take place in the absence of light. The energy from light is solely responsible for the process of photosynthesis.

SECTION A answer two questions only

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(2a)
Deficiency diseases are diseases that are caused by the lack of certain essential nutrients, especially vitamins and minerals, in one’s diet over a prolonged period of time

(2aii)
TABULATE
– Beri-Beri ; Intake of vitamin B
– Kwashiorkor; Intake of protein
– Scurvy; Intake vitamin C
– Goitre ; Intake of iodine in diet
– Anaemia; Intake of iron and copper

(2bi)
-Put a few small, freshly cut pieces of yam in a clean test tube, then Pour 10 mL distilled water into the test tube.
-Now, boil the contents of the test tube for about 5 minutes. Allow the test tube to cool.
-Filter the contents of the test tube through a filter paper. Test the obtained filtrate for the presence of starch by adding iodine.
-If colour changes to pink then iodine is presence

(2bii)
-Heat a solution of the orange fruit then add Benedict’s reagent and observing the colour change orange.
-It is a clear blue solution of sodiumand copper salts.
-In the presence of simple sugars, the blue solution changes color to green, yellow, and brick-red, depending.

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(3a)
TABULATE
(i) Disease: Cholera
Causative organism: Bacterium (vibro cholerae)
Vector: Housefly
Control: Keeping environment clean

(ii) Disease: Sleeping sickness
Causative organism: Trypanosome
Vector: tse-tse fly
Control: use of antiseptic

(iii) Disease: Malaria
Causative organism: Plasmodium (protozoa)
Vector: Female anopheles mosquito
Control: Draining of swamps

(iv) Disease: Ringworm
Causative organism: Trichophyton and microsporum
Vector: None
Control: Keeping of skin clean and dry

(3bi)
Salting is the dusting of farm products with table salt

(3bii)
Irradiation is the drying of some crops or products using the heat from the sun

(3biii)
Smoking is the drying of some farm products over a smoke of a naked fire

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(1aii)

(1ai)

When the head moves or changes position,the endolymph fluid in the semi-cricular canals moves and stimulates the nerve endings. The nerve endings then transmit the impulses through vestibular to the cerebellum of the brain where the new position at the head is interpreted and the appropriate responses sent to the muscular system to maintain body balance

(1aiii)

The middle  ear in human  can be split into three parts; external, mdiddle and inner. The middle ear lies within the temporal bone, and extends from the tympanic membrane to the lateral wall of the inner ear. The main function of the middle ear is to transmit vibrations from the tympanic membrane to the inner ear via the auditory ossicles.

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