IGCSE Biology Paper-4: Specimen Questions with Answers 70 - 72 of 279

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Question 70

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Essay▾

Make a chart related to three bacterial disease, causing agent, symptoms and mode of spread.

Explanation

Table Shows Name of Bacteria Disease Causing Agent, Symptoms and Mode of Spread
DiseasePathogenSymptomsMode of spread
DiphtheriaCorynebacterium diphtheriaSore throat, hoarseness, difficulty in breathingDroplet infection
Whooping coughBordetella pertussisWhooping sound, face becomes red during coughing, convulsionsDroplet infection
TetanusClostridium tetaniSpasms of muscles of the jaw and faceWound infection

Question 71

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How cells present in skin protect it by ultraviolet radiations?

Explanation

They produce melanin. Melanin are natural pigments found in most organisms. Melanin is an effective absorber of light; the pigment is able to dissipate over 99.9 % of absorbed UV radiation. Because of this property, melanin is to protect skin cells from UV-B radiation damage, reducing the risk of cancer.

Passage

Figure shows a reflex of baby.

Figure Shows a Reflex of Baby

Question 72 (1 of 2 Based on Passage)

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Which type of reflex it is?

Explanation

Such type of reflex are Primitive reflexes which originating in the central nervous system that are shown by normal infants. It shows as early as 16 weeks in utero and persists until five or six months of age. When an entity is placed in the infant՚s hand and strokes their palm, the fingers will close and they will grasp it with a palmar grasp. The grip is strong but unpredictable, though it may be able to support the child՚s weight, they may also release their grip suddenly and without warning. The reverse motion can be enhance by stroking the back or side of the hand.

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