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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Why reflex in infant is necessary?

Explanation

Reflex is of great clinical significance, especially in terms of the detection of spasticity. It is useful to know normal or abnormal responses of an infant. Grasp reflex of the hands and feet is mediated by a spinal reflex mechanism, which appears to be under the regulatory control of non-primary motor areas by the spinal interneurons.

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