IGCSE Biology Paper-2: Specimen Questions with Answers 150 - 151 of 203

Question 150

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Question

MCQ▾

What are the products of anaerobic respiration in muscles?

Choices

Choice (4)
a.Ethanol only
b.Lactic acid and carbon dioxide
c.Ethanol and carbon dioxide
d.Lactic acid only

Answer

d.

Explanation

Production of lactic acid:

In this process, hydrogen atoms removed from the glucose molecule during glycolysis are added to pyruvic acid molecule and thus lactic acid is formed.

  • Lactic acid is produced in the muscle cells of human beings and other animals. During strenuous physical activity such as running, the amount of oxygen delivered to the muscle cells may be insufficient to keep pace with that of cellular respiration.
  • Under such circumstances lactic acid is formed which accumulates in the muscle cells and causes muscle fatigue.

Question 151

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Question

MCQ▾

A frog is swimming in pond and finally reaches on land.

What will be the respiratory organ needed by frog for its survival in both habitats?

Key

√ Present

× Absent

Choices

Choice (4)
a.Buccal cavit-×, Skin-×, Lungs- √
b.Buccal cavit-×, Skin-×, Lungs-×
c.Buccal cavit-√, Skin-√, Lungs- √
d.Buccal cavit-√, Skin-√, Lungs- ×

Answer

c.

Explanation

Respiratory system

  • Frog respires through skin (Cutaneous respiration), bucco-pharyngeal lining and through lungs (Pulmonary respiration). During aestivation and hibernation, the only mode of respiration is cutaneous.
  • The lungs are hollow, non-lobular, and positive pressure type. The pulmonary respiration has 3-phases, i. e. Aspiration, Inspiration, and Expiration. During aspiration sternohyal muscles of lower-jaw contract and air through nostrils is filled into bucco-pharynx.
  • During inspiration, the lower-jaw is raised (due to contraction of petrohyal muscles) and nostrils are closed. The air is forced into the lungs (+ve pressure lungs). In expiration, the air comes out of the body through nostrils.
Respiratory system

Respiratory System

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