LIFE SCIENCE

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OBJECTIVE LIFE SCIENCE

ECOLOGY

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Given that CO2 is produced by cellular respiration, why does the amount of CO2 in the atmosphere remain relatively constant? (When answering this question, exclude the impact of human activities on atmospheric CO2.)
A
CO2 is converted in photosynthesis to carbohydrates.
B
CO2 is split apart during photosynthesis.
C
CO2 mostly forms carbonate rocks.
D
CO2 is trapped in dead organisms’ bodies.
Explanation: 

Detailed explanation-1: -Photosynthesis is the process wherein green plants fix atmospheric carbondioxide in presence of sunlight into carbohydrates. So, carbondioxide released into the atmosphere by respiration is counterbalanced by its photosynthetic fixation.

Detailed explanation-2: -Carbon dioxide and rate of photosynthesis An increase in the carbon dioxide concentration increases the rate at which carbon is incorporated into carbohydrate in the light-independent reaction, and so the rate of photosynthesis generally increases until limited by another factor.

Detailed explanation-3: -So, carbon dioxide released into the atmosphere by respiration is counterbalanced by its photosynthetic fixation. Sunlight drives splitting of water during light reactions; carbon dioxide is fixed during dark reactions of photosynthesis.

Detailed explanation-4: -Plants take carbon dioixide CO2 from atmosphere to perform photosynthesis and release out oxygen O2 which is inhaled by man and animals in turn giving out carbon dioxide which plant use for photosynthesis. Thus this maintains a nearly constant level of oxygen and carbon dioixide in the atmosphere.

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