IGCSE Biology Paper-2: Specimen Questions with Answers 137 - 137 of 203
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Question 137
Question
MCQ▾Which processes result in organisms gaining carbon compounds, and in the addition of carbon dioxide to the atmosphere?
Choices
| Choice (4) | |
|---|---|
a. | Organisms gaining carbon compounds-photosynthesis and combustion, Addition of carbon dioxide to the atmosphere- respiration by animals |
b. | Organisms gaining carbon compounds-photosynthesis and feeding, Addition of carbon dioxide to the atmosphere- respiration by plants |
c. | Organisms gaining carbon compounds-photosynthesis and combustion, Addition of carbon dioxide to the atmosphere-respiration by plants |
d. | Organisms gaining carbon compounds-photosynthesis and feeding, Addition of carbon dioxide to the atmosphere- dead organisms changing to fossil fuels |
Answer
b.Explanation
- Carbon is present in carbohydrates, proteins, and fats.
- Green plants take up carbon as for photosynthesis.
- Carbon is present as in atmosphere, as graphite and carbonates in rocks and in fossil fuels (coal, petroleum) .
- Ocean is big reservoirs of carbon.
- Carbon is released as in atmosphere during respiration of plants and animals burning of fossil fuels
- For each element, the cycling process involves –
- Reservoir: That portion of earth that acts as a storehouse for the element.
- Exchange pool: That portion of the environment from which the producers take nutrients.
- The biotic community: Through which chemicals moves along the food chains to and from the exchange pool.
- Carbon is also released in atmosphere as methane by rice fields and marshes.
- Carbon cycle is cyclic representation of carbon assimilation by green plants (photosynthesis) which then passes into bodies of animals (plants are eaten) and finally during respiration of plants & animals & decompositions by microbes, the carbon dioxide is returned back to the atmosphere. Thus, carbon is cycled through transfer and transformation between biotic and abiotic components.