IGCSE Biology Paper-2: Specimen Questions with Answers 137 - 137 of 203

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.