Question

On land, plants get carbon from ___________.

• A. Carbonate rocks in the surroundings
• B. Supplements added to the soil
• C. The CO\textsubscript{2} dissolved in soil water
• D. Fixation of atmospheric CO\textsubscript{2} during photosynthesis

Hint:

Carbon enters the terrestrial ecosystem through photosynthesis.

Answer 1

The Correct Option is D

Step 1: Understanding carbon source for plants.
Carbon is a major element required for the synthesis of carbohydrates and other organic molecules in plants.
Step 2: Primary source of carbon.
Terrestrial plants obtain carbon mainly from atmospheric carbon dioxide, which is fixed during the process of photosynthesis.
Step 3: Analysis of options.
(A) Incorrect — rocks are not a direct carbon source for plants.
(B) Incorrect — soil supplements do not provide carbon directly.
(C) Incorrect — soil CO\textsubscript{2} is negligible compared to atmospheric CO\textsubscript{2}.
(D) Correct — atmospheric CO\textsubscript{2} is fixed during photosynthesis.
Step 4: Conclusion.
On land, plants get carbon by fixation of atmospheric CO\textsubscript{2 during photosynthesis}.