Q15 / 79 · NEST (NISER) 2026 · Biology
There is a difference between the predicted and observed global carbon budget. The possible reason is:
- Correct answerAHigher $\text{CO}_2$ levels stimulate plant growth and productivity, leading to more carbon being sequestered in plant tissues and root systems.
- BThe thinning of the stratospheric ozone layer allows higher levels of ultraviolet radiation directly breaking down $\text{CO}_2$ molecules.
- COceans are absorbing more carbon due to increased temperature, resulting in increased acidification.
- DHigher $\text{CO}_2$ levels lead to increased soil respiration rates, releasing more carbon into the atmosphere.
Solution
The difference between the predicted and observed global carbon budget is often referred to as the missing carbon sink. This discrepancy arises because the amount of carbon dioxide accumulating in the atmosphere is less than expected based on human emissions and known ocean uptake.
A primary explanation for this missing sink is the $\text{CO}_2$ fertilization effect. Higher atmospheric $\text{CO}_2$ concentrations stimulate photosynthesis, leading to enhanced plant growth and productivity. Consequently, more carbon is sequestered in terrestrial ecosystems, particularly in plant tissues and root systems, accounting for the unaccounted carbon.
Answer: Higher $\text{CO}_2$ levels stimulate plant growth and productivity, leading to more carbon being sequestered in plant tissues and root systems.
A primary explanation for this missing sink is the $\text{CO}_2$ fertilization effect. Higher atmospheric $\text{CO}_2$ concentrations stimulate photosynthesis, leading to enhanced plant growth and productivity. Consequently, more carbon is sequestered in terrestrial ecosystems, particularly in plant tissues and root systems, accounting for the unaccounted carbon.
Answer: Higher $\text{CO}_2$ levels stimulate plant growth and productivity, leading to more carbon being sequestered in plant tissues and root systems.
Hence, the correct answer is option: 'A'.