Question

On an annual basis, approximately what percentage of all the carbon dioxide in the atmosphere is fixed by photosynthesis?

• A. $100\%$
• B. $70\%$
• C. $10\%$
• D. $1\%$

Answer 1

The correct option is C

$10\%$

The synthesis of organic compounds from carbon dioxide and water through photosynthesis uses only 10% of the seven billion metric tonnes of carbon dioxide present in the atmosphere each year. This enormous amount of biological activity is because of the combined activity of photosynthetic bacteria, protists and plants.