Question

which increases the amount of carbon dioxide in the atmosphere, acting as a carbon source? a. photosynthesis b. carbon uptake in the ocean c. respiration d. formation of carbonates in the ocean

Explanation:

• Photosynthesis: Plants use carbon dioxide ($CO_2$) from the atmosphere to produce glucose and oxygen. So, it acts as a carbon sink (removes $CO_2$ from the atmosphere), not a source.
• Carbon uptake in the ocean: Oceans absorb a significant amount of $CO_2$ from the atmosphere. This is also a carbon - sink mechanism.
• Respiration: Both plants and animals (and other organisms) respire. The general equation for aerobic respiration is $C_6H_{12}O_6+6O_2

ightarrow6CO_2 + 6H_2O+Energy$. So, it releases $CO_2$ into the atmosphere, acting as a carbon source.

• Formation of carbonates in the ocean: Carbonates (e.g., $CaCO_3$) are formed when $CO_2$ reacts with other substances in the ocean. This process removes $CO_2$ from the water (and by extension, can affect the amount of $CO_2$ that diffuses into the ocean from the atmosphere), acting as a carbon - sink.

Answer:

C. Respiration