Which of the following metabolic processes consumes \( \mathrm{CO}_2 \)?

• A. Citric acid cycle
• B. Photosynthesis
• C. Fermentation
• D. Glycolysis

Answer: (B)

Verified step by step guidance

1. Understand the role of carbon dioxide ( ${\mathrm{CO}}_2$) in metabolic processes. It can either be produced as a byproduct or consumed as a reactant depending on the process.
2. Review the Citric Acid Cycle (Krebs Cycle): This process occurs in cellular respiration and primarily produces ${\mathrm{CO}}_2$ as a byproduct, rather than consuming it.
3. Examine Photosynthesis: In this process, plants and other photosynthetic organisms use ${\mathrm{CO}}_2$ as a reactant during the Calvin Cycle to produce glucose. This is the metabolic process that consumes ${\mathrm{CO}}_2$.
4. Analyze Fermentation: This anaerobic process does not involve the consumption of ${\mathrm{CO}}_2$. Instead, it focuses on regenerating NAD+ for glycolysis and may produce ethanol or lactic acid as byproducts.
5. Consider Glycolysis: This is the initial step of cellular respiration, breaking down glucose into pyruvate. It does not consume or produce ${\mathrm{CO}}_2$ directly.