What is the relationship between photosynthesis and cellular respiration?
A. All forms of animal life engage in both these processes.
B. Cellular respiration is one of the steps in the process of photosynthesis.
C. Photosynthesis is one of the steps in the process of cellular respiration.
D. The reactants of one reaction are the products of the other.
The Correct Answer and Explanation is:
The correct answer is:
D. The reactants of one reaction are the products of the other.
Explanation:
Photosynthesis and cellular respiration are complementary biochemical processes that support life on Earth by cycling energy and matter. These processes are integral to the energy balance in ecosystems, particularly between plants and animals.
Photosynthesis occurs in the chloroplasts of plant cells and some bacteria. During this process, plants use sunlight, water (H₂O), and carbon dioxide (CO₂) to produce glucose (C₆H₁₂O₆) and oxygen (O₂) as a byproduct. The chemical equation for photosynthesis is:
[
6\text{CO}2 + 6\text{H}_2\text{O} + \text{sunlight} \rightarrow \text{C}_6\text{H}{12}\text{O}_6 + 6\text{O}_2
]
Cellular respiration takes place in the mitochondria of both plant and animal cells, where organisms use oxygen and glucose to produce energy in the form of adenosine triphosphate (ATP). During cellular respiration, glucose and oxygen are broken down into carbon dioxide and water, releasing energy. The chemical equation for cellular respiration is:
[
\text{C}6\text{H}{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + \text{ATP (energy)}
]
These reactions are opposites, where the reactants of photosynthesis (CO₂ and H₂O) become the products of cellular respiration and vice versa, making Option D the correct answer. This cycle allows plants to produce the oxygen and glucose that animals (and plants themselves) require for respiration, while cellular respiration provides the CO₂ and H₂O needed by plants for photosynthesis.
Through these interlinked processes, energy from the sun is ultimately captured, stored, and transferred to organisms at various levels in the food chain. This relationship between photosynthesis and respiration is fundamental to the Earth’s carbon cycle, contributing to the balance of oxygen and carbon dioxide in the atmosphere, supporting life across ecosystems.