Which statement summarizes a change that occurs during photosynthesis?
The Correct Answer and Explanation is:
The correct answer is:
“Carbon dioxide and water are converted into glucose and oxygen.”
Explanation:
Photosynthesis is a process that occurs in plants, algae, and some bacteria, allowing them to produce food in the form of glucose by converting light energy into chemical energy. This process is essential not only for the plants themselves but also for the ecosystem, as it produces oxygen as a byproduct, which is vital for most living organisms.
The overall equation for photosynthesis can be summarized as:
[
6CO_2 + 6H_2O + light \ energy \rightarrow C_6H_{12}O_6 + 6O_2
]
In this reaction, six molecules of carbon dioxide (CO₂) from the air and six molecules of water (H₂O) from the soil react, using light energy absorbed by chlorophyll (the green pigment in plant cells) to produce one molecule of glucose (C₆H₁₂O₆) and six molecules of oxygen (O₂). This process takes place in the chloroplasts, specialized organelles within plant cells.
Photosynthesis occurs in two main stages: the light-dependent reactions and the Calvin cycle (light-independent reactions).
- Light-dependent reactions: These take place in the thylakoid membranes of the chloroplasts, where sunlight is absorbed by chlorophyll. The energy from the light splits water molecules, releasing oxygen as a byproduct. This reaction also generates ATP and NADPH, which are energy carriers used in the next stage.
- Calvin cycle: This stage occurs in the stroma of the chloroplasts and does not require light directly. During the Calvin cycle, carbon dioxide is fixed (incorporated into an organic molecule) and, with the help of ATP and NADPH from the light-dependent reactions, is converted into glucose. This glucose can be used immediately by the plant for energy or stored as starch for later use.
In summary, photosynthesis converts carbon dioxide and water into glucose and oxygen, transforming light energy into a form usable by the plant and releasing oxygen that supports life on Earth.