How do plants recycle carbon during photosynthesis? (1 point)
• The carbon in water is recycled during photosynthesis.
• The carbon in carbon dioxide is recycled during photosynthesis.
• The carbon in glucose is recycled during photosynthesis.
The carbon in oxygen molecules is recycled during photosynthesis.
The carbon in carbon dioxide is recycled during photosynthesis.
The carbon in carbon dioxide is recycled during photosynthesis.
The correct answer is: The carbon in carbon dioxide is recycled during photosynthesis.
During photosynthesis, plants use sunlight, water, and carbon dioxide to produce glucose (a sugar) and oxygen. Carbon dioxide (CO2) is the source of carbon for plants during photosynthesis. Here's how plants recycle carbon during photosynthesis:
1. Carbon Dioxide Absorption: Plants have tiny openings called stomata on the surface of their leaves. These stomata allow carbon dioxide from the atmosphere to enter the plant.
2. Electron Transport: Inside the cells of plant leaves, chloroplasts are responsible for photosynthesis. Within the chloroplasts, a pigment called chlorophyll captures the energy from sunlight. This energy is used to split water molecules into hydrogen (H+) and oxygen (O2) in a process called photolysis.
3. Carbon Fixation: The hydrogen produced during photolysis is combined with carbon dioxide in a series of enzyme-controlled reactions called the Calvin cycle. This process converts carbon dioxide into a sugar molecule called glucose. The carbon from carbon dioxide is "fixed" into the glucose molecule.
4. Glucose Production: The glucose produced in the Calvin cycle serves as the building block for various plant molecules, such as cellulose for cell walls and starch for energy storage. Some of the glucose is used by the plant for immediate energy, while the excess glucose is stored in roots, stems, and other plant parts.
So, the carbon in carbon dioxide is recycled and transformed into glucose during photosynthesis.
How do plants recycle hydrogen during cellular respiration? (1 point)
• The hydrogen in water is recycled when glucose is formed.
• The hydrogen in hydrogen gas is recycled when glucose is formed.
The hydrogen in glucose is recycled when hydrogen gas is formed.
• The hydrogen in glucose is recycled when water is formed.
The hydrogen in glucose is recycled when water is formed.
How many molecules of water are recycled when one molecule of glucose is created during photosynthesis? (1 point)
• 12
3
• 6
1
6
Scientists used radioactive hydrogen to make water. They grew plants using the radioactive water. What happened to the radioactive hydrogen during photosynthesis? (1 point)
• It was recycled when ligh energy was formed.
• It was recycled when water was formed.
• It was recycled when hydrogen gas was formed.
• It was recycled when glucose was formed.