How many G3P molecules are required to make 1 glucose molecule?
2
Why is G3P a key intermediate in photosynthesis?
- G3P is made in the Calvin Cycle.
- It stores energy for the plant.
- G3P is used to make glucose and other sugars.
- It can be turned into amino acids, lipids, and nucleotides.
- It’s important for plant growth and metabolism.
How many CO2 molecules are required to make 1 glucose molecule? How many turns of the Calvin cycle is needed for this?
6 molecules are required
6 turns of the calvin cycle (1 CO2 per turn)
Define photorespiration
is an unfavourable process which decreases the production of sugars by photosynthesis.
ex.; On a hot, dry day, a plant’s stomata (pores) close to conserve water, which limits CO₂ intake. With less CO₂ available, Rubisco binds to oxygen more often, leading to photorespiration and reducing sugar production.
Describe how CAM plants are unique
- Water-storing plants: CAM plants, like cacti, aloe, and pineapple, store water and thrive in dry, desert environments.
- Stomata behavior: They open stomata at night and close them during the day to conserve water (temporal separation).
- Nighttime carbon fixation: At night, stomata open, and the plant takes in CO₂, storing it as malic acid in vacuoles.
- Daytime process: During the day, stomata are closed. The stored malic acid releases CO₂, which is used in the Calvin cycle to make sugars.
- CAM stands for Crassulacean Acid Metabolism, a method of carbon fixation found in certain plants.
Explain how the Calvin Cycle is affected for C3 plants during sunny, hot, and dry days AND during low light conditions
C3 Plants:
Hot, Sunny, and Dry Days:
* Stomata close to save water, but less CO₂ enters.
* RuBisCO can also bind to oxygen instead of CO₂, causing photorespiration, which wastes energy and reduces sugar production.
Low Light Conditions:
* Less light means less energy for photosynthesis.
* The Calvin Cycle works slower and produces less sugar.
Explain how both C4 plants and CAM plants have adapted to survive sunny, hot, and dry days
- C4 plants: Capture CO₂ as a 4-carbon compound in mesophyll cells and move it to bundle-sheath cells, minimizing water loss and photorespiration (e.g., corn, sugar cane).
- CAM plants: Open stomata at night to capture CO₂, storing it as malic acid. During the day, stomata close to save water, and CO₂ is used for the Calvin Cycle (e.g., cacti, pineapple).
