Understanding the Calvin Cycle and Photorespiration

The video explores the Calvin cycle, focusing on the enzyme rubisco and its role in carbon fixation. It highlights rubisco's quirk, photorespiration, where it fixes oxygen instead of carbon, leading to inefficiencies. The video explains conditions that favor photorespiration, such as hot weather, and discusses the salvage pathway plants use to mitigate carbon loss.

What is the primary role of Rubisco in the Calvin Cycle?

• To transport electrons

• To fix carbon dioxide into organic molecules

• To break down glucose

• To fix oxygen into organic molecules

In the Calvin Cycle, what happens to the six carbon molecules initially formed?

• They remain as six carbon molecules

• They split into twelve three-carbon molecules

• They convert into glucose directly

• They are used to produce ATP

What is the significance of the enzyme Rubisco's name?

• It indicates its role in oxygen fixation

• It suggests its involvement in both oxygen and carbon dioxide fixation

• It shows its function in glucose breakdown

• It highlights its role in ATP synthesis

Why does photorespiration occur more frequently in hot conditions?

• Rubisco's affinity for oxygen increases

• Plants open their stomata more frequently

• Plants produce more glucose

• Rubisco has a higher affinity for carbon dioxide

What happens to the ratio of O2 to CO2 when stomata are closed?

• The ratio decreases

• The ratio becomes zero

• The ratio increases

• The ratio remains the same

What is a consequence of photorespiration in plants?

• Increased glucose production

• Loss of fixed carbon

• Improved water retention

• Enhanced ATP synthesis

How do plants attempt to recover carbon lost during photorespiration?

• By opening stomata

• Through a salvage pathway

• By increasing photosynthesis

• By producing more Rubisco

What is the role of peroxisomes in the salvage pathway?

• They synthesize glucose

• They produce ATP

• They fix carbon dioxide

• They convert glycolate to glycine

Why is photorespiration considered inefficient?

• It enhances carbon fixation

• It uses oxygen and releases carbon dioxide

• It produces more glucose

• It increases ATP production

What percentage of protein mass in plant leaves is represented by Rubisco?

• 10%

• 40%

• 20%

• 30%