Photosynthesis Mechanisms in Plants

The video explains the differences between C-3, C-4, and CAM photosynthesis. C-3 photosynthesis is inefficient due to photorespiration, where oxygen reacts with ribulose biphosphate. C-4 plants, like corn and sugarcane, fix carbon into a 4-carbon molecule, reducing photorespiration. CAM plants, such as cacti, adapt to arid environments by fixing carbon at night, storing it as malate, and using it during the day while keeping stomata closed to conserve water.

What is a major drawback of C-3 photosynthesis?

• It cannot occur in the presence of water.

• It requires too much sunlight.

• It can react with oxygen, leading to inefficiency.

• It produces too much oxygen.

How do C-4 plants improve photosynthesis efficiency?

• By using more sunlight.

• By fixing carbon in a 4-carbon molecule.

• By closing stomata during the day.

• By storing water in leaves.

Which of the following plants is known for performing C-4 photosynthesis?

• Cactus

• Corn

• Pine

• Oak

Why do desert plants need to close their stomata during the day?

• To increase carbon dioxide intake.

• To enhance sunlight absorption.

• To conserve water.

• To prevent oxygen from entering.

What is the primary adaptation of CAM plants?

• They store water in their roots.

• They fix carbon during the day.

• They fix carbon at night.

• They use oxygen instead of carbon dioxide.

In CAM plants, where is the fixed carbon stored at night?

• In the leaves.

• In the roots.

• In the vacuoles.

• In the chloroplasts.

What enzyme is responsible for carbon fixation in CAM plants?

• PEP carboxylase

• Rubisco

• ATP synthase

• NADPH oxidase

How do CAM plants perform photosynthesis during the day?

• By increasing sunlight exposure.

• By absorbing water through leaves.

• By using stored malate to release CO2.

• By opening stomata to let in CO2.

What is the main advantage of CAM photosynthesis for desert plants?

• It allows for more efficient sugar production.

• It increases oxygen production.

• It reduces the need for sunlight.

• It conserves water by closing stomata during the day.

What is the role of malate in CAM plants?

• It absorbs sunlight.

• It acts as a carbon dioxide store.

• It stores water.

• It releases oxygen.