BioInteractive Photorespiration and Alternative Carbon Fixation 2

Question 1

What is CAM photosynthesis?

Accepted Answer

A strategy where CO2 is fixed at night and stored as organic acids, then released for the Calvin cycle during the day

Answer

Photosynthesis that occurs only in cold climates

Answer

A form of cyclic electron flow

Answer

Carbon fixation that bypasses RuBisCO

Question 2

Which plants use CAM photosynthesis?

Accepted Answer

Cacti and succulents

Answer

Corn and sugarcane

Answer

Wheat and rice

Answer

Mosses and liverworts

Question 3

What is the key advantage of CAM over C3 photosynthesis in desert environments?

Accepted Answer

Stomata open only at night, dramatically reducing water loss

Answer

CAM plants fix more CO2 per day

Answer

CAM plants grow faster

Answer

CAM plants require less sunlight

Question 4

In C3 plants, what is the first stable product of carbon fixation?

Accepted Answer

3-phosphoglycerate (3-PGA)

Answer

Glucose

Answer

Oxaloacetate

Answer

Pyruvate

Question 5

Why is RuBisCO considered an inefficient enzyme?

Accepted Answer

It has a slow catalytic rate, a dual affinity for both CO2 and O2, and is easily inhibited

Answer

It cannot function above 20°C

Answer

It only works in bundle sheath cells

Answer

It requires light to function

Question 6

How does elevated atmospheric CO2 affect photorespiration in C3 plants?

Accepted Answer

It suppresses photorespiration by increasing CO2/O2 ratio at RuBisCO's active site

Answer

It increases photorespiration

Answer

It has no effect on photorespiration

Answer

It converts C3 plants to C4 plants