Photosynthesis Photorespiration and C4/CAM Pathways 3

Question 1

C3 plants are named because the first stable product of carbon fixation is a compound with how many carbons?

Accepted Answer

3 carbons

Answer

2 carbons

Answer

4 carbons

Answer

6 carbons

Question 2

Which type of photosynthesis is generally most efficient in cool, moist environments with moderate light intensity?

Accepted Answer

C3 photosynthesis

Answer

CAM photosynthesis

Answer

C4 photosynthesis

Answer

Photorespiration-driven photosynthesis

Question 3

Photorespiration is considered energetically wasteful primarily because it:

Accepted Answer

Consumes ATP and O2 while releasing CO2 without net sugar production

Answer

Produces excess NADPH that cannot be used in the Calvin cycle

Answer

Degrades chlorophyll pigments under high light conditions

Answer

Inhibits electron transport in the thylakoid membrane

Question 4

Which of the following crop plants is a well-known example of C4 photosynthesis?

Accepted Answer

Corn/Maize (Zea mays)

Answer

Wheat (Triticum aestivum)

Answer

Rice (Oryza sativa)

Answer

Soybean (Glycine max)

Question 5

The spatial separation of initial CO2 fixation and the Calvin cycle in C4 plants occurs between which two cell types?

Accepted Answer

Mesophyll cells and bundle sheath cells

Answer

Guard cells and epidermal cells

Answer

Palisade cells and spongy mesophyll cells

Answer

Xylem cells and phloem cells

Question 6

In CAM plants, keeping stomata closed during the day primarily conserves which essential resource?

Accepted Answer

Water

Answer

NADPH

Answer

ATP

Answer

Oxygen

Question 7

Which statement correctly distinguishes C4 photosynthesis from CAM photosynthesis?

Accepted Answer

C4 plants separate initial CO2 fixation and the Calvin cycle spatially; CAM plants separate them temporally

Answer

C4 plants fix CO2 only at night; CAM plants fix CO2 only during the day

Answer

C4 plants use RuBisCO for initial fixation; CAM plants use only PEP carboxylase for all fixation steps

Answer

C4 plants are adapted to cold alpine climates; CAM plants are adapted to tropical rainforests