C4 vs CAM Plants

Question 1

What is the main difference between C4 and CAM plants

Answer 1

The majority of plants are C3 plants.

The main difference between C4 and CAM plants is the way they minimize water loss.

C4 plants relocate the CO2 molecules to minimize photorespiration ( a process that occurs in Calvin Cycle during plant metabolism.)

CAM plants choose when to extract CO2 from the environment.

Question 2

Photorespiration

Answer 2

Photorespiration is a wasteful pathway that occurs when the Calvin cycle enzyme rubisco acts on oxygen rather than carbon dioxide.

Question 3

C3 plants

Answer 3

A “normal” plant—one that doesn’t have photosynthetic adaptations to reduce photorespiration—is called a
C3 plant.

The first step of the Calvin cycle is the fixation of carbon dioxide by rubisco, and plants that use only this “standard” mechanism of carbon fixation are called
C3 for the three-carbon compound (3-PGA) the reaction produces

Question 4

C4 plants

Answer 4

In C4 plants, the light-dependent reactions and the Calvin cycle are physically separated, with the light-dependent reactions occurring in the mesophyll cells (spongy tissue in the middle of the leaf) and the Calvin cycle occurring in special cells around the leaf veins. These cells are called bundle-sheath cells.

Question 5

CAM plants

Answer 5

Some plants that are adapted to dry environments, such as cacti and pineapples, use the crassulacean acid metabolism (CAM) pathway to minimize photorespiration. This name comes from the family of plants, the Crassulaceae, in which scientists first discovered the pathway.

Question 6

Comparisons of C 3, C4, and CAM plants

Answer 6

All use the Calvin cycle to make sugars from CO2.

These pathways for fixing
CO2 have different advantages and disadvantages and make plants suited for different habitats. The C3 mechanism works well in cool environments C4 and CAM plants are adapted to hot, dry areas.
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Question 7

What is the function of RuBisCo?

Answer 7

Ribulose-1,5-bisphosphate carboxylase-oxygenase

5 carbon molecule

The main function of RuBisCO is involved in the first major step of carbon fixation in photosynthesis and photorespiration.

It catalyses the first step of carbon fixation in the C3 pathway or Calvin cycle, i.e. carboxylation of RuBP.

It results in the formation of 2 molecules of 3-PGA.

Question 8

What are the 3 stages of the Calvin Cycle

Answer 8

The Calvin cycle has three stages.
In stage 1, the enzyme RuBisCO incorporates carbon dioxide into an organic molecule.

In stage 2, the organic molecule is reduced.

In stage 3, RuBP, the molecule that starts the cycle, is regenerated so that the cycle can continue.