Compare C3 C4 and CAM mechanisms of photosynthesis a What ar

Compare C3, C4 and CAM mechanisms of photosynthesis. a) What are the molecules that accept CO2 in each of the mechanisms? b) What are the products of CO2 fixation? c) What are the first enzymes in CO2 fixation, where are they located? d) What is the difference between C4 and CAM photosynthesis? e) Briefly explain the advantages of C4 and CAM in stress (heat and drought) adaption.

Solution

Answer:

A).

RUBP accepts CO2 in C3 cycle

First PEP and then RUBP in both C4 and CAM cycle.

B). Glucose is product of CO2 fixation

C).

C3 cycle: RUBP carboxylase accept CO2. It is present in the stroma of chloroplast

C4 cycle: PEP carboxylase accept CO2. It is present in the mesophyll cells.

CAM cycle: PEP carboxylase accept CO2. It is present in the mesophyll cells.

D).

C4 cycle occurs in two locations i.e., mesophyll cells and bundle sheath cells (spatial variation)

CAM cycle occurs in mesophyll cells but in different times, i.e., night and day (temporal variation)

E). Even at high temperature C4 cycle occurs whereas CAM cycle doesn\'t occur. Because, stomata remain close during hot conditions to prevent water loss in CAM plants. So C4 cycle is advantage than the CAM cycle.