Oserve the diagram and answer the following.
(a) Which group of plants exibit these two types of cells?
(b) What is the first product of $\mathrm{C}_4$ cycle?
(c) Which enzyme is there in bundle sheath cells and mesophyll cells?
(a) Monocot plants belonging to Graminae/Poaceae family, e.g., sugarcane, maize etc., possess these two types of cells. i.e., bundle sheath and mesophyll cell (in kranz anatomy).
(b) A 4-carbon compound oxaloacetic acid is the first product of $\mathrm{C}_4$ cycle.
(c) Mesophyll cells have PEP carboxylase to fix atmospheric $\mathrm{CO}_2$ to form a 4-carbon compound oxalo acetic acid, whereas bundle sheath cells have RuBP carboxylase which fix $\mathrm{CO}_2$ by this enzyme to form 3-carbon compound 3 PGA (3 phosphoglyceric acid).
A cyclic process is occurring in $C_3$ plant, which is light dependent and needs $\mathrm{O}_2$. This process doesn't produce energy rather it consumes energy.
(a) Can you name the given process?
(b) Is it essential for survival?
(c) What are the end products of this process?
(d) Where does it occur?
(a) Photorespiration is the process, which do not produce energy rather consum it.
(b) It is not needed for the survival of $\mathrm{C}_3$ plant.
(c) The end product of this process is $\mathrm{H}_2 \mathrm{O}_2$.
(d) This process involves three cell organelles of the plant cell.
(i) Chloroplast (ii) Peroxisome (iii) Mitochondria
Suppose Euphorbia and maize are grown in the tropical area.
(a) Which one of them do you think will be able to survive under such conditions?
(b) Which one of them is more efficient in terms of photosynthetic activity?
(c) What difference do you think are there in their leaf anatomy?
(a) Euphorbia is a CAM plant. It fixes $\mathrm{CO}_2$ during night and uses it in day time. It will be able to survive in hot tropical climate.
(b) Maize being a $\mathrm{C}_4$ plant is more efficient in terms of photosynthetic activity as it is able to use $\mathrm{CO}_2$ at lower level as well as high $\mathrm{O}_2$ and temperature.
(c) Maize plants show kranz anatomy in their leaves. They have granal chloroplast in mesophyll cells and agranal in bundle sheath cells. Euphorbia does not have $\mathrm{C}_4$ cycle so kranz anatomy is not found in them.