The girdling experiment cannot be done in monocots. The monocot stem has vascular bundles scattered all over the width of stem so, we cannot reach that specific band of the phloem tissues as we get in dicots.

(a) 2 molecules of ATP for phosphorylation and two molecules of NADPH for reduction are required per $\mathrm{CO}_2$ molecule fixed.

(b) The calvin cycle occurs in the stroma of the chloroplast.

Plants cannot carry out photosynthesis in moonlight because it does not carry enough energy to excite chlorophyll molecule, i.e., reaction centres PS I and PS II, so light dependent reactions does not get initiate. Thus, no photosynthesis occurs in presence of moonlight.

The terms associated with $\mathrm{C}_4$ cycle are

Hatch Slack Pathway The process of synthesis of glucose in $\mathrm{C}_4$ plants is different from $\mathrm{C}_3$ plants which was discovered by two scientists MD Hatch and CR Slack (1977). Hence, named Hatch Slack pathway.

PEP Carboxylase It is an enzyme present in mesophyll cells of $\mathrm{C}_4$ plants. It fixes $\mathrm{CO}_2$ to form 4-carbon compound, i.e., oxaloacetate (OAA).

Bundle Sheath Cells These are specialised sclerenchymatous cells present arround the vascular bundle, in the veins of monocot leaves. These have agranal chloroplast. $\mathrm{C}_3$ cycle occurs in these cells to manufacture glucose in $\mathrm{C}_4$ plants.

Calvin Cycle This cycle operates in bundle sheath cells and fixes $\mathrm{CO}_2$ to form glucose molecules.

NADP reductase enzyme is located on the outer side of lamella or thylakoid of the chloroplast. This enzyme causes breakdown of proton gradient to release energy, i.e., NADPH.