(i) Group A shows maximum photosynthesis. chlorophyll pigments of the spectrum is (400 - 450 nm), hence the photosynthesis is high.
(ii) Group B will show negligible amount of photosynthesis, because chlorophyll does not absorb any light in this region (500 - 550nm). It reflects green.

(i) C₄ cycle/Di - carboxylic acid pathway/ Di - carboxylation pathway is an adaptive mechanism.
(ii) It takes place in two phases. First phase takes place in stroma of mesophyll cells, where the CO₂ acceptor molecule 3-Carbon compound, phosphoenol pyruvate (PEP) to form 4-carbon oxalo acetic acid (OAA). The first product is a 4-carbon and so it is named as C₄ cycle. Oxalo acetic acid is a dicarboxylic acid and hence this cycle is also known as dicarboxylic acid pathway.
(iii) Carbondioxide fixation takes place in two places one in mesophyll and another in bundle sheath cell.
(iv) C₄ plants requires 5 ATP and 2NADPH + H⁺ to fix one molecule of CO₂.

Stage: I Mesophyll Cells

(i) Oxaloacetic acid (OAA) is converted into malic acid or aspartic acid and is transported to the bundle sheath cells through plasmodesmata.
Stage: II Bundle Sheath Cells
(i) Malic acid undergoes decarboxylation and produces a 3 carbon compound Pyruvic acid and CO₂.
(ii) The released CO₂ combines with RUBP and follows the calvin cycle and finally sugar is released to the phloem.
(iii) Pyruvic acid is transported to the mesophyll cells.

The plants undergoes Photorespiration.
(i) It is the excess respiration taking place in photosynthetic cells due to absence of CO₂ and increase of O₂.
(ii) This condition changes the carboxylase role of RUBISCO into oxygenase.

C₄ plants are more advantageous than C₃ plants because increasing the proportion of C₄ plants on earth could assist biosequestration of CO₂ and represent an important cilmate change avoidance strategy.