Photosynthesis MCQs for NEET — Botany Questions with Answers

CO₂ acceptor molecule in C4 plants is phosphoenol pyruvate (PEP). C4 plants are more efficient in picking up CO₂ even when it is found in low connection because of high affinity of PEP. PEP carboxylase (PEPcase) is the key enzyme which catalyses the primary fixation of CO₂. 

In photosystem (PS-I), the photocentre is a special chlorophyll-a molecule called P₇₀₀ . It is active in both red and far-red light, while a very small amount of special form of clorophyll-a called P₆₈₀ constitutes the reaction centre of photosystems-II (PS-II), which is inactive in far-red light (beyond 680 nm).

 C₄ plants have charasteristic leaf anatomy, called 'Kranz anatomy'. 'Kranz' means 'wreath' (ring) and is a reflection of the arrangement of cells. The large sized bundle sheath cells may form several layers around the vascular bundles. These cells are characterised by having a large number of a chloroplast, thick walls inpervious to gaseous exchange and no intercellular spaces. 

Plants that utilise primarily RuBP to fix CO₂ , which results in the formation of a 3 carbon compound (3PGA) are called C3 plants. Hatch and Slack proposed a new pathway in plants for CO₂ fixation via the carboxylation of PEP (Phosphoenol pyruvate). Because the products are 4 carbon compound, the plants are known as C4 plants. 

Certain important mineral elements like Mg, Fe, Mn, Cu, Cl, P are closely associated with key reactions of photosynthesis. Therefore deficiency of these minerals ultimately reduce photosynthesis.

Pigment system I of higher plants has main reaction centre P₇₀₀ and pigment system II P₆₈₀. But, bacterial pigment system is sensitive to far red light P₈₉₀.

P-210; para – 1.

P- 213; first line

P-214, point (c)

P-214, point (c)