Assertion : Photosynthetically $C_4$ plants are less efficient than $\mathrm{C}_3$ plants. Reason : The…
Assertion : Photosynthetically $C_4$ plants are less efficient than $\mathrm{C}_3$ plants.
Reason : The operation of $\mathrm{C}_4$ pathway requires the involvement of only bundle-sheath cells.
If both assertion and reason are true and reason is the correct explanation of the assertion
If both assertion and reason are true but reason is not the correct explanation of the assertion
If assertion is true, but reason is false
Both assertion and reason are false statements.
Solution
$\mathrm{C}_4$ plants are those plants that produce $\mathrm{C}_4$ compound like malic acid or aspartic acid as the first stable compound of $\mathrm{CO}_2$ fixation cycle, eg. maize, sugar cane etc. These plants can grow in dense tropical, forests where there is poor supply of $\mathrm{CO}_2$ because there is internal supply of $\mathrm{CO}_2$. Also photorespiration is negligible or absent in these plants. So, they are photosynthetically more efficient than $\mathrm{C}_3$ plants. These plants show a special type of leaf anatomy called Kranz anatomy. $\mathrm{C}_4$ plants uses mesophyll cells and bundle sheath cells in the outer part of their leaves. The $\mathrm{C}_4$ pathway shows 2 carboxylation reactions one in mesophyll chloroplast and the other in bundle sheath. Chloroplasts $-\mathrm{CO}_2$ acceptor is PEP and not RuBP and PEP carboxylase is the key enzyme.