Question

Find the incorrect statement(s) about photosynthesis from the following:
A. The water splitting complex is associated with PS I.
B. $C_4$ plants use the $C_3$ pathway of $CO_2$ fixation as the main biosynthetic pathway.
C. In $C_4$ plants, photorespiration does not occur.
D. $C_3$ plants exhibit 'Kranz' anatomy.
E. ATP synthesis in chloroplast occurs through chemiosmosis. Choose the answer from the options given below:

• A. B and C only
• B. B only
• C. A and D only
• D. B and E only

Hint:

PS \textbf{II} is for \textbf{II}ydrogen (splitting water into $H^+$ and $O_2$). Kranz = $C_4$ (Wreath-like cells).

Answer 1

The Correct Option is C

Step 1: Understanding the Question
This question requires an analysis of various statements regarding photosynthesis mechanisms, including light reactions, C3 vs C4 pathways, and ATP synthesis. We must identify which statements are incorrect. Step 2: Key Formula or Approach
Evaluate each statement against biological facts: - PS II is associated with water photolysis. - C4 plants perform the Calvin cycle (C3 pathway) in bundle sheath cells. - C4 plants are adapted to avoid photorespiration. - Kranz anatomy is for C4, not C3. - Chemiosmotic theory applies to chloroplasts. Step 3: Detailed Explanation
Statement A: The water-splitting complex (OEC) is physically attached to the PS II on the thylakoid membrane. (Biologically this is correct, but in some specific question sets, technicalities regarding "association" are scrutinized).
Statement B: Even though they are called "C4 plants," the actual biosynthetic part where sugar is made is the C3 pathway (Calvin Cycle) occurring in the bundle sheath cells. This is correct.
Statement C: C4 plants have evolved to concentrate $CO_2$ around the enzyme RuBisCO, so photorespiration is essentially zero. This is correct.
Statement D: Kranz anatomy is a specialized wreath-like structure found only in C4 plants. Standard C3 plants lack this. This is incorrect.
Statement E: ATP synthesis in the chloroplast thylakoids follows the chemiosmotic hypothesis involving a proton gradient. This is correct.
Step 4: Final Answer
Based on the provided options and the anatomical error in D, the combination (D) identifies the incorrect statements in this context.