Question

Crassulacean acid metabolism is present in

• A. Wheat
• B. Agave
• C. Sweet potato
• D. Sorghum

Hint:

Photosynthetic pathways:
$C_3$: Wheat, Rice, Soybean.
$C_4$: Maize, Sorghum, Sugarcane.
CAM: Agave, Pineapple, Cactus, Opuntia.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Crassulacean Acid Metabolism (CAM) is a specialized photosynthetic carbon fixation pathway evolved in succulent xerophytes to maximize water use efficiency in arid environments.
Key Formula or Approach:
\[ \text{Night: } \text{CO}_2 + \text{PEP} \xrightarrow{\text{PEPC}} \text{Malic Acid (Vacuole)} \quad | \quad \text{Day: Malic acid decarboxylated to } \text{CO}_2 \text{ for RuBisCO} \]

Step 2: Detailed Explanation:
CAM plants keep their stomata open at night (scotoactive stomatal opening) to absorb $\text{CO}_2$ with minimal transpiration water loss, converting it into malic acid stored in large vacuoles.
During the day, stomata remain tightly closed, and the stored malic acid is decarboxylated to release $\text{CO}_2$ internally for the Calvin cycle.
Agave, along with Pineapple, Opuntia, Kalanchoe, and Sedum, is a classic succulent CAM plant.
(Wheat is $C_3$; Sorghum is $C_4$).

Step 3: Final Answer:
Thus, Crassulacean acid metabolism is present in Agave, corresponding to option (B).