Q.32 Among those given below which plant families have CAM species?
- Poaceae
- Zygophyllaceae
- Cucurbitaceae
- Asteraceae
Zygophyllaceae is the plant family among the options that has CAM species.
CAM (Crassulacean Acid Metabolism) is a photosynthetic adaptation where CO₂ fixation occurs at night to minimize water loss in arid conditions, unlike typical C3 or C4 pathways.
Option Breakdown
-
Poaceae: Primarily C4 grasses like maize and wheat; no known CAM species, as they use Kranz anatomy for daytime CO₂ concentration.
-
Zygophyllaceae: Correct. Includes CAM species like Kalanchoe (often associated) and genera such as Zygophyllum, adapted to deserts via nocturnal stomata opening.
-
Cucurbitaceae: C3 family (e.g., cucumber, pumpkins); lacks CAM, focusing on vine growth without water-saving modifications.
-
Asteraceae: Mostly C3 (e.g., sunflowers); rare facultative CAM reports, but not characteristic of the family.
Which plant families have CAM species? Zygophyllaceae stands out with CAM-adapted members thriving in dry habitats through Crassulacean Acid Metabolism. This water-efficient pathway fixes CO₂ at night, crucial for xerophytes.
CAM Pathway Basics
CAM plants open stomata nocturnally, storing CO₂ as malic acid in vacuoles, then decarboxylate it daytime for Calvin cycle use. Found in ~7% of plants, including succulents.
Family Analysis Table
Family CAM Species? Key Examples/Notes Poaceae No C4 dominant (maize); hot but not CAM Zygophyllaceae Yes Zygophyllum, desert shrubs Cucurbitaceae No C3 vines like melon Asteraceae No Mostly C3 daisies -
