CAM plants

Definition

CAM plants, or Crassulacean Acid Metabolism plants, are a group of photosynthetic organisms that utilize a specialized method of carbon fixation to adapt to arid environments. These plants open their stomata at night to absorb carbon dioxide and store it as malate, which is converted back to carbon dioxide during the day for photosynthesis. This unique adaptation allows CAM plants to conserve water and thrive in conditions where other plants might struggle.

5 Must Know Facts For Your Next Test

1. CAM plants include species like succulents, cacti, and some orchids, which are particularly well-suited for dry environments.
2. By opening their stomata at night instead of during the day, CAM plants significantly reduce water loss through transpiration.
3. The malate produced at night is stored in vacuoles until daytime, when it is converted back to carbon dioxide for use in the Calvin cycle.
4. This adaptation allows CAM plants to perform photosynthesis even when water availability is low, giving them a competitive advantage in their habitats.
5. CAM pathways can be found in some C4 plants as well, showcasing a flexibility in carbon fixation strategies among different species.

Review Questions

• How do CAM plants adapt their stomatal behavior to minimize water loss compared to other types of plants?
  • CAM plants adapt by opening their stomata at night instead of during the day. This nocturnal gas exchange allows them to absorb carbon dioxide while minimizing water loss, as temperatures are cooler and humidity is usually higher at night. In contrast, many other plants open their stomata during the day for photosynthesis, which can lead to significant water loss due to transpiration under hot sun.
• Discuss the importance of malate in the carbon fixation process of CAM plants and how it differs from C3 and C4 pathways.
  • Malate plays a crucial role in CAM plants by acting as a storage form of carbon dioxide. At night, CAM plants convert absorbed CO2 into malate and store it in vacuoles. During the day, they convert malate back into CO2 for use in photosynthesis. This differs from C3 and C4 pathways where CO2 is directly fixed during the day without such storage. The unique nighttime fixation process of CAM allows these plants to optimize photosynthesis while conserving water.
• Evaluate how the evolution of CAM photosynthesis reflects the environmental challenges faced by certain plant species.
  • The evolution of CAM photosynthesis showcases how certain plant species have adapted to survive extreme environmental challenges, particularly drought conditions. By modifying their photosynthetic processes to fix CO2 at night and store it as malate, these plants can maintain productivity while conserving water resources. This evolutionary strategy highlights the resilience and adaptability of life forms in response to changing climates and habitats, emphasizing how different metabolic pathways can be critical for survival in harsh environments.

Related terms

Photosynthesis: The process by which green plants, algae, and some bacteria convert light energy into chemical energy in the form of glucose using carbon dioxide and water.

Stomata: Tiny openings on the surface of leaves that regulate gas exchange, allowing carbon dioxide in and oxygen out.

Malate:

A four-carbon compound that is formed during the night in CAM plants and serves as a temporary storage form of carbon dioxide.