CAM plants

Definition

CAM plants, or Crassulacean Acid Metabolism plants, are a type of photosynthetic organism that have adapted to arid environments by using a unique process to fix carbon dioxide at night instead of during the day. This adaptation minimizes water loss during the hottest parts of the day, allowing these plants to thrive in conditions where water is scarce. CAM plants are often succulent and include species such as cacti and some orchids, showcasing an innovative strategy for survival in challenging climates.

5 Must Know Facts For Your Next Test

1. CAM plants open their stomata at night to take in carbon dioxide, which is stored as malic acid until daylight when photosynthesis occurs.
2. This nighttime carbon fixation helps reduce water loss because temperatures are cooler and humidity is typically higher at night.
3. The CAM pathway is energetically less efficient compared to C3 photosynthesis but allows CAM plants to survive in extreme drought conditions.
4. Many CAM plants are also capable of performing C3 photosynthesis under optimal conditions, providing them with flexibility in different environments.
5. Examples of common CAM plants include succulents like aloe vera, various cacti, and some members of the bromeliad family.

Review Questions

• How do CAM plants differ from C3 and C4 plants in terms of their photosynthetic processes?
  • CAM plants differ from C3 and C4 plants primarily in their timing of carbon dioxide fixation. While C3 plants fix CO2 during the day and C4 plants do so during the day but with an additional step that reduces photorespiration, CAM plants fix CO2 at night. This unique timing allows CAM plants to conserve water by keeping their stomata closed during the heat of the day, making them well-suited for arid environments.
• What physiological adaptations enable CAM plants to thrive in arid environments compared to other plant types?
  • CAM plants possess several physiological adaptations that allow them to thrive in dry conditions. They have specialized mechanisms for opening their stomata at night, which minimizes water loss while allowing for CO2 uptake. Additionally, they store the fixed carbon as malic acid until daylight when photosynthesis can occur. Their thick, fleshy leaves also help store water, further enhancing their ability to survive in arid habitats.
• Evaluate the ecological significance of CAM plants in desert ecosystems and their role in carbon cycling.
  • CAM plants play a crucial role in desert ecosystems by providing food and habitat for various organisms while contributing to carbon cycling in harsh environments. By efficiently capturing carbon dioxide at night and using it during daylight hours for photosynthesis, they help maintain ecosystem productivity even under extreme conditions. Furthermore, their ability to survive with minimal water contributes to soil stability and prevents erosion, highlighting their ecological importance within these fragile environments.

Related terms

Photosynthesis: The process by which green plants and some other organisms 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 allow for gas exchange; they open during the night in CAM plants to minimize water loss.

Water Use Efficiency: A measure of how effectively a plant uses water for photosynthesis; CAM plants have high water use efficiency due to their unique carbon fixation process.