High temperature

Definition

High temperature refers to elevated environmental conditions that can impact biological processes, particularly in plants during photosynthesis. In the context of plants, high temperatures can lead to increased rates of photorespiration, affecting the efficiency of carbon fixation and overall energy production. This stress condition often prompts plants to adopt alternative pathways such as C4 and CAM to mitigate the adverse effects of heat.

5 Must Know Facts For Your Next Test

1. High temperatures can cause stomatal closure in plants, limiting CO2 intake and subsequently leading to reduced photosynthesis.
2. Under high-temperature conditions, the rate of photorespiration can increase significantly, which can be detrimental to plant growth and yield.
3. C4 plants have a specialized anatomy that allows them to maintain higher photosynthetic efficiency even under high temperatures compared to C3 plants.
4. The CAM pathway is particularly advantageous for succulents and desert plants, allowing them to conserve water while still performing photosynthesis in high temperatures.
5. Plants adapted to high temperatures often exhibit changes in their metabolic pathways to prioritize energy conservation and reduce stress-induced damage.

Review Questions

• How does high temperature influence the process of photorespiration in plants?
  • High temperatures increase the activity of photorespiration because the enzyme RuBisCO has a higher affinity for oxygen than carbon dioxide under these conditions. As temperatures rise, the closure of stomata to prevent water loss limits CO2 availability, further promoting photorespiration. This leads to an inefficient use of energy and reduced productivity in plants that rely on the standard C3 pathway.
• Discuss the adaptive advantages of C4 and CAM pathways for plants living in high-temperature environments.
  • C4 and CAM pathways provide significant advantages for plants in high-temperature environments by reducing photorespiration and improving water use efficiency. C4 plants utilize a mechanism that concentrates CO2 at the site of the Calvin cycle, which allows them to continue photosynthesizing effectively even when stomata are partially closed. On the other hand, CAM plants fix CO2 at night when temperatures are cooler, reducing water loss while still maintaining photosynthesis during the day. These adaptations enable survival and growth under conditions that would be stressful for C3 plants.
• Evaluate how climate change and increasing global temperatures might affect the distribution and success of C4 versus C3 plant species.
  • As global temperatures rise due to climate change, C4 plant species may gain a competitive advantage over C3 species because they are better adapted to high-temperature conditions. The increased frequency of heatwaves could lead to greater photorespiration rates in C3 plants, negatively impacting their growth and reproductive success. Consequently, ecosystems may shift towards dominance by C4 species as they thrive in hotter environments, potentially altering biodiversity and ecological interactions within those habitats.

Related terms

Photorespiration: A process where the enzyme RuBisCO oxygenates ribulose-1,5-bisphosphate, leading to a decrease in photosynthetic efficiency and an increase in energy expenditure.

C4 Pathway: A photosynthetic process that minimizes photorespiration by initially fixing carbon dioxide into a four-carbon compound, allowing plants to thrive in high-temperature environments.

CAM Pathway: Crassulacean acid metabolism is a photosynthetic adaptation that allows plants to fix carbon dioxide at night, reducing water loss and optimizing carbon fixation in arid environments.