C3 plants

Definition

C3 plants are a type of plant that fix carbon dioxide during photosynthesis primarily through the Calvin cycle, where the initial product is a three-carbon compound called 3-phosphoglycerate (3-PGA). This process occurs in the mesophyll cells and is most efficient under moderate light and temperature conditions, making these plants well-suited for cooler, wetter climates.

5 Must Know Facts For Your Next Test

1. C3 plants are named for their three-carbon compound (3-PGA) formed during the initial step of carbon fixation in the Calvin cycle.
2. They include many temperate crops like wheat, rice, and soybeans, thriving in cooler climates with adequate water.
3. C3 photosynthesis is less efficient in hot and dry conditions due to increased rates of photorespiration, which can occur when oxygen levels are higher than carbon dioxide levels.
4. In C3 plants, the entire process of photosynthesis primarily occurs in the mesophyll cells, as opposed to specialized structures seen in C4 and CAM plants.
5. The efficiency of C3 plants can be enhanced through agricultural practices like proper irrigation and crop rotation to optimize conditions for photosynthesis.

Review Questions

• How do C3 plants utilize the Calvin cycle for carbon fixation, and what is the significance of 3-PGA in this process?
  • C3 plants use the Calvin cycle as their primary method of carbon fixation, where they convert atmospheric carbon dioxide into organic compounds. The first stable product of this cycle is 3-phosphoglycerate (3-PGA), a three-carbon molecule. The formation of 3-PGA is significant as it represents the point at which carbon from CO2 is incorporated into organic matter, ultimately contributing to the plant's growth and energy needs.
• Discuss the advantages and disadvantages of C3 plants compared to C4 plants regarding photosynthetic efficiency in varying environmental conditions.
  • C3 plants have advantages under cool, moist conditions where they can efficiently carry out photosynthesis without much photorespiration. However, they face disadvantages in hot and dry environments because photorespiration reduces their efficiency by consuming energy without producing sugars. In contrast, C4 plants have adapted to minimize photorespiration by initially fixing CO2 into a four-carbon compound, making them more efficient in high temperatures and low water availability.
• Evaluate how climate change might impact the distribution and productivity of C3 plants globally, considering their physiological traits.
  • Climate change could significantly alter the distribution and productivity of C3 plants due to their sensitivity to temperature and moisture levels. As global temperatures rise and droughts become more common, C3 plants may struggle with increased rates of photorespiration, leading to reduced photosynthetic efficiency and yields. Regions currently suited for C3 crops might shift or become less viable, necessitating changes in agricultural practices or crop choices to maintain food security and adapt to new environmental conditions.

Related terms

Calvin Cycle:

The series of biochemical reactions in photosynthesis that convert carbon dioxide and other compounds into glucose, utilizing ATP and NADPH produced in the light-dependent reactions.

Photorespiration: A process that occurs in C3 plants when oxygen competes with carbon dioxide for binding to ribulose bisphosphate (RuBP), leading to a decrease in photosynthetic efficiency.

C4 plants:

A type of plant that employs a different pathway for carbon fixation, where carbon dioxide is initially fixed into a four-carbon compound before entering the Calvin cycle, allowing for increased efficiency under high light and temperature conditions.