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An increase in the atmospheric CO₂ level increases the rate of photosynthesis - VCE - SSCE Biology - Question 8 - 2014 - Paper 1
Question 8
An increase in the atmospheric CO₂ level increases the rate of photosynthesis. The rate of photosynthesis increases because - the rate of the light-independent rea... show full transcript
Worked Solution & Example Answer:An increase in the atmospheric CO₂ level increases the rate of photosynthesis - VCE - SSCE Biology - Question 8 - 2014 - Paper 1
Step 1
the rate of the light-independent reactions on the thylakoid membranes of the chloroplasts increases.
Answer
As the CO₂ concentration rises, it enhances the availability of substrates required for the light-independent reactions (Calvin cycle). This leads to an increase in the overall rate of photosynthesis because more glucose can be produced.
Step 2
water loss from the leaf decreases, resulting in the availability of water for photosynthesis increasing.
Answer
Higher CO₂ levels often result in the stomata partially closing to prevent excessive water loss. This helps maintain higher water availability, which is crucial for photosynthesis since water is a reactant in the process.
Step 3
the increased CO₂ level lowers the pH inside the chloroplasts and increases the rate of enzyme-catalysed reactions.
Answer
Elevated CO₂ levels can cause a decrease in pH, creating an optimal environment for the enzymes involved in photosynthesis. This can enhance the efficiency of these enzymes, speeding up the chemical reactions that contribute to the process.
Step 4
the rate of the light-independent reactions in the stroma increases with the increase in CO₂ level.
Answer
The increase in CO₂ directly affects the light-independent reactions in the stroma. More CO₂ allows for a greater fixation of carbon during the Calvin cycle, thus increasing the rate at which glucose is synthesized.