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Figure 9 shows the effect of light intensity and temperature on the rate of photosynthesis - Edexcel - GCSE Biology Combined Science - Question 5 - 2018 - Paper 1
Question 5
Figure 9 shows the effect of light intensity and temperature on the rate of photosynthesis. (i) Describe the effect of light intensity on the rate of photosynthesis... show full transcript
Worked Solution & Example Answer:Figure 9 shows the effect of light intensity and temperature on the rate of photosynthesis - Edexcel - GCSE Biology Combined Science - Question 5 - 2018 - Paper 1
Step 1
Describe the effect of light intensity on the rate of photosynthesis.
Answer
As light intensity increases, the rate of photosynthesis also increases. This is due to the higher availability of light energy, which enhances the process of photosynthesis. However, the rate levels off once a certain light intensity is reached, indicating that other factors are limiting the rate of photosynthesis.
Step 2
Explain the effect of temperature on the rate of photosynthesis.
Answer
The rate of photosynthesis is directly affected by temperature. As temperature increases, the rate of photosynthesis rises due to increased enzyme activity, which allows more enzyme-substrate complexes to form. However, if the temperature continues to rise beyond the optimum, enzymes can become denatured, leading to a decrease in the rate of photosynthesis.
Step 3
Explain how substances are moved through a plant by transpiration and translocation.
Answer
Transpiration involves the movement of water from the roots through the plant, particularly through the xylem, and driven by evaporation of water from the leaves. Water moves primarily in one direction—upwards—due to capillary action and cohesive properties. On the other hand, translocation refers to the movement of sugars, primarily sucrose, from the leaves through the phloem. This process is bidirectional and transports nutrients where they are needed within the plant.