Photosynthesis
Q1.
(a)      Complete the equation for photosynthesis.
  light
energy
____________ + ____________  ____________ + oxygen
(2)
(b)     Scientists investigated how temperature affects the rate of photosynthesis.
The scientists grew some orange trees in a greenhouse.
They used discs cut from the leaves of the young orange trees.
The scientists used the rate of oxygen production by the leaf discs to show the rate of photosynthesis.
(i)      The leaf discs did not produce any oxygen in the dark.
Why?
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(1)
(ii)     The leaf discs took in oxygen in the dark.
Explain why.
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(2)
(c)     In their investigation, the scientists measured the rate of oxygen release by the leaf discs in the light. The scientists then measured the rate of oxygen uptake by the leaf discs in the dark.
The graph shows the effect of temperature on
•   oxygen production in the light
•   oxygen production in the light added to oxygen uptake in the dark.
 
Use the information from the graph to answer each of the following questions.
(i)      Describe the effect of temperature on oxygen production in the light.
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(2)
(ii)     Explain the effect of temperature on oxygen production in the light when the temperature is increased:
from 25 °C to 35 °C
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from 40 °C to 50 °C.
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(2)
(d)     A farmer in the UK wants to grow orange trees in a greenhouse. He wants to sell the oranges he produces at a local market.
He decides to heat the greenhouse to 35 °C.
Explain why he should not heat the greenhouse to a temperature higher than 35 °C.
Use information from the graph in your answer.
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(3)
(Total 12 marks)