Two moss samples, L and H, have the same rate of photosynthesis at 25 ∘C25\,^\circ\text{C}25∘C.
Sample L is placed at 8 ∘C8\,^\circ\text{C}8∘C and sample H is placed at 58 ∘C58\,^\circ\text{C}58∘C. Both samples are then returned to 25 ∘C25\,^\circ\text{C}25∘C under the original light intensity and carbon dioxide concentration.
The rate for sample L returns to its initial value, but the rate for sample H remains much lower.
Which explanation best accounts for the different responses?
Low temperature caused L to absorb less carbon dioxide, whereas high temperature caused H to absorb less light energy.
Low temperature permanently altered enzyme active sites in L, whereas high temperature temporarily reduced molecular kinetic energy in H.
Low temperature temporarily reduced molecular kinetic energy in L, whereas high temperature permanently altered enzyme active sites in H.
Low temperature made photosynthesis endothermic in L, whereas high temperature made photosynthesis exothermic in H.
87 exam-style questions on Edexcel GCSE Biology 6.1 Photosynthesis, covering 6.1.1 Photosynthetic organisms as producers, 6.1.2a Limiting factors on the rate of photosynthesis, 6.1.2b Interactions of limiting factors on photosynthesis, and 6.1.3 Inverse square law and light intensity. Each one has a worked solution and a mark scheme showing where the marks go.