Biology 9700 · AS & A Level · Photosynthesis as an energy transfer process
Photosynthesis as an energy transfer process — practice question
In plants such as rice, $Oryza\ sativa$, rubisco shows a low activity rate, and this reduces the rate of photosynthesis. The cereal crop sorghum, $Sorghum\ bicolor$, shows a high activity rate of rubisco. A genetically modified (GM) type of rice was made. Sections of the quaternary structure of rubisco in rice were changed so that they matched the rubisco in sorghum. The activity rate of rubisco in non-GM rice and GM rice was measured at different atmospheric carbon dioxide ($CO_2$) concentrations. The results are shown in Fig. 8.1.
(a(i))[3]
Compare the two curves in Fig. 8.1 and explain why the non-GM rice curve becomes level.
(a(ii))[1]
Suggest which section of the rubisco molecule was modified to create the GM rice variety.
(b(i))[1]
Name the process carried out by the enzyme rubisco.
(b(ii))[1]
State the reaction type when GP is changed to TP.
(b(iii))[1]
RuBP is re-formed from TP molecules. State how many molecules of RuBP are made from 10 molecules of TP.
(b(iv))[2]
TP molecules that are not used for the regeneration of RuBP can be used to synthesise other compounds. State two molecules that can be made from these TP molecules.
Worked solution & mark scheme
This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: “greater rubisco activity in GM rice” …