2017 HCI H2 Biology Prelims Paper 3 Answers

HWA CHONG INSTITUTION / 2016-2017 H2 BIOLOGY / Preliminary Examinations / Paper 3 / MS 1 HWA CHONG INSTITUTION (COLLEGE SECTION) 2017 JC2 9744 H2 BIOLOGY PRELIMINARY EXAMINATIONS PAPER 3 MARK SCHEME SECTION A Question 1 (a)(i) State why rubisco is said to have quaternary structure. [1] Ref to: more than one polypeptide (a)(ii) Explain what makes a molecule such as rubisco soluble. [1] 1. Ref to: globular protein 2. Ref to: hydrophilic / polar / charged amino acid residues at the surface of the molecule 3. Ref to: hydrophobic / non-polar / non-charged amino acid residues at the inside of the molecule 4. Ref to: hydrogen bonds with water (molecules) (b) Explain why rubisco does not need to be in an active form in the absence of light. [3] 1. Ref to: no light dependent reaction and no light independent reaction 2. Ref to: no ATP / reduced NADP 3. Ref to: no need to fix CO 2 (c) Explain the consequences to the plant of the reaction involving oxygen. [2] 1. Ref to: no CO 2 being fixed 2. Ref to: no (new) PGA / GP being made 3. Ref to: no (new) TP / glucose being made 4. Ref to: no (new) RuBP being (re)generated 5. Ref to: ATP used in making RuBP being wasted 6. Calvin cycle / light independent reaction / Photosynthesis decreased (d) With reference to Fig. 1.2, predict whether C3 or C4 plants are favoured in the context of global warming in the tropics. Explain how these plants are better adapted physiologically. [4] 1. Ref to: C4 plants being favoured over C3 plants at high temperatures above 26 C 2. Ref to: Plants closing their stomata, resulting in reduced CO 2 diffusion into the leaf 3. Ref to: risk of O 2 competing with CO2 for rubisco in C3 plants / AW 4. Ref to: less CO 2 fixed, resulting in lower yield of C3 plants / AW (e)(i) Describe how yeast converts glucose to ethanol. [2] 1. Ref to: anaerobic conditions 2. Ref to: pyruvate forming ethanal 3. Ref to: reduction of ethanal (e)(ii) Explain why it may be better in the long term to use ethanol made from corn starch, rather than petrol, as a fuel for cars. [2] 1. Ref to: corn as renewable resource 2. Ref to: uptake of CO 2 by corn in photosynthesis 3. AVP

HWA CHONG INSTITUTION / 2016-2017 H2 BIOLOGY / Preliminary Examinations / Paper 3 / MS 2 (f)(i) With reference to Table 1.1, suggest the source of biodiesel chosen by an oil company if reduction of greenhouse gas emissions were the sole criterion. [1] palm oil from Malaysia (f)(ii) Explain your answer to (f)(i). [2] 1. Ref to: lowest emission due to change of land use and from cultivation, processing and distribution 2. Cite appropriate values (g) Identify two criteria, apart from cost, that should also