UNIVERSITY OF YORK. BA, BSc, and MSc Degree Examinations Department: BIOLOGY. Title of Exam: Biofuels and biotechnology. Time Allowed: 2 hours

Transcription

1 Examination Candidate Number: UNIVERSITY OF YORK Desk Number: BA, BSc, and MSc Degree Examinations Department: BIOLOGY Title of Exam: Biofuels and biotechnology Time Allowed: 2 hours Marking Scheme: Total marks available for this paper: 100 Section A: Short Answer / Problem / Experimental Design questions (50 marks) Section B: Essay question (marked out of 100, weighted 50 marks) The marks available for each question are indicated on the paper Instructions: Section A: Answer all questions in the spaces provided on the examination paper Section B: Answer either question A or question B. Write your answer on the separate paper provided and attach it to the back of the question paper using the treasury tag provided For marker use only: For office use only: Total as % DO NOT WRITE ON THIS BOOKLET BEFORE THE EXAM BEGINS DO NOT TURN OVER THIS PAGE UNTIL INSTRUCTED TO DO SO BY AN INVIGILATOR page 1 of 7

2 SECTION A: Short Answer / Problem / Experimental Design questions Answer all questions in the spaces provided Mark total for this section: For biofuels, their uptake and use by consumers depends on many factors beyond the science. a) In the context of the UK, what are our current commitments to using biofuels in cars and lorries? (2 marks) b) What changes are likely to be made to these policies between now and 2020 (3 marks) c) If the price of Brent crude oil in January 2018 was $100 per barrel, how would this impact on markets for biofuels? (2 marks) d) What is the simplest single thing the government could do today to encourage people to use biofuels in their cars? (1 mark) 2. Much biofuel production is mediated by microbial fermentation pathways. page 2 of 7

3 a) Compared to other common fermentations used to make biofuels, what is unique about the ABE fermentation? b) If you were going to make ethanol industrially, would you use yeast or Zymonomas mobilis as your production organism? Justify your answer by outlining the pro- and cons of these two producers. (5 marks) 3. Imagine you are trying to improve lignocellulose degrading capabilities by looking for cellulases with enhanced properties. a) Describe a strategy you could use to identify genes encoding page 3 of 7

4 functional cellulases from the genome of a new microbe you have sequenced that lives on decaying plant biomass. b) If you wanted to use your new cellulase in an E. coli strain that you were engineering for consolidated bioprocessing, what methods might you use to ensure that this protein is effectively secreted? (4 marks) page 4 of 7

5 4. What did Floudas et al. (2015, Science) propose as part of the explanation for the rapid accumulation of coal during the carboniferous period? As part of your answer, explain what coal is at a molecular level (1 mark), and what mechanisms and factors slowed the rates of coal formation in the late carboniferous (3 marks). How did Floudas et al. reach their conclusions (2 marks)? 5. With reference to the major components of plant secondary cell walls, explain what features of the woody cell walls of gymnosperms might make them a more attractive feedstock for bioethanol production by yeast than the woody cell walls of angiosperms? 6. Primary plant cell walls are strong but extensible enough to allow cell expansion, whereas secondary cell walls provide strength, rigidity and page 5 of 7

6 durability. Both are based on a framework of cellulose microfibrils, explain how the nature of the other polymers of the cell wall and their interactions influence these properties. (9 marks) page 6 of 7

7 SECTION B: Essay question Answer one question on the separate paper provided Remember to write your candidate number at the top of the page and indicate whether you have answered question A or B Mark total for this section: 50 EITHER A) Given the range of renewable energy sources available, explain why the UK needs to consider the development of cellulosic bioethanol production in the coming decades and how this might be achieved. OR B) Two of the major transportation biofuels, bioethanol and biobutanol, are currently produced from microbes using natural fermentation pathways. Both products are toxic to the producing cell, limiting overall productivity. Critically assess different routes to engineer improved organisms that can tolerate high levels of product. page 7 of 7