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1.3 Respiration

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Question 39

An investigation is conducted to compare the metabolic pathways of yeast (Saccharomyces cerevisiae) under different gas environments using two identical bioreactors containing a sterile 10% glucose solution:

  • Bioreactor 1 is continuously bubbled with pure nitrogen gas (N2N_2N2​) to maintain strict anoxic (anaerobic) conditions.
  • Bioreactor 2 is continuously bubbled with sterile air containing oxygen (O2O_2O2​) to maintain oxic (aerobic) conditions.

Both bioreactors are monitored over a 12-hour period at a constant ambient temperature of 25∘C25^\circ\text{C}25∘C to measure the accumulation of ethanol and the total thermal energy released.

Which of the following correctly describes the relative ethanol concentration and the relative heat energy released by the end of the experiment?

A

Bioreactor 2 has a higher ethanol concentration; Bioreactor 1 has a higher heat energy release.

B

Bioreactor 1 has a higher ethanol concentration; Bioreactor 1 has a higher heat energy release.

C

Bioreactor 1 has a higher ethanol concentration; Bioreactor 2 has a higher heat energy release.

D

Bioreactor 2 has a higher ethanol concentration; Bioreactor 2 has a higher heat energy release.

Markscheme

1.3 Respiration Questions

  1. GCSE
  2. /Biology
  3. /1.3 Respiration

113 exam-style questions on OCR GCSE Biology 1.3 Respiration, covering 1.3.1 Cellular respiration supplies ATP, 1.3.2 Aerobic and anaerobic respiration, 1.3.3 Sugars and carbohydrates, 1.3.4 Amino acids and proteins, and 1.3.5 Fatty acids and lipids. Each one has a worked solution and a mark scheme showing where the marks go.

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