With and without oxygen: respiration and fermentation

Grade 9 Science Worksheet

Circle the best answer.

1. Read this first

   ATP card (sourced values)

   path	ATP in total per 1 glucose
   Aerobic respiration	about 30
   Fermentation	2

2. 1.

   Kira's class models a cell with no oxygen that ferments 5 glucose. Using the card, how many ATP does the cell make in total?

   • 20 ATP, 4 for each glucose
   • 150 ATP, 30 for each glucose
   • 0 ATP, since there is no oxygen
   • 10 ATP, 2 for each glucose
3. 2.

   Luz uses the card to find how many more ATP 1 glucose gives by aerobic respiration than by fermentation.

   • About 32 more ATP
   • About 30 more ATP
   • About 15 more ATP
   • About 28 more ATP
4. 3.

   Flow diagram (model, not to scale), drawn in a muscle cell with no oxygen. Glycolysis of 1 glucose makes 2 NADH in a muscle cell with no oxygen. Noah asks how many NAD+ fermentation regenerates.

   • 4 NAD+, two for each pyruvate
   • 1 NAD+, one for each glucose
   • 0 NAD+, because fermentation uses it up
   • 2 NAD+, one for each NADH
5. 4.

   A yeast cell in dough has no oxygen, and its fermentation step is blocked. Pia asks what happens to glycolysis, and why.

   • It stops, because no NAD+ is regenerated for its sixth step
   • It speeds up, because NADH builds up and acts as fuel
   • It continues, because fermentation makes the oxygen it needs
   • It continues, and makes about 30 ATP from the glucose

6. Use this

   Flow diagram (model data, not to scale), drawn in a cell with no oxygen. Input box on the left: 1 glucose. Start: 2 NAD+ and 0 NADH. After glycolysis, in the cytoplasm: 0 NAD+, 2 NADH and 2 pyruvate. After fermentation, in the cytoplasm: 2 NAD+, 0 NADH and 2 lactate.

7. 5.

   Ren counts NAD+ in a cell with no oxygen as 1 glucose goes through glycolysis and then fermentation. How does the end count compare with the start?

   • More: oxygen restores extra NAD+ at the end
   • Fewer: glycolysis uses up the NAD+ for good
   • The same: 2 NAD+ at the end, as at the start
   • More: fermentation makes extra NAD+ from glucose

8. Case card (model)

   a hard sprint. In the muscle cells, the oxygen supply is low. Pyruvate from glycolysis is available. The choices name four processes.

9. 6.

   Tala runs a hard sprint, and the muscle cells run short of oxygen. Which process keeps glycolysis going in those muscle cells?

   • No fermentation; that is done by yeast cells instead
   • Aerobic respiration, which needs no oxygen in muscle cells
   • No process; muscle cells stop making ATP until oxygen returns
   • Lactic acid fermentation, which regenerates NAD+

10. Case card (model)

    Warm milk with live yogurt bacteria. The milk becomes sour and thick. The milk sugar is lactose. The choices name four statements.

11. 7.

    Bacteria in warm milk make the milk sour and thick. Which statement about these bacteria does Zee find matches the evidence?

    • They respire with oxygen and release CO2, which thickens the milk
    • They make about 30 ATP from each sugar, which sours the milk
    • They are yeast cells releasing CO2, which thickens the milk
    • They ferment lactose into lactic acid, which sours the milk and clumps its proteins

12. Case card (model)

    a sample of wetland mud with no oxygen. Microbes pass electrons along an electron transport chain to sulfate. The sulfate becomes hydrogen sulfide gas. The choices name four processes.

13. 8.

    Waterlogged mud has no oxygen left. Ari reads that some microbes there make ATP with an electron transport chain that ends with sulfate. What is this process?

    • Fermentation, since it also runs without oxygen
    • No ATP process, since microbes need oxygen to make ATP
    • Aerobic respiration, since sulfate contains oxygen atoms
    • Anaerobic respiration, since the chain ends with a molecule other than oxygen
14. 9.

    “A pH below 4.6 gives a yogurt texture (University of Guam extension)” Esme's class reads the milk culture card (model data). At what time has the pH first dropped below 4.6, and what lowers it?

    • 4 hours; lactic acid made by the bacteria
    • 6 hours; the bacteria need oxygen to make the acid
    • 6 hours; yeast cells must have made the acid
    • 6 hours; lactic acid made by the bacteria

15. Mud core card (model data)

    depth (cm)	oxygen (mg/L)
    0	8
    2	3
    5	0
    10	0

16. 10.

    Jun's class reads the mud core card (model data). At what depth does oxygen first read 0, and what must microbes there do for ATP?

    • 5 cm; they make no ATP without oxygen
    • 5 cm; they must ferment or use another final electron acceptor
    • 5 cm; fermentation and anaerobic respiration are the same thing
    • 2 cm; aerobic respiration has already stopped there