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
   • 0 ATP, since there is no oxygen
   • 10 ATP, 2 for each glucose
   • 150 ATP, 30 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 30 more ATP
   • About 28 more ATP
   • About 15 more ATP
   • About 32 more ATP
4. 3.

   A model cell with no oxygen needs 40 ATP in total. Using the card, how many glucose must Milo's cell ferment?

   • About 1 glucose
   • 10 glucose
   • 20 glucose
   • 80 glucose
5. 4.

   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.

   • 2 NAD+, one for each NADH
   • 0 NAD+, because fermentation uses it up
   • 1 NAD+, one for each glucose
   • 4 NAD+, two for each pyruvate
6. 5.

   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

7. 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.

8. 6.

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

9. 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.

10. 7.

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

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

11. 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.

12. 8.

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

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

13. Dough card (model data)

    time (min)	dough with yeast (cm)	dough without yeast (cm)
    0	4	4
    30	6	4
    60	8	4
    90	10	4

14. 9.

    Bo's class reads the dough card (read about only). By how many cm did the yeast dough rise in 90 minutes, and what does the other dough show?

    • 6 cm; the dough without yeast rose too, but less
    • 6 cm; the dough without yeast did not rise
    • 10 cm; the dough without yeast did not rise
    • 6 cm; the dough without yeast shows the yeast used up the sugar
15. 10.

    “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?

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