With and without oxygen: respiration and fermentation

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

1. 1.

   Bo reads a flow diagram of a cell with plenty of oxygen. After glycolysis, which branch runs, and where?

   • Branch A, in the cytoplasm, where glycolysis happens
   • Branch B, in the mitochondrion, since fermentation comes first
   • Branch B, in the cytoplasm, because fermentation uses the oxygen
   • Branch A, in the mitochondrion

2. Read this first

   Use this

   Flow diagram (model, not to scale), drawn across a cell. Input box on the left: 1 glucose. Stage A turns 1 glucose into 2 pyruvate, with a net of 2 ATP. Then branch 1 (oxygen present) and branch 2 (oxygen absent) both start from the pyruvate.

3. 2.

   Esme sees stage A at the start of both branches. In stage A, 1 glucose becomes 2 pyruvate. Name stage A and its place.

   • Glycolysis, in the cytoplasm
   • Fermentation, in the mitochondrion
   • Glycolysis, in the mitochondrion
   • Fermentation, in the cytoplasm
4. 3.

   Jun reads a reaction in a muscle cell low on oxygen: pyruvate + NADH → A + NAD+. What goes in box A?

   • Lactate, also called lactic acid
   • Carbon dioxide, released as a gas
   • NADH, made again from the NAD+
   • ATP, made by the fermentation step
5. 4.

   Flow diagram (model, not to scale). No wavy arrow is drawn. Kira reads about yeast in bread dough. The yeast ferment sugar and release gas A, which makes the dough rise. Name gas A.

   • Lactic acid, a liquid from the sugar
   • Carbon dioxide gas (CO2)
   • Oxygen gas (O2) from the air
   • Hydrogen gas (H2) from the sugar
6. 5.

   The words are aerobic respiration. Four meanings are listed in the choices. Milo matches the words aerobic respiration to their meaning. Which meaning is right?

   • Respiration that uses oxygen as the final electron acceptor
   • Respiration that makes ATP without using any oxygen
   • A way to turn NADH back into NAD+ with pyruvate
   • Respiration that nets about 2 ATP per glucose in total
7. 6.

   The word is fermentation. Four jobs are listed in the choices. Noah matches the word fermentation to its job in a cell. Which job is right?

   • Turning NADH back into NAD+ so glycolysis can continue
   • Using oxygen to finish breaking down the pyruvate
   • Making NADH so the cell has more electron carriers
   • Making most of the cell's ATP after glycolysis
8. 7.

   The word is anaerobic, on a card about mud. Four meanings are listed in the choices. Pia sees the word anaerobic on a card about mud. What does anaerobic describe?

   • A process that cannot make any ATP
   • A process found in yeast cells alone
   • A process that runs without oxygen
   • A process that needs oxygen to get started

9. ATP card (sourced values)

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

10. 8.

    Ren reads the ATP card. How many ATP does fermentation make in total from 1 glucose?

    • 0 ATP
    • 4 ATP
    • 2 ATP
    • about 30 ATP

11. Cell card (model data)

    cell	oxygen	ATP in total
    Cell P	present	about 30
    Cell Q	absent	2

12. 9.

    Tala reads a card of two cells that each start with 1 glucose. Which cell makes more ATP in total?

    • Cell P, with about 2 ATP, since oxygen cells make less
    • Cell Q, because fermentation makes more ATP
    • Cell P, with about 30 ATP
    • Neither, because the two cells make the same

13. Use this

    Flow diagram (model, not to scale), drawn in the cytoplasm. Input box on the left: 1 glucose. Output boxes on the right: 2 pyruvate; net 2 ATP; B NADH, where B is a blank number.

14. 10.

    Zee reads the glycolysis box. How many NADH does glycolysis make from 1 glucose?

    • 0 NADH, because NADH is made in the mitochondrion
    • 4 NADH, two for each pyruvate
    • 1 NADH, one for each glucose
    • 2 NADH, one for each pyruvate