Cellular respiration: the equation and its three stages

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

1. 1.

   “model, not to scale” Ari reads a diagram of one stage of breaking down glucose. In box A, 1 glucose is split into 2 pyruvate. Where in the cell does stage A happen?

   • In the nucleus
   • In the cytoplasm
   • On the inner mitochondrial membrane
   • In the mitochondrial matrix
2. 2.

   Flow diagram (model, not to scale), drawn across a cell with one mitochondrion. No wavy arrow label is drawn. Bo reads a diagram of the citric acid cycle. In box B, an acetyl group joins a four-carbon molecule and CO2 is released. Where does stage B happen?

   • On the inner mitochondrial membrane
   • On a ribosome next to the nucleus
   • In the mitochondrial matrix
   • In the cytoplasm outside the mitochondrion

3. Read this first

   Use this

   Flow diagram (model, not to scale), drawn across a cell with one mitochondrion. Inputs in boxes on the left: electrons from NADH; oxygen. Outputs in boxes on the right: water. Box C is the chain of proteins. A wavy arrow points out: energy used to make ATP.

4. 3.

   Esme reads that oxygen is used at box C, a chain of proteins that passes electrons along. Where is this electron transport chain found?

   • In a vacuole near the cell membrane
   • On the inner mitochondrial membrane
   • In the matrix inside the mitochondrion
   • In the cytoplasm outside the mitochondrion

5. Equation card, from OpenStax Biology 2e

   C6H12O6 + 6O2 → 6CO2 + 6H2O + energy. Inputs in boxes on the left: glucose, C6H12O6; oxygen, 6O2. Outputs in boxes on the right: carbon dioxide, 6CO2; water, 6H2O. A wavy arrow points out: energy. The cell is a leaf cell kept in the dark.

6. 4.

   Jun reads that a leaf cell kept in the dark breaks down glucose to make ATP. Which two things does the respiration equation show going in?

   • Glucose and oxygen
   • Light and carbon dioxide
   • Glucose and carbon dioxide
   • Carbon dioxide and water

7. Equation card, from OpenStax Biology 2e

   C6H12O6 + 6O2 → 6CO2 + 6H2O + energy. Inputs in boxes on the left: glucose, C6H12O6; oxygen, 6O2. Outputs in boxes on the right: carbon dioxide, 6CO2; water, 6H2O. A wavy arrow points out: energy.

8. 5.

   Kira reads the respiration equation. How many oxygen molecules, O2, does the equation use for each glucose?

   • 2, the small number after the O
   • 12, the count of oxygen atoms instead
   • 1, the same count as the glucose
   • 6, the large number in front of the O2
9. 6.

   Flow diagram (model, not to scale), drawn on the inner membrane of a mitochondrion. Luz follows oxygen to the last stage. Oxygen picks up electrons and hydrogen ions at the end of the chain. What product forms in box D?

   • Carbon dioxide, CO2
   • Glucose, C6H12O6
   • Water, H2O
   • Pyruvate, from glycolysis

10. Glycolysis ATP count (real data, from OpenStax Biology 2e)

    measure	ATP per glucose
    ATP spent	2
    ATP made	4

11. 7.

    Noah reads that glycolysis spends 2 ATP and makes 4 ATP from one glucose. Which phrase describes the ATP glycolysis adds for the cell?

    • ATP made by the electron transport chain
    • A net gain of 4 ATP, with nothing spent
    • A small net gain of 2 ATP per glucose
    • Most of the ATP made from one glucose

12. Use this

    Flow diagram (model, not to scale), drawn inside a pea plant cell. No wavy arrow label is drawn. The cell has chloroplasts and mitochondria.

13. 8.

    Pia looks at a pea plant cell that has chloroplasts and mitochondria. What do the mitochondria do?

    • They stay idle, since chloroplasts handle the plant's energy
    • They use sugars to make ATP
    • They make glucose from light
    • They take in air through the leaf for the plant
14. 9.

    Ren reads a chart of where the ATP from glucose is made. Blank box D makes about 90 percent of the ATP. Which label fits D?

    • The citric acid cycle in the matrix
    • Pyruvate oxidation in the matrix
    • Glycolysis in the cytoplasm
    • Chemiosmosis on the inner membrane
15. 10.

    No wavy arrow label is drawn. Zee sees pyruvate broken down in the mitochondrial matrix, with a gas leaving at box G. The gas is made from pyruvate's carbon. Which label fits G?

    • Glucose, rebuilt from the pyruvate
    • Carbon dioxide, with carbon from pyruvate
    • Water vapor, formed from the pyruvate
    • Oxygen, the same gas the cell took in