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

2. 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.

3. 2.

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

4. 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.

5. 3.

   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?

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

6. 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.

7. 4.

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

   • 12, the count of oxygen atoms instead
   • 1, the same count as the glucose
   • 6, the large number in front of the O2
   • 2, the small number after the O
8. 5.

   Flow diagram (model, not to scale), drawn across a cell. Milo hears that cells carry out cellular respiration. Which phrase tells what cellular respiration means?

   • Breathing air in and out through the lungs
   • Using glucose and oxygen in cells to make ATP
   • Making glucose from light, water and carbon dioxide
   • Making new energy inside the cell from nothing

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

   measure	ATP per glucose
   ATP spent	2
   ATP made	4

10. 6.

    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
    • Most of the ATP made from one glucose
    • A small net gain of 2 ATP per glucose

11. 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.

12. 7.

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

    • They make glucose from light
    • They stay idle, since chloroplasts handle the plant's energy
    • They use sugars to make ATP
    • They take in air through the leaf for the plant
13. 8.

    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?

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

14. Use this

    Flow diagram (model, not to scale), drawn across a cell. Inputs in boxes on the left: glucose; oxygen. Outputs in boxes on the right: carbon dioxide; water. A wavy arrow F points out of the reaction; its label is blank.

15. 9.

    Tala sees glucose and oxygen go into a cell, with a wavy arrow F pointing out. Which label fits the wavy arrow F?

    • Air breathed out by the lungs
    • Light energy from the Sun
    • New energy made by the cell
    • Energy moved into ATP and heat
16. 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
    • Oxygen, the same gas the cell took in
    • Water vapor, formed from the pyruvate