ATP: the cell's energy carrier

Grade 9 Science Worksheet

Circle the best answer.

1. 1.

   Flow diagram (model, not to scale), drawn inside the cell membrane. Esme reads that ATP gives a phosphate to a pump protein in the cell membrane, and the pump changes shape. What does this show?

   • Energy coupling: energy released from ATP powers the pump
   • Used up: the ATP is gone for good after one change
   • Regeneration: the pump makes new ATP
   • Storage: the pump holds ATP for later
2. 2.

   Flow diagram (model, not to scale), drawn inside the cell. A wavy arrow points out of the reaction: energy released. Jun counts phosphate groups when ATP and water become ADP and Pi. How many are on the left side and on the right side?

   • 3 on the left, 4 on the right
   • 1 on the left, 3 on the right
   • 3 on the left, 3 on the right
   • 3 on the left, 2 on the right
3. 3.

   Kira follows 6 ATP molecules that are broken down into ADP and Pi. After the change, how are all the phosphate groups shared?

   • 18 in ADP molecules and 6 as Pi
   • 6 in ADP molecules and 12 as Pi
   • 18 in ADP molecules and 0 as Pi
   • 12 in ADP molecules and 6 as Pi

4. Read this first

   Use this

   Flow diagram (model, not to scale), drawn inside the mitochondrion. Inputs in boxes on the left: 5 ADP molecules; 5 Pi groups. Outputs in boxes on the right: 5 ATP molecules; water. No wavy arrow label is drawn.

5. 4.

   Luz sees 5 ADP and 5 Pi joined into ATP in a mitochondrion. How many ATP form, and how many phosphate groups does each hold?

   • 5 ATP, each with 2 phosphate groups
   • 10 ATP, each with 3 phosphate groups
   • 5 ATP, each with 3 phosphate groups
   • 5 ATP, each with 4 phosphate groups

6. Free energy of ATP hydrolysis (real data, from OpenStax Biology 2e)

   conditions	∆G (kcal/mol)	∆G (kJ/mol)
   standard conditions	−7.3	−30.5
   living cell	−14	−57

7. 5.

   Milo compares the two ATP hydrolysis values on the card. Which statement is right?

   • In a living cell, hydrolysis releases almost double the energy of the standard value
   • In a living cell, hydrolysis releases less energy, since −14 is smaller than −7.3
   • The standard value is the one measured inside living cells
   • Both values show energy taken in, since they are negative

8. Two model cells (model data)

   cell	mitochondria in one slice	ATP rebuilt per minute
   Cell P (resting muscle)	40	600
   Cell Q (working muscle)	400	6000

9. 6.

   Noah reads a model card for two muscle cells. Which statement does the card support?

   • Cell P makes ATP from nothing, so it needs few mitochondria
   • Cell P keeps ATP for hours, so it rebuilds less
   • Cell Q has 10 times the mitochondria and rebuilds 10 times the ATP
   • Cell Q uses its ATP up for good, so it needs fewer mitochondria
10. 7.

    Flow diagram (model, not to scale), drawn inside the cell. No wavy arrow label is drawn. Pia learns that a negative ∆G means a reaction releases energy. Which of the two changes has a positive ∆G, and why?

    • Change 1, because breaking ATP down releases energy
    • Change 2, because joining ADP and Pi needs energy in
    • Neither, because ATP changes need no energy exchange
    • Change 2, because the new bond releases energy
11. 8.

    “model, not to scale” Ren reads that a leg muscle cell rebuilds ATP from ADP and Pi. Where does the energy for this come from?

    • From glucose broken down in cellular respiration
    • From ATP stored in the cell last year
    • From the phosphate group, which holds energy of its own
    • From ATP itself, which makes its own energy

12. Use this

    Flow diagram (model, not to scale), drawn inside the plant cell. Inputs in boxes on the left: ADP; Pi. Outputs in boxes on the right: ATP. A wavy arrow points into the reaction: energy from light, and energy from glucose breakdown.

13. 9.

    Tala studies a leaf cell in daylight. Which two cell parts help rebuild its ATP, and what energy does each use?

    • Mitochondrion alone, because light cannot make ATP
    • Chloroplast alone, because plants skip cellular respiration
    • Chloroplast uses light; mitochondrion uses glucose
    • Chloroplast uses glucose; mitochondrion uses light

14. Use this

    Flow diagram (model, not to scale), drawn inside the cell. No wavy arrow label is drawn. In this model cell, the pathways that break down glucose are stopped.

15. 10.

    Zee reads a model cell where the pathways that break down glucose are stopped. After the ATP already present is used, what happens to ATP rebuilding, and why?

    • Rebuilding goes on, because ADP and Pi make energy by themselves
    • Rebuilding goes on, because stored ATP lasts for months
    • Rebuilding stops, because used ATP cannot be rebuilt, even with energy
    • Rebuilding stops, because no energy arrives to join ADP and Pi