ATP: the cell's energy carrier

Grade 9 Science Worksheet

Circle the best answer.

1. 1.

   No wavy arrow label is drawn. Ari reads that a muscle cell is moving its contractile proteins. Which change supplies the energy, and does it release or take in energy?

   • ATP to ADP and Pi: it takes in energy
   • ADP and Pi to ATP: it releases energy
   • ATP to ADP and Pi: it releases energy
   • ADP and Pi to ATP: it takes in energy
2. 2.

   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?

   • Used up: the ATP is gone for good after one change
   • Energy coupling: energy released from ATP powers the pump
   • Regeneration: the pump makes new ATP
   • Storage: the pump holds ATP for later
3. 3.

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

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

5. Read this first

   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

6. 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
   • Both values show energy taken in, since they are negative
   • 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

7. 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

8. 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 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
   • Cell P keeps ATP for hours, so it rebuilds less
9. 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 2, because joining ADP and Pi needs energy in
   • Change 2, because the new bond releases energy
   • Neither, because ATP changes need no energy exchange
   • Change 1, because breaking ATP down releases energy
10. 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 ATP itself, which makes its own energy
    • From the phosphate group, which holds energy of its own

11. 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.

12. 9.

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

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

13. 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.

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