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?

   • ADP and Pi to ATP: it takes 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

2. Read this first

   Use this

   Flow diagram (model, not to scale), drawn inside the chloroplast. Inputs in boxes on the left: ADP; Pi. Outputs in boxes on the right: ATP; water. No wavy arrow label is drawn. Light shines on a pea leaf cell.

3. 2.

   Bo reads that light shines on a pea leaf and a chloroplast joins ADP and Pi into ATP. How is this change classified?

   • Hydrolysis: ATP splits and releases the light's energy
   • Regeneration: ADP and Pi join, and light supplies the energy
   • Regeneration: ADP and Pi join with no energy needed
   • Regeneration: ADP and Pi join, and the joining releases energy
4. 3.

   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
   • Storage: the pump holds ATP for later
   • Regeneration: the pump makes new ATP
   • Energy coupling: energy released from ATP powers the pump
5. 4.

   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, 2 on the right
   • 3 on the left, 3 on the right

6. 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.

7. 5.

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

8. 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

9. 6.

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

   • The standard value is the one measured inside living cells
   • 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

10. 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

11. 7.

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

    • 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
    • Cell P makes ATP from nothing, so it needs few mitochondria
12. 8.

    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
13. 9.

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

14. 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.

15. 10.

    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
    • Chloroplast uses light; mitochondrion uses glucose
    • Chloroplast uses glucose; mitochondrion uses light
    • Mitochondrion alone, because light cannot make ATP