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

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

6. 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 3 phosphate groups
   • 5 ATP, each with 4 phosphate groups
   • 5 ATP, each with 2 phosphate groups
   • 10 ATP, each with 3 phosphate groups

7. 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

8. 5.

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

   • 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
   • In a living cell, hydrolysis releases almost double the energy of the standard value
   • The standard value is the one measured inside living cells

9. 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

10. 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 P keeps ATP for hours, so it rebuilds less
    • Cell Q uses its ATP up for good, so it needs fewer mitochondria
11. 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
12. 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 ATP itself, which makes its own energy
    • From ATP stored in the cell last year
    • From the phosphate group, which holds energy of its own
    • From glucose broken down in cellular respiration

13. 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.

14. 9.

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

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

15. 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.

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