Photosynthesis: the balanced equation and where the energy goes

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

1. Read this first

   Use this

   Flow diagram (model, not to scale), drawn inside the chloroplast. Inputs in boxes on the left: 6CO₂; 6H₂O. Outputs in boxes on the right: C₆H₁₂O₆; 6O₂. A wavy arrow points into the reaction: light energy.

2. 1.

   Ari reads 6CO₂ in the flow diagram. What does the 6 in front of CO₂ tell Ari?

   • 6 molecules of carbon dioxide
   • 6 grams of carbon dioxide
   • 6 carbon atoms in one CO₂ molecule
   • 6 oxygen atoms in one CO₂ molecule
3. 2.

   Bo sees light energy on the left side of the photosynthesis equation. What kind of part is light energy?

   • An input: matter that adds atoms to glucose
   • An input: energy that goes in and is stored
   • An output: energy that the reaction releases
   • An output: energy that leaves as oxygen gas

4. Use this

   Flow diagram (model, not to scale), drawn inside the chloroplast. Inputs in boxes on the left: carbon dioxide; water. Outputs in boxes on the right: glucose; oxygen gas. A wavy arrow points into the reaction: light energy. Arrow X runs from the water box to the oxygen gas box. Arrow Y runs from the carbon dioxide box to the oxygen gas box.

5. 3.

   Esme follows the oxygen gas released by a leaf. Which arrow shows where that oxygen comes from?

   • Arrow X, from the water: splitting water frees oxygen
   • Arrow Y, from the carbon dioxide: CO₂ gives up its oxygen
   • Neither arrow: the leaf takes oxygen in from the air
   • Arrow X reversed, from the oxygen gas to the water

6. Use the table

   Formula card (model data, not to scale): one glucose molecule, C₆H₁₂O₆.

   element	subscript
   C	6
   H	12
   O	6

7. 4.

   Jun reads the formula card for one glucose molecule. How many oxygen atoms does one molecule hold?

   • 24 oxygen atoms
   • 6 oxygen atoms
   • 12 oxygen atoms
   • 1 oxygen atom

8. Use this

   Flow diagram (model, not to scale), drawn inside the chloroplast. Inputs in boxes on the left: 6CO₂; 6H₂O. Outputs in boxes on the right: C₆H₁₂O₆; 6O₂. A wavy arrow points into the reaction: light energy.

9. 5.

   Kira reads 6CO₂ on the left. Atoms = coefficient × subscript. How many oxygen atoms is that?

   • 8 oxygen atoms
   • 2 oxygen atoms
   • 12 oxygen atoms
   • 6 oxygen atoms
10. 6.

    The 6H₂O on the left holds 12 hydrogen atoms. Luz counts hydrogen atoms in C₆H₁₂O₆ and 6O₂ on the right. How many are there?

    • 0 hydrogen atoms, since hydrogen is used up
    • 12 hydrogen atoms, all in the glucose
    • 24 hydrogen atoms, since O₂ adds 12 more
    • 6 hydrogen atoms, since half are lost

11. Use this

    Flow diagram (model, not to scale), drawn inside the leaf. Inputs in boxes on the left: carbon dioxide, which enters through the openings marked S; water, from the roots. Outputs in boxes on the right: glucose; oxygen gas, which leaves through the openings marked S. S marks tiny openings on the underside of the leaf.

12. 7.

    Milo reads that gas moves through stomata in the leaf diagram. Which phrase tells what stomata are?

    • The leaf layer where sugar is made
    • Cell parts that absorb light for the leaf
    • Small openings in a leaf that take in soil to build sugar
    • Small openings in a leaf for gas exchange
14. 8.

    Noah reads that plant cells carry out photosynthesis in chloroplasts. Which phrase tells what a chloroplast is?

    • A cell part that breaks glucose down to make ATP
    • A cell part that carries out photosynthesis
    • A cell part that turns carbon dioxide into oxygen gas
    • A leaf opening that lets gases in and out
15. 9.

    Pia reads that plants are photoautotrophs. Which phrase tells what a photoautotroph is?

    Use the picture in question 8.

    • An organism that makes its own food using light
    • An organism that builds its body from soil it takes in
    • An organism that relies on sugars made by other organisms
    • An organism that gets energy from inorganic chemicals

16. Use this

    Flow diagram (model, not to scale), drawn inside the chloroplast. Inputs in boxes on the left: 6CO₂; 6H₂O. Outputs in boxes on the right: C₆H₁₂O₆; 6O₂. Letter D marks a wavy arrow touching the reaction; its label is blank.

17. 10.

    Ren reads a flow diagram of photosynthesis with a blank wavy arrow D touching the reaction. Which label fits D?

    • Energy out: released as the glucose forms
    • No energy moves: CO₂ and glucose hold equal energy
    • Light energy in: taken in and stored in the glucose bonds
    • Light energy in: it becomes the atoms of the glucose