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9th grade · Science · Unit 6 of 14

Photosynthesis & Respiration

How cells make and use energy

What your child practices

The reactants, products and location of photosynthesis and cellular respiration, why they are complementary, and how they link plants, animals and the carbon cycle.

Texas Essential Knowledge and Skills (TEKS) teks student expectation: B.11(A) · matter and energy in photosynthesis and cellular respiration

How we explain it

Children can open this short lesson before they practice.

  1. Photosynthesis (in chloroplasts): carbon dioxide + water + light → glucose + oxygen.
  2. Cellular respiration (in mitochondria): glucose + oxygen → carbon dioxide + water + energy.
  3. The products of each are the reactants of the other, which cycles carbon.

Example: Which process releases oxygen: photosynthesis or respiration? Respiration uses oxygen. Photosynthesis gives it off. Answer: photosynthesis

Photosynthesis & Respiration in Texas

In the Texas Essential Knowledge and Skills (TEKS), this is unit 6 of 14 in 9th grade Science, after Evolution & Selection and before Biomolecules & Enzymes.

Gradelings describes a child's practice on this unit as Beginning, Approaching, Meeting or Exceeding (Four practice steps). That reflects practice, not a report-card mark: the teacher decides the mark.

Source: Texas Education Agency (TEA)

Sample questions

A taste of this unit. In the app, questions change every time and get easier or harder to match your child.

  1. Question 1

    A sealed jar holds a healthy plant and a small snail in the light. Why can both survive for a while?

    • Neither one uses energy
    • The plant makes no oxygen
    • The plant's oxygen supports the snail's respiration, and the snail's carbon dioxide supports the plant
    • The snail makes oxygen

  2. Question 2

    Which is an energy transformation in photosynthesis?

    • light energy to chemical energy
    • kinetic energy to light energy
    • thermal energy to sound energy
    • chemical energy to light energy

  3. Question 3

    Which gas released by photosynthesis do animals use in cellular respiration?

    • carbon dioxide
    • oxygen
    • nitrogen
    • hydrogen

  4. Question 4

    At night a plant makes no glucose by photosynthesis. What does it do with carbon dioxide?

    • It stops all chemical reactions
    • It takes in even more carbon dioxide
    • It releases carbon dioxide from cellular respiration
    • It releases only oxygen

  5. Question 5

    In 6 H₂O, how many hydrogen atoms are there altogether?

    answer box

  6. Question 6

    What are the reactants of cellular respiration?

    • glucose and oxygen
    • carbon dioxide and water
    • light and water
    • glucose and carbon dioxide

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