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9th grade · Science · Unit 6 of 7

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.

Minnesota K-12 Academic Standards benchmark: 9L.3.1.1.3; 9L.3.1.1.4 · how photosynthesis stores energy and cellular respiration releases it

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 Minnesota

In the Minnesota K-12 Academic Standards, this is unit 6 of 7 in 9th grade Science, after Electric Current and before Evolution & Selection.

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: Minnesota Department of Education (MDE)

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

    What are the products of photosynthesis?

    • water and oxygen only
    • carbon dioxide and glucose
    • carbon dioxide and water
    • glucose and oxygen

  2. Question 2

    Why are photosynthesis and cellular respiration called complementary?

    • They both need light
    • The products of each are the reactants of the other
    • They both make oxygen
    • They both happen only in animals

  3. Question 3

    Where in a plant cell does photosynthesis happen?

    • mitochondria
    • the nucleus
    • chloroplasts
    • the cell wall

  4. Question 4

    What are the products of cellular respiration?

    • oxygen and water only
    • glucose and oxygen
    • glucose and light
    • carbon dioxide, water and usable energy

  5. Question 5

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

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

  6. Question 6

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

    • nitrogen
    • carbon dioxide
    • hydrogen
    • oxygen

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