Worked example
Which process uses light energy to make sugar from carbon dioxide and water in the simplified overall model?
Answer & why
Answer: photosynthesis
Photosynthesis transfers light energy into chemical energy stored in sugars.
Grade 7 · Science
Compare photosynthesis and cellular respiration
Use simplified overall models to compare matter inputs and outputs of photosynthesis and aerobic respiration.
6 authored questions + worked example
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All questions
All 6 authored questions for this skill.
Question 1
A claim says that green plants only photosynthesize and never respire. Which correction is appropriate?
- photosynthesis
- both processes occur in plants
- aerobic cellular respiration
- neither process
A hint
Photosynthesis uses carbon dioxide, water and light energy to form sugars and oxygen in the simplified model.
Answer & why
Answer: both processes occur in plants
Plant cells respire; photosynthetic plant cells can also photosynthesize when conditions allow.
Question 2
Which process has oxygen as an overall product in the simplified light-driven sugar-making model?
- photosynthesis
- aerobic cellular respiration
- neither process
- both processes occur in plants
A hint
Photosynthesis uses carbon dioxide, water and light energy to form sugars and oxygen in the simplified model.
Answer & why
Answer: photosynthesis
The overall photosynthesis model includes oxygen among its products.
Question 3
Which process has oxygen as an overall reactant when sugar is broken down aerobically?
- both processes occur in plants
- aerobic cellular respiration
- neither process
- photosynthesis
A hint
Photosynthesis uses carbon dioxide, water and light energy to form sugars and oxygen in the simplified model.
Answer & why
Answer: aerobic cellular respiration
Aerobic respiration requires oxygen in its overall reaction.
Question 4
An object slides down a ramp without any biological activity. Which of these cell processes describes that motion itself?
- neither process
- both processes occur in plants
- aerobic cellular respiration
- photosynthesis
A hint
Photosynthesis uses carbon dioxide, water and light energy to form sugars and oxygen in the simplified model.
Answer & why
Answer: neither process
Sliding on a ramp is mechanical motion, not photosynthesis or cellular respiration.
Question 5
Which process uses light energy to make sugar from carbon dioxide and water in the simplified overall model?
- neither process
- aerobic cellular respiration
- photosynthesis
- both processes occur in plants
A hint
Photosynthesis uses carbon dioxide, water and light energy to form sugars and oxygen in the simplified model.
Answer & why
Answer: photosynthesis
Photosynthesis transfers light energy into chemical energy stored in sugars.
Question 6
Which process uses sugar and oxygen while releasing carbon dioxide and water in the overall model?
- photosynthesis
- aerobic cellular respiration
- neither process
- both processes occur in plants
A hint
Photosynthesis uses carbon dioxide, water and light energy to form sugars and oxygen in the simplified model.
Answer & why
Answer: aerobic cellular respiration
Aerobic respiration transfers energy from fuel molecules to cellular processes.