Photosynthesis: How Plants Make Food

Biology

This content explains the process of photosynthesis, how plants use light, water, and carbon dioxide to create glucose and oxygen. It also discusses the importance of photosynthesis for providing energy and oxygen to most life on Earth, and its role in the carbon cycle.

Photosynthesis Plant Biology Ecology

21 Questions Easy Ages 8+ Mar 9, 2026

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About this Study Set

This study set covers Biology through 21 practice questions. This content explains the process of photosynthesis, how plants use light, water, and carbon dioxide to create glucose and oxygen. It also discusses the importance of photosynthesis for providing energy and oxygen to most life on Earth, and its role in the carbon cycle. Every question includes the correct answer so you can learn as you go — pick any format above to get started.

Questions & Answers

Browse all 21 questions from the Photosynthesis: How Plants Make Food study set below. Each question shows the correct answer — select a study format above to practice interactively.

1 What does the prefix 'photo' mean?

A Making
B Light
C Energy
D Water

2 What does the suffix 'synthesis' mean?

A Making
B Light
C Energy
D Water

3 What are the two main reactants used by plants in photosynthesis?

A Glucose and oxygen
B Sunlight and chlorophyll
C Water and carbon dioxide
D Soil and air

4 What is the source of energy for photosynthesis?

A Water
B Carbon dioxide
C Sunlight
D Chlorophyll

5 What green pigment captures the energy in sunlight?

A Glucose
B Oxygen
C Water
D Chlorophyll

6 Where is chlorophyll found in plants?

A Roots
B Stems
C Leaves
D Flowers

7 What are the two new substances made during photosynthesis?

A Water and carbon dioxide
B Sunlight and energy
C Glucose and oxygen
D Chlorophyll and soil

8 What is the word equation for photosynthesis?

A Glucose + oxygen -> water + carbon dioxide
B Water + carbon dioxide -> glucose + oxygen
C Sunlight + chlorophyll -> glucose + water
D Oxygen + water -> carbon dioxide + glucose

9 Where does photosynthesis primarily happen in a plant?

A Roots
B Flowers
C Leaves
D Stems

10 Why is photosynthesis important for most other organisms?

A It produces carbon dioxide
B It provides energy in the form of chemical energy in nutrients
C It absorbs sunlight
D It releases water vapor

11 What do carbohydrates contain that was originally in sunlight?

A Water
B Carbon dioxide
C Energy
D Oxygen

12 According to food chains, where does most of the energy in all the food in the world come from?

A Animals
B Fungi
C Plants
D Bacteria

13 What is the second major reason photosynthesis is important?

A It produces water
B It provides oxygen for the Earth's atmosphere
C It creates soil
D It absorbs carbon dioxide

14 What do animals and plants need oxygen for?

A Photosynthesis
B Respiration
C Digestion
D Growth

15 Oxygen is a waste product of which process?

A Respiration
B Digestion
C Photosynthesis
D Germination

16 Approximately what percentage of the air around us is oxygen?

A 5%
B 10%
C 20%
D 50%

17 When the Earth was first formed, what was almost absent in its atmosphere?

A Carbon dioxide
B Water vapor
C Nitrogen
D Oxygen

18 Scientists think oxygen first began to collect in the air when what began to photosynthesise?

A Plants
B Animals
C Bacteria
D Fungi

19 If photosynthesis had never begun on Earth, what would have been unable to live here?

A Plants
B Bacteria
C Animals
D Fungi

20 Explain how a lizard eating a grasshopper relies on photosynthesis for energy.

A The lizard directly eats plants for energy.
B The grasshopper eats plants which contain energy captured by photosynthesis, and the lizard eats the grasshopper.
C The lizard uses sunlight to make its own food.
D Photosynthesis produces oxygen which the lizard breathes to get energy.

21 Explain one other reason (apart from food) why a lizard would not be able to survive if there were no plants on Earth.

A There would be no soil for the lizard to burrow in.
B There would be no oxygen for the lizard to breathe.
C The temperature would be too high.
D There would be no water available.

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