AQA · GCSE · Combined Science
Course version: 8464 · Version from Sept 2018
Photosynthetic reaction: light glucose + oxygen
This statement is part of the word equation for photosynthesis, showing that light energy is needed and that glucose and oxygen are produced.
Checked against the AQA 8464 specification (opens in a new tab) on .
- Point 2 of 5
- 3 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
This statement is part of the word equation for photosynthesis, showing that light energy is needed and that glucose and oxygen are produced. The full word equation is carbon dioxide + water → glucose + oxygen, with light energy shown above the arrow. Light is absorbed by chlorophyll in chloroplasts and provides the energy to convert carbon dioxide and water into glucose. Oxygen is released as a by-product. The glucose formed is used in respiration, stored as starch, or used to build cellulose, amino acids and lipids.
What earns the marks
- Places light above the arrow in the word equation, showing it is required but not a reactant.
- Names glucose and oxygen as the products of photosynthesis.
- States that light energy is absorbed by chlorophyll in chloroplasts.
- Explains that the reaction is endothermic and stores energy in glucose.
- Links glucose to uses such as respiration, starch storage and growth.
- Identifies oxygen as a by-product released into the environment.
Common mistakes and how to put them right
Writing light as a reactant on the left of the arrow.
Put it right: Light is a condition shown above the arrow, not a chemical reactant.
Confusing the products with the reactants.
Put it right: Glucose and oxygen are produced, while carbon dioxide and water are used up.
Stating that oxygen is used by the plant in photosynthesis.
Put it right: Oxygen is released, and the plant uses oxygen in respiration.
Exam tips
- Draw the word equation with light clearly above the arrow to show it is a requirement, not a reactant.
- When explaining the equation, state where light is absorbed and what happens to the energy.
- Use the products to explain why photosynthesis is important for life, for example glucose for respiration and oxygen for aerobic respiration.
Try the lesson
The start of the Photosynthetic reaction: light glucose + oxygen lesson, made from checked teaching notes for this specification point.
Have a go first
Which two products are formed during photosynthesis?
Listen
This statement is part of the word equation for photosynthesis, showing that light energy is needed and that glucose and oxygen are produced. The full word equation is carbon dioxide + water → glucose + oxygen, with light energy shown above the arrow. Light is absorbed by chlorophyll in chloroplasts and provides the energy to convert carbon dioxide and water into glucose. Oxygen is released as a by-product. The glucose formed is used in respiration, stored as starch, or used to build cellulose, amino acids and lipids. A strong answer earns marks for these points. Places light above the arrow in the word equation, showing it is required but not a reactant. Names glucose and oxygen as the products of photosynthesis. States that light energy is absorbed by chlorophyll in chloroplasts. Explains that the reaction is endothermic and stores energy in glucose. A common slip: Writing light as a reactant on the left of the arrow. Instead, light is a condition shown above the arrow, not a chemical reactant. Exam tip: Draw the word equation with light clearly above the arrow to show it is a requirement, not a reactant.
See it
Key words
Say what each word means before you turn the card.
Light
Try answering aloud or in your head before turning the card.
Glucose
Try answering aloud or in your head before turning the card.
Oxygen
Try answering aloud or in your head before turning the card.
See every definition
- Light
- Shown above the arrow in the word equation, it is required but not a reactant and is absorbed by chlorophyll in chloroplasts.
- Glucose
- A product of photosynthesis that stores energy and is used in respiration, stored as starch, or used to build cellulose, amino acids and lipids.
- Oxygen
- A product of photosynthesis released as a by-product into the environment.
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
3Box 3
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