AQA · GCSE · Combined Science

    Course version: 8464 · Version from Sept 2018

    Uses of glucose from photosynthesis: used for respiration

    One important fate of the glucose made in photosynthesis is use in respiration.

    • 4 key terms

    Study notes

    From the checked teaching notes for this specification point.

    The idea

    One important fate of the glucose made in photosynthesis is use in respiration. In respiration, glucose is broken down in a series of enzyme-controlled reactions to release energy. Aerobic respiration uses oxygen and produces carbon dioxide and water, while anaerobic respiration in plants produces ethanol and carbon dioxide with less energy released. The energy released is used to build larger molecules from smaller ones, enable muscle contraction in animals, maintain a constant body temperature in birds and mammals, and support active transport and other cellular processes in plants. In plants, respiration occurs continuously in all living cells, including at night when photosynthesis cannot occur. The glucose used may be freshly made in photosynthesis or released from stored starch.

    What earns the marks

    • Glucose is broken down during respiration to release energy for the plant's cells.
    • Aerobic respiration in plants uses oxygen and produces carbon dioxide and water.
    • Anaerobic respiration in plant cells produces ethanol and carbon dioxide and releases less energy than aerobic respiration.
    • The energy released by respiration is used for processes such as building larger molecules, active transport and cell division.
    • Respiration in plants occurs continuously, including at night when photosynthesis is not taking place.
    • Glucose for respiration can come directly from photosynthesis or from the breakdown of stored starch.

    Common mistakes and how to put them right

    • Saying that plants photosynthesise instead of respiring.

      Put it right: Plants respire all the time and also photosynthesise when light is available.

    • Writing that respiration produces energy as a substance.

      Put it right: Respiration releases energy from glucose; energy is not a product substance like carbon dioxide or water.

    • Confusing anaerobic respiration in plants with anaerobic respiration in animals.

      Put it right: Plant cells produce ethanol and carbon dioxide, whereas animal cells produce lactic acid.

    Exam tips

    • State clearly that respiration releases energy from glucose rather than creating energy.
    • Include the correct reactants and products when describing aerobic respiration: glucose and oxygen react to form carbon dioxide and water.
    • Use the phrase 'all living cells respire continuously' to show that respiration is not limited to daylight hours.

    Try the lesson

    The start of the Uses of glucose from photosynthesis: used for respiration lesson, made from checked teaching notes for this specification point.

    Have a go first

    What is the main reason a plant uses some of the glucose made in photosynthesis for respiration?

    Listen

    One important fate of the glucose made in photosynthesis is use in respiration. In respiration, glucose is broken down in a series of enzyme-controlled reactions to release energy. Aerobic respiration uses oxygen and produces carbon dioxide and water, while anaerobic respiration in plants produces ethanol and carbon dioxide with less energy released. The energy released is used to build larger molecules from smaller ones, enable muscle contraction in animals, maintain a constant body temperature in birds and mammals, and support active transport and other cellular processes in plants. In plants, respiration occurs continuously in all living cells, including at night when photosynthesis cannot occur. The glucose used may be freshly made in photosynthesis or released from stored starch. A strong answer earns marks for these points. Glucose is broken down during respiration to release energy for the plant's cells. Aerobic respiration in plants uses oxygen and produces carbon dioxide and water. Anaerobic respiration in plant cells produces ethanol and carbon dioxide and releases less energy than aerobic respiration. The energy released by respiration is used for processes such as building larger molecules, active transport and cell division. A common slip: Saying that plants photosynthesise instead of respiring. Instead, plants respire all the time and also photosynthesise when light is available. Exam tip: State clearly that respiration releases energy from glucose rather than creating energy.

    See it

    A flowchart starting with a node labelled Glucose, which leads to Respiration: enzyme-controlled reactions. From this node two branches emerge: Aerobic respiration, which leads to Uses oxygen and to Produces carbon dioxide and water; and Anaerobic respiration in plants, which leads to Produces ethanol and carbon dioxide and to Releases less energy. The respiration node also leads to Energy released, which leads to Used for processes such as building larger molecules, active transport and cell division.
    It shows glucose being broken down in respiration, the difference between aerobic and anaerobic respiration in plants, and what the released energy is used for.

    Key words

    Say what each word means before you turn the card.

    Respiration

    Try answering aloud or in your head before turning the card.

    Aerobic respiration

    Try answering aloud or in your head before turning the card.

    Anaerobic respiration

    Try answering aloud or in your head before turning the card.

    Continuous respiration

    Try answering aloud or in your head before turning the card.

    See every definition
    Respiration
    Glucose is broken down in a series of enzyme-controlled reactions to release energy.
    Aerobic respiration
    Uses oxygen and produces carbon dioxide and water.
    Anaerobic respiration
    In plants produces ethanol and carbon dioxide with less energy released.
    Continuous respiration
    In plants, respiration occurs continuously in all living cells, including at night when photosynthesis cannot occur.

    Label the diagram

    Some boxes have lost their names. Pick the right name for each number.

    The diagram again, with 3 boxes numbered instead of named. A flowchart starting with a node labelled Glucose, which leads to Respiration: enzyme-controlled reactions. From this node two branches emerge: Aerobic respiration, which leads to Uses oxygen and to Produces carbon dioxide and water; and Anaerobic respiration in plants, which leads to Produces ethanol and carbon dioxide and to Releases less energy. The respiration node also leads to Energy released, which leads to Used for processes such as building larger molecules, active transport and cell division.

    • 1Box 1

    • 2Box 2

    • 3Box 3

    0 of 3 labelled

    There is more to this lesson

    The full lesson goes on to check your understanding and help you earn the marks. Create a free account to carry on, with your progress saved.

    Carry on with the full lesson

    A week of Premium from your first lesson · Then the free plan continues · No card, no charge

    Test your understanding of Uses of glucose from photosynthesis: used for respiration

    Active recall beats re-reading. Take an instant quiz now to test what you’ve learned and lock it into long-term memory.

    Take topic quiz

    A week of Premium from your first lesson · Then the free plan continues · No card, no charge

    Start free

    Cookies on MasteryMind

    Essential cookies keep you signed in.

    Analytics and advertising cookies stay off unless you accept.

    Read our Privacy Policy.