Curriculum
Course: SQA National 5 Biology
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Curriculum

SQA National 5 Biology

1. Unit 1 — Cell Biology

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2. Unit 2 — Multicellular Organisms

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3. Unit 3 — Life on Earth

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Text lesson

1.6.1 Respiration in Cells

1.6.1 Respiration in Cells: Explain that respiration releases energy from glucose to make ATP, state where it takes place and list the processes that depend on the energy.

1.6.1 Respiration in Cells

Respiration is not breathing; it is a chemical process inside cells.

Chemical process
  • Respiration is a series of enzyme-controlled reactions that break down nutrient molecules, mainly glucose.
Releases energy
  • The energy released is used to make ATP, a molecule that stores and transfers energy for the cell.
All cells
  • Respiration takes place in every living cell, all the time.
Mitochondria
  • Most of the reactions of aerobic respiration take place in mitochondria.
1

Energy released from glucose is used to join a phosphate to ADP, making ATP.
2

ATP moves to the part of the cell where energy is needed.
3

When ATP is broken down to ADP and phosphate, it releases energy for cell activities.
4

ADP and phosphate are recycled and used again in respiration to make more ATP.
Uses of Energy
Muscle contraction
  • Muscle cells use ATP to contract and so allow movement of the body.
Protein synthesis
  • Joining amino acids into proteins needs energy supplied by ATP.
Cell division
  • Growth and replacement of cells require energy for the processes of mitosis.
Active transport
  • Moving substances across membranes against a gradient depends on ATP.
Nerve impulses and temperature
  • Generating nerve impulses and maintaining body temperature in mammals also need energy.

1.6.1 – Key Points for the Exam

  • Respiration: Enzyme-controlled reactions that release energy from nutrients such as glucose.
  • ATP: The molecule that transfers energy to cell processes.
  • ADP: The molecule left when ATP releases energy, which can be recycled to make ATP.
  • Mitochondrion: The organelle where most of aerobic respiration occurs.
  • Aerobic: Happening with oxygen.

Common Mistakes

  • Confusing respiration with breathing or gas exchange.
  • Saying that energy is made in respiration; energy is released and transferred, not created.
  • Writing that only animals respire; plants and all other living things respire as well.
  • Thinking mitochondria are where photosynthesis occurs; that is chloroplasts.
YOUR STUDY PATH

1.6.1 Respiration in Cells

SQA National 5 Biology / 1. Unit 1 — Cell Biology

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