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Respiration: Question 1

Syllabus 12.1

Multiple choice Core 1 mark

A child scrapes their knee while cycling. Over the next two weeks the wound heals: damaged skin cells are replaced, new collagen protein fibres are built, and nutrients are delivered to the healing tissue.

Which one of these processes involved in healing this wound does NOT need energy released by respiration?

Choose an answer to check it, then compare with the worked solution below.
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Worked solution

Step 1: Recall the uses of energy released by respiration

Respiration releases energy that living organisms use for a specific set of processes, including: muscle contraction, protein synthesis, cell division, active transport, growth, the passage of nerve impulses, and maintaining a constant body temperature. Any process on this list needs a continuous supply of energy from respiration in order to keep happening.

Step 2: Match each process in the wound to this list

  • Option A (cell division): replacing damaged skin cells by division is a form of growth and cell division, both of which need energy from respiration.
  • Option C (protein synthesis): building new collagen fibres means joining amino acids together into protein molecules. This is protein synthesis, which needs energy from respiration.
  • Option D (active transport): moving amino acids into the healing cells by active transport specifically needs energy, often to move substances against a concentration gradient.
  • Option B (diffusion): oxygen moves from a region of higher concentration in the blood plasma to a region of lower concentration inside the healing cells. This is diffusion, a passive process driven only by the random movement of particles down a concentration gradient. It needs no energy input from the cell.

Step 3: Identify the process that does not need respiration’s energy

Diffusion is not on the list of processes that use energy released by respiration, because it happens automatically as a result of particles’ own random movement, without any energy being supplied by the cell.

Final answer

The process that does not need energy released by respiration is the diffusion of oxygen into the healing cells, option B.