Cell specialisation: Students should be able to, when provided with appropriate information, explain how the structure of different types of cell relate to their function in a tissue, an organ or organ system, or the whole organism.

The idea

Cells are specialised when their shape and internal structures suit a particular job. To explain this, link each structural feature to its function using information provided in the question. For example, a sperm cell has a tail for swimming, many mitochondria to release energy, and an acrosome containing enzymes to digest the egg's jelly coat (zona pellucida). A nerve cell is long to carry electrical impulses over distance. A root hair cell has a large surface area to absorb water and mineral ions efficiently. You must explain how a cell's structure helps the tissue, organ, organ system or whole organism carry out its function.

What earns the marks

• Identifies a named specialised cell and states its function, for example a red blood cell transporting oxygen.
• Links a specific structural feature to its function, such as a biconcave shape giving a large surface area for oxygen diffusion.
• Explains how the cell contributes to a tissue, organ, organ system or whole organism, for example ciliated cells forming tissue that moves mucus.
• Uses the information provided in the question rather than relying only on remembered examples.
• Explains more than one adaptation where relevant, for example a sperm cell's tail, mitochondria and acrosome.

Common mistakes and how to put them right

• Describing a cell's appearance without linking it to function.

  Put it right by adding 'this allows it to...' after each feature.

• Confusing the levels of organisation, for example calling an organ a cell.

  Put it right by checking the question's required level.

• Giving a general answer that ignores the information supplied.

  Put it right by reading the data and using specific details.

Exam tips

• Use a clear structure for each point: name the feature, then state the function it enables.
• If the question supplies information, quote or refer to it directly so your answer is clearly based on the given context.