A student states: 'Blood is not a tissue because it is a liquid.' Explain why the student is incorrect, using your knowledge of the levels of organisation in a multicellular organism.

AQA GCSE Biology (8461) — 4.2.1 Principles of organisation · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

Blood is a tissue because it is a group of cells that have a similar structure and function.

Blood contains red blood cells, white blood cells and platelets that all perform the same general function of defence, transport and clotting.

These cells are surrounded by plasma, a liquid, but the liquid does not change the fact that the cells are organised together as a tissue.

Therefore the student’s statement that blood is not a tissue because it is liquid is incorrect.

Examiner tips

  • Use the definition of tissue – group of cells with similar structure and function.
  • Mention the specific cells in blood and their functions.
  • Explain that the liquid state does not affect tissue status.
  • Keep the answer concise and to the point.

Common mistakes

  • Saying blood is not a tissue because it is liquid.
  • Failing to mention the cells that make up blood.
  • Using vague language such as "blood is made of cells" without linking to the definition of tissue.

Mark scheme (4 marks)

  1. Blood IS a tissue
  2. A tissue is a group of cells with a similar structure and function
  3. Blood contains cells (red blood cells / white blood cells / platelets) within plasma
  4. The physical state (being liquid) does not prevent something from being a tissue / tissues do not have to be solid

Key terms in this question

tissue · blood · organ · cell

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