GCSERevise
AQASpec 4.2.1Foundation & Higher~30 min

Organisation in Animals

Biology · Topic revision workspace

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Read the notes, score 80% and know 75% of the cards.

Topic overview

What you need to know

Organisation in Animals is a key part of GCSE Biology. Connect structures to their functions and explain biological processes as clear causal sequences. A group of similar cells working together to perform a specific function. E.g. muscle tissue, epithelial tissue. A structure made of different tissues working together. E.g. the stomach contains muscular, glandular, and epithelial tissue. A group of organs working together to perform a particular function. E.g. the digestive system.

Exam tip

Use precise scientific vocabulary and make each link in an explanation explicit.

Revision notes

Core ideas

Secure these ideas first. Say each definition in your own words, then connect it to the topic overview.

  • Tissue: A group of similar cells working together to perform a specific function. E.g. muscle tissue, epithelial tissue.
  • Organ: A structure made of different tissues working together. E.g. the stomach contains muscular, glandular, and epithelial tissue.
  • Organ System: A group of organs working together to perform a particular function. E.g. the digestive system.
  • Enzyme: A biological catalyst that speeds up chemical reactions without being used up. Made of protein with a specific active site.

Revision notes

Apply it in the exam

The exam will rarely ask for an isolated definition. Practise selecting the right idea and using it as part of a complete explanation or method.

  • Active Site: The region on an enzyme where the substrate binds. It has a specific shape complementary to the substrate.
  • Denatured: When an enzyme's active site changes shape (due to high temperature or extreme pH) so the substrate can no longer fit.
  • Digestive System: The organ system that breaks down food into small soluble molecules for absorption: mouth → oesophagus → stomach → small intestine → large intestine.
  • Villi: Tiny finger-like projections lining the small intestine that increase surface area for absorption of digested food.

Core knowledge

Key facts for Organisation in Animals

1

Tissue

A group of similar cells working together to perform a specific function. E.g. muscle tissue, epithelial tissue.

2

Organ

A structure made of different tissues working together. E.g. the stomach contains muscular, glandular, and epithelial tissue.

3

Organ System

A group of organs working together to perform a particular function. E.g. the digestive system.

4

Enzyme

A biological catalyst that speeds up chemical reactions without being used up. Made of protein with a specific active site.

5

Active Site

The region on an enzyme where the substrate binds. It has a specific shape complementary to the substrate.

6

Denatured

When an enzyme's active site changes shape (due to high temperature or extreme pH) so the substrate can no longer fit.

7

Digestive System

The organ system that breaks down food into small soluble molecules for absorption: mouth → oesophagus → stomach → small intestine → large intestine.

8

Villi

Tiny finger-like projections lining the small intestine that increase surface area for absorption of digested food.

Active recall

Close the notes and answer these

  1. 1.Without looking, explain tissue and give one example or consequence.
  2. 2.Without looking, explain organ and give one example or consequence.
  3. 3.Without looking, explain organ system and give one example or consequence.
  4. 4.Without looking, explain enzyme and give one example or consequence.

Content reviewed 23 July 2026 against the current linked specification.

Finished learning?

Mark the notes complete, then test what you can recall.

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