Principles of OrganisationAQA GCSE Biology: Flashcards
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What is the order of organisation from smallest to largest in a multicellular organism?
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- What is the order of organisation from smallest to largest in a multicellular organism?
- Cells → tissues → organs → organ systems → organism.
- Define a tissue.
- A group of cells with a similar structure and function.
- Define an organ.
- An aggregation of different tissues performing specific functions.
- Define an organ system.
- A group of organs that work together to perform particular functions.
- Why is the digestive system called an organ system?
- Because several different organs work together to digest and absorb food.
- What is an enzyme?
- A biological catalyst, made of protein, that speeds up a specific reaction.
- What is the active site of an enzyme?
- The region of the enzyme with a shape complementary to its substrate.
- Explain the 'lock and key' theory of enzyme action.
- The enzyme (lock) has an active site shaped to fit only a specific substrate (key), allowing the reaction to occur.
- What happens to an enzyme at extreme temperature or pH?
- It denatures — its active site changes shape and it can no longer catalyse the reaction.
- What is a double circulatory system?
- A system where blood passes through the heart twice per full circuit: once to the lungs, once around the body.
- Give an example of an organ made of muscle tissue.
- The heart.
- Why can't a substrate react if it doesn't match an enzyme's active site?
- Because the substrate's shape is not complementary to the active site, so it cannot bind (like the wrong key in a lock).
- What happens to enzyme activity as temperature rises towards the optimum?
- Activity increases, then falls sharply past the optimum as the enzyme denatures.
- True or false: an organ is made of only one type of tissue.
- False — an organ is made of several different tissues working together.
- Name two organ systems in the human body.
- Any two of: digestive system, circulatory system, respiratory system, nervous system.