Introduction to Enzymes

Enzymes are biological molecules, specifically proteins, that speed up chemical reactions in the body. They are essential for processes such as digestion, respiration, and muscle function. Without enzymes, these reactions would happen too slowly to sustain life. Each enzyme has a specific shape that allows it to work with only certain molecules, called substrates. This “lock and key” model ensures that enzymes only catalyse specific reactions.

Key Concepts about Enzymes

1. Function of Enzymes: Enzymes are catalysts, meaning they speed up reactions without being used up themselves.
2. Enzyme Structure: Enzymes have a unique shape that fits only specific substrates.
3. Lock and Key Model: Each enzyme has an active site that fits its specific substrate, like a lock fits a key.
4. Optimal Conditions: Enzymes work best at certain temperatures and pH levels. Outside these conditions, they can lose their shape, a process called denaturation.
5. Examples of Enzymes: Amylase helps break down starch, protease breaks down proteins, and lipase breaks down fats.

Understanding enzymes is crucial in biology as they control almost every reaction in our bodies, from digesting food to producing energy.

Exam Questions on Enzymes

Here are 20 questions each at easy, medium, and hard levels to test understanding of enzymes.

Easy Level Questions

Basic Understanding of Enzymes

1. What is an enzyme?
2. What role do enzymes play in the body?
3. What type of molecule are enzymes?
4. What does “catalyst” mean?
5. What is a substrate?
6. Name an enzyme that breaks down starch.
7. What enzyme breaks down proteins?
8. What is the “lock and key” model?
9. What enzyme breaks down fats?
10. What happens to an enzyme after it has catalysed a reaction?
11. What is the “active site” of an enzyme?
12. How do enzymes affect the speed of reactions?
13. At what temperature do most enzymes work best?
14. What happens to enzymes at very high temperatures?
15. Why is pH important for enzyme activity?
16. What happens if an enzyme is denatured?
17. What is the optimum pH for most enzymes in the body?
18. What is the function of amylase?
19. Why are enzymes specific to certain reactions?
20. What type of reaction does lipase help with?

Medium Level Questions

Intermediate Knowledge of Enzyme Functions and Processes

1. Explain the “lock and key” model for enzymes.
2. Describe how temperature affects enzyme activity.
3. What is meant by “optimum conditions” for an enzyme?
4. How does pH affect enzyme structure?
5. What is the role of protease in digestion?
6. How does amylase help in digestion?
7. Describe the effect of low temperatures on enzymes.
8. What is the difference between an enzyme and a substrate?
9. Why do enzymes only work with specific substrates?
10. How do enzymes help with metabolism?
11. Explain why enzymes do not get “used up” in reactions.
12. Why is it dangerous for enzymes to be exposed to extreme pH levels?
13. Describe the role of lipase in the body.
14. How is enzyme activity measured?
15. What can happen to enzymes if they are in very acidic or basic conditions?
16. Why are enzymes essential in respiration?
17. What would happen to digestion without enzymes?
18. Describe how enzymes help in muscle function.
19. What are “digestive enzymes”?
20. How do enzymes help the body save energy?

Hard Level Questions

Advanced Concepts and Applications on Enzyme Activity

1. Explain how enzymes speed up reactions at the molecular level.
2. Describe the role of cofactors in enzyme activity.
3. How does enzyme concentration affect reaction rate?
4. Explain the induced fit model of enzyme action.
5. What happens to enzyme structure when it is denatured?
6. How do competitive inhibitors affect enzyme function?
7. Describe the role of enzymes in cellular respiration.
8. Why do enzymes become inactive at very low temperatures?
9. How does an increase in substrate concentration affect enzyme activity?
10. Explain the relationship between enzyme structure and enzyme function.
11. What is the difference between the lock and key model and the induced fit model?
12. How do enzymes lower activation energy?
13. What is an allosteric site, and how does it affect enzymes?
14. Describe how pH changes can alter the active site of an enzyme.
15. How can inhibitors be useful in medicine?
16. Explain the role of enzymes in photosynthesis.
17. Why are enzymes unable to function after denaturation?
18. How does enzyme activity vary between different body tissues?
19. Describe how enzymes are used in the food industry.
20. Explain why enzyme research is important in developing new medicines.

Answers and Explanations

Easy Level Answers

1. A protein that speeds up chemical reactions – Enzymes are biological catalysts.
2. They help reactions happen faster – Enzymes increase reaction speed.
3. Proteins – Enzymes are made of amino acids.
4. A substance that speeds up reactions – Catalysts make reactions faster.
5. A molecule that an enzyme acts on – The substrate fits into the enzyme.
6. Amylase – Breaks down starch into sugars.
7. Protease – Breaks down proteins.
8. Model showing how enzymes fit with substrates – Enzyme and substrate fit like a lock and key.
9. Lipase – Breaks down fats.
10. It can be used again – Enzymes are not used up in reactions.
11. Part of enzyme where substrate fits – The active site is specific to each substrate.
12. They speed it up – Enzymes make reactions happen faster.
13. Around body temperature (37°C) – Most enzymes in the body work best at 37°C.
14. They denature – High temperatures change enzyme shape.
15. pH affects enzyme shape – Enzymes work best at specific pH levels.
16. It loses its shape – Denatured enzymes can’t bind to substrates.
17. Around pH 7 – Most body enzymes work best at neutral pH.
18. Breaks down starch – Amylase converts starch to sugar.
19. Their shape fits only certain substrates – Enzyme specificity depends on shape.
20. Breaking down fats – Lipase helps digest fats.

Medium Level Answers

1. Enzyme fits with substrate like lock and key – Only the correct substrate fits the enzyme.
2. Higher temperatures increase activity until too hot – Then the enzyme denatures.
3. Conditions where enzyme works best – Optimal temperature and pH help enzymes.
4. Extreme pH can change enzyme shape – This can make them inactive.
5. Breaks down protein into amino acids – Protease helps with protein digestion.
6. Breaks starch into sugars – Amylase aids in carbohydrate digestion.
7. Enzyme activity slows down – Low temperatures make reactions slow.
8. Enzyme speeds reaction, substrate is acted on – Enzymes and substrates have different roles.
9. Shape only fits certain molecules – Specific enzymes only work with matching substrates.
10. They break down and build molecules – Enzymes aid all metabolic processes.
11. They can be reused – Enzymes aren’t changed by the reaction.
12. It changes their shape and makes them inactive – Extreme pH can denature enzymes.
13. Breaks down fats into fatty acids – Lipase is important in fat digestion.
14. By measuring product amount or reaction speed – Activity shows how fast an enzyme works.
15. They can denature and stop working – Extreme pH alters enzyme structure.
16. Needed for energy production – Enzymes speed up respiration.
17. Digestion would be very slow – Enzymes make digestion faster.
18. Help break down and build muscle tissue – Enzymes support muscle function.
19. Enzymes that aid in digestion – Examples include amylase, protease, and lipase.
20. They lower energy needed for reactions – Enzymes save energy by speeding up reactions.

Hard Level Answers

1. Reduce activation energy needed – Enzymes lower the energy needed for reactions to start.
2. Non-protein helpers for enzymes – Cofactors help enzymes work properly.
3. Higher concentration increases reaction rate – More enzymes lead to faster reactions.
4. Enzyme changes shape to fit substrate – Induced fit adjusts enzyme to substrate.
5. Loses shape and can’t bind substrate – Denaturation makes enzymes inactive.
6. Compete with substrate for active site – Inhibitors slow enzyme activity.
7. Control reactions for energy release – Enzymes are essential in respiration.
8. Activity slows at low temperatures – Enzymes are less effective when cold.
9. More substrate increases reaction until saturation – Reaction rate increases until all enzymes are in use.
10. Shape determines function – Only specific substrates fit the enzyme shape.
11. Lock and key is fixed; induced fit adjusts shape – Induced fit changes shape to match substrate.
12. Lower the energy needed to start a reaction – Enzymes make it easier for reactions to occur.
13. Site that changes enzyme activity – Allosteric sites can inhibit or activate enzymes.
14. Changes enzyme shape, affecting function – pH changes alter the active site.
15. They can block enzyme activity – Inhibitors help control enzyme reactions.
16. Catalyse steps in photosynthesis – Enzymes are crucial in plant energy production.
17. Denatured enzymes lose their functional shape – This stops them from working.
18. Different enzymes suit different conditions – Enzymes vary across body tissues.
19. Used to break down food in products – Enzymes help process foods like dairy.
20. Help develop targeted treatments – Enzyme research supports drug development.

These questions and answers provide Year 7 students with a comprehensive understanding of enzymes, covering foundational knowledge, intermediate details, and advanced applications. This will effectively prepare them for their Key Stage 3 exams.