Year 9 Biology: Enzymes, Organisation, and the Digestive System

Introduction to Enzymes

What are Enzymes?

Enzymes are special proteins that help speed up chemical reactions in our bodies. Think of them as tiny workers that make things happen faster. Without enzymes, many processes in our body would take too long!

How Do Enzymes Work?

Enzymes work by binding to specific molecules called substrates. This binding happens at a special site on the enzyme called the active site. When the enzyme and substrate join together, they form a temporary structure that helps change the substrate into a different product.

Example:

Imagine a lock and a key. The enzyme is like the lock, and the substrate is the key. Only the right key (substrate) will fit into the lock (enzyme) to open it.

Factors Affecting Enzyme Activity

1. Temperature: Enzymes work best at a certain temperature, usually around 37°C (body temperature). If it’s too hot or too cold, the enzyme may not work well.
2. pH Level: Each enzyme has a specific pH level it works best at. For example, pepsin, an enzyme in the stomach, works best in acidic conditions.
3. Concentration: The amount of enzyme and substrate can affect how quickly a reaction happens. More enzymes mean faster reactions, up to a point!

The Organisation of the Digestive System

What is the Digestive System?

The digestive system is a group of organs that work together to break down food so our bodies can use it. It starts from when we put food in our mouth and ends when waste leaves our body.

Parts of the Digestive System

1. Mouth: Chews food and mixes it with saliva, which contains enzymes like amylase that start breaking down carbohydrates.
2. Oesophagus: A tube that carries food from the mouth to the stomach.
3. Stomach: Uses acids and enzymes (like pepsin) to break down food further.
4. Small Intestine: Most digestion and absorption of nutrients happen here. Enzymes from the pancreas and bile from the liver help break down food.
5. Large Intestine: Absorbs water and forms waste.
6. Rectum and Anus: Store and release waste.

The Role of Enzymes in Digestion

Enzymes play a crucial role in digestion. Different types of enzymes break down different kinds of food:

• Amylase: Breaks down carbohydrates into sugars.
• Protease: Breaks down proteins into amino acids.
• Lipase: Breaks down fats into fatty acids and glycerol.

Tips and Tricks for Understanding Enzymes and Digestion

• Visualise: Draw diagrams of the digestive system. Label each part and note what happens there.
• Use Analogies: Relate enzymes to everyday objects, like locks and keys, to remember how they work.
• Flashcards: Create flashcards with enzyme names on one side and what they break down on the other.
• Group Study: Discuss with friends to help reinforce what you’ve learned.

Questions

Easy Level (20 Questions)

1. What are enzymes?
2. What do enzymes help speed up?
3. Where does digestion start?
4. What is the function of the stomach?
5. Name one enzyme found in saliva.
6. What is the role of the small intestine?
7. What does the large intestine do?
8. How does temperature affect enzyme activity?
9. What is the active site of an enzyme?
10. Name one type of enzyme and what it breaks down.
11. Why is pH important for enzymes?
12. What tube carries food to the stomach?
13. What do we call the waste that leaves our body?
14. What is the function of bile?
15. What structure helps absorb nutrients in the small intestine?
16. What happens to food in the mouth?
17. What is the main purpose of the digestive system?
18. Which enzyme works best in acidic conditions?
19. What do lipases break down?
20. What is the process of breaking down food into smaller pieces called?

Medium Level (20 Questions)

1. Explain how enzymes and substrates interact.
2. What happens to enzymes when they are too hot?
3. Describe the process of digestion in the stomach.
4. How do enzymes assist in the absorption of nutrients?
5. What are the main differences between the small and large intestines?
6. Name three factors that can affect enzyme activity.
7. What is amylase, and where is it found?
8. Describe the role of protease in digestion.
9. How does the structure of an enzyme relate to its function?
10. Why is the digestive system important for survival?
11. What is the role of the oesophagus in the digestive system?
12. How do enzymes help in breaking down fats?
13. Describe how food is mixed in the stomach.
14. What is the importance of saliva in digestion?
15. What happens to waste in the large intestine?
16. How do enzymes lower the activation energy of reactions?
17. What can happen to enzymes if the pH is too high or too low?
18. Why is the small intestine called “small”?
19. Describe how bile helps with fat digestion.
20. How do digestive enzymes differ from other enzymes in the body?

Hard Level (20 Questions)

1. Explain the lock and key model of enzyme action.
2. How do competitive and non-competitive inhibitors affect enzyme activity?
3. Discuss the importance of enzyme specificity.
4. What are cofactors and coenzymes, and how do they assist enzymes?
5. Describe how the body regulates enzyme activity.
6. What role do enzymes play in metabolism?
7. Compare and contrast the roles of the pancreas and liver in digestion.
8. How do enzymes change the rate of chemical reactions?
9. Explain what happens during enzyme denaturation.
10. Discuss how an increase in substrate concentration affects enzyme activity.
11. Describe the role of villi in the small intestine.
12. What are the consequences of enzyme malfunction in the digestive system?
13. Explain how enzymes can be used in biotechnology.
14. Discuss the role of hormones in the digestive system.
15. Compare the digestion of carbohydrates, proteins, and fats.
16. What happens to enzymes after they have catalysed a reaction?
17. Discuss the impact of temperature on enzyme denaturation.
18. How does the body absorb nutrients after digestion?
19. What is the significance of the digestive system’s surface area?
20. Explain how enzymes can be affected by inhibitors and activators.

Answers

Easy Level Answers

1. Enzymes are special proteins.
2. They help speed up chemical reactions.
3. Digestion starts in the mouth.
4. The stomach breaks down food with acids and enzymes.
5. Amylase is found in saliva.
6. The small intestine absorbs nutrients.
7. The large intestine absorbs water and forms waste.
8. High temperatures can denature enzymes.
9. The active site is where the substrate binds.
10. Amylase breaks down carbohydrates.
11. pH affects how well enzymes work.
12. The oesophagus carries food to the stomach.
13. Waste is called faeces.
14. Bile helps digest fats.
15. Villi absorb nutrients in the small intestine.
16. Food is chewed and mixed with saliva.
17. The digestive system breaks down food for energy.
18. Pepsin works best in acidic conditions.
19. Lipases break down fats.
20. The process is called digestion.

Medium Level Answers

1. Enzymes bind to substrates at the active site.
2. They can become denatured and stop working.
3. The stomach uses acids and enzymes to digest food.
4. Enzymes break down food into nutrients that can be absorbed.
5. The small intestine absorbs nutrients; the large intestine absorbs water.
6. Temperature, pH, and concentration affect enzyme activity.
7. Amylase breaks down starch and is found in saliva.
8. Protease breaks down proteins into amino acids.
9. The shape of an enzyme allows it to bind to specific substrates.
10. It helps us get nutrients from food.
11. The oesophagus transports food to the stomach.
12. They break down fats into fatty acids and glycerol.
13. The stomach mixes food with gastric juices.
14. Saliva moistens food and contains enzymes.
15. Waste is stored and then expelled.
16. Enzymes lower the energy needed for reactions.
17. Enzymes can become inactive if pH is too high or low.
18. The small intestine is narrower than the large intestine.
19. Bile emulsifies fats to help digestion.
20. Digestive enzymes are specialized for breaking down food.

Hard Level Answers

1. The lock and key model describes how enzymes fit with substrates.
2. Inhibitors decrease enzyme activity, while activators increase it.
3. Enzyme specificity means each enzyme works on a specific substrate.
4. Cofactors and coenzymes assist enzymes in their functions.
5. The body regulates enzymes through feedback and hormonal control.
6. Enzymes speed up metabolic reactions in the body.
7. The pancreas produces digestive enzymes; the liver produces bile.
8. Enzymes increase the rate of reactions without being consumed.
9. Denaturation is when enzymes lose their shape and function.
10. More substrate can increase reaction rates until saturation.
11. Villi increase surface area for nutrient absorption.
12. Malfunction can lead to digestive issues or nutrient deficiencies.
13. Enzymes are used to produce food products or in medicine.
14. Hormones regulate digestive processes, like insulin for sugar.
15. Carbohydrates are broken down into sugars, proteins into amino acids, and fats into fatty acids.
16. They can be reused for new reactions.
17. High temperatures can denature enzymes, stopping their function.
18. Nutrients are absorbed through the walls of the small intestine.
19. A large surface area allows for more efficient absorption.
20. Inhibitors slow down enzyme activity, while activators speed it up.