Chapter 3 - Metabolism

Question 1

Define metabolism.

Answer 1

Metabolism is the sum total of all the chemical reactions occurring in the body.

Question 2

Distinguish between catabolism and anabolism.

Answer 2

Catabolism is the breaking down of larger molecules into smaller ones, e.g. cellular respiration. Anabolism is the building of large molecules from smaller ones, e.g. protein synthesis.

Question 3

What effect do enzymes have on a chemical reaction’s activation energy?

Answer 3

Enzymes lower the activation energy needed for a reaction, making reactions happen much faster.

Question 4

Explain the lock-and-key model in enzyme catalysis.

Answer 4

The active site is where the substrate fits. Substrates are the reactants that combine to form products. Enzymes are specifically designed to fit particular molecules.

Question 5

List factors that affect enzyme activity.

Answer 5

1. Concentration of the enzyme: Higher concentration increases reaction rate.
2. Substrate concentration: Increasing substrate concentration increases reaction rate until all active sites are occupied.
3. Temperature: Reaction rate increases with temperature until enzymes denature beyond 40-50°C.

Question 6

Define a nutrient.

Answer 6

A nutrient is a substance in food that is used by the cell for growth and repair.

Question 7

What are the key nutrients/organic compounds in food?

Answer 7

1. Water: Important in metabolism as a solvent.
2. Carbohydrates: Main source of energy, containing carbon, hydrogen, and oxygen.
3. Lipids: Include fats and oils, composed of fatty acids and glycerol.
4. Proteins: Made of amino acids, crucial for enzymes.

Question 8

Define cellular respiration.

Answer 8

Cellular respiration is the process by which organic molecules are broken down in the cells to release energy for cell activities.

Question 9

What are the two basic uses for the energy released during cell respiration?

Answer 9

1. Growth and repair of cells.
2. Transmission of nerve impulses.

Question 10

Describe the role of ATP in cellular respiration.

Answer 10

ATP is formed when an inorganic phosphate group is joined to ADP, storing energy from cellular respiration for use in cellular processes.

Question 11

Describe anaerobic respiration.

Answer 11

Anaerobic respiration allows for energy creation without oxygen, occurs in the cytoplasm during vigorous exercise, and involves glycolysis and fermentation producing lactic acid.

Question 12

Describe aerobic respiration.

Answer 12

Aerobic respiration creates ATP using oxygen, occurs in the mitochondria, and involves glycolysis, conversion to acetyl coenzyme A, the Krebs cycle, and the electron transport system.

Question 13

What are the word and chemical equations for aerobic respiration?

Answer 13

Word equation: Glucose + oxygen → carbon dioxide + water + energy.
Chemical equation: C_6 H_12 O_6 + 6O_2 → 6CO_2 + 6H_2O + Energy.

Question 14

List examples of cell activities that require ATP.

Answer 14

1. Endocytosis.
2. Exocytosis.
3. Active transport.
4. Cell division.
5. Protein synthesis.
6. Transmission of nerve impulses.

Question 15

Define synthesis.

Answer 15

Synthesis is the process of building compounds from more elementary substances through chemical reactions.

Question 16

Active site

Answer 16

The spot where the substrate fits