Chapter 7: Cellular Respiration

Question 1

What is cellular respiration?

Answer 1

• process of breaking down food (glucose) to release energy for vital activities in all living cells

Question 2

What is the necessity of energy in metabolic processes?

Answer 2

• cell division for growth
• muscle contraction
• gametes production
• synthesis of protein, hormones, and enzymes
• transmission of nerve impulses

Question 3

Where is glucose obtained from?

Answer 3

• digestion of carbohydrates in humans and animals

- photosynthesis in plants

Question 4

What are the two types of cellular respiration?

Answer 4

• aerobic

- anaerobic

Question 5

What are aerobic respiration and anaerobic respiration?

Answer 5

Aerobic
- breakdown of glucose in the presence of oxygen to release energy
- occurs in the mitochondria
Anaerobic
- breakdown of glucose in the absence of oxygen to release energy
- occurs in the cytoplasm

Question 6

Aerobic respiration involves two main series of biochemical reactions which are_______ _______.

Answer 6

i) the breakdown of glucose to pyruvate called glycolysis which occurs in the cytoplasm
ii) the oxidation of pyruvate in the mitochondria to release energy, carbon dioxide, and water

Question 7

Describe the processes in aerobic respiration to release energy.

Answer 7

• Breakdown of glucose by glycolysis occurs cytoplasm
• this produces two molecules of pyruvate
• in the mitochondria, the pyruvate is oxidized to produce carbon dioxide, water, and energy
• the energy is used to form ATP by combining a molecule of inorganic phosphate (P) with a molecule of ADP
• ATP is the source of energy for all cellular activities

Question 8

What is fermentation?

Answer 8

• incomplete breakdown of glucose in limited supply or absence of oxygen

Question 9

What are the two types of fermentation?

Answer 9

• lactic acid fermentation

- alcohol fermentation

Question 10

Explain lactic acid fermentation.

Answer 10

• glucose is not completely oxidized
• only two ATP molecules are released
• glucose -> lactic acid + energy
• occurs in human cells and lactobacillus

Question 11

During aerobic respiration, at least _____ _____ of ATP or 2898 kJ of energy is released.

Answer 11

• 38 molecules

Question 12

Explain lactic acid fermentation in human muscle cells.

Answer 12

• during vigorous exercise, breathing rate increases
• rate of oxygen used exceeds the rate of oxygen supplied
• the cells are in an oxygen-deficiency state and is said to undergo oxygen debt
• glucose cannot be broken down completely
• for each glucose molecule broken down, only 2 ATP molecules will be produced
• produced lactic acid accumulates until it reaches a level of concentration that can cause fatigue and muscle cramps
• once the activity stops, aerobic respiration takes place and oxygen debt is paid
• remaining lactic acid is converted into glucose and stored as glycogen

Question 13

Explain lactic acid fermentation in lactobacillus bacteria.

Answer 13

• used in milk fermentation to produce yogurt
• acts on lactose and turns it into lactic acid
• lactic acid will then coagulate casein to produce yogurt
• lactic acid is the source of a sour taste in yogurt

Question 14

What is alcohol fermentation?

Answer 14

• incomplete breakdown of glucose to produce ethanol, carbon dioxide, and energy
• Glucose -> Ethanol + carbon dioxide + energy (2ATP)

Question 15

Explain alcohol fermentation in yeast.

Answer 15

• yeast secretes the enzyme zymase to speed up fermentation
• glucose not completely broken down and produces ethanol, CO2, and energy
• ethanol produced is used to make alcoholic drinks such as wine and beer
• CO2 is used as a raising agent in bread making to make the bread dough rise

Question 16

Explain alcohol fermentation in plants.

Answer 16

• occurs in plants in waterlogged soil where there is a lack of oxygen
• paddy plant is adapted to grow with its root submerged
• paddy plants have a higher tolerance for the ethanol produced because they produce alcohol dehydrogenase enzymes to break down ethanol into non-toxic carbon dioxide.

Question 17

What are the similarities between aerobic respiration and anaerobic respiration?

Answer 17

• release energy from oxidative breakdown of glucose
• releases energy in the form of ATP
• catalyzed by an enzyme
• both processes are cellular respiration

Question 18

What are the differences between aerobic respiration and anaerobic respiration?

Answer 18

Aerobic
- in cytoplasm and mitochondria
- oxygen is required
- glucose is completely broken down
- 38 ATP molecules of energy are released
- products: water and carbon dioxide
Anaerobic
- in cytoplasm
- oxygen is not required
- glucose is partially broken down
- 2ATP molecules are released
- Products: lactic acid, ethanol, and carbon dioxide