B9 Respiration

Question 1

What is aerobic respiration?

Answer 1

An exothermic reaction in which glucose reacts with oxygen to release energy which can be used by cells

Question 2

What is the formula for aerobic respiration?

Answer 2

Glucose + Oxygen = Carbon Dioxide + Water (+energy)

Question 3

in which part of the cell does aerobic respiration take place?

Answer 3

Aerobic respiration uses oxygen and most of the reaction takes place in the mitochondria

Question 4

Why do organisms need the energy released by respiration?

Answer 4

• Synthesis of larger molecules
• Muscle contraction
• Maintenance of body temperature
• Active Transport

Question 5

What is anaerobic respiration?

Answer 5

An exothermic reaction in which glucose is broken down to release energy in the absence of oxygen

Question 6

What is produced from anaerobic respiration of yeast and plants?

Answer 6

Plants and yeast can respire without oxygen as well, breaking down glucose in the absence of oxygen to produce ethanol and carbon dioxide

Question 7

What is anaerobic respiration called in yeast cells and why is it important?

Answer 7

Fermentation. It is important as it is used in the production of yeast and alcoholic drinks

Question 8

What are the differences between Aerobic and Anaerobic respiration?

Answer 8

Oxygen: Aerobic: needed; Anaerobic: not needed
Glucose breakdown: Aerobic: complete; Anaerobic: not complete
Products: Aerobic: Carbon dioxide and water; Anaerobic: Animal cells - lactic acid; yeast - carbon dioxide and ethanol
Energy release: Aerobic a lot; Anaerobic a little

Question 9

What is cellular respiration?

Answer 9

Remember that cellular respiration is not breathing; it is a chemical process of transferring energy from glucose in all living cells.

Question 10

What is the equation for anaerobic respiration in animals?

Answer 10

Glucose – lactic acid (+energy)

Question 11

Why is anaerobic respiration less efficient than aerobic?

Answer 11

Glucose is not completely broken down, so less energy is transferred

Question 12

Why can anaerobic respiration lead to muscle fatigue?

Answer 12

Lactic acid build up in muscles preventing efficient contraction

Question 13

What are the effects of exercise?

Answer 13

When exercising, the number of muscle contractions increases, therefore there is a greater energy demand, which means that the muscles need a greater supply of
oxygen for aerobic respiration. The human body reacts to the increased demand for oxygen in a number of ways:
- The breathing rate and breath volume increase during exercise to increase the amount of oxygen absorbed into the bloodstream by diffusion, and the
amount of carbon dioxide removed
- The heart rate increases
These reactions increase the supply of oxygenated blood to the muscles

Question 14

Why some energy comes from anaerobic respiration during strenuous exercise?

Answer 14

If exercising vigorously, the body may not be able to supply sufficient oxygen to the muscles to meet the demand for energy. In this situation, some of the energy supplied to the muscles comes from
anaerobic respiration, which is the incomplete breakdown of glucose without oxygen.
This releases much less energy than aerobic respiration and results in the formation of lactic acid as glucose is incompletely oxidised.

Question 15

What is meant by “oxygen debt”?

Answer 15

The “oxygen debt” is the amount of extra oxygen the body needs after exercise to react with the accumulated lactic acid and remove it from the cells

Question 16

How do muscles store glucose?

Answer 16

As glycogen

Question 17

What changes take place in the body when muscular activity increases?

Answer 17

• Heart rate increases and arteries dilate- increased flow of oxygenated blood to muscles
• Breathing rate increases and breathing is deeper - increases the rate of gaseous exchanges
• Stored glycogen is converted back into glucose

Question 18

How is lactic acid transported away from the muscles?

Answer 18

Blood flow through the muscles transports lactic acid to the liver, where it is oxidised back to glucose

Question 19

How does the body deal with lactic acid

Answer 19

The body can deal with lactic acid in one of two ways:
- It can be oxidised (reacted with oxygen) to form carbon dioxide and water – the
same products formed in aerobic respiration
- Alternatively, blood flowing through the muscles transports the lactic acid to the liver where it is converted back into glucose

Question 20

What is metabolism?

Answer 20

Metabolism is the sum of all the reactions in a cell or the body – these reactions happen all of the time

Question 21

How do cells use the energy transferred by respiration (in terms of metabolism)?

Answer 21

The energy transferred by respiration in cells is used by the organism for the continual enzyme controlled processes of metabolism that synthesise new
molecules.
Enzymes control all of the reactions occurring in cells; often the products of one reaction are the reactants for another (and so on)

Question 22

What are examples of metabolic reactions?

Answer 22

• Conversion of glucose to cellulose in plants to build and strengthen cell walls
• Conversion of glucose into glycogen in animals and starch in plants for storage
• The formation of lipid molecules from a molecule of glycerol and three molecules of fatty acids to form triglycerides which are used for energy storage and as insulation in animals
• In plants: the use of glucose and nitrate ions to form amino acids which in turn are used to synthesise proteins required by cells (such as enzymes)
• Glucose is broken down in the process of respiration to release energy in all cells
• In animals, the breakdown of excess proteins to form urea for excretion