Bioenergetics: Aerobic & Anaerobic Respiration

Question 1

Is aerobic respiration endothermic or exothermic?

Answer 1

exothermic

Question 2

What is aerobic repsiration?

Answer 2

A reaction in which glucose reacts with oxygen to release energy which can be used by cells.

Question 3

What are the word and symbol equations for aerobic respiration?

Answer 3

glucose + oxygen → carbon dioxide + water (+energy)

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O (+energy)

Question 4

Where does aerobic respiration take place?

Answer 4

mitochondria

Question 5

Why do organisms require the energy released by respiration

Answer 5

• synthesis of larger molecules from smaller ones (eg. proteins → amino acids)
• muscle contraction
• maintenance of body temperature

Question 6

What is anaerobic respiration?

Answer 6

A reaction in which glucose is broken down to release energy in the absence of oxygen.

Question 7

Is anaerobic respiration an endothermic or an exothermic reaction?

Answer 7

exothermic

Question 8

What is the word equation for anaerobic respiration?

Answer 8

glucose → lactic acid (+energy)

Question 9

Why is anaerobic respiration less efficient compared to aerobic respiration?

Answer 9

• glucose is not completely broken down
• so less energy is transferred

Question 10

Why can anaerobic respiration lead to muscle fatigue?

Answer 10

• lactic acid builds up in muscles
• this prevents efficient contraction

Question 11

What is an oxygen debt?

Answer 11

Th amount of oxygen needed to convert lactic acid back into glucose after anaerobic respiration.

Question 12

What is fermentation?

Answer 12

A type of anaerobic respiration that occurs in yeast cells.

Question 13

What is the equation for fermentation?

Answer 13

glucose → ethanol + carbon dioxide (+energy)

Question 14

Why is the fermentation reaction important?

Answer 14

It is used in:
- production of bread
- production of alcoholic drinks

Question 15

What are the differences between aerobic and anaerobic respiration?

Answer 15

• aerobic requires oxygen; anaerobic does not
• aerobic produces CO₂ and water; anaerobic produces lactic acid or ethanol + CO₂
• aerobic transfers a greater amount of energy

Question 16

How do muscles store glucose?

Answer 16

as glycogen

Question 17

Why does more respiration need to be done during exercise?

Answer 17

More energy is required due to:
- more muscular contraction being done
- heart rate increasing
- breathing rate increasing

Question 18

How is lactic acid transported away from the muscles?

Answer 18

• blood flow through muscles transports lactic acid to the liver
• here it is oxidised back to glucose

Question 19

What is metabolism?

Answer 19

The sum of all the reactions that take place in a cell or organism.

Question 20

Give examples of metabolic reactions.

Answer 20

• glucose into starch/glycogen/cellulose
• glycerol and fatty acids into lipids
• respiration
• photosynthesis
• glucose and nitrate ions into amino acids

Question 21

Why does breathing rate increase during exercise? (2)

Answer 21

• to get more oxygen into the blood (1) for use in respiration (1)
• to remove more CO₂ (1) produced in respiration (1)

Question 22

Why does heart rate increase during exercise? (2)

Answer 22

• to increase blood flowing to muscles which provides them with more oxygen and more glucose and removes CO₂ and lactic acid more quickly (from the muscles