4.2 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 are the equations for aerobic respiration? (word and symbol)

Answer 2

glucose + oxygen –> carbon dioxide + water (+ energy)

C6H12O6 + 6O2 –> 6CO2 + 6H2O (+ energy)

Question 3

Where does aerobic respiration take place?

Answer 3

In the mitochondria

Question 4

Why do organisms require 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 the word equation for anaerobic respiration?

Answer 6

glucose –> lactic acid (+ energy)

Question 7

Why is anaerobic respiration less efficient than aerobic respiration?

Answer 7

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

Question 8

Why can anaerobic respiration lead to muscle fatigue?

Answer 8

Lactic acid (product of anaerobic respiration) builds up in muscles, preventing efficient contraction.

Question 9

What is an oxygen debt?

Answer 9

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

Question 10

What is fermentation?

Answer 10

A type of anaerobic respiration that occurs in yeast cells

Question 11

What is the word equation for fermentation?

Answer 11

Glucose –> ethanol + carbon dioxide (+ energy)

Question 12

Why is the fermentation reaction important?

Answer 12

It is used in the production of bread and alcoholic drinks

Question 13

What are the differences between aerobic and anaerobic respiration?

Answer 13

● 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 14

How do muscles store glucose?

Answer 14

As glycogen in their cells

Question 15

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

Answer 15

● Heart rate increases and arteries dilate which increases the flow of oxygenated blood to muscles

● Breathing rate increases and breathing is deeper
which increases the rate of gaseous exchange

● Stored glycogen is
converted back into glucose

Question 16

How is lactic acid transported away from the muscles? (Higher)

Answer 16

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

Question 16

What is metabolism?

Answer 16

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

Question 17

How do cells use the energy transferred by energy?

Answer 17

To continuously carry out enzyme-controlled processes which lead to the synthesis of new molecules

Question 18

Give examples of metabolic reactions

Answer 18

● Glucose into
starch/glycogen/ cellulose

● Glycerol and fatty acids into lipids

● Glucose and nitrate ions into amino acids

● Photosynthesis

● Respiration

● Breakdown of excess proteins into urea