B9. Respiration

Question 1

What is the primary purpose of respiration in living organisms?

Answer 1

The primary purpose of respiration is to release energy from glucose molecules for cellular processes.

Question 2

Which organelle is the site of respiration?

Answer 2

The mitochondria are the site respiration.

Question 3

What type of reaction is respiration?

Answer 3

It is an exothermic reaction - this means the reaction releases energy.

Question 4

What is the word equation for aerobic respiration?

Answer 4

Glucose + Oxygen —> Carbon dioxide + Water vapour + Energy

Question 5

What is the chemical equation for aerobic respiration?

Answer 5

C₆H₁₂O₆ + 6O₂ —> 6CO₂ + 6H₂O

Question 6

Why do our bodies need energy?

Answer 6

• For growth
• For movement
• Muscle contraction
• Control of body temperature

Question 7

What is anaerobic respiration?

Answer 7

During vigorous exercise anaerobic respiration can occur without oxygen. Glucose is NOT fully broken down releasing only a small amount of ATP energy.

Question 8

State the word equation for anaerobic respiration in animals.

Answer 8

Glucose —> Lactic acid

Question 9

State the word equation for anaerobic respiration in plant and yeast cells.

Answer 9

Glucose —> Ethanol + Carbon dioxide

Question 10

What is oxygen debt?

Answer 10

Oxygen debt is the amount of extra oxygen the body needs after (anaerobic) exercise to react with the accumulated lactic acid and remove it from the cells.

Question 11

How is oxygen debt repaid?

Answer 11

After intenese exercise, the person starts panting to take in extra oxygen.

The oxygen reacts with the lactic acid built up in the muscles to fully break it down.

Blood flowing throught the muscles also transports lactic acid to the liver where it is converted back into glucose.

Question 12

Name 2 factors that would affect the rate of respiration.

Answer 12

• Change in temperature
• Change in pH

Question 13

Explain how (and why) the breathing rate changes during exercise.

Answer 13

During exercise the breathing rate increases.

This is to supply more oxygen to the exercising muscles and to remove excess carbon dioxide being produced.

Question 14

Explain how (and why) the heart rate changes during exercise.

Answer 14

During exercise the heart rate increases.

This supplies more oxygen to the exercising muscles.

It also supplies more glucose to the exercising muscles.

This ensures a faster rate of respiration.

It also increases the rate of lactic acid removal from the muscles.

Question 15

Glucose is stored in the muscles in the form of ___________.

Answer 15

Glycogen

Question 16

Differentiate between aerobic and anaerobic respiration.

Answer 16

Aerobic respiration requires oxygen and releases a large amount of energy, while anaerobic respiration doesn’t require oxygen and releases much less energy.

Question 17

Name one organism that undergoes anaerobic respiration.

Answer 17

Yeast is an example of an organism that undergoes anaerobic respiration, producing ethanol and carbon dioxide as byproducts.

Question 18

In which organisms is alcoholic fermentation a common form of anaerobic respiration?

Answer 18

Alcoholic fermentation is commonly found in yeast and some bacteria.

Question 19

What are the products of anaerobic respiration in animals?

Answer 19

In animals, anaerobic respiration produces lactic acid and a small amount of ATP.

Question 20

Which process occurs when oxygen is unavailable during cellular respiration?

Answer 20

Anaerobic respiration occurs when oxygen is unavailable, leading to the release of a small amount of energy without the use of oxygen.

Question 21

How many ATP molecules are produced when one glucose molecule if fully broken down in aerobic respiration?

Answer 21

38 ATP

Question 22

When might lactic acid form in the muscles?

Answer 22

During periods of vigorous exercise, when oxygen is limited in muscle cells.