Respiration

Question 1

Where does respiration occur?

Answer 1

This process occurs in every cell in the body of all living organisms

Question 2

Why does respiration occur?

Answer 2

In order to supply ATP (energy) to cells

Question 3

What kind of process is respiration?

Answer 3

Exothermic

Question 4

What is aerobic respiration? (3)

Answer 4

• Uses oxygen
• Yields the most energy
• Occurs in the mitochondria

Question 5

What is anaerobic respiration? (4)

Answer 5

• Occurs when there is not enough oxygen
• Does not yield as much energy
• Used as last resort (e.g. sprint where there is insufficient oxygen)
• Incomplete oxidation of glucose

Question 6

What is the equation for aerobic respiration?

Answer 6

C6H12O6 (glucose) + 6O2 (oxygen) –> 6CO2 (carbon dioxide) + 6H2O (water)

Question 7

What is the equation for anaerobic respiration in animals?

Answer 7

Glucose –> Lactic acid

Question 8

What is fermentation? (2)

Answer 8

• Anaerobic respiration in plant and yeast cells
• Used to make bread and alcoholic drinks

Question 9

What is the equation for anaerobic respiration in plant and yeast cells

Answer 9

Glucose –> Ethanol + Carbon Dioxide

Question 10

What does hydrogen carbonate indicator detect?

Answer 10

It measures the increases and decreases in carbon dioxide concentration.

Question 11

Explain the colours of hydrogen carbonate indicator (3)

Answer 11

• Red: atmospheric CO2 levels (rate of photosynthesis = rate of respiration)
• Purple: CO2 levels decrease in bright light (rate of photosynthesis > rate of respiration)
• Yellow: CO2 levels decrease in darkness (rate of photosynthesis < rate of respiration)

Question 12

Describe an experiment to investigate the evolution of carbon dioxide from respiring seeds or other suitable living organisms (4)

Answer 12

• Connect a capillary tube from the air into a flask containing sodium hydroxide (absorbs CO2)
• Connect this flask with a tube to another flask containing hydrogen carbonate (should turn red)
• Connect this flask with a tube to another flask containing germinating seeds/respiring animals
• Connect this flask with a tube containing hydrogen carbonate (should turn yellow)

Question 13

Describe an experiment to investigate the heat of carbon dioxide from respiring seeds or other suitable living organisms (5)

Answer 13

• Use 2 vacuum flasks, one with living germinating seeds and others containing dead/boiled seeds (with control)
• Put a thermometer wrapped in cotton wool (to prevent heat from escaping to surroundings) to measure temperature
• Measure initial temperature
• Leave for a few days and measure end temperature
• Results: living seeds will release heat due to aerobic respiration (exothermic reaction), so temperature will be greater