CCEA Biology - Respiratory System, Breathing & Respiration

Question 1

Anaerobic Respiration can be demonstrated by

1 mark

Answer 1

Removing oxygen from yeast’s surroundings.

Question 2

Anaerobic Respiration Practical:
Procedure Simplified

(8 marks)

Answer 2

• Boil glucose solution to sterilise it and remove O2.
• Cool before adding yeast.
• Place layer of oil on top of the glucose solution.
• Yeast will respire anaerobically producing alcohol, heat and CO2 (collected in limewater)

Question 3

Anaerobic Respiration Practical:
Procedure Detailed

(6 marks)

Answer 3

• Boil glucose solution to sterilise it and remove any O2: leaving behind the glucose needed for anaerobic respiration.
• Cool before adding yeast (high temps kill it).
• Place layer of oil on top of glucose solution = prevent O2 entering.
• Yeast will respire anaerobically producing alcohol, heat and CO2 - can be collected in limewater.

Question 4

What kills the glucose needed for anaerobic respiration?

1 mark

Answer 4

High temps

Question 5

Investigating factors affecting the respiration of yeast:
Temperature - Detailed Procedure

(12 marks)

Answer 5

Mix yeast into a solution of glucose and water - provides glucose and O2 needed for respiration.

Leave at room temp for 1 hour.

Place mixture in a test tube.

Place a boiling tube over the test tube and invert - test tube will now be upside down.

Place in water bath at 10°C.

Measure height of bubble at top of test tube.

After 30 mins; measure the height of the bubble at the top of the test tube.

Repeat steps 2 to 7 at different temps (e.g. 20°C, 30°C, 40°C and 50°C).

Calculate change in bubble height - record results in a table.

Draw graph of; change in height against the temperature.

Question 6

Investigating factors affecting the respiration of yeast:
Temperature - Procedure Simplified

(13 marks)

Answer 6

Mix yeast into a solution of glucose and water - provides glucose and O2 needed for respiration.

Leave at room temp for 1 hour.

Place mixture in a test tube.

Place a boiling tube over the test tube and invert.

Place in water bath at 10°C.

Measure height of bubble at top of test tube.

After 30 mins; measure the height of the bubble.

Repeat steps 2 to 7 at different temps

Calculate change in bubble height - record results in a table.

Draw graph of; change in height against the temperature.

Question 7

Investigating factors affecting the respiration of yeast: Results

(3 marks)

Answer 7

Optimum temp for respiration will produce the largest bubble of carbon dioxide after 30 mins -respiration will have happened fastest.

Question 8

Investigating factors affecting the respiration of yeast: Different sugars - Detailed Procedure

(10 marks)

Answer 8

Mix yeast into solution of glucose and water – provides the glucose and O2 needed for respiration.

Leave at room temp for 1 hour.

Place mix in a test tube.

Place a boiling tube over the test tube and invert - test tube will now be upside down.

Place in water bath at 30°C.

Measure the height of the bubble at top of the test tube.

After 30 mins, measure height of the bubble at top of the test tube.

Repeat steps 1-7 with yeast mixtures in different sugars (e.g. sucrose, fructose, lactose, maltose).

Calculate the change in bubble height - record results in a table.

Question 9

Limewater

2 mark

Answer 9

Chemical that changes from colourless to cloudy/milky when CO2 is added.