Question bank1.2 What happens in cells (and what do cells need)?

1.2 What happens in cells (and what do cells need)?

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Question 10

A student investigates how pH affects catalase in potato.

For each pH value, she:

places equal masses of potato in the same volume and concentration of hydrogen peroxide
uses a buffer solution to control the pH
keeps the mixture at $∘C30\ ^\circ\text{C}$
collects the oxygen produced in 60 seconds using a gas syringe.

She tests each pH value once.

pH	Volume of oxygen collected in 60 s in $cm3\text{cm}^3$
3	0.6
6	14.4
7	18.0
8	16.8

The rate of oxygen production is found using:

$oxygentime\text{rate} = \dfrac{\text{volume of oxygen}}{\text{time}}$

Calculate the rate at pH 6.

Write your answer in $s−1\text{cm}^3\,\text{s}^{-1}$ to 2 significant figures.

[1]

The student uses the results to claim that the optimum pH of the catalase is exactly pH 7.

Evaluate this claim.

[3]

Suggest two modifications that would provide stronger evidence for the optimum pH.

[2]

Only 0.6 cm³ of oxygen was collected at pH 3.

Explain this result.

[2]

Question bank1.2 What happens in cells (and what do cells need)?

1.2 What happens in cells (and what do cells need)?

Question 10

A student investigates how pH affects catalase in potato.

For each pH value, she:

places equal masses of potato in the same volume and concentration of hydrogen peroxide
uses a buffer solution to control the pH
keeps the mixture at $∘C30\ ^\circ\text{C}$
collects the oxygen produced in 60 seconds using a gas syringe.

She tests each pH value once.

pH	Volume of oxygen collected in 60 s in $cm3\text{cm}^3$
3	0.6
6	14.4
7	18.0
8	16.8

The rate of oxygen production is found using:

$oxygentime\text{rate} = \dfrac{\text{volume of oxygen}}{\text{time}}$

Calculate the rate at pH 6.

Write your answer in $s−1\text{cm}^3\,\text{s}^{-1}$ to 2 significant figures.

[1]

The student uses the results to claim that the optimum pH of the catalase is exactly pH 7.

Evaluate this claim.

[3]

Suggest two modifications that would provide stronger evidence for the optimum pH.

[2]

Only 0.6 cm³ of oxygen was collected at pH 3.

Explain this result.

[2]

1.2 What happens in cells (and what do cells need)?

Question 10

Markscheme

1.2 What happens in cells (and what do cells need)?

Question 10

Markscheme

1.2 What happens in cells (and what do cells need)?

Question 10

1.2 What happens in cells (and what do cells need)? Questions

1.2 What happens in cells (and what do cells need)?

Question 10

1.2 What happens in cells (and what do cells need)? Questions