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

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Question 20

Students are investigating the effect of temperature on the rate of lipid breakdown by the enzyme lipase.

They mix lipase with a lipid emulsion at different temperatures: $∘C20\text{ }^\circ\text{C}$ , $∘C40\text{ }^\circ\text{C}$ , and $∘C60\text{ }^\circ\text{C}$ .

As lipase breaks down lipids into fatty acids, the pH of the mixture decreases. The students measure the time taken for the pH to decrease from $8.0$ to $6.5$ .

State whether the "time taken for the pH to decrease" is the independent, dependent, or control variable.

[1]

Complete the following sentences to explain why the rate of lipid breakdown is greater at $∘C40\text{ }^\circ\text{C}$ than at $∘C20\text{ }^\circ\text{C}$ :

Lipids decompose $‾\underline{\quad\quad\quad\quad}$ at $∘C40\text{ }^\circ\text{C}$ than at $∘C20\text{ }^\circ\text{C}$ .
Increasing the temperature increases the $‾\underline{\quad\quad\quad\quad}$ energy of the molecules.
This results in more frequent $‾\underline{\quad\quad\quad\quad}$ between the lipase enzymes and the $‾\underline{\quad\quad\quad\quad}$ molecules.

[4]

The students want to find the precise temperature at which the lipase enzymes denature and completely stop functioning. Suggest two ways they can extend or modify their experiment to find this out.

[2]

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

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Question 20

Students are investigating the effect of temperature on the rate of lipid breakdown by the enzyme lipase.

They mix lipase with a lipid emulsion at different temperatures: $∘C20\text{ }^\circ\text{C}$ , $∘C40\text{ }^\circ\text{C}$ , and $∘C60\text{ }^\circ\text{C}$ .

As lipase breaks down lipids into fatty acids, the pH of the mixture decreases. The students measure the time taken for the pH to decrease from $8.0$ to $6.5$ .

State whether the "time taken for the pH to decrease" is the independent, dependent, or control variable.

[1]

Complete the following sentences to explain why the rate of lipid breakdown is greater at $∘C40\text{ }^\circ\text{C}$ than at $∘C20\text{ }^\circ\text{C}$ :

Lipids decompose $‾\underline{\quad\quad\quad\quad}$ at $∘C40\text{ }^\circ\text{C}$ than at $∘C20\text{ }^\circ\text{C}$ .
Increasing the temperature increases the $‾\underline{\quad\quad\quad\quad}$ energy of the molecules.
This results in more frequent $‾\underline{\quad\quad\quad\quad}$ between the lipase enzymes and the $‾\underline{\quad\quad\quad\quad}$ molecules.

[4]

The students want to find the precise temperature at which the lipase enzymes denature and completely stop functioning. Suggest two ways they can extend or modify their experiment to find this out.

[2]

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

Question 20

Markscheme

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

Question 20

Markscheme

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

Question 20

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

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

Question 20

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