DP Biology (first assessment 2025)

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Question 23M.2.HL.TZ1.4

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Date May 2023 Marks available [Maximum mark: 6] Reference code 23M.2.HL.TZ1.4
Level HL Paper 2 Time zone TZ1
Command term Explain, Identify, Outline, State Question number 4 Adapted from N/A
4.
[Maximum mark: 6]
23M.2.HL.TZ1.4

The diagram shows water molecules as they might be arranged in liquid water and the interactions between them.

(a.i)

State how many water molecules are shown in the diagram. 

[1]

Markscheme

10;

(a.ii)

Identify the interactions that are shown between the water molecules.

[1]

Markscheme

hydrogen bonds/H bond;

(b.i)

With reference to the diagram, explain how water in sweat evaporates.

[2]

Markscheme
  1. heat increases molecular motion/vibration;
  2. (hydrogen) bonds break/bonds between water molecules break;
  3. water evaporation is separation of water molecules/water changes from liquid to gas/vapour;
  4. heat removed from skin surface/body;

 

(b.ii)

Outline the reasons for secretion of sweat in humans.

[2]

Markscheme
  1. cooling/removal of heat/lowering body temperature;
  2. to prevent overheating
    OR
    to help maintain body temperature/for temperature homeostasis/for thermoregulation
    OR
    to keep temperature at 37 °C;

 

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