DP Biology (first assessment 2025)

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Question EXEX.2.HL.TZ0.4a

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Date Example questions Example questions Marks available [Maximum mark: 2] Reference code EXEX.2.HL.TZ0.4a
Level HL Paper 2 Time zone TZ0
Command term Explain Question number a Adapted from N/A
a.
[Maximum mark: 2]
EXEX.2.HL.TZ0.4a
(a)

Explain one reason gas exchange is more challenging in larger species of organisms.

[2]

Markscheme

         Reason:

  1. (as organisms get larger) distance to centre of the body increases
    OR
    the surface area for diffusion relative to the volume/ surface area to volume ratio becomes smaller/ decreases;  

    Explanation:
  2. which causes gas exchange/ diffusion of oxygen in/ carbon dioxide out to be too slow
    OR
    there is less area/space for diffusion to occur;

 

Explanation must match reason to award marking point b

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