DP Biology (first assessment 2025)

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Question 23M.2.HL.TZ2.4b

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Date May 2023 Marks available [Maximum mark: 2] Reference code 23M.2.HL.TZ2.4b
Level HL Paper 2 Time zone TZ2
Command term Explain Question number b Adapted from N/A
b.
[Maximum mark: 2]
23M.2.HL.TZ2.4b
(b)

Pangolins are unique among mammals in having evolved scales, which are a recognition feature of reptiles. Explain which features you expect pangolins to have, which would show that they are mammals, not reptiles.

[2]

Markscheme
  1. hair;
  2. mammary glands/milk secretion;
  3. alveoli in lungs;
  4. lower mandible/jaw consisting of just one bone;
  5. giving birth to live young/are placental (apart from duck-billed platypus/echidna);
  6. external ears/ pinna;
  7. warm-blooded/endothermic/constant body temperature;

Mpa: pangolin underside may be covered with sparse fur.

Do not accept double circulation. Mpe: accept “do not lay eggs” as WTTE Do not accept internal fertilization.

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