DP Biology (first assessment 2025)

Question 23M.2.HL.TZ2.4

Date	May 2023	Marks available	[Maximum mark: 7]	Reference code	23M.2.HL.TZ2.4
Level	HL	Paper	2	Time zone	TZ2
Command term	Explain, State	Question number	4	Adapted from	N/A

[Maximum mark: 7]

23M.2.HL.TZ2.4

The Chinese pangolin (Manis pentadactyla) is a critically endangered species that has declined in numbers by 80 % since 2000. It inhabits both forest and grassland, where it uses long, powerful claws to open ant and termite nests and ingests the insects using a long, sticky tongue.

^{[Source: By U.S. Fish and Wildlife Service Headquarters - Manis pentadactyla, CC BY 2.0,}
^{https://commons.wikimedia.org/w/index.php?curid=56589200.}
^{Photo credit to Ms. Sarita Jnawali of NTNC – Central Zoo The United States is}
^{cosponsoring four separate proposals to increase CITES protections for pangolins}
^{from Appendix II to Appendix I, U.S. Fish and Wildlife Service Headquarters -}
^{Manis pentadactyla. CC BY 2.0. File:Manis pentadactyla (29054818144).jpg.}
^{Created: 14 September 2016.]}

(a.i)

State with a reason whether pangolins are autotrophic or heterotrophic.

[1]

Markscheme

heterotrophic because it feeds on/eats food/other organisms /eats ants/termites/ doesn’t photosynthesise/does not produce its own food;

Do not accept “it is not autotrophic” as it is part of the stem question.

(a.ii)

Explain what information is needed to find the trophic level of pangolins.

[2]

Markscheme

what (prey) it eats/feeds on/ stomach content;
the trophic level of what (prey) it eats/feeds on/the trophic level of ants/termites;
trophic level is the position an organism occupies in the food chain/web;

Do not award points for indicating that predator information is needed.

(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

hair;
mammary glands/milk secretion;
alveoli in lungs;
lower mandible/jaw consisting of just one bone;
giving birth to live young/are placental (apart from duck-billed platypus/echidna);
external ears/ pinna;
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.

(c)

The Chinese pangolin, Manis pentadactyla, has a diploid chromosome number of 40.

(c.i)

State how many chromosomes there would be in gametes of this species.

[1]

Markscheme

20;

(c.ii)

Sex is determined in the same way in pangolins as in humans. State how many autosomes there are in somatic cells of M. pentadactyla.

[1]