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Date May 2019 Marks available 1 Reference code 19M.1.HL.TZ2.26
Level Higher level Paper Paper 1 Time zone Time zone 2
Command term Deduce Question number 26 Adapted from N/A

Question

The cladogram shows some major orders of placental mammals and is based on biochemical evidence.

[Source: © International Baccalaureate Organization 2019]

 

Which conclusion can be drawn from evidence in the cladogram?

A. Primates and Sirenia have not evolved from a common ancestor.

B. Primates and Cetacea do not form part of any clade.

C. Cetacea are less closely related to Sirenia than to Primates.

D. Xenarthra have not been changed by evolution for longer than other clades.

Markscheme

C

Examiners report

Some candidates failed to realize that Xenarthra are more closely related to Primates than to Sirenia as they evolved more recently from the former. Xenarthra evolved from Boreoeutheria into different species and after that did not change by evolution, while all other species did change.

Syllabus sections

Core » Topic 5: Evolution and biodiversity » 5.4 Cladistics
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