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Question 20N.2.HL.TZ0.a

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Date November 2020 Marks available [Maximum mark: 3] Reference code 20N.2.HL.TZ0.a
Level HL Paper 2 Time zone TZ0
Command term Outline Question number a Adapted from N/A
a.
[Maximum mark: 3]
20N.2.HL.TZ0.a

More than 8 million different species are alive today but over the course of evolution, more than 4 billion may have existed.

Outline the criteria that should be used to assess whether a group of organisms is a species.

[3]

Markscheme

a. organisms can potentially interbreed;

b. to produce fertile offspring;

c. same sequence of genes (on chromosomes) / same types of chromosomes;

d. similar traits/phenotype/WTTE;

e. same chromosome number/karyotype;

Examiners report

This was the most successfully answered part of Question 8. Many knew that members of a species can interbreed and produce fertile offspring. Surprisingly few mentioned that similarities in characteristics or phenotype are found in species.

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