THE VARIETY OF LIVING ORGANISMS

Classifying Organisms : Test it!

Classifying Organisms : Test it!

1.One of the earliest methods used to classify birds was using their call.

a. Explain why scientists could use this to investigate relationships between birds of the same species.
b. Today, scientists can find relationships at a molecular level. How can scientists use protein structure to investigate relationships between birds of the same species?
c. Scientists can also use DNA hybridisation to investigate relationships between species. They measure temperatures to see how closely related species are. Explain why.

2.
The protein cytochrome c is found in all eukaryotic cells. The table below shows the sequence of amino acids 10 to 13 in a human and a chimpanzee.

Species

Amino acids in this position in cytochrome c

10

11

12

13

Human

Phe

Ile

Met

Lys

Chimpanzee

Phe

Ile

Met

Lys

a. What can see say about the relationship between humans and chimpanzees using these results?
b. Give an example of why cytochrome c is useful in determining relationships between different species.

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ANSWERS

1.

a. A bird call is species specific. The bigger the similarity between the calls the closer the relationship between the species.
b. Answers include:
i. The more similarities there are in the amino acid structure, the more closely related the species.
ii. Species which are similar have a similar immune response to particular proteins.
c. The higher the temperature required the more hydrogen bonds were formed and so the more complementary bases.

2.

a. Humans and chimpanzees are closely related.
b. It’s found in all eukaryotes.