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CB4c.3
Classification – Extend
You do not need to remember any details about Bacillus subtilis, Methanosarcina barkeri or Euglena for your
exam, but exam questions could ask you to apply your knowledge to unfamiliar situations.
1
Bacillus subtilis is unicellular. Its cells have no nuclei. Its genes do not contain unused pieces of DNA. It
moves using flagella. Methanosarcina barkeri is single-celled. Its cells do not have nuclei. Its genes contain
unused pieces of DNA. It is not able to move by itself.
a
Give one reason why both these organisms were originally put in the same kingdom.
b
These organisms are now often put in two domains. Why are they in different domains?
c
Bacillus subtilis is in the Bacteria domain. What domain is Methanosarcina barkeri in?
E1 Explain why Archaea were placed in their own domain only after genetic analysis became available.
2
The drawing shows a single-celled organism from the genus Euglena. For many years, scientists argued
about whether organisms from this genus were animals, plants or neither.
a
Describe one feature that could put Euglena in the plant kingdom.
b
State why members of the Euglena genus are not plants.
c
What kingdom does the Euglena genus belong in?
d
What domain is the genus Euglena in? Explain your reasoning.
e
What is genetic analysis?
f
Explain why genetic analysis would have settled the argument about which kingdom Euglena belongs
to earlier.
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