Diversity of microorganisms — A/L Biology

How do I practise Diversity of microorganisms?

1 question with a worked solution

1. Which structural feature definitively distinguishes Domain Archaea from Domain Bacteria?
   1. A) Presence of 70S ribosomes in cytoplasm
   2. B) Absence of a membrane-bound nucleus
   3. C) Membrane lipids containing branched hydrocarbons with ether linkages
   4. D) Presence of circular double-stranded DNA
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   Correct answer: C) Membrane lipids containing branched hydrocarbons with ether linkages

   Archaea have unique plasma membranes composed of branched isoprenoid chains linked to glycerol by ether bonds (not ester bonds), allowing survival in extreme environments. Bacteria have unbranched fatty acids with ester linkages and peptidoglycan cell walls.

   Show worked solution

   Step 1: Check shared prokaryotic traits: both lack nucleus, have circular DNA, and 70S ribosomes. Step 2: Differentiating biochemical traits: Archaea have ether-linked branched lipid membranes and lack peptidoglycan; Bacteria have ester-linked unbranched lipids and peptidoglycan. Answer: Membrane lipids containing branched hydrocarbons with ether linkages.
   Modelled on: the A/L Biology examination pattern

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Where does Diversity of microorganisms fit in the syllabus?

Year 1 · Term 3