Plasmids, Mobile Elements and How Resistance Spreads · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Resistance travels as luggage

Science · Microbiology · ages 20-21
Name ______________________   Date ____________

  1. Which transfer route spreads plasmids fastest through a crowd?

    • Transformation
    • Conjugation
    • Cell division alone

  2. What is a plasmid?

    • A small circle copying apart from the chromosome
    • A piece of the ribosome
    • A kind of virus shell

  3. A cell can lose its plasmid at division while keeping its chromosome unchanged.

    Circle one:   True   False

  4. Treating with one drug keeps resistance to three others alive. Why?

    • One package carries all, so one selection keeps the bundle
    • The drugs are identical
    • Mutations never fade

  5. A strain gains resistance to four drugs overnight. What best explains it?

    • Four separate slow mutations at once
    • The drugs destroyed each other
    • One plasmid carrying all four genes arrived together

  6. The drug is withdrawn for many generations. What happens to plasmid frequency?

    • It climbs forever
    • It freezes exactly
    • It slides as droppers outgrow keepers

  7. Chromosomes carry optional extras while plasmids carry the essential housekeeping genes.

    Circle one:   True   False

  8. A student blames four overnight resistances on four lucky mutations. What is the error?

    • Mutations never happen
    • A single bundled transfer explains joint arrival far better
    • Plasmids cannot move
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Resistance travels as luggage W1-mt_Vk0qOY64qv-s1

  1. Conjugation · Living contact passes copies far quicker than dividing.
  2. A small circle copying apart from the chromosome · It replicates on its own beside the chromosome.
  3. True · The optional circle can be missed while the essentials pass on.
  4. One package carries all, so one selection keeps the bundle · Selecting any part of the package keeps the whole.
  5. One plasmid carrying all four genes arrived together · A single package event delivers the whole bundle.
  6. It slides as droppers outgrow keepers · Copying costs drag carriers down with no payoff.
  7. False · The roles run opposite: chromosome essentials, plasmid extras.
  8. A single bundled transfer explains joint arrival far better · Joint arrival in one step smells of packaging.
Worksheet · LightMySky