Taxonomy, the Three Domains and What a Species Name Encodes · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Naming life by its family tree

Science · Genetics & Evolution · ages 16-17
Name ______________________   Date ____________

  1. There are three domains: Bacteria, Archaea and Eukarya.

    Circle one:   True   False

  2. What does a rank in the hierarchy claim?

    • Shared ancestry of its members
    • Identical appearance of its members
    • Equal size of its members

  3. In Quercus alba, what is Quercus?

    • The species
    • The genus
    • The domain

  4. Bird and bat wings look alike. Why might grouping by them mislead?

    • Wings are never inherited
    • Birds are not animals
    • They evolved separately, not from a shared winged ancestor

  5. What is a clade?

    • An ancestor plus all its descendants
    • Any two lookalikes
    • One single organism

  6. Why was the old picture of the prokaryotes revised?

    • Scientists preferred the number three
    • Molecular evidence contradicted the older picture
    • Fossils of domains were found

  7. Two organisms sharing a genus share a more recent ancestor than two sharing only a domain.

    Circle one:   True   False

  8. New gene data shows a genus sits on a different branch. What should happen?

    • Keep the old name to avoid confusion
    • Discard the gene data as irrelevant
    • Revise the classification to match the ancestry
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Answer key

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

Naming life by its family tree W1-mt_12ucjuHtHE-s1

  1. True · Molecular data split life into exactly these three.
  2. Shared ancestry of its members · Each rank says its members share an ancestor.
  3. The genus · The first word names the genus; the second names the species.
  4. They evolved separately, not from a shared winged ancestor · Lookalikes from convergent evolution do not prove shared ancestry.
  5. An ancestor plus all its descendants · A clade is one ancestor with every branch it grew.
  6. Molecular evidence contradicted the older picture · Molecule comparisons forced the split into two domains.
  7. True · Lower ranks nest deeper, so their ancestor is nearer.
  8. Revise the classification to match the ancestry · Classification is a hypothesis, so fresh evidence redraws it.
Worksheet · LightMySky