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Biology · Grades 7–11

Classification, biodiversity and relatedness

Separate similarity, ancestry and the evidence used to classify.

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Learn the idea

Classification

Organisms can be grouped using shared characteristics and evolutionary evidence.

Biodiversity

Diversity includes genetic, species and ecosystem dimensions.

Trees

A branching evolutionary tree models common ancestry; branch-tip order alone is not a progress ranking.

Evidence

Molecular, anatomical and other data can revise relationships as understanding improves.

Worked examples

Which is one dimension of biodiversity?

Biodiversity includes genetic variation as well as species and ecosystems.

Genetic diversity within populations.

What does a branch point in a simple evolutionary tree represent?

Branching depicts ancestry relationships.

A modeled common ancestor.

Check your understanding

  1. Does being drawn farther right on a tree mean a species is more evolved?

    1. Yes, always.
    2. No.
    3. Only if the line is thicker.

  2. A survey lists 4 plant species, 3 insect species and 2 bird species, with no duplicates. How many species are listed?

  3. Why is similar appearance not sufficient by itself to prove very recent common ancestry?

Answers and marking notes

Answers and marking notes
  1. No.

    Tip layout is not a progress scale.

  2. 9

    4 + 3 + 2 = 9.

  3. Similar traits can arise under similar pressures, and more evidence is needed.

    Convergent similarities can complicate appearance-based inference.

Further reading and review references

These are reference links, not copied exercises, institutional endorsement or proof of independent review.

Independent educational review required. Grade bands are approximate; these are not officially aligned curricula.