IB Biology A3.2 Classification and Cladistics Test Questions

Why are evolutionary relationships important in classification?

• They are based solely on habitat similarities.

• They reveal common ancestry and allow grouping based on evolutionary history.

• They depend entirely on the number of chromosomes.

• They ignore genetic data in favor of appearance.

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How do shared morphological characteristics contribute to forming clades?

• They show adaptations to identical environments only.

• They indicate common ancestry, allowing scientists to group organisms with true evolutionary relationships.

• They result from random variation.

• They are irrelevant when genetic data is available.

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What is a "clade" in cladistics?

• A group of organisms that share the same habitat.

• A group that includes an ancestor and all its descendants.

• A group defined solely by similar external features.

• A collection of species based on their ecological role.

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What does the "root" of a cladogram represent?

• The point of maximum species diversity.

• The most recent common ancestor of all taxa depicted.

• The oldest fossil ever found.

• A reference for current species' habitats.

In a cladogram, what is a "node"?

• A terminal end that represents a species.

• A point where a lineage splits into two or more branches.

• A marker for extinct species only.

• An arbitrary point used for scale.

What does a "terminal branch" in a cladogram represent?

• A branch that splits repeatedly into subgroups.

• An individual taxon or species with no further splits.

• The common ancestor of all species.

• A hypothetical ancestral species.

What is meant by a "common ancestor" in evolutionary biology?

• A species that resembles all modern species.

• An ancestral species from which two or more descendant species have evolved.

• The most abundant species in a group.

• A species that remains unchanged over time.

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NGSS.HS-LS4-1

How are DNA base sequences used to classify organisms into clades?

• They provide genetic data that reveal similarities and differences for grouping.

• They are used only to determine chromosome number.

• They solely indicate ecological adaptations.

• They measure the size of an organism's genome.

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Why is chromosome number generally considered less reliable for cladistic classification?

• It is the same for all organisms.

• It can change due to fusion or fission events and may not reflect detailed genetic differences.

• It directly indicates the organism's age.

• It is always influenced by environmental conditions.

What is a potential pitfall of relying solely on morphological characteristics for classification?

• Morphology always perfectly reflects evolutionary relationships.

• Convergent evolution may produce similar traits in unrelated species.

• Morphological data are more reliable than genetic data.

• Morphology can only be observed in fossils.