IB Biology Topic A3.2: Classification and Cladistics Questionbank

(a) Outline the characteristics used to distinguish between the three domains of life.

(b) Describe how organisms are classified into taxa.

(c) Explain why classification systems are constantly revised.

The disagreement between “splitters” and “lumpers” in taxonomy shows that scientific classification is…

The gradual accumulation of differences in DNA and protein sequences over time can act as a molecular clock for estimating when lineages diverged.

(a) Explain how differences between sequences can be used to estimate the time since two species diverged from a common ancestor.

(b) Outline three factors that can cause molecular clock estimates to be unreliable.

(c) Discuss the strengths and limitations of using the molecular clock to date evolutionary events.

A

B

C

D

sometimes revised when new evidence (e.g. DNA) becomes available

influenced by interpretation of traits and patterns of relatedness

based on different species concepts and chosen diagnostic characters

determined only by visible differences in appearance