Biology · Unit 7 · Paper 3

Natural Selection unit test

A test on this unit alone, marked as a percentage and a letter grade — for the test your class is actually sitting, rather than for May. Answer everything, then submit once: seeing the answer to question 3 before attempting question 4 makes the final percentage meaningless.

Paper 1 Paper 2 Paper 3

Each paper is built from this unit’s 38 terms and is the same for everyone, so a teacher can assign “Unit 7, Paper 3” and every student sits the identical test. Multiple choice is marked objectively; the written sections you mark yourself against the model answer and rubric.

Suggested time 31 min 28 points0/17 attempted

Cladogram and shared derived characters

Hardy-Weinberg equations

Hardy-Weinberg conditions

Lab: Artificial Selection

Allopatric vs sympatric speciation

Genetic drift

Fitness

Gene flow

Bottleneck effect

Variation as the raw material

Reproductive isolation

Mutation as the ultimate source of alleles

Short answer 1. Define or explain: Endosymbiosis as evolutionary evidence

3 pts

Short answer 2. Define or explain: Convergent evolution

3 pts

Short answer 3. Define or explain: Molecular clock

3 pts

Short answer 4. Define or explain: Natural selection

3 pts

Free response

4 pts

A researcher constructed a phylogenetic tree for five species using sequence data from a shared gene. Species A and B differ at 4 nucleotide positions; A and C differ at 19; A and D differ at 42; and A and E differ at 44. Species D and E differ from each other at 6 positions.

(a) Identify which species is most closely related to species A, and justify your answer using the data.

(b) Explain why species D and E are placed on the same branch of the tree, separate from A, B, and C.

(d) Describe one assumption a researcher makes when using the number of sequence differences to estimate how long ago two species diverged.