WEEK 11 - SAMPLE LAB EXAM QUESTION
- QUESTION:
- What is the significance of the iridium spike in the
impact clay at the K/T boundary?
- Describe two features of the snail shell on display that
would reduce the animal's vulnerability to predation.
- Why is geographic isolation of a population usually the
first step in speciation?
- ANSWER:
- Iridium is abundant in asteroids, very rare on earth.
Its high concentration at the K/T boundary may be
taken as evidence of an asteroid impact triggering the
mass extinction.
- Narrow aperture, with ridges to further reduce opening.
- Thick shell
- Thickened aperture lip
etc...
- Geographic isolation provides the initial block to gene
flow, allowing genetic divergence to develop between
the newly isolated populations.
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