History Of The Biosphere

Question 1

Three reasons the fossil record is biased or incomplete

Answer 1

1. Fossilization is rare - most organisms decompose before fossilizing
2. Bias toward organisms with hard parts - bones, shells, and teeth are more likely to be preserved
3. Environment bias - fossils are more likely to form in certain conditions.

Question 2

How are relative ages established in the fossil record

Answer 2

Analyzing the position of fossils in sedimentary rock layers (strata) - deeper layers are older than those above them.

Question 3

What technique is used to establish actual ages in the fossil record? Brefiely describe how it works (half-life)

Answer 3

Radiometric dating is used which measures the decay of radioactive isotopes in rocks/fossils. Half life is the time it takes for half of the radioactive isotope to decay.

Question 4

What are the four eons of the geologic record and approximately what range of years does each include

Answer 4

1. Hadean EON : 4.6 to 4.0 BYA
2. Archaea EON : 4.2 to 2.5 BYA
3. Proterozoic EON : 2.5 BYA
4. Phanerozoic EON : 541 MYA

Question 5

How do plate tectonics influence biodiversity

Answer 5

Change the position and connections between continents, isolating populations and causing speciation or extinction.

Question 6

How does mass extinction affect biodiversity

Answer 6

Eliminates larger number of species, opening ecological niches

Question 7

How does adaptive radiation affect biodiversity

Answer 7

Follow extinction or environmental changes, where surviving groups diversify rapidly to exploit new niches.