Lecture 2

Question 1

Describe earliest fossil evidence of life and of photosynthesis, and (roughly) place these fossils in the timeline of earths history

Answer 1

Earliest known fossils (life): 3.5 bya
- Prokaryote microfossils
- Stromatolites
Earliest evidence of Ph: 3.4 bya
- Banded iron formations

Question 2

Explain why the evolution of photosynthesis presented both catastrophe and huge opportunity to life on earth

Answer 2

Catastrophe:
- No more dissolved iron to capture 02
- Oxygen begins to accumulate in atmosphere
- Toxic to life that evolved in anaerobic environment
Opportunity:
- Allows oxidation of carbon compounds
- Allows organisms to be more complex, more active and larger
- Allows life to survive in surface waters, on shores, and move to land for the first time

Question 3

(Roughly) date the occurrence of life on land, and name some characters of the first land plants

Answer 3

-0.45 bya
-bryophyte-like( seedless, non-vascular)
- Shared, derived characters of plants and their closest algal relatives facilitated colonization of land - sporopollenin, flagellated sperm

Question 4

Discuss how diversification of land plants enabled diversification of other lineages

Answer 4

• Better access to light
• Better access to nutrients
• Better CO2 availability
• Escape from predation

Question 5

Place important events in earths history in correct order

Answer 5

3.5- earliest known fossils (strom)
3.4- photosynthesis
2.2- O2 catastrophe
2.1- eukaryotes
1.5-1- Primary endosymbiotic event
0.65- multicellular fossils
0.45- plants on land
0.38- vascular plants are well-est
0.29- gymnosperms are well-est
0.14- flowering plants
0.002- Humans