Plant and Planetary Evolution Flashcards
Why are we studying evolution in forest plant biology?
Evolution is the key to plant biodiversity and it is the cornerstone of modern biology.
Helps us understand how organisms have changed over time
How old is the Earth?
4.6 billion years (byr) old
Where do we find fossil traces of bacteria?
Stromatolites found all over the world
Why are bacterial cells simple?
They have no nucleus or other organelles.
When were the origins of life?
4.1 billion years ago
What is important within the evolution of species?
variation among organisms is what allows evolutionary selection to happen.
How did life arise?
No one knows, but probably the ocean
What was the Earth’s atmosphere like in early Earth?
Mostly nitrogen gas
CO2 concentrations were higher (10-30% of the atmosphere)
Large amounts of hydrogens, and hydrogen sulfide
No free oxygen
What eventually came in short supply?
Chemical energy
What gave organisms a significant advantage in survival?
Capturing light energy
What were one of the most successful organisms and why?
Cyanobacteria
They developed photosynthesis using water as a source of electrons
How long did cyanobacteria dominate the earth?
2 billion years
What is the Snowball Earth hypothesis?
events were caused by a combination of low atmospheric CO2 concentrations and dimmer sunlight
Why was the atmosphere able to accumulate oxygen at low levels 2.4 billion years ago?
The availability of oxygen permitted the evolution of aerobic respiration
Why are eukaryotic organisms more complex?
They have cells with nuclei and other organelles like chloroplasts and mitochondria.
What did the evolution of eukaryotes coincide with?
Sexual reproduction
Why is sexual reproduction important for evolution?
Sexual reproduction promotes the production of variable progeny
This gives a greater pool for selection to choose from to speed evolutionary processes.
What do all communities need?
Primary producers
What was the order of the appearance of plants?
The colonization of land
Differences between sea and land environments “Adapting to the desiccating environment”
Early land plants
Why did the move from an aquatic to terrestrial environment have a big impact on the planet?
Made conditions suitable for land animals and fungi
Had massive effects on Earth’s climate by creating a cooler atmosphere since it drew down lots of CO2.
Why did it take so long for plants to evolve?
The development of the ozone layers made it possible by removing ultraviolet light from sun
O2 finally reached higher levels that allowed ozone to accumulate.
How is weather different in the ocean than the land?
Ocean temperatures are moderate in comparison to daily/season terrestrial changes.
How is water availability different?
Water is almost always available
Terrestrial environments need to obtain and conserve water
How is reproduction different?
Water: reproductive cells can swim around to find each other
Terrestrial: tougher time for new mechanisms to exchange gametes.
