History of Life Flashcards
How old is the earth estimated to be?
4.5 Billion Years Old
When were the 1st living organisms on earth?
3.5-3.9 Billion years ago
How do we measure earth’s age?
By using Radiometric dating
Measured by the decay of long-lived radioactive isotopes of elements in rocks and minerals and that decay with half lives of 700 million to more than 100 billion years to stable isotopes of other elements:
Radiometric Dating
Radiometric Dating measures the last time that the rock being dated was either melted or disturbed sufficiently to ______ its radioactive elements.
Rehomogenize
Ratio of __Oxygen to __Oxygen isotopes in Zicron Minerals.
18 to 16
Liquid water formed how many years ago?
4.3 Billion
If a rock has been to the Earth’s surface and interacted with water, it will be significantly ‘_____’ and more enriched in 18Oxygen.
heavier
6 Charactaristics of living things:
- ability to reproduce
- ability to store and use information
- ability to evolve
- metabolism (assimilate and use energy)
- ability to respond to environment
- composed of cells
Earliest living organisms all were ______ (single cell) or perhaps colonial
unicellular
Earliest living organisms all were ______ (lack nucleus, most organelles)
prokaryotes
Earliest living organisms all were ______ (do not require oxygen; in fact, would likely have died if exposed to oxygen)
anaerobic
Earliest living organisms all were ______ (ate things) or ________ (made orn food using heat energy)
heterotrophs / chemoautotrophs
All living cells need at least 3 things. What are they?
- The raw materials to make them
- A membrane to enclose the cell contents
- some kind of instruction molecule to direct accurate reproductions
What are the 4 possible methods for generating organic molecules from the basic elements found on the ancient earth?
Option 1: in the atmosphere
Option 2: Underwater
Option 3: In Ice
Option 4: From Space
Ancient atmosphere had:
Hydrogen Nitrogen Ammonia Methane CO2 Some water vapor But no oxygen
Underwater: _____ _____ emit bubbles of superheated gases, including ammonia, methane, CO2, hydrogen
Thermal Vents
As ____ cool, organic molecules form
Gases
___ does not penetrate water very far, so the molecules don’t break down
UV
As ice forms, organic molecules form inside tiny pockets of ____ and _______ that are trapped inside.
Gases and liquid water
Organic molecules from space is called the ____ _____.
Panspermia Hypothesis.
Simple organic molecules are found in comets, ____ ____, ____, and some _____.
interstellar dust, clouds, meteors.
