Unit One: Life on Earth Flashcards
(27 cards)
What is said to be life’s origin?
various meteorite strikes
What meteorite has been said to fall from mars to earth with extraterrestrial life?
ALH84001
4 +3/4 lbs, formed by molten lava
What are the two types of life?
1. Biotic (living)
2. Abiotic (non-living)
What are the biotic characteristics of viruses
- nucleic acids
- ability to reproduce and replicate
- ability to evolve and adapt
What are the abiotic characteristics of viruses
- cannot synthesize their own proteins
- cannot live without host attatchment
- cannot reproduce
What are the characteristics of all life forms?
- Display orderly fashion
- Harness and utilize energy for mechanical purposes
- Reproduction
- Responding to stimuli
- Homeostasis
- Growth and Development
- Evolution
What are some characteristics of the earth
- earth is 4.6 billion years old
- first prokaryotes: 3.5 billion years
- first eukaryotes: 2.0 billion years
- dinosaur extinction: 65 million years
- modern humans: 150,000 years
What are the 4 classes of molecules
- Nucleic Acids (DNA, RNA, ATP)
- Proteins (amino acids)
- Lipids (fats)
- Polysaccarhides (carbohydrate)
What are the 3 hypothesis’ to early years of earth
- Reducing Atmosphere
- Deep Sea Vents
- Extraterrestrial Origin
Reducing Atmosphere Hypothesis (1)
- beginning (primordial) atmopshere
- water vapour (H2, CO2, NH3, CH4)
- almost complete absence of O2
What is the Oparin-Haldane Hypothesis
- early atmosphere was reducing (eliminating O2 and O3)
- simple organic molecule formation
- amino acids first –> complex polymers
- molecule development through UV light
What is the confirmed modern atmospheric content
- oxidizing atmosphere
- high levels of O2 prevents formation of complex molecules
Deep Sea Vents Hypothesis (2)
- complex organic molecules originated on ocean floor through deep sea vents
- cracks near volanic activity
- produces nutrient rich water
- NH3, CH4, H2S
Extraterrestrial Origin Hypothesis (3)
- key organic molecules originated from outer space
- organic molecules: carbon based
- carbonaceous chondrites: meteorites with organic molecules
Earliest Form of Life: Heterotrophs
- heterotrophs
- organisms containing organic molecules
- consumers
- earliest forms were considered anerobic
Earliest Form of Life: Autotrophs
- autotrophs
- contain carbon from environment (inorganic form CO2)
- photoautotrophs additionally use light as an energy source
What is Organic Photosynthesis
- light to support various functions
- increase in atmospheric oxygen
What evidence points to proof of organic photosynthesis
- banded iron
- striped red rock sediment
- red on striped rock sediment come from rust
Where did the source of O2 come from in organic photosynthesis
- photosynthetic prokaryotes + cyanobacteria
- extract electrons from H2O
- liberates O2
- relies on oxidation of water for electrons
What was the VERY first organism on planet Earth
- protists
- 200,000 eukaryotes
- mostly unicellular
- not animals, plants, or fungi
- paramecium, aemoba
What are Fossil Records
- only direct evidence from millions of years ago
- represents a small fraction of existed life
- fossils form in sedimentary rocks
What are Fossil Records
- only direct evidence from millions of years ago
- represents a small fraction of existed life
- fossils form in sedimentary rocks
What are Strata
- layers of sediments
- particles setting on the bottom of water bodies
- lowest layer = oldest
- fossil formation and preservation
- hard tissues, unconsumable
- lack of oxygen prevents decomposition
ex: tree resin, ice glace
What are some examples of Fossil Records
- Petrified Wood
- Sedimentation
- Strata
- Mosquitoes in Amber
- Mammoth in Permafrost
