Flashcards
Archean History Cont. (14)
Flashcards do conjunto (26)
- 1How bright was the sun in the Archean?It was dim due to high CO2
- 2Were CO2 levels in the atmosphere high or low?High
- 3How do we know (what lines of evidence?) that Earth's earliest atmosphere had very little to no free oxygen gas?Paleosols (fossil soil), BIFs, detrital pyrite (not rusted) and detrital uraninite (not in current atmosphere) was found in Archean rocks.
- 4What is abiogenesis?= origin of life hypothesis (explains how life started)
-Is NOT part of evolutionary theory (which explains the diversity of life) - 5What are the basic requirements for life as we know it?Organic chemicals (Carbon; CHON), liquid water (only Earth has this at the surface), and energy supply (lifeforms have a metabolism)
- 6Where did life likely originate?-In the oceans
-Water has good solvent & heat capacity - 7Can amino acids (= the building blocks of life) and nucleotides (= linked-together amino acids & the building blocks of RNA and DNA) form naturally/inorganically? If so, how?Yes B/C Miller-Urey experiments proved this.
How? IDK - 8Could amino acids have arrived on Earth from outer space?Yes
-Some from the asteroid belt have amino acids on them - 9Could polynucleotides (like RNA) have formed naturally? How?-Yes
-Montmorillonite is a common clay mineral - it is a catalyst for linking reactions. - 10What is the significance of seafloor hydrothermal vents?It is a possible location where 1st life originated (or oceans or water pockets in deep subsurface rocks)
- 11Were the first cells likely heterotrophs (th or autotrophs?Likely autotrophs
- 12☼What are the characteristics of procaryotic cells?☼-small, simple cells
-few organelles
-No nucleus
-Asexual reproduction - 13☼What are the characteristics of eucaryotic cells?☼-Large, complex cells
-Many organelles
-Have a nucleus
-Asexual & sexual reproduction - 14The procaryotes consist of what two domains of life?Kingdom Bacteria
Kingdom Archaea - 15The eucaryotes include what kingdoms of life?Kingdom Protista
Kingdom Fungi
Kingdom Plantae
Kingdom Animalia - 16☼What defines a protist?☼- 1-celled eucaryote
-some: photosynthetic
Some: heterotrophs
-Most are aquatic - 17☼What defines a Fungi?☼-Multicellular, non-photosynthesizing eucaryote (not plants)
- 18☼What defines a Plantae☼-Multi cellular, photosynthesizing eucaryotes
- 19☼What defines Animalia?☼-Multicellular, non-photosynthesizing eucaryotes capable of spontaneous movement
- 20The fossil record is dominated by what three kingdoms of life?Animals, Plants, Protists
- 21What organisms dominated on Earth during the Archean?All procaryotes
Microbes
Bacteria - 22What is the fossil record of such the Archean dominating organisms?-Stromatolites
-Body fossils of cells (~3.5-2.5 Ga) - 23What are the oldest Earth fossils? Where are they found?Oldest fossils are chemofossils
--3.83 Ga rock in sw Greenland (from photosynthetic microbes)
-☼4.1 Ga zircon form Australia with graphite inclusion☼ - 24What are stromatolites?Large, layered structures built up by mats of cyanobacteria
- 25What are chemofossils?Chemicals in rocks that are biologic in origin
- 26What are the oldest supposed chemofossils?-3.83 Ga rock in sw Greenland (from photosynthetic microbes)
-☼4.1 Ga zircon form Australia with graphite inclusion☼