The flashcards below were created by user
heidi.tjeerdsma
on FreezingBlue Flashcards.
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What was the earth called before life?
prebiotic
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How old is the earth estimated to be?
4.5 billion years
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How were simple biological chemicals such as amino acids and DNA bases made during early earth?
using energy from lightning--with no consumers of the chemicals, they can accumulate
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What can break down the chemicals, so they collect in areas with less sun?
ozone
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What was probably the first self-replicating molecule?
RNA
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What are the oldest organisms and how old are they?
- bacteria
- 3.5 to 3.9 billion years ago
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What did bacteria use up?
hydrogen sulfide from volcanoes
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After bacteria used up hydrogen sulfide from volcanoes, what did it use as its source of hydrogen?
water
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What does bacteria start to produce once it develops photosynthesis?
oxygen
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What is proof of oxygen showing up on Earth?
seeing how old the oldest rust is (rust is oxidized iron)
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How long ago did oxygen show up?
2.3 billion years ago
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What did oxygen do to some organisms when it first showed up?
poisoned some
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How long ago did eukaryotes develop?
1.7 billion years ago
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What was the benefit of multicellular organisms?
their larger size made them harder to eat
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How long ago did animals show up?
600 million years ago
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What are advantages to land life?
- for plants, much stronger sunlight
- higher amounts of nutrients in soil than in water
- no predators (yet)
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What are the problems for plants on land?
- need to acquire water--first plants were in wetlands, low to ground
- used to pollinate using water--new plants used eggs and sperm on the same plant, developed pollen, then seeds, flowers
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What were the first animals on land?
arthropods (insects, spiders, scorpions, crabs)
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Why is development of specialized cells important?
each cell no longer has to do everything, can spend more energy on particular functions
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What are skeletons on the outside?
exoskeleton
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What were probably the ancestor for amphibians?
lobefin fish
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What were two things that lobefin fish had that helped them transition to land?
- primitive lungs
- fins for crawling
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What improvements over amphibians did reptiles have?
- shelled eggs
- internal fertilization
- water resistant skin
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What were some advantages for birds and mammals over reptiles?
- feathers, hair
- they could remain active at night
- birds kept feathers and eggs, mammals kept hair, developed live young method of birth
- birds likely descended from reptilian dinosaurs
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