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Chapter 13 exam #2
Terms in this set (30)
When did life began on earth
Changes in body structures and molecules have slowly accumulated through that time, producing the variety of organisms we see today.
3.8 billion years ago
when did earth form?
4.6 billion years ago
Scientists use the geologic timescale to divide the history of the Earth into eons and eras. These periods are defined by major geological or biological events, such as mass extinctions.
The earliest evidence came from fossils
clues to evolution
A fossil is any evidence of an organism that is more than 10,000 years old.
Spores and seeds
where are fossils found `
what is their relationship to each other?
relative dating, age, the deeper the older
fossils are not found today because tht means that
they are extinct
the fossil record is diverse
transition ( make one transition from one to the next) fossils are limited
it is difficult for something to become fossilized
Earthquakes and erosion might destroy fossils, but what might cause them not to form?
what do fossils tell us
about the organism and te enviorment
These are chambered mollusks (?) similar to the nautilus.
Places fossils in relation to events or each other, but does not assign a specific age.
Places fossils in order from oldest to most recent
Absolute Dating and Radioactive Decay:
Researchers can use testing methods on either the fossil or the adjacent materials to determine an approximate age
Uses radioactive isotopes (?) as a "clock"
Isotopes decay at a characteristic, unchangeable and measurable rate, called a half-life.
The carbon isotope Carbon-14 has a half-life of 5730 years. (?) Other isotopes with various half-lives are used to measure older organisms.
Biogeography looks at where organisms live, where they have lived in the past, and how populations have moved:
The geographic distribution of species
How could apparently related species be on different sides of the planet?
all of the earth together, plate tectonics
The Earth has changed over the last 200 million years!
This movement cycle may have occurred several times.
According to the theory of plate tectonics, Earth's surface has several rigid layers which move in response to forces within the planet
Earthquakes and volcanoes are evidence that the plates are still in motion.
Biogeography Considers Species' Geographical Locations
Fossils help geographers piece together Earth's continents
Biogeographical studies shed light on evolutionary events.
Structures that are similar due to shared ancestry.
May not have same function.
Naturalists also found species that seemed physically alike in some ways but not others:
These two cacti have similar shapes and similar habitat, but different reproductive parts.
This is convergent evolution, often giving rise to analogous structures, which are structures that are alike due to similar environmental pressures rather than common ancestry.
If they look alike on the outside, are they going to be the same on the inside?
If they look different on the outside, will they be different on the inside?
What about structures found that have no use at all?
What is the relationship between DNA and proteins
dna has the direction to make proteins
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