Unit 5 Review
Published on May 10, 2018
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PRESENTATION OUTLINE
To prepare for the unit test, start by writing down everything you know about what science has observed about the development of life on Earth.
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As we go through the slides, write down any information that you were missing on your original notes.
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Earth
4 billion years ago
Early Earth
- violent thunderstorms and lightning
- meteorites crashing
- volcanoes erupting
- no oxygen yet
You can't breathe here! The atmosphere contains water vapor, hydrogen gas, ammonia, methane, nitrogen gas, and carbon dioxide.
Stanley Miller
Created an experiment that modeled early Earth and amino acids spontaneously formed!
Miller's Experiment
- nitrogen
- hydrogen
- amonia
- electricity
Why are amino acids used as evidence for how life began?
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Proteins are made of amino acids.
Life is made out of proteins.
Photo by Caroline Davis2010
Cyanobacteria
photosynthetic bacteria (use photosynthesis) that are evidence of Earth's first life
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Prokaryotes = Oxygen
Additional simple life begins to form once the oxygen atmosphere forms.
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Lamark had some of the earliest ideas about evolution. He thought if an animal needed the trait, they would just develop it and pass it to their offspring. We now know traits that are developed while something is alive are not passed to offspring.
The Best Survive
Survival of the fittest means the living things with the best traits have offspring.
Photo by Matthew Cramblett
Homologous structures
living things share similar traits
Vestigial Structures
the life form still has the trait but it isn't used
Untitled Slide
Untitled Slide
Species
a population of the same organism that can't have offspring with other types of organisms
splitting up a group or organisms into isolated groups causes the groups to get different mutations
After a while the split up groups can no longer breed with each other.
New species has formed!
Photo by Jason Wu
Summary
- Fossils of cyanobacteria form the main evidence for life on Early Earth
- Early prokaryotes conduct photosynthesis which puts oxygen into Earth's atmosphere
- Early Earth's primordial soup (stuff in the oceans) contained nitrogen, hydrogen, and ammonia
Summary Page 2
- Homologous structures ( similar things like arms, mouths, etc) show how life had a shared ancestor and changed gradually over time.
- Another piece of evidence for a shared ancestor and change over time is how similar animal embryos are at different points of development.
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- Vestigial structures are body parts that aren't used but are found and used in other organisms.
- DNA is similar between organisms
- Proteins made by RNA are similar in some animals
- Adaptations are genetic and help an organism survive (color, behavior, fur...)
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- Traits that are developed while something is alive are not passed to offspring.
- Evolution is best described as genetic change over time.
- Environmental changes can include things like change in plant life, temperature, food increase or decrease, changes in shelter.
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- Populations change as Earth's environments change and cause survival of the fittest to happen. For example, desert animals have developed adaptations to cope with living with little water.
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- A biological species can mate and have fertile offspring.
- Speciation is when a new species forms.
- A new species is formed when 2 populations can't interbreed.
Summary Page 6
- Radiometric dating can date things like rock samples to determine the age of our planet.
- Radiometric dating looks of the break down of atoms to calculate age.
