Evolution Flashcards
Scientists estimate that the earth, moon, and other planets are about how old?
4.5 billion years.
How do scientists estimate the age of the earth (what process do they use)?
Radiometric dating.
What is radiometric dating for determining the age of the earth?
Using isotopes that are old, such as uranium, which turns into a different element over time. Look at the oldest rocks and observe the amount of isotope, less material=older.
Define half-life.
The time it takes for half of a substance to decay and turn into a different isotope.
What is the half-life of carbon?
5,730 years.
What is the half-life of uranium?
4.5 billion years.
How much uranium should we expect to see today?
1/2 of the original amount because we have gone through one half-life.
What is Carbon 14?
It is an isotope with extra neutrons. All of our cells have the same ratio of carbon 14. It is useful for carbon dating because when we die, the carbon in our bones stays and decreases over time.
What is spontaneous generation/origin?
The idea that life could come from non-living things.
What was the “evidence” to support spontaneous generation?
If you leave meat out, maggots will just “appear.”
How was spontaneous generation disproven?
An experiment was conducted. An open container with meat had maggots, a cork-sealed container had no maggots anywhere, and a gauze-covered container had no maggots on the meat, but there were maggots on top of the gauze.
What are two origin of life theories?
It came from outer space, or primordial soup.
What is the theory of the origin of life coming from outer space?
The theory is that there was life on a comet that crashed to earth.
What is the primordial soup theory?
Since early life was supposedly from the oceans, it is theorized that there was a puddle of materials, such as amino acids, that could form simple cells with the help of electricity.
What is one piece of evidence for the primordial soup theory?
Miller and Urey’s experiment.
What was Miller and Urey’s experiment?
They took gases present on earth that were unrelated to life (methane, hydrogen gas, H2O gas, etc.) and added a spark to simulate lightning. Organic compounds could form in this way as long as there was water. It produced simple amino acids.
What was the significance of Miller and Urey’s experiment?
It did not create life, but it created things necessary for life to show up.
What is the issue with the primordial soup theory?
The absence of the ozone, which would result in dangerous UV light passing through life and destroying DNA.
Because of the lack of ozone, where do scientists think early life was found?
In deep-sea vents. The further down, the greater UV protection. Also, hydrothermal vents have water and certain necessary gases for life.
What is the first step in the formation of life?
Simple organic molecules (sugars, amino acids, fatty acids, nitrogenous bases). The formation of these was shown by the Miller and Urey experiment.
What is the second step in the formation of life (after simple organic molecules)?
Complex organic molecules (carbohydrates, proteins, phospholipids, nucleotides). Certain experiments demonstrate how phospholipids can show up in the right conditions.
When you mix phospholipids with water, what do you get? (Third step in the formation of life).
Protobionts and microspheres.
What are protobionts and microspheres?
A microsphere is a fat that is balled up with water on the outside. The phospholipid creates a container. It creates a different environment on the inside called a protobiont (because it is necessary to separate the inside environment from the outside of a protocell).
What do microspheres and protobionts lead to? (Fourth step in the formation of life)
Prokaryotic cells like archaebacteria.
What do scientists say is the oldest and simplest form of bacteria? What is the evidence for this?
Archaebacteria. There is fossil evidence, but no experimental evidence for this because we cannot create bacteria in a lab.
What organism was likely the dominant form of life for a very long time?
Archaebacteria.
What is endosymbiosis?
A mutualistic relationship in which one organism lives inside another. Endo=inside, symbiosis=living together.
What structure inside our cells resembles archaebacteria?
Mitochondria.
How are mitochondria similar to archaebacteria?
They have their own unique DNA, they can reproduce on their own, and they are similar in size and shape to bacteria.
How does endosymbiosis relate to mitochondria?
Mitochondria may resemble prokaryotic archaebacteria, but they are in a symbiotic relationship with our cells. They cannot survive without our cells, and our cells cannot survive without them.
How does endosymbiosis relate to chloroplasts?
In a similar process to mitochondria, chloroplasts could have once been separate organisms taken in by similar cells and then formed a symbiotic relationship.
What is the support for endosymbiosis?
- Mitochondria and chloroplasts are similar in size to prokaryotes. 2. Mitochondria and chloroplasts have their own DNA and ribosomes. 3. Mitochondria and chloroplasts replicate by binary fission during cell division.
What is the order of events from the formation of earth to humans existing?
Formation of earth (hot, molten); formation of core; moon formation; formation of zircon crystal; formation of acasta; isua; apex chart (earliest fossils); rise in atmospheric oxygen; first cell with a nucleus; first hard-shelled animals; dinosaurs; humans.
What is zircon crystal?
One of the first solid rocks.
What is acasta?
The oldest rock that has not been recycled by plate tectonics.
What is isua?
First sedimentary evidence for oceans and earliest isotopic evidence for life.
According to the apex chart, what do the earliest fossils resemble? How old are they?
They resemble bacteria. They are about 3.5 billion years old.
How long did it take for life to show up?
1 billion years.
When did atmospheric oxygen show up?
2 billion years ago.
How did atmospheric oxygen show up?
Cyanobacteria, which were the first photosynthetic organisms. They allowed for more life.
What did the presence of oxygen from the cyanobacteria allow to happen?
It allowed the ozone to form.
What did the development of the ozone allow to happen?
It allowed a huge number of new creatures to show up, specifically land animals because it acts as a shield from UV radiation.
Before the ozone, where was the only habitable place on earth?
The ocean.
Why are mass extinction events significant for new life?
Exctintion events lead to new species. After extinction events, the number of taxonomic species increases because the change in the environment (volcanic ash clouds, temperature changes, extinctions, etc.) open up new niches for organisms to fill.
What did the end of the dinosaur period lead to?
The start of the mammal hypothesis because the dinosaur extinction created space for mammals.
Who was Lamarck?
The first person to propose an explanation for evolution. He proposed the law of acquired characteristics.
What is the law of acquired characteristics?
The idea that evolution occurs through the use and disuse of physical features, like giraffes’ necks getting longer so that they could get food.
Who was Lyell?
One of the first people to show that the earth is very old using principles of geology.
Who was Malthus?
An economist who looked at necessary human resources and learned that overpopulation leads to the depletion of resources.
Who was Charles Darwin?
A naturalist and a theologian who toured the world on his ship, the Beagle, as he made observations and collected specimens.
What did Darwin do during his journey?
He observed and recorded various plants and animals, and he observed farmers breeding crops and animals for better characteristics. These helped him make his work.
Define evolution.
A change in allele frequency over time.
What was Darwin’s explanation for natural selection?
The environment, not the organism/individual, determines the fit trait. The organism cannot decide to adapt or evolve.
