Ast 309L - Search. for Ext. Life EXAM 2

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What is "LUCA"
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What is "LUCA"
The organism from which all current life on Earth originates
Which one of the following is not considered an important step in the origin of life on Earth?
the protective ozone layer that shields us from harmful ultraviolet radiation
Biologists think that the processes that led to the origin of life resemble most closely:
Prebiotic chemistry naturally formed the molecular building blocks and catalytic reactions then led to more complex and replicating molecules
The origin of life on Earth most likely occurred:
Between 4.0 and 3.5 billion years ago
Some of the first living organisms probably resembled:
cells without nuclei that used RNA as their genetic material
Why do we talk about clay minerals in connection with the origin of life on Earth?
Because their layered structure has been shown to facilitate the formation of long-chained organic molecules
Early life arose in an oxygen-free environment, but if any of these microbes had somehow come in contact with oxygen, the most likely effect would have been:
To kill them
The oxygen in Earth's oceans and atmosphere was originally released by
cyanobacteria: a division of microorganisms that are related to the bacteria but are capable of photosynthesis. They are prokaryotic and represent the earliest known form of life on the earth.
Which one of the following is not considered a possible cause of the Cambrian explosion?

a) the increased level of free oxygen
b) the end of a Snowball Earth episode
c) the impact of a 10-km sized asteroid
d) very inefficient predators
e) the evolution of eyes
c) the impact of a 10-km sized asteroid
What is the evidence that an impact of a large (10-15km) sized asteroid caused the K-T mass extinction?
We first found a global layer of iridium and soot, and later a large crater that formed at that time
What was the significance of the K-T event for mammals?they rapidly diversified to fill the ecological niches that were suddenly availablethe fact that modern humans evolved from chimpanzees is:Is wrong, both species evolved from a common ancestor millions of years agothe closest living relative to a Chimpanzee in the animal domain is:I am (homo sapiens)What is an extremophile?An organism that thrives in conditions that would be lethal to humans and other animals (or even microbes)what is the importance of the discovery of extremophiles to astrobiology?It shows that life can adapt to surprisingly extreme conditions which are similar to conditions that exist on other bodies in the solar systemWhich planet in our solar system has the highest surface temperatures?VenusThe planet Mercury is generally not regarded a suitable place for extraterrestrial life. Which one of the following statements is not a reason why we think that?the planet has a thick CO2 atmosphereWhat is the primary component in Venus's atmosphere?Carbon DioxideWhich mechanism controls the surface temperature on Venus?the Greenhouse effectWhich one of the following statements about Mars is incorrect?Today's Mars has a strong magnetic field because of the large amount of iron on the surfaceWe think there is still plenty of water on Mars, but where is it?It sits in subsurface ice, in a large permafrost layerWhich one of the following statements about the large volcano Olympus Mons on Mars is incorrect?It was created by the same plate tectonic motion that created the Valles MarinerisWhat kind of evidence did we find for past liquid water on Mars?We see structures like dried out rivers and flood plains on the surfaceHow and why - do we think - did Mars lose most of its atmosphere?Because Mars cooled quicker than the Earth and lost its protective magnetic field, which allowed the solar wind to erode the atmosphereHow did the microbiological experiments on the two Viking landers work?they searched for metabolic reactions in the samplesWhich Viking experiment delivered results that were exactly as expected for the presence of living microbes in the soil sample?The Label Release (LR) experimentWhich measurement performed by Viking, which was not part of the microbiological experiments, convinced most scientists in the late 1970s that Viking had not found life on Mars?the absence of any detectable amount of organic compounds in the soil samplesIf life ever emerged on Mars, what is the most likely place for it to exist today?In the subsurface where it is protected against the harsh UV radiationBiologist are convinced that without them, the first life could not have formed on Earth. What was that?CatalystsWhich one is the most important difference between prokaryotes and eukaryotes?prokaryotes have no nucleus in which the genetic material is containedWhat was the Cambrian Explosion?a dramatic increase in animal and plant diversity at the beginning of the Cambrian eraThe move of life on Earth - in particular - of complex, multicellular, life from the oceans on to land required a very special prerequisite. Which one?the presence of a protective ozone layer to shield life on land against harmful UV radiation from the SunWhich of the following statements about human evolution is incorrect?humans evolved from chimpanzeesWhy does the atmosphere of Venus contain so much more CO2 than Earth's?On Earth most of the CO2 is locked away in sea sediments (carbonate rocks)Mars is sometimes perceived as a second Earth. Why is this incorrect?Mars has a much smaller mass and it is also much smaller than EarthWhy is Mars still a very interesting planet for astrobiology?Because we have compelling evidence that Mars once had liquid surface water