Question 1

If the most pessimistic assumptions in the Drake equation were true,we would:

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Question 2

Describe the difference between prokaryotes and eukaryotes.

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Question 3

In 1974,astronomers sent a message toward globular cluster M13.If life exists there,and it returns our signal,we won't receive it for at least another 48,000 years.Why not?

Accepted Answer

M13 is approximately 25,000 light years away from Earth, which means that even if our message travels at the speed of light, it will take 25,000 years to reach M13. And if the life forms there respond immediately, their signal will take another 25,000 years to reach Earth, making a total travel time of 50,000 years before we receive their response.

Question 4

What are the four main chemicals that make up all living organisms on the Earth?

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Question 5

If the entire history of the Earth were scaled to fit into one day,what time of day would microorganisms first form,oxygen start becoming a significant component of the atmosphere,and humans split off from their genetic ancestors?

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Question 6

Carbon forms the backbone of our DNA because:

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Carbon can form up to 4 covalent bonds in order to achieve a stable configuration, which makes it ideal as a backbone for molecules like DNA.

Question 7

Examine the figure below.  The habitable zone around a star depends most on its:

Accepted Answer

The habitable zone around a star is the region where liquid water can exist on the surface of a planetary body. The location of this zone depends on the star's mass and age because these determine its luminosity and temperature. A more massive and older star will have a larger habitable zone compared to a smaller and younger star. Radius and distance do have some influence, but they are not the primary factors. Color and velocity are not related to the habitable zone.

Question 8

Why is a very hot star not a good candidate to find life?

Accepted Answer

A very hot star has a short lifetime, meaning it will burn through its fuel quickly and potentially not give enough time for life to evolve.

Question 9

What is SETI,what is its main objective,and how does it plan to achieve its objective?

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Question 10

SETI's Allen Telescope Array (image below)is designed to search __________ for signs of intelligent life.

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Question 11

Describe the experiments of Harold Urey and Stanley Miller (shown in the image below)in understanding the origins of life.

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Question 12

Given the following information,what would be the number of intelligent civilizations in our galaxy? If all stars formed planets; each planet has a 0.1 percent chance of supporting life; every time conditions are right life develops; and only 0.001 percent of the time intelligent life develops surviving indefinitely.

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Question 13

Calculate the maximum likelihood that any technically advanced civilization that arose still exists in our galaxy today.

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Question 14

What determines whether or not a specific mutation is passed on to future generations?

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Question 15

Based on what you know of the Earth's evolution,what percent of Earth-like planets in a star cluster with an age of 2 billion years has intelligent life?

Accepted Answer

Based on our understanding of Earth's evolution, we only have evidence of the existence of intelligent life on our planet. We do not have any conclusive evidence of the existence of other intelligent life forms on other planets. Therefore, until we have concrete evidence of the existence of extraterrestrial intelligent life forms, the most reasonable assumption would be that the percentage is 0 percent.

Question 16

A value of N = 0.1 for the Drake equation signifies that:

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Question 17

We search for intelligent life in the universe by:

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Question 18

Why is a cold star not a good candidate to find life?

Accepted Answer

A cold star is not a good candidate to find life because the habitable zone around such stars is very narrow, which makes it difficult for planets in that zone to maintain a stable temperature range suitable for life to exist.

Question 19

Why would the 21-cm line be a good place to search for signals from intelligent life in the universe?

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Question 20

If you wanted to find intelligent life in the universe,what spectral types of stars would you study and why?

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Quiz 18: Life in the Universe