CP 24 Life in the Universe Flashcards
Plants and animals are
just two small branches of the diverse “tree of life” on Earth.
How did oxygen (O2) get into Earth’s atmosphere?
It was released by life through the process of photosynthesis.
Based on DNA studies, it seems that all life on Earth __________.
shares a common ancestor
According to fossil evidence how far back in time did life on Earth exist?
about 3.5 billion years or more
Which of the following best describes the predominant scientific view of the origin of life on Earth?
We may never know precisely how life arose, but current evidence suggests that life probably can arise naturally under the conditions that prevailed on the early Earth.
Fossil evidence suggests that life on Earth arose
almost immediately after Earth formed.
very soon after the end of the heavy bombardment.
about a billion years before the rise of the dinosaurs.
very soon after the end of the heavy bombardment.
Why is Europa considered a good candidate for the possible existence of life?
Strong evidence suggests that it has a deep, subsurface ocean of liquid water.
What best describes what we mean by a habitable world?
a planet or moon that could support life, if any life happened to be on it
The Sun’s habitable zone __________.
extends from some place a little beyond the orbit of Venus to some place near the orbit of Mars
Why don’t we expect to find life on planets orbiting high-mass stars?
The lifetime of a high-mass star is too short.
How does the habitable zone around a star of spectral type G compare to that around a star of spectral type M?
It is larger.
We are not yet capable of detecting life on planets around other stars. But as our technology develops, our first real chance of detecting such life will probably come from _________.
examining spectral lines from the atmospheres of distant planets
At present, what is the primary way that the search for extraterrestrial intelligence (SETI) is carried out?
by using radio telescopes to search for signals from extraterrestrial civilizations
Which of the following best describes how the Drake equation is useful?
It helps us understand what we need to know to determine the likelihood of finding other civilizations.
We have sent several spacecraft on trajectories that will ultimately take them into interstellar space (including Pioneer 10 and 11, Voyager 1 and 2, New Horizons). How long will it take these spacecraft to travel as far as the nearest stars?
tens of thousands of years
