Exam 17: Astrobiology: Life on Other Worlds

As Earth evolved with life, an oxygen abundance of only 0.1 percent would have created a(n) _______________, protecting organisms from the Sun's ultraviolet radiation.

The formula proposed for determining the number of technological civilizations in the Milky Way Galaxy with which we might communicate, is known as the _______________.

What technology do astronomers use to search for extraterrestrial life?

Earth required only 1 million years to produce the first cells and another million years for intelligence to emerge.

_______________ are fossilized remains of colonies of single-celled organisms that built up layer after layer of trapped sediments.

In 1974, astronomers broadcasted a radio message of greeting towards the globular cluster M13, 25,000 light-years away.

Earth sends out more signals into space by accident than with intent.

What is the radio window astronomers use to search for alien transmitted communication? What is this window nicknamed?

In all living things on Earth, the chemical reactions making, breaking, and combining carbon chains take place in _______________ within the cell of living organisms.

Which is the process that explains how life adapts itself to a changing environment?

Figure 25-1 Examine the accompanying figure (Figure 25-1) . Which portion of the radio window astronomers use to search for extraterrestrial communication?

The first cells must have been simple, single-celled organisms similar to modern _______________.

What is the name for the radio frequency window astronomers use to search for extraterrestrial communication?