Khan Academy- Reading: Science / This passage is from Luis Villareal, "Are Viruses Alive?" © 2008 by Scientific American.

The main purpose of the passage is to...

explore reasons why a definition is ambiguous.

As used in line 7, "profoundly" most means...

extremely.

Over the course of the passage, the main focus shifts from...

the presentation of a question to an analysis of factors affecting its answer.

The author implies that viruses are not considered living primarily because they are not...

capable of sustaining life without a host organism.

The words "emergent," line 44, and "verge," line 48, in paragraph five primarily serve to...

characterize the relationship of viruses to life.

Which choice best describes the author's tone in describing the research describe in paragraph six?

Objective

Why does the authour imply about viruses in the paragraph five?

Viruses' lack of complex systems means that they fail to meet the standards for life.

The "rock," line 29, primarily serves to provide an example of an item that...

is easy to classify, unlike a virus.

Which choice provides the best evidence for answer to the previous question?

lines 20-25 ("Viruses...spread")

Which choice provides the best evidence for the air previous question?

lines 43-46 ("A virus...virus")

The author uses the information in lines 49-64 mainly to support the assertion that...

researchers have recently shown that viruses are closer to being alive than previously thought.