Exam 24: Life

Scientists have shown that ammonia and methane, mixed together with liquid water and either hydrogen, carbon dioxide, or nitrogen, and exposed to electrical sparks, can produce some of the amino acids essential for life.

If we model the history of the universe as a single day, at what time would the first Homo sapiens appear?

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

The habitable zone around a star depends most on its:

Complex microorganisms that have complex DNA enclosed in a cell nucleus are called:

Where do we think life first formed on the Earth?

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 likely has intelligent life?

What was the goal of the experiment depicted below?

The field of astrobiology uses our knowledge of ___________ to study life in the universe.

Mutations always lead to improvements in an organism's ability to survive and reproduce.

If the entire history of the universe 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?

Which one of the following is NOT one of the three categories of terrestrial life based on their DNA characteristics?

We search for intelligent life in the universe most effectively by:

Using life on Earth as an example, calculate the maximum likelihood that any technologically advanced civilization that arose still exists on its home planet today.

Animals are most closely related to which of the following branches?

When the Pioneer and Voyager spacecraft were launched into space in the 1970s, they were outfitted with messages describing where they came from. Why is it fairly unlikely that an alien civilization will use them to find us?

Which of the following Solar System objects is NOT a good candidate for future searches for life?

As living organisms evolved to become more complex during the history of the Earth, did this violate the second law of thermodynamics?

Some forms of life on Earth are silicon-based.

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