24. History of Life on Earth

Why is the four-stage hypothesis for the abiotic origin of life useful?

The early atmosphere on Earth is thought to have lacked which of the following gases?

Currently scientists think the early atmosphere probably consisted of __________.

The Miller and Urey abiotic synthesis experiment (and subsequent, similar experiments) showed that __________.

How many different species have been identified by science? How many are estimated to exist?

Fossilized stromatolitesa. formed around deep-sea vents.b. resemble structures formed by bacterial communities that are found today in some shallow marine bays.c. provide evidence that plants moved onto land in the company of fungi around 500 million years ago.d. contain the first undisputed fossils of eukaryotes.

A cell is placed in a solution that is hypotonic to the cell. Which of the following best describes movement of water in this situation?a. Water will only flow into the cell.b. Water will only flow out of the cell.c. Water will flow into and out of the cell, but the overall net movement will be out of the cell.d. Water will flow into and out of the cell, but the overall net movement will be into the cell.

Choose the best definition of a fossil.a. a rock that contains information about an organismb. a bone, tooth, shell, or other hard part of an organism that has been preservedc. any trace of an organism that lived in the pastd. any part of a dead organism