Life has three domains, and one of these domains has four kingdoms within it. Name both the domains and the kingdoms.

Life is thought to have begun as early as ______ years ago. One important event that took place in the long, early time span called the Precambrian was the appearance of ____ in Earth’s atmosphere, all of it produced as a by-product of photosynthesis carried out by a type of ______.

The Cambrian Explosion was an explosion in the number of ______ life-forms.

Each of the eras or periods within the geological timescale is characterized by a particular grouping of ______ preserved today as ______.

True or false: The first animals and plants evolved early in life’s history.

Life is generally regarded as having begun with the development of ______ molecules or chemical systems.

In what way are the bryophyte plants and the amphibian animals alike?

Put the following in the proper time sequence, earliest first:

a. first dinosaurs

b. first bacteria

c. first amphibians

d. first primates

e. oxygen accumulation in the atmosphere

f. first land plants

g. first birds

The time-frames in the geological timescale generally denote ____.

a. 10,000-year increments

b. 10-million-year increments

c. the reappearance of certain life-forms

d. transitions in life-forms

e. the appearance of larger life-forms

The first life on Earth may have been:

a. eukaryotic cells

b. RNA molecules

c. bacteria

d. formed on land

e. algae