Notes 7 & 8 Review

Question 1

Although life was single celled for a long time, life was still evolving. What were several ways in which unicellular life changed during the long period while life was single celled?

Answer 1

While life was single celled, cells invented organelles. The earliest
prokaryotic cells did not have these compartments, but later
eukaryotic cells did. Cells also invented processes such as
photosynthesis (making food from light and other abiotic sources)
and protein synthesis (making proteins, an important type of
biomolecule).

Question 2

Life originated in water, but the story of life is in part the evolution of groups changing to live outside of and away from water. Describe 2 adaptations animals evolved to live in drier environments.

Answer 2

A. When early tetrapods first evolved the ability to live out of water
they needed to keep their skin moist and they needed to lay their
eggs in water, like many amphibians today. Later groups evolved
skin that could dry out and eggs that could be laid on dry land.

Question 4

What do the periods of time of the geologic timescale have to do with rocks?

Answer 4

Some rocks form over time in layers. The deeper the layers, the
older the rock. The more shallow the layers, the younger the
rock. Scientists have identified the time periods when
individual layers of rock formed. The layers of rock and time
periods when they formed have been given names, such as
Jurassic and Cambrian.