Life Has a History focus questions key

Answer the following questions as you navigate through Life Has A History.

1. Of the 30 million species of living things estimated to exist today, how many of them are not animals?

28.5 million of the estimated species of living things are not animals.

2. Find the timeline. How many millions of years did dinosaurs exist on Earth before they became extinct?

Dinosaurs existed for roughly 160 million years before they became extinct.

3. Name at least 5 things other than bones that can be preserved as fossils.

Shells, tree trunks, footprints, pollen and tiny organisms can also be preserved as fossils. In addition to those shown in the module, students may also mention leaves, skin impressions, burrows, insects, eggs and nests, etc.

4. Explain what divergence is.

Divergence is the splitting of one species into two or more descendant species.

5. In your own words, describe what cladograms represent.

A cladogram is a branching diagram used to represent evolutionary relationships and patterns of divergence amongst groups of organisms.

6. What types of evidence are used to determine evolutionary relationships?

Evolutionary relationships are determined by comparing similarities and differences in morphology, behavior, embryology, DNA and other molecular characteristics.

7. In your own words, explain how Geospiza Fortis is a good example of natural selection.

In 1976 a drought killed off the plants that had smaller, more delicate seeds. Only those G. Fortis with a body and bill size large enough to feed on the larger, harder seeds were able to exploit the available seed sources to survive and reproduce. The population of G. Fortis dropped from 1400 to 200. The following year the G. fortis population consisted entirely of individuals with large bills and large bodies. Change had occurred within the population over time due to a changing environment and natural selection.

8. Describe two other mechanisms for evolution in addition to natural selection.

Two evolutionary mechanisms in addition to natural selection are genetic mutation (a permanent change in a cell's DNA) and geographic isolation (a separation between populations of the same species caused by geographic distance or barriers).

9. Give an example of an animal that has gone extinct because of human influence and explain what happened.

Answers will vary.