Chapter 23

Question 1

Macroevolution

Answer 1

Broad changes above the species level.

Question 2

Radiometric Dating

Answer 2

A radioactive parent isotope decays to a daughter isotope at a constant rate. Each isotope has a known half-life, the time required for half the parent isotope to decay.

Question 3

Geologic Record

Answer 3

A standard time scale dividing Earth’s history into four eons. Phanerozoic, Proterozoic, Archaean, Hadean

Question 4

Mass Extincition

Answer 4

Dramatic increase in the rate of extinction caused by global environment change.

Question 5

Adaptive Radiation

Answer 5

The evolution of many diversely adapted species from a common ancestor.

Question 6

Heterochrony

Answer 6

An evolutionary change in the rate or timing of developmental events.

Question 7

Paedomorphosis

Answer 7

The rate of reproductive development accelerates compared with somatic development. The sexually mature species retain body features that were juvenile structures in an ancestral species.

Question 8

Homeotic Genes

Answer 8

Master regulatory genes that determine the organization of basic features.

Question 9

Permian Extinction

Answer 9

Occurred 250 million years ago. In less than 500,000 years caused the extinction of about 95% of marine animal species.