Evolution and Natural Selection

4. How a new kind of plant or animal species is created.
8. Something an animal does usually in response to some type of external stimulus in order to survive.
12. Any cell or organism that possesses a clearly defined nucleus.
14. The reduction in genomic variability that occurs when a small group of individuals becomes separated from a larger population.
15. The capacity of bacteria to withstand the effects of a harmful chemical agent.
16. The transfer of genetic material from one population to another.
17. One of two or more versions of a genetic sequence at a particular region on a chromosome.
19. The production of new organisms by the combination of genetic information of two individuals of different sexes.
20. The process through which populations of living organisms adapt and change.

1. The presence of differences in sequences of genes between individual organisms of a species.
2. An internal body process to regulate and maintain homeostasis for an organism to survive in the environment in which it exists.
3. The evolutionary process whereby an organism becomes better able to live in its habitat or habitats.
5. An extreme example of genetic drift that happens when the size of a population is severely reduced.
6. Single-celled microorganisms that lack a nuclear membrane, are metabolically active and divided by binary fission.
7. Symbiotically break down food for other organisms, producing food through photosynthesis and chemosynthesis, and decomposing waste.
9. The change in frequency of an existing gene variant in the population due to random chance.
10. The variation and distribution of traits in a population depend on genetic and environmental factors.
11. The complete disappearance of a species from Earth.
13. Any substance that inhibits the growth and replication of a bacterium or kills it outright.
18. A mode of reproduction in which a new offspring is produced by a single parent.