BIOLOGY CROSSWORD

8. the theory that changes in the earth's crust during geological history have resulted from the action of continuous and uniform processes.
10. the remains or impression of a prehistoric organism preserved in petrified form or as a mold or cast in rock.
11. the process by which different kinds of living organisms are thought to have developed and diversified from earlier forms during the history of the earth.
12. a length or portion of time.
14. is the proportion of this total variation between individuals in a given population due to genetic variation.
16. the theory that changes in the earth's crust during geological history have resulted chiefly from sudden violent and unusual events.
17. each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons.
18. a cloud of gas and dust in outer space, visible in the night sky either as an indistinct bright patch or as a dark silhouette against other luminous matter.
19. a change or the process of change by which an organism or species becomes better suited to its environment.

1. is a summation of all the organisms of the same group or species, which live in a particular geographical area.
2. a change or difference in condition, amount, or level, typically with certain limits.
3. the hypothesis that evolution proceeds chiefly by the accumulation of gradual changes.
4. the state or process of a species, family, or larger group being or becoming extinct.
5. the branch of biology that deals with the geographical distribution of plants and animals
6. evolutionary change within a species or small group of organisms, especially over a short period.
7. the branch of science concerned with fossil animals and plants.
9. a group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding.
13. a long and distinct period of history with a particular feature or characteristic.
15. an organism's ability to survive and reproduce in a particular environment.
16. the influence of closely associated species on each other in their evolution.