| A | B |
|---|
| acquired traits | traits that develop during an individual's liftime and which are not inherited |
| artificial selection | intentional breeding of organisms by specific traits |
| artificially inseminated | procedure in which the male's sperm is placed in the female's oviduct or uterus |
| breeds | groups of similar organisms within a species |
| controlled breeding | a type of artificial selection carried out to produce best traits of a breed |
| crossbreeding | method by which organisms of different breeds are mated to combine their desirable traits |
| evolution | process of change that occurs in living things over time |
| extinct | any species that no longer exists today |
| fraternal twins | twin offspring that arise from two separate fertilized eggs; can be opposite sexes |
| genetic engineering | scientific development of new types of plants and animals by inserting genes for desirable traits from different species |
| geographic isolation | physical separation of populations |
| hybridization | method by which organisms of different breeds are mated to combine their desirable traits |
| identical twins | two offspring that arise from one fertilized egg that splits after the two-celled embryo stage; always of the same sex |
| inbreeding | breeding method in which only closely related members of the same breed are mated |
| inherited trait | trait controlled by genes, passed from parent to offspring |
| mutant | an individual bearing a new genetic trait |
| mutations | changes in an inherited trait caused by a permanent change in a gene |
| natural selection | process by which more fit individuals survive to reproduce |
| sex chromosomes | the X and Y chromosomes; the pair of chromosomes that determines the sex of an offspring |
| sex-linked traits | inherited traits controlled by a gene carried on a sex chromosome; traits that occur more often in males than in females |
| speciation | process by which new species evolve over time |
