| A | B |
|---|
| diploid (2n) | the normal number of chromosomes for a body cell (2 copies of each) |
| monoploid | also a haploid--half the normal number of chromosomes (1 copy) |
| homologous pairs | chromosomes that contain genes for the same traits and are the same size |
| gametogenesis | the process that produces gamates |
| spermatogenesis | the production of sperm |
| oogenesis | the production of an egg |
| gonads | specialized organs that produce gamates |
| hermaphrodite | an organism that has both male and female gonads |
| meiosis | process referred to as reduction division--involved in gametogenesis |
| 2 | number of divisions in meiosis |
| synapsis | matching up of homologous chromosomes forming tetrads |
| crossing over | exchange of genetic material during synapsis |
| testes | male gonads |
| sperm | produced by the testes |
| polar bodies | three cells that disintegrate from unequal cytoplasmic division |
| ovum | another name for the egg cell |
| fertilization | the union of a haploid sperm with a haploid egg |
| external fertilization | gamates join outside the body of the female |
| internal fertilization | gamates join within the reproductive tract of the female |
| cleavage | the series of mitotic cell divisions a zyote goes through |
| embryo | what the zygote is called once cleavage begins |
| blastula | a hollow sphere of cells formed by cleavage |
| gastrulation | process indents one side of the blastula |
| gastrula | the name for the blastula once it is indented |
| ectoderm | the outer layer |
| mesoderm | middle layer |
| endoderm | inner layer |
| differentiation | when the three layers specialize into different parts |
| yolk | source of food for an embryo in an egg |
| amnion | contains fluid;acts as a shock absorber |
| allantois | stores nitrogenous waste as uric acid |
| chorion | outermost embryonic membrane |
| internal development | growth of an embryo inside the female |
| penis | adaptation for internal fertilization |
| placenta | the organ in which the mother and embryo exchange food, gases, and wastes |
| umbilical cord | attaches the embryo to the placenta |
