| A | B |
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| Heredity | The transmission of traits from one generation to the next. |
| Variation | Differences between members of the same species |
| Genetics | the scientific study of heredity and hereditary variation |
| Gene | A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA |
| Asexual reproduction | A type of reproduction involving one parent that produces genetically identical offspring by budding or by the division of a single cell or the entire organism into two or more parts |
| Clone | A lineage of genetically identical individuals or cells |
| Sexual Reproduction | A type of reproduction in which two parents give rise to offspring that have unique combinations of genes inherited from the gametes og the two parents |
| Life cycle | The generation-to-generation sequence of stages in the reproductive history of an organim |
| Somatic cycle | Any cell in a multicellular organism except sperm and egg cell |
| Karyotype | A display of the chromosome pairs of a cell arranged by size and shape |
| Homologous chromosomes | Chromosomes of the same length , centromere position, and staining pattern that possess genes for the same characters at corresponding loci. |
| Sex chromosomes | One of the pair of chromosomes responsible for determining the sex of the individual |
| Autosome | A chromosome that is not directly involved in determining sex, as opposed to a sex chromosome. |
| Tetrad | The four closely associated chromatids of a homologous pair that are visible in the light microscope |
| Chiasmata | X-shaped regions visible in the light microscope; Physical manifestations of a genetic rearrangement called crossing over |
| Chiasma | Singular of chiasmata; X-shaped region visible in the light microscope; Physical manifestations of a genetic rearrangement called crossing over |
| Crossing over | The reciprocal exchange of genetic material between non-sister chromatids during synapsis of meiosis 1; Produces individual chromosomes that combine genes inherited from two parents |
| Haploid cell | A cell containing one set of chromosomes. |
| Fertilization | The union of haploid gametes to produce a diploid zygote. |
| Syngamy | The process of cellular union during fertilization. |
| Zygote | The diploid product of the union of haploid gametes in conception; a fertilized egg. |
| Diploid cell | A cell containing two sets of chromosomes (2n), one set inherited from each parent. |
| Meiosis | A two-stage type of cell division in sexually reproducing organisms that results in cells with the chromosome number of the original cell. |
| Alternation of generations | A life-cycle in which there is both a multicellular diploid form, the sporophyte, and a multicellular haploid form, the gametophyte; characteristic of plants and some algae. |
| Sporophyte | In organisms undergoing alternation of generations, the multcellular diploid form that results from a union of gametes and that meiotically produces haploid spores that grow into the gametophyte generation. |
| Spores | In the life cycle of a plant or alga undergoing alternation of generations, a meiotically produced haploid cell that divides mitotically, generating a multicellular individual, the gametophyte, without fusing with another cell. |
| Gametophyte | In organisms undergoing alternation of generations, the multicellular haploid form that mitotically produce haploid gametes that unite and grow into the sporophyte generation. |
| Meiosis I | The first division of a two-stage process of cell division in sexually reproducing organisms that results in cells with half the chromosome number of the original cell. |
| Meiosis II | The second division of a two-stage process of cell division in sexually reproducing organisms that results in cells with half the chromosome number of the original cell. |
| Synapsis | The pairing of replicated homologous chromosomes during prophase I of meiosis. |
