| Term | Definition |
|---|
| allele | alternative forms of a gene for each variation of a trait of an organism |
| dominant | observed trait of an organism that masks the recessive form of a trait |
| fertilization | fusion of male and female gametes |
| gamete | male and female sex cells; sperm and eggs |
| genetics | branch of biology that studies heredity |
| genotype | combination of genes in an organism |
| heredity | passing on of characteristics from parents to offspring |
| heterozygous | when there are two different alleles for a trait |
| homozygous | when there are two identical alleles for a trait |
| hybrid | offspring formed by parents having different forms of a trait |
| law of independent assortment | Mendelian principle stating that genes for different traits are inherited independently of each other |
| law of segregation | Mendelian principle explaining that because each plant has two different alleles, it can produce two different types of gametes. During fertilization, male and female gametes randomly pair to produce four combination of alleles |
| phenotype | outward appearance of an organism, regardless of its genes |
| pollination | from male reproductive organs to female reproductive organs of plants, usually within the same species |
| recessive | trait of an organism that can be masked by the dominant form of a trait |
| trait | characteristic that is inherited; can be either dominant or recessive |
| zygote | diploid cell formed when a sperm fertilizes an egg |
| crossing over | exchange of genetic material between nonsister chromatids from homologous chromosomes during prophase I of meiosis; results in new allele combinations |
| diploid | cell with two of each kind of chromosome; is said to contain a diploid, or 2n, number of chromosomes |
| egg | haploid female sex cell produced by meiosis |
| genetic recombination | major source of genetic variation among organisms caused by reassortment or crossing over during meiosis |
| haploid | cell with one of each kind of chromosome; is said to contain a haploid, or n, number of chromosomes |
| homologous chromosome | paired chromosomes with genes for the same traits arranged in the same order |
| meiosis | type of cell division where one body cell produces four gametes, each containing half the number of chromosomes as a parent's body cell |
| nondisjunction | failure of homologous chromosomes to separate properly during meiosis; results in gametes with too many or too few chromosomes |
| sexual reproduction | pattern of reproduction that involves the production and subsequent fusion of haploid sex cells |
| sperm | haploid male sex cells produced by meiosis |
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