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Biology Chapter 9
Term | Definition |
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Genetics | The science of heredity and of the mechanisms by which traits are passed from parents to offspring. |
Heredity | The passing of genetic traits from parent to offspring. |
Trait | A genetically determined variant of a characteristic. |
Pollination | The transfer of pollen from the male reproductive structures (the anthers) to the tip of a female reproductive structure (the pistil) of a flower in angiosperms or to the ovule in gymnosperms. |
Self-pollination | The transfer of pollen grains from an anther to the stigma of the same flower or to the stigma of another flower on the same plant. |
Cross-pollination | A reproductive process in which pollen from one plant is transferred to the stigma of another plant. |
True-breeding | Describes organisms or genotypes that are homozygous for a specific trait and thus always produce offspring that have the same phenotype for that trait. |
P Generation | Parental generation, the first two individuals that mate in a genetic cross. |
F1 Generation | The first generation of offspring, obtained from an experimental cross of two organisms. |
F2 Generation | The second generation of offspring, obtained from an experimental cross of two organisms; the offspring of the F1 generation. |
Dominant | Describes the allele that is fully expressed when carried by only one of a pair of homologous chromosomes. |
Recessive | Describes a trait or an allele that is expressed only when two recessive alleles for the same characteristic are inherited. |
Law of Segregation | Mendel's law that states that the pairs of homologous chromosomes separate in meiosis so that only one chromosome from each pair is present in each gamete. |
Law of Independent Assortment | The law that states that genes separate independently of one another in meiosis. |
Molecular Genetics | The study of the structure of nucleic acids and the function and regulation of genes. |
Allele | One of the alternative forms of a gene that governs a characteristic, such as hair color. |