Biology 30: Genetics Exam Questions And Answers

progeny - ANS offspring dominant trait - ANS a characteristic that is expressed when one or both alleles in an individual are the dominant form recessive trait - ANS a characteristic that is expressed only when both alleles in an individual are the recessive form allele - ANS one of the alternative forms of a gene homozygous - ANS having identical alleles from the same gene heterozygous - ANS having different alleles for the same gene genotype - ANS the genetic complement of an organism phenotype - ANS the observable characteristics of an organism segregation - ANS the separation of alleles during meiosis phenotypic ratio - ANS the ratio of offspring with a dominant trait to the alternative, recessive trait genotypic ratio - ANS the ratio of offspring with each possible allele combination from a particular cross Punnett square - ANS a chart used to determine the predicted outcome of a genetic cross test cross - ANS the cross of an individual of unknown genotype to an individual that is fully recessive pedigree chart - ANS a chart that is used to record the transmission of a particular trait or traits over several generations wild type - ANS the most common allele of a gene with multiple alleles mutant - ANS any allele of a gene other than the wild type allele incomplete dominance - ANS the expression of both forms of an allele in a heterozygous individual in the cells of an organism, producing an incomplete phenotype codominance - ANS the expression of both forms of an allele in a heterozygous individual in different cells of the same organism dihybrid cross - ANS a genetic cross involving two genes, each of which has more than one allele selective breeding - ANS the crossing of desired traits from plants and animals to produce offspring with both characteristics inbreeding - ANS the process whereby breeding stock is drawn from a limited number of individuals possessing desirable phenotypes polygenic trait - ANS inherited characteristics that are determined by more than one gene epistatic gene - ANS a gene that makes the expression of another gene or genes autosome - ANS a chromosome not involved in sex determination linked genes - ANS genes that are located on the same chromosome sex-linked trait - ANS trait that is determined by genes located on the sex chromosomes recessive lethal - ANS a trait that, when both recessive alleles are present, results in death or severe malformation of the offspring; usually, recessive traits occur more frequently in males Barr body - ANS a small, dark spot of chromatin located in the nucleus of a female mammalian sex-linked traits - ANS trait that is determined by genes located on the sex chromosomes linkage group - ANS a group of linked genes on a chromosome locus (pl. loci) - ANS a specific location along a chromosome where a particular gene is found marker gene - ANS a gene that confers an easily identifiable phenotype and is used to trace the inheritance of other genes that are difficult to identify; it must be located on the same chromosome, and ideally, at a very small distance from the gene being followed