Gene Linkage and Mapping, Human Genetics and Pedigrees

Which conclusion is a result of Thomas Hunt Morgan’s research with fruit flies?

• Chromosome assortment during meiosis is not random.

• Linked genes are located on the same chromosome.

• The physical distance between genes can be determined.

• Genes recombine independently during mitosis.

Which observation of Morgan’s is evidence that crossing over occurs?

• Linked genes are sometimes inherited separately.

• Some dominant traits are always inherited together.

• Inheritance of gene combinations is not random.

• Fruit flies have only two groups of linked traits.

Two genes on a given chromosome that are most likely to be inherited together are

• 6.8 map units apart.

• 10 map units apart.

• 2 map units apart.

• 18.5 map units apart.

Suppose the cross-over percentages for three gene pairs are: A to B = 9.5%, B to C = 14.5%, and A to C = 5%. Which of the following sequences could represent the order of these genes on a chromosome?

• CAB

• ABC

• CBA

• ACB

A chart that traces the phenotypes and genotypes within a family is called a

• pedigree.

• karyotype.

• Punnett square.

• chromosome map.

Which of the following types of genetic information can be identified easily with a karyotype?

• homologous chromosomes

• dominant traits

• exact locations of genes

• recessive alleles

_________ assort independently during meiosis.

• Spindle fibers

• Chromatids

• Chromosomes

• Genes

Cross-over frequencies are related to _________ between genes.

• inheritance

• differences

• similarity

• distances

Males (XY) express all of their _______ genes.

• autosomal

• sex-linked

• linked

• defective

In a pedigree chart, if the phenotype is more common in males, the gene is likely ________.

• autosomal

• sex-linked

• linked

• defective