BIOL 219 – The Living Cell:

Chapter 20 - Sample test questions. Chick on the answer you think is most appropriate to see if you are right.

During meiosis, chromatids in homologous pairs of chromosomes often twist around each other, break, exchange segments, and rejoin. This process usually contributes to:
A. the formation of polyploid offspring.
B. nondisjunction of homologous chromosomes.
C. the production of identical twins.
D. increased variability in offspring.

In certain breeds of dogs, deafness is due to a recessive allele (d) of a particular gene, and normal hearing is due to its dominant allele (D). What percentage of the offspring of a normal heterozygous dog and a deaf dog would be expected to have normal hearing?
A. 0%
B. 25%
C. 50%
D. 100%
E. It is not possible to tell from the information given

Assuming A and B are dominant and a and b are recessive, in the cross AaBb x AaBb, Mendel's principle of independent assortment predicts that the ratio of the four possible phenotypes of the offspring will be:
A. 1:1:1:1
B. 3:2:2:1
C. 4:2:2:1
D. 9:3:3:1
E. 9:7:3:1

The allele associated with sickle cell anemia apparently reached a high frequency in some human populations due to:
A. random mating.
B. superior survivability of heterozygotes in areas where malaria is present.
C. migration of individuals with the allele into other populations.
D. a high mutation rate at that specific gene.
E. genetic drift.

Geneticists have observed that cats that commonly inherit blue eyes also tend to be have a predisposition toward inherited deafness. The two traits are controlled by different genes. Which of the following concepts might best explain the observation?
A. segregation.
B. dominance.
C. gene linkage.
D. crossing-over.