ch. 15

biologist realized that the behavior of chromosomes during cell division is the underlying cause of the genetic probabilities that mendel observed. specifically, mendel's laws of segregation & independent assortment are caused by: a. the behavior of chromosomes during anaphase I & metaphase I, respectively b. the behavior of chromosomes during mitotic prophase only c. the behavior of chromosomes during prophase I & prophase II, respectively d. the behavior of chromosomes during anaphase I & metaphase II, respectively e. the behavior of chromosomes during mitotic anaphase & metaphase, respectively

a.

for the recessive disease hemophilia, males are much more likely to inherit the condition than females. why is this true? a. hemophilia is a contagious disease to which males are more susceptible b. the gene for hemophilia is carried on the x chromosome c. hemophilia is the wild type d. the gene for hemophilia is carried on the y chromosome e. the gene for hemophilia is carried on an autosome

b.

our understanding of genetics deepened in the late 19th cent. bc better microscopes: a. allowed scientists to see the DNA present w in chromosomes b. allowed biologists to study meiosis & mitosis, revealing the parallels btwn the behaviors of genes & chromosomes c. led to the discovery of mitochondria d. revealed new & unanticipated ft. of mendel's pea plant varieties e. all of the other answers options are correct.

b.

the trisomy that causes down syndrome occurs bc homologous chromosomes fail to separate during meiosis. what is this unfortunate event called? a. gametic infertility b. nondisjunction c. meiotic failure d. cellular sterility e. sticky chiasmata

b.

a cross btwn YyRr x yyrr gives the phenotypic ratio 7:7:1:1. which of the following explains this strange ratio? a. incomplete dominance b. codominance c. linked genes d. polygenic inheritance e. mendel's principles of segregation & independent assortment

c.

a dihybrid test cross (YyRr x yyrr) produces (15) recombinant offspring out of a total of (1,000) offspring. what is the recombination frequency of the (2) gene pairs? a. 0.5% b. 3% c. 6% d. 1.5% e. 30%

d.

thomas hunt morgan discovered that some genes are linked. This means that the genes: a. govern traits that have nothing to do w (1) another b. govern traits (such as hair texture & hair color) that are functionally related c. have the same alleles residing on them d. are on the same chromosome e. reside on the sex chromosomes

d.

what is the expected phenotypic ratio of the following cross: AaBb x aabb? in this ex, A is dominant to a & B is dominant to b. a. 16:0:0:0 b. 8:4:2:2 c. 4:4:4:4 d. 1:1:1:1 e. 9:3:3:1

d.

if a father carries a dominant x-linked disease, what is the chance that his son will also get the disease? a. 50% b. 25% c. 75% d. 100% e. 0%

e.

what is a description of the genetic location of several genes based on recombination frequencies called? a. hypercholesterolemia b. a carrier c. a pedigree d. linked genes e. a linkage map

e.