Microsoft Word - blank.doc

NEL The Basis of Heredity 625

Chapter 18

22.In Canada, it is illegal to marry your immediate relatives. Using

the principles of genetics, explainwhy inbreeding of humans

is discouraged.

D I

AB

C E F GH

JKL M NO

Mother O’s Family Tree

Father K’s Family Tree

A B

C D E F G H I J

K L M NOP Q R S

I

II

III

I

II

III

Figure 3

27.Predictthe genotypes of the parent plants.

28.The plant breeder crosses two individuals from the F 1

generation that have high oil-content and four seeds per

pod. If all the members of the F 2 generation all have high

oil-content and four seeds per pod, predictthe genotypes

of the two F 1 parent plants chosen by the breeder.

29.The breeder wants to confirm the genotype of the two F 1

parent plants using a cross. What genotype should the

plant she crosses the F 1 parent plants have? Explain.

Use the following information to answer questions 23 to 26.

When paper impregnated with the bitter chemical

phenylthiocarbamide (PTC) is placed on the tongue, about

70 % of people can taste the chemical. The ability to taste PTC

is determined by a dominant taster allele (T). Those who

cannot taste PTC are homozygous for the recessive alleles (t).

A second gene on another chromosome determines skin

pigmentation. Allele (A) is dominant, and determines normal

pigmentation. People who are homozygous for the recessive

allele (a) will be albino. A normally pigmented woman who

cannot taste PTC has a father who is an albino and a PTC

taster. She marries a normally pigmented man who is

homozygous for the dominant (A) allele for pigmentation.

The man can taste PTC, but his mother cannot.

Use the following information to answer questions 27 to 29.

In a specific variety of soybeans, the allele for seeds containing

a high oil-content (H) is dominant to the allele for low

oil-content (h). A gene located on another chromosome

determines the number of seeds in a pod. Through crossing

experiments, it was determined that the allele that determines

four seeds per pod (E) is dominant to the allele that

determines two seeds per pod (ee). A plant breeder crosses

two soybean plants of this variety, both of which have high

oil-content and four seeds per pod. The phenotypes of the F 1

generation and their ratios are shown in Table 1.

23.Predict all the possible genotypes for these two traits for

children by this couple.

24.Determinethe probability that a child from this couple will

not be able to taste PTC.

25.Determinethe probability that a child from this couple will

be albino?

26.Determinethe probability that a child from this couple will

be able to taste PTC and be albino.

DE

DE

DE

DE

DE

DE

DE

Table 1 Phenotypes of the F 1 Generation

Phenotype Ratio

high oil-content—four seeds per pod 9

high oil-content—two seeds per pod 3

low oil-content—four seeds per pod 3

low oil-content—two seeds per pod 1