Question 1

In a cross of individuals who both possess this genotype, AaBbCc, what proportion of the offspring is predicted to have the genotype, AABBCC?

Accepted Answer

A)   1/4
B)   1/8
C)   1/16
D)   1/64 D

Question 2

Feather color in budgies is determined by two different genes, Y for pigment on the outside of the feather, and B for pigment on the inside of the feather. YYBB, YyBB, or YYBb is green; yyBB or yyBb is blue; YYbb or Yybb is yellow; and yybb is white. Two blue budgies were crossed. Over the years, they produced 22 offspring, five of which were white. What are the most likely genotypes for the two blue budgies?

Accepted Answer

A)   yyBB and yyBB
B)   yyBB and yyBb
C)   yyBb and yyBb
D)   yyBb and yybb C

Question 3

What fraction of the offspring from a cross between two animals with the genotype AaBbCc are expected to be homozygous recessive for the three traits?

Accepted Answer

A)   1/4
B)   1/8
C)   1/16
D)   1/64 D

Question 4

A brown dog crossed with a yellow dog produced 12 brown offspring. A second brown individual was obtained. When the yellow dog was crossed with this animal, six brown and six yellow offspring were born. Which of the following best explains the results of the second cross?

Accepted Answer

A)   yellow is a recessive trait; brown is a dominant trait
B)   yellow is a dominant trait; brown is incompletely dominant
C)   yellow and brown are codominant
D)   yellow is a recessive trait; brown is codominant

Question 5

The figure shows the pedigree of a family. Dark-shaded symbols represent individuals with one of the two major types of colon cancer. Numbers under the symbols are the individual's age at the time of diagnosis. Males are represented by squares, females by circles.  Based on this pedigree, this trait is most likely inherited ________.

Accepted Answer

A)   by older individuals
B)   as a recessive trait
C)   as a result of epistasis
D)   as a dominant trait

Question 6

Which of the following statements about the law of independent assortment is correct?

Accepted Answer

A)   It describes the inheritance of different genes relative to one another.
B)   It describes the inheritance of different alleles relative to one another.
C)   It is the consequence of having two copies of each chromosome in somatic cells and one copy in gametes.
D)   It is the reason that dominant alleles are visible in the organism's phenotype.

Question 7

Radish flowers may be red, purple, or white. A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring. The flower color trait in radishes is an example of which of the following inheritance patterns?

Accepted Answer

A)   a multiple allelic system
B)   sex linkage
C)   codominance
D)   incomplete dominance

Question 8

Which of the following calculations requires the use of the addition rule of probability?

Accepted Answer

A)   Calculating the probability of green plants from the cross AaGg × AaGg, where G is the symbol for black and A is the symbol for tall.
B)   Calculating the probability that parents who are heterozygous for both cystic fibrosis and polydactyly genes will have a child with both cystic fibrosis and polydactyly.
C)   Calculating the probability that a cross between an Hh and an hh plant will result in four offspring that are each homozygous recessive.
D)   Calculating the probability of a child having either sickle-cell anemia or cystic fibrosis if parents are each heterozygous for both.

Question 9

The following question refers to the figure of a family's pedigree chart, some of whose members exhibit the dominant trait, W. Affected individuals are indicated by a dark square or circle.  What is the probability that individual III-1 is Ww?

Accepted Answer

A)   3/4
B)   1/4
C)   2/4
D)   1

Question 10

Which of the following sentences state a significant conclusion that Gregor Mendel drew from his experiments with pea plants?

Accepted Answer

A)   There is considerable genetic variation in garden peas.
B)   Traits are inherited in discrete units and are not the result of "blending."
C)   Recessive genes occur more frequently in the F1 generation than do dominant ones.
D)   Genes are composed of DNA.

Question 11

In a certain species of diploid fish a single gene controls skin color. Researchers have found four different alleles of this gene within the fish population. How many different gamete genotypes are possible in an individual of this species?

Accepted Answer

A)   2
B)   4
C)   8
D)   16

Question 12

Gene S controls the sharpness of spines in a type of cactus. Cacti with the dominant allele, S, have sharp spines, whereas homozygous recessive ss cacti have dull spines. A second gene, N, determines whether or not cacti have spines. Homozygous recessive nn cacti have no spines at all. If cacti heterozygous for both traits, SsNn, were allowed to self-pollinate, the offspring would segregate into which of the following phenotype ratios?

Accepted Answer

A)   3 sharp-spined:1 spineless
B)   1 sharp-spined:2 dull-spined:1 spineless
C)   1 sharp-spined:1 dull-spined:1 spineless
D)   9 sharp-spined:3 dull-spined:4 spineless

Question 13

Which of the following statements correctly explains the fact that all seven of the pea plant traits studied by Mendel obeyed the principle of independent assortment?

Accepted Answer

A)   None of the traits obeyed the law of segregation.
B)   The diploid number of chromosomes in the pea plants was seven.
C)   All of the genes controlling the traits had only two different alleles.
D)   All of the genes controlling the traits were on different chromosomes.

Question 14

Black fur in mice (b) is dominant to brown fur (b). Short tails (S) are dominant to long tails (s). What fraction of the progeny of crosses BbSs × BBss will be expected to have black fur and long tails?

Accepted Answer

A)   1/16
B)   3/8
C)   1/2
D)   9/16

Question 15

The following question refers to the figure of a family's pedigree chart, some of whose members exhibit the dominant trait, W. Affected individuals are indicated by a dark square or circle.  What is the genotype of individual II-5?

Accepted Answer

A)   WW
B)   Ww
C)   ww
D)   ww or Ww

Question 16

Albinism is a recessive trait where an individual does not produce the pigment melanin. A man and woman both produce melanin, but both have one parent with albinism. What is the probability that their first child will have albinism?

Accepted Answer

A)   0
B)   1/2
C)   1/4
D)   1

Question 17

Which of the following statements correctly explains the observation that parents with two different phenotypes produced offspring with a phenotype that is a blend of the two parental varieties?

Accepted Answer

A)   Neither of the parental alleles is dominant over the other.
B)   Both of the parents have dominant alleles.
C)   Neither of the parental alleles is expressed in the offspring
D)   Both of the parents are homozygous at that locus

Question 18

Use the figure and the following description to answer the question.
In a particular plant, leaf color is controlled by gene locus D. Plants with at least one allele D have dark green leaves, and plants with the homozygous recessive dd genotype have light green leaves. A true-breeding, dark-leaved plant is crossed with a light-leaved one, and the F1 offspring is allowed to self-pollinate. The predicted outcome of the F1 cross is diagrammed in the Punnett square shown in the figure, where 1, 2, 3, and 4 represent the genotypes corresponding to each box within the square. 
Which of the boxes marked 1-4 correspond to plants with dark leaves?

Accepted Answer

A)   1 only
B)   4 only
C)   1, 2, and 3
D)   2, 3 and 4

Question 19

Feather color in budgies is determined by two different genes: Y for pigment on the outside of the feather, and B for pigment on the inside of the feather. YYBB, YyBB, or YYBb is green; yyBB or yyBb is blue; YYbb or Yybb is yellow; and yybb is white. A blue budgie is crossed with a white budgie. Which of the following results in the offspring is most possible?

Accepted Answer

A)   green offspring only
B)   white offspring only
C)   blue offspring only
D)   blue and white offspring

Question 20

Which of the following inheritance patterns describes the ability of a single allele to have multiple phenotypic effects?

Accepted Answer

A)   incomplete dominance
B)   multiple alleles
C)   pleiotropy
D)   epistasis

Exam 14: Mendelian Genetics