Question 1

Use the following information to answer the questions below.
Labrador retrievers are black,brown,or yellow.In a cross of a black female with a brown male,results can be either all black puppies,1/2 black to 1/2 brown puppies,or 3/4 black to 1/4 yellow puppies.
-In one type cross of black × black,the results were as follows:
9/16 black
4/16 yellow
3/16 brown
The genotype aabb must result in which of the following?

Accepted Answer

A) black 
B) brown 
C) yellow 
D) a lethal result 
E) white

Question 2

Use the following information to answer the questions below.
Two true-breeding stocks of pea plants are crossed.One parent has red,axial flowers and the other has white,terminal flowers; all F₁ individuals have red,axial flowers.The genes for flower colour and location assort independently.
-If 1000 F₂ offspring resulted from the cross,approximately how many of them would you expect to have red,terminal flowers?

Accepted Answer

A) 65 
B) 190 
C) 250 
D) 565 
E) 750

Question 3

Use the following information to answer the questions below.
Tallness (T)in snapdragons is dominant to dwarfness (t),while red (R)flower colour is dominant to white (r).The heterozygous condition results in pink (Rr)flower colour.
-If snapdragons are heterozygous for height as well as for flower colour,a mating between them will result in what ratio?

Accepted Answer

A) 9:3:3:1 
B) 6:3:3:2:1:1 
C) 1:2:1 
D) 27:9:9:9:3:3:3:1 
E) 9:4:3

Question 4

Use the information given here to answer the following questions.
Feather colour in budgies is determined by two different genes,Y and B,one for pigment on the outside and one for 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 is not possible?

Accepted Answer

A) green offspring only 
B) yellow offspring only 
C) blue offspring only 
D) green and yellow offspring 
E) a 9:3:3:1 ratio

Question 5

A black guinea pig crossed with an albino guinea pig produced twelve black offspring.When the albino was crossed with a second black animal,six blacks and six albinos were obtained.What is the best explanation for this genetic situation?

Accepted Answer

A) Albino is recessive; black is dominant. 
B) Albino is dominant; black is incompletely dominant. 
C) Albino and black are codominant. 
D) Albino is recessive; black is codominant. 
E) Black shows incomplete dominance.

Question 6

Use the following pedigree shown below for a family in which 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.
 
-What is the genotype of the deceased individual in generation II?

Accepted Answer

A) homozygous for a gene for colon cancer 
B) homozygous for both cancer alleles from his mother 
C) heterozygous for a gene for colon cancer 
D) affected by the same colon cancer environmental factor as his mother 
E) carrier of all of the several known genes for colon cancer

Question 7

Mendel's observation of the segregation of alleles in gamete formation has its basis in which of the following phases of cell division?

Accepted Answer

A) prophase I of meiosis 
B) anaphase II of meiosis 
C) metaphase I of meiosis 
D) anaphase I of meiosis 
E) anaphase of mitosis

Question 8

A man has extra digits (six fingers on each hand and six toes on each foot).His wife and their daughter have a normal number of digits.Having extra digits is a dominant trait.The couple's second child has extra digits.What is the probability that their next (third)child will have extra digits?

Accepted Answer

A) 1/2 
B) 1/16 
C) 1/8 
D) 3/4 
E) 1

Question 9

Which of the following is the best statement of the use of the addition rule of probability?

Accepted Answer

A) the probability that two or more independent events will both occur 
B) the probability that two or more independent events will both occur in the offspring of one set of parents 
C) the probability that either one of two independent events will occur 
D) the probability of producing two or more heterozygous offspring 
E) the likelihood that a trait is due to two or more meiotic events

Question 10

Most genes have many more than two alleles.However,which of the following is also true?

Accepted Answer

A) At least one allele for a gene always produces a dominant phenotype. 
B) Most of the alleles will never be found in a live-born organism. 
C) All of the alleles but one will produce harmful effects if homozygous. 
D) There may still be only two phenotypes for the trait. 
E) More than two alleles in a genotype is considered lethal.

Question 11

In cattle,roan coat colour (mixed red and white hairs)occurs in the heterozygous (Rr)offspring of red (RR)and white (rr)homozygotes.Which of the following crosses would produce offspring in the ratio of 1 red:2 roan:1 white?

Accepted Answer

A) red × white 
B) roan × roan 
C) white × roan 
D) red × roan 
E) The answer cannot be determined from the information provided.

Question 12

What was the most 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 results of "blending." 
C) Recessive genes occur more frequently in the F₁ generation than do dominant ones. 
D) Genes are composed of DNA. 
E) An organism that is homozygous for many recessive traits is at a disadvantage.

Question 13

Which of the following describes the ability of a single gene to have multiple phenotypic effects?

Accepted Answer

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

Question 14

Mendel's second law of independent assortment has its basis in which of the following events of meiosis I?

Accepted Answer

A) synapsis of homologous chromosomes 
B) crossing over 
C) alignment of tetrads at the equator 
D) separation of homologues at anaphase 
E) separation of cells at telophase

Question 15

Use the following information to answer the questions below.
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 part of the radish we eat may be oval or long,with long being the dominant characteristic.
-The flower colour trait in radishes is an example of which of the following?

Accepted Answer

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

Question 16

How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE?

Accepted Answer

A) 4 
B) 8 
C) 16 
D) 32 
E) 64

Question 17

The following questions refer to the pedigree chart in the figure below for a family,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) 2/3 
E) 1

Question 18

The frequency of heterozygosity for the sickle-cell anemia allele is unusually high,presumably because this reduces the frequency of malaria.Such a relationship is related to which of the following?

Accepted Answer

A) Mendel's law of independent assortment 
B) Mendel's law of segregation 
C) Darwin's explanation of natural selection 
D) Darwin's observations of competition 
E) the malarial parasite changing the allele

Question 19

Assuming independent assortment for all gene pairs,what is the probability that the following parents,AABbCc × AaBbCc,will produce an AaBbCc offspring?

Accepted Answer

A) 1/2 
B) 1/16 
C) 1/8 
D) 3/4 
E) 1

Question 20

Refer to the following information to answer the questions below.
Humanoids on the newly explored planet Brin (in a hypothetical galaxy in ~50 years from the present)have a gene structure similar to our own,but many very different plants and animals.
-One species of a small birdlike animal has an extremely variable tail length,which is a highly polymorphic trait.Geneticists have come to realize that there are eight separate genes for tail length per haploid genome,with each gene having two alleles.One allele for each gene (a,b,and so on)increases the length by 1 cm,whereas the other allele (a₂,b₂,and so on)increases it by 0.5 cm.One bird was analyzed and found to have the following genotype:
A₁a₁b₂b₂c₁c₂d₁d₂e₂e₂f₁f₂g₁g₁h₁h₂
What is the length of its tail?

Accepted Answer

A) 6 cm 
B) 8 cm 
C) 12 cm 
D) 24 cm 
E) 36 cm

Exam 14: Mendel and the Gene Idea