Question 1

In genetic crosses, the symbol Aa refers to a:

Accepted Answer

A) genotype. 
B) phenotype. 
C) morphotype. 
D) holotype. 
E) archetype.

Question 2

Imagine that a rancher has a herd of cattle with brown hides and short horns. All of his cattle are also relatively short in stature. If all of these traits were true-breeding, what could you say about the progeny of these cattle?

Accepted Answer

A) It is impossible to determine the traits of such progenyF1F1F1S1F1F1F10they will likely demonstrate different hide colors, horn lengths, and heights. 
B) The progeny of these cattle will have short horns, but a variety of hide colors and heights. 
C) The progeny of these cattle will have brown, black, white, and spotted hides. 
D) Because the cattle are true-breeding, the progeny of this herd will all be sterile. 
E) The progeny of these cattle will be short in stature and have brown hides and short horns.

Question 3

Segregation of alleles corresponds to the separation of:

Accepted Answer

A) genes. 
B) genotypes. 
C) chromosomes. 
D) phenotypes.

Question 4

One of Mendel's most important discoveries was:

Accepted Answer

A) dominance. 
B) segregation. 
C) mutation. 
D) equivalence of reciprocal crosses.

Question 5

In genetics, the dash symbol (-) is a "wild card" that stands for either the dominant allele or the recessive allele; for example, R- means the individual has either the genotype RR or Rr. In Duroc-Jersey pigs, genotypes R- S- have a red coat color, R- ss and rr S- have sandy-colored coats, and rr ss pigs are white. R and S show independent assortment. What cross is expected to result in all sandy-colored progeny?

Accepted Answer

A) RR SS × rr ss 
B) RR Ss × Rr SS 
C) Rs Ss × Rr Ss 
D) RR ss × rr SS 
E) rr ss × rr ss

Question 6

Consider a gene with n alleles A1, A2, …, An. How many distinct homozygous genotypes are possible?

Accepted Answer

A) 1 × n 
B) 2 × n 
C) 3 × n 
D) 4 × n 
E) 5 × n

Question 7

If Mendel based his data only on two traits, and the genes influencing those traits were linked and located close together on the same chromosome, which of his laws would he NOT have been able to resolve?

Accepted Answer

A) segregation 
B) independent assortment

Question 8

In genetics, the dash symbol (-) is a "wild card" that stands for either the dominant allele or the recessive allele; for example, R- means the individual has either the genotype RR or Rr. In Duroc-Jersey pigs, genotypes R- S- have a red coat color, R- ss and rr S- have sandy-colored coats, and rr ss pigs are white. R and S show independent assortment. What is the ratio of red : sandy : white among progeny of the cross Rr Ss × Rr Ss?

Accepted Answer

A) 12:3:1 
B) 9:3:1 
C) 10:3:3 
D) 9:6:1 
E) None of the answer options is correct.

Question 9

Consider a gene with four alleles A1, A2, A3, and A4. If the cross A1A2 × A3A3 yields two offspring, what is the probability that both of them have the same genotype?

Accepted Answer

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

Question 10

What made the plant hybridization studies performed by Mendel more successful than plant hybridization studies performed by others?

Accepted Answer

A) Mendel did not use true-breeding organisms because he wanted to assess the inheritance of more than one trait per breeding. 
B) Mendel was the first to identify characteristics of pea plants that could be observed as phenotypes. 
C) Mendel's understanding of natural selection inspired his methodology to examine the effect of environmental stressors on genetic diversity. 
D) Mendel used statistical analysis to analyze the phenotypes he observed. 
E) Mendel used qualitative analysis to evaluate the genotypes he observed.

Question 11

Your grandmother has a rare disease for which a new genetic test has just been developed. If you are interested in a genetic test to determine whether you are affected, which of the following would you need to know to BEST interpret your test?

Accepted Answer

A) if you have one or two copies of a dominant allele 
B) your father's genotype 
C) the penetrance of disease in people of your genotype 
D) the degree of variable expressivity if you lack a copy of the affected allele

Question 12

In genetics, the dash symbol (-) is a "wild card" that stands for either the dominant allele or the recessive allele; for example, A- means the individual has either the genotype AA or Aa. Two genes that undergo independent assortment affect flower color in sweet peas. Each gene as two alleles, one of which is dominant for flower color. Genotypes of the form A- B- have purple flowers, whereas those of the form A- bb, aa B-, and aa bb have white flowers. What ratio of purple : white is expected from the cross Aa Bb × Aa Bb?

Accepted Answer

A) 9:7 
B) 10:6 
C) 12:4 
D) 13:3 
E) 15:1

Question 13

If the phenotype of pea pod color is determined by incomplete dominance and the combination of an allele for yellow seeds and an allele for green seeds yields blue seeds, you would expect the F2 generation from an original cross of true-breeding green stock with true-breeding yellow stock to be:

Accepted Answer

A) 25% yellow, 50% blue, 25% green. 
B) 67% green, 33% yellow. 
C) 67% blue, 33% yellow. 
D) 100% green. 
E) 100% blue.

Question 14

An allele is:

Accepted Answer

A) one of several forms of a gene. 
B) the particular combination of genes for a given trait in a given organism. 
C) the expression of a trait in an individual. 
D) the location of a gene on a chromosome. 
E) None of the answer options is correct.

Question 15

Which of the following is TRUE of incomplete penetrance?

Accepted Answer

A) Environmental factors do not influence penetrance. 
B) Incomplete penetrance implies that some individuals will experience less severe forms of disease such as cancer or Alzheimer's. 
C) Gene interactions have been shown to result in incomplete penetrance in some cases. 
D) Incomplete penetrance refers to cases in which individuals developing a particular disease (e.g., cancer or Alzheimer's)lack the typical genotype for this disease.

Question 16

A high school student wants to repeat Mendel's classic experiments for her science fair. To stay true to Mendel's work, what must the student do?

Accepted Answer

A) She must allow true-breeding pea plants to self-fertilize. 
B) She must remove the male organs (anthers)from plants she has designated as females. 
C) She must hand-pollinate the pea plants and keep careful track of the traits demonstrated by male and female parents. 
D) She must leave the pollinated plants uncovered, so that they can receive adequate amounts of light, carbon dioxide, and water. 
E) She must remove the male organs (anthers)from plants she has designated as females, and she must hand-pollinate plants and keep track of the traits seen in male and female parents.

Question 17

Mendel's principle of independent assortment corresponds to which part of meiosis?

Accepted Answer

A) random pairing of homologs during prophase I 
B) random alignment of homologs on the metaphase plate during metaphase I 
C) separation of chromosomes in anaphase I 
D) random alignment of homologs on the metaphase plate during metaphase II 
E) separation of daughter chromatids during anaphase II

Question 18

Which of the following is TRUE regarding linked genes?

Accepted Answer

A) Linked genes are always located on different chromosomes. 
B) Linked genes are located on the same chromosome. 
C) Linked genes demonstrate independent assortment. 
D) Linked genes do not follow patterns of independent assortment. 
E) Linked genes are located in the same chromosome and do not follow patterns of independent assortment.

Question 19

A phenotype is:

Accepted Answer

A) one of several forms of a gene. 
B) the particular combination of alleles present in a given organism. 
C) the expression of a trait in an individual. 
D) the location of a gene on a chromosome. 
E) None of the other answer options is correct.

Question 20

Mendel was the first to demonstrate:

Accepted Answer

A) dominance. 
B) segregation. 
C) independent assortment. 
D) equivalence of reciprocal crosses. 
E) All of these choices are correct.

Exam 16: Mendelian Inheritance