Question 1

Skin color comes from the pigment

Accepted Answer

A)  melatonin. 
B)  melanin. 
C)  anthocyanin. 
D)  giberellin. 
E)  fucoxanthin. 
A)  melatonin. 
B)  melanin. 
C)  anthocyanin. 
D)  giberellin. 
E)  fucoxanthin.

Question 2

Selecting the Exception Four of the five answers listed below are accepted as valid explanations of genetic behavior. Select the exception.

Accepted Answer

A)  blending 
B)  dominance 
C)  segregation 
D)  independent assortment 
E)  probability 
A)  blending 
B)  dominance 
C)  segregation 
D)  independent assortment 
E)  probability

Question 3

Human skin and eye color are traits that are

Accepted Answer

A)  the result of polygenic inheritance. 
B)  examples of continuous variation. 
C)  incompletely penetrant. 
D)  the result of polygenic inheritance and examples of continuous variation. 
E)  the result of polygenic inheritance, examples of continuous variation, and incompletely penetrant. 
A)  the result of polygenic inheritance. 
B)  examples of continuous variation. 
C)  incompletely penetrant. 
D)  the result of polygenic inheritance and examples of continuous variation. 
E)  the result of polygenic inheritance, examples of continuous variation, and incompletely penetrant.

Question 4

The genotype aa is referred to as

Accepted Answer

A)  heterozygous. 
B)  hybrid. 
C)  homozygous recessive. 
D)  homozygous dominant. 
E)  codominant. 
A)  heterozygous. 
B)  hybrid. 
C)  homozygous recessive. 
D)  homozygous dominant. 
E)  codominant.

Question 5

Various forms of a gene at a given locus are called

Accepted Answer

A)  chiasmata. 
B)  alleles. 
C)  autosomes. 
D)  loci. 
E)  chromatids. 
A)  chiasmata. 
B)  alleles. 
C)  autosomes. 
D)  loci. 
E)  chromatids.

Question 6

The probability of producing a child with cc at #4 is

Accepted Answer

A)  1/4. 
B)  25 percent. 
C)  1 out of 4. 
D)  0.25. 
E)  all of these 
A)  1/4. 
B)  25 percent. 
C)  1 out of 4. 
D)  0.25. 
E)  all of these

Question 7

If some people who inherit a dominant allele have the phenotype associated with it and others who inherit it do not, the allele is said to demonstrate

Accepted Answer

A)  incomplete dominance. 
B)  incomplete penetrance. 
C)  codominance. 
D)  continuous variation. 
E)  polygenicity. 
A)  incomplete dominance. 
B)  incomplete penetrance. 
C)  codominance. 
D)  continuous variation. 
E)  polygenicity.

Question 8

Approximately how many genes do humans possess?

Accepted Answer

A)  100,000 
B)  50,000 
C)  40,000 
D)  25,500 
E)  21,500 
A)  100,000 
B)  50,000 
C)  40,000 
D)  25,500 
E)  21,500

Question 9

There are nine coat colors known in foxes. If a red fox were crossed with a double-black fox, all the hybrids would be red above and black below in a pattern known as a blended cross. If two blended crosses were mated, the F 2 ratio would be as follows: 1 red, 2 smokey red, 2 cross red, 4 blended cross, 1 standard silver, 2 substandard silver, 1 Alaskan silver, 2 sub-Alaskan silver, and 1 double-black. 
 (a) Using the letters A/a and B/b to serve as the genes for these animals, develop a genotype for each variety listed. 
 (b) Two crosses will produce all blended-cross offspring. One is used above (red fox x double-black); what is the other? 
 (c) List the genotype and phenotype of all the pure-breeding foxes. 
 (d) Give the genotypic and phenotypic ratio of a cross between two substandard silvers. 
 (e) Give the genotype and phenotype of the offspring produced in a cross of 1 sub-Alaskan silver and a cross red.

Accepted Answer

(a) 1 AA BB red 
   2 AA Bb smokey red

Question 10

In cocker spaniels, black coat color (B) is dominant over red (b) , and solid color (S) is dominant over spotted (s) . In the F 2 generation of a cross between BB ss with bb SS , what fraction of the offspring would be expected to be black and spotted?

Accepted Answer

A)  1/16 
B)  9/16 
C)  1/9 
D)  3/16 
E)  3/4 
A)  1/16 
B)  9/16 
C)  1/9 
D)  3/16 
E)  3/4

Question 11

Assume short hair (L) is dominant to long hair (l) , and black hair (B) is dominant to brown (b) . If you found a black, short-haired animal, you could determine its genotype by crossing it to an animal with a genotype of

Accepted Answer

A)  LL BB . 
B)  ll BB . 
C)  ll Bb . 
D)  ll bb . 
E)  LL bb . 
A)  LL BB . 
B)  ll BB . 
C)  ll Bb . 
D)  ll bb . 
E)  LL bb .

Question 12

What fraction of the time will the cross of Aa Bb Cc with Aa Bb Cc produce an offspring of genotype aa bb cc ?

Accepted Answer

A)  1/64 
B)  1/32 
C)  3/64 
D)  1/16 
E)  9/64 
A)  1/64 
B)  1/32 
C)  3/64 
D)  1/16 
E)  9/64

Question 13

In cocker spaniels, black coat color (B) is dominant over red (b) , and solid color (S) is dominant over spotted (s) . If a red male was crossed with a black female to produce a red, spotted puppy, the genotypes of the parents (with male genotype first) would be

Accepted Answer

A)  Bb Ss x Bb Ss . 
B)  bb Ss x Bb Ss . 
C)  bb ss x Bb Ss . 
D)  bb Ss x Bb ss . 
E)  Bb ss x Bb ss . 
A)  Bb Ss x Bb Ss . 
B)  bb Ss x Bb Ss . 
C)  bb ss x Bb Ss . 
D)  bb Ss x Bb ss . 
E)  Bb ss x Bb ss .

Question 14

In a certain variety of plants, a cross between a red-flowered plant and a white-flowered plant produced an all-red flower F 1. In the F 2 there were 140 red-flowered plants, 50 cream-flowered plants, and 65 white-flowered plants. 
 (a) Offer an explanation for this F 2 ratio. 
 (b) What ratio would be produced in a testcross of the F 1 hybrid? 
 (c) What ratio would be produced if all the white-flowered F 2 plants were crossed among themselves?

Accepted Answer

(a) R -red, r -cream, A -color

Question 15

A graphic tool used to determine the probable outcome of genetic crosses is the

Accepted Answer

A)  Mendelian box. 
B)  Archimedian triangle. 
C)  Euclid box. 
D)  Hardy-Weinberg graph. 
E)  Punnett square. 
A)  Mendelian box. 
B)  Archimedian triangle. 
C)  Euclid box. 
D)  Hardy-Weinberg graph. 
E)  Punnett square.

Question 16

What fraction of the time will the cross of Aa Bb Cc with Aa Bb Cc produce an offspring that expresses the dominant traits A and B and cc ( A _  B _ cc )?

Accepted Answer

A)  1/32 
B)  3/64 
C)  1/16 
D)  9/64 
E)  27/64 
A)  1/32 
B)  3/64 
C)  1/16 
D)  9/64 
E)  27/64

Question 17

In rabbits, there are four alleles at the c locus. Arranged in dominance sequence, they are: C (agouti) c ch (chinchilla) c h (Himalayan) and c (albino) 
 (a) Is it possible to cross two agouti rabbits and produce both chinchilla and Himalayan offspring? 
 (b) Is it possible to cross two chinchillas and produce 1/2 chinchilla and 1/2 Himalayan?

Accepted Answer

(a) no 
 (b) not lik

Question 18

If long or round are homozygous forms of an incompletely dominant gene and oval is the phenotype of the heterozygote, give the F 2 ratio of the cross between long and round (both genotype and phenotype).

Accepted Answer

1 LL , 2 L

Question 19

Geneticists study _______ to determine the possible outcomes of single-gene traits.

Accepted Answer

A)  probability 
B)  segregation 
C)  dominance 
D)  independent assortment 
E)  phenotype 
A)  probability 
B)  segregation 
C)  dominance 
D)  independent assortment 
E)  phenotype

Question 20

Skin color and eye color are examples of

Accepted Answer

A)  traits related to pleiotropic genes. 
B)  single gene traits. 
C)  polygenic traits. 
D)  bigenic traits. 
E)  mutually exclusive traits. 
A)  traits related to pleiotropic genes. 
B)  single gene traits. 
C)  polygenic traits. 
D)  bigenic traits. 
E)  mutually exclusive traits.

Exam 19: Introduction to Genetics

Skin color comes from the pigment

Selecting the Exception Four of the five answers listed below are accepted as valid explanations of genetic behavior. Select the exception.

Human skin and eye color are traits that are

The genotype aa is referred to as

Various forms of a gene at a given locus are called

The probability of producing a child with cc at #4 is

If some people who inherit a dominant allele have the phenotype associated with it and others who inherit it do not, the allele is said to demonstrate

Approximately how many genes do humans possess?

In cocker spaniels, black coat color (B) is dominant over red (b) , and solid color (S) is dominant over spotted (s) . In the F 2 generation of a cross between BB ss with bb SS , what fraction of the offspring would be expected to be black and spotted?

Assume short hair (L) is dominant to long hair (l) , and black hair (B) is dominant to brown (b) . If you found a black, short-haired animal, you could determine its genotype by crossing it to an animal with a genotype of

What fraction of the time will the cross of Aa Bb Cc with Aa Bb Cc produce an offspring of genotype aa bb cc ?

In cocker spaniels, black coat color (B) is dominant over red (b) , and solid color (S) is dominant over spotted (s) . If a red male was crossed with a black female to produce a red, spotted puppy, the genotypes of the parents (with male genotype first) would be

A graphic tool used to determine the probable outcome of genetic crosses is the

What fraction of the time will the cross of Aa Bb Cc with Aa Bb Cc produce an offspring that expresses the dominant traits A and B and cc ( A _ B _ cc )?

If long or round are homozygous forms of an incompletely dominant gene and oval is the phenotype of the heterozygote, give the F 2 ratio of the cross between long and round (both genotype and phenotype).

Geneticists study _______ to determine the possible outcomes of single-gene traits.

Skin color and eye color are examples of

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In cocker spaniels, black coat color (B) is dominant over red (b) , and solid color (S) is dominant over spotted (s) . In the F ₂ generation of a cross between BB ss with bb SS , what fraction of the offspring would be expected to be black and spotted?

If long or round are homozygous forms of an incompletely dominant gene and oval is the phenotype of the heterozygote, give the F ₂ ratio of the cross between long and round (both genotype and phenotype).