Question 1

The hypothesis that hybrid vigor, or heterosis, results from the superiority of the heterozygote in comparison to either homozygote is known as _______.

Accepted Answer

The answer of The hypothesis that hybrid vigor, or heterosis,...

Question 2

A key factor that allowed Mendel to interpret the results of his breeding experiments was that

Accepted Answer

A)  the varieties of peas he used were "true-breeding." 
B)  peas naturally self-pollinate. 
C)  peas can reproduce asexually. 
D)  pollination could be controlled. 
E)  Both a and d

Question 3

In a(n) _______ cross, genes for two different characters separate.

Accepted Answer

A)  monohybrid 
B)  dihybrid 
C)  trihybrid 
D)  F1 
E)  F2

Question 4

In tomatoes, tall is dominant to short, and smooth fruits are dominant to hairy fruits. A plant homozygous for both dominant traits is crossed with a plant homozygous for both recessive traits. The F1 progeny are tested and crossed with the following results: 78 tall, smooth fruits; 82 dwarf, hairy fruits; 22 tall, hairy fruits; and 18 dwarf, smooth fruits. These data indicate that the genes are

Accepted Answer

A)  on different chromosomes. 
B)  linked, but do not cross over. 
C)  linked and show 10 percent recombination. 
D)  linked and show 20 percent recombination. 
E)  linked and show 40 percent recombination.

Question 5

The region of the chromosome occupied by a gene is called the _______.

Accepted Answer

The answer of The region of the chromosome occupied by...

Question 6

Hemophilia is a trait carried by the mother and passed to her sons. The allele for hemophilia, therefore,

Accepted Answer

A)  is carried on one of the mother's autosomal chromosomes. 
B)  is carried on the Y chromosome. 
C)  can be carried on the X or Y chromosome. 
D)  is on the X chromosome and can only be inherited by the son if the mother is a carrier (heterozygous). 
E)  is carried in the mitochondrial genome because sons inherit this allele from their mothers.

Question 7

Sex in humans is determined by

Accepted Answer

A)  a gene called SRY found on the Y chromosome. 
B)  a gene called SRY found on the X chromosome. 
C)  a gene called SDG found on an autosomal
Chromosome. 
D)  the simple presence or absence of a Y chromosome. 
E)  a gene called SDG found on the Y chromosome.

Question 8

In Mendel's experiments, if the allele for tall (T) plants was incompletely dominant over the allele for short (t) plants, what offspring would have resulted from crossing two Tt plants?

Accepted Answer

A)  1/4 tall; 1/2 intermediate height; 1/4 short 
B)  1/2 tall; 1/4 intermediate height; 1/4 short 
C)  1/4 tall; 1/4 intermediate height; 1/2 short 
D)  All tall offspring 
E)  All intermediate height offspring

Question 9

Despite the law of independent assortment, when two loci are on the same chromosome, the phenotypes of the progeny sometimes do not fit the predicted phenotypes due to

Accepted Answer

A)  translocation. 
B)  inversions. 
C)  chromatid affinities. 
D)  linkage. 
E)  reciprocal chromosomal exchanges.

Question 10

Draw a sample pedigree with three generations in which the paternal grandfather has a rare dominant autosomal trait. What is the probability that one of his children will have the disease? What is the probability that one of his grandchildren will have the disease?

Accepted Answer

The answer of Draw a sample pedigree with three generations...

Question 11

An individual has a karyotype that is XX but is phenotypically male. What could explain this result?

Accepted Answer

A)  The Y chromosome was not visible in the karyotype. 
B)  Sex determination is determined by the autosomes and not the X chromosomes. 
C)  A translocation has occurred, placing the SRY gene on one of the X chromosomes. 
D)  The DAX 1 protein is overproduced. 
E)  A nondisjunction event has resulted in Kleinfelter syndrome.

Question 12

A bacterial cell's genotype can be altered by

Accepted Answer

A)  the introduction of a plasmid that carries some of the bacteria's genes. 
B)  mating with a bacterial cell with the same genotype. 
C)  homologous recombination with human DNA. 
D)  the forming of a conjugation tube with another bacterial cell. 
E)  the transferring of genetic material from a different strain of bacteria.

Question 13

Wild type fruit flies have red eyes. A white-eyed female fly is crossed with a red-eyed male fly. All of the females from the cross are red-eyed and all of the males, white-eyed. What type of inheritance pattern is this?

Accepted Answer

A)  Independent assortment 
B)  Autosomal dominant 
C)  Autosomal recessive 
D)  Incomplete dominance 
E)  Sex-linked on X chromosome

Question 14

Penetrance and expressivity are related to

Accepted Answer

A)  the increased expression of a particular trait when a hybrid species is formed. 
B)  quantitative traits that diminish or intensify a particular phenotype. 
C)  the influence of environment on the expression of a particular genotype. 
D)  the expression of one gene masking the effects of another gene. 
E)  the expression of a dominant phenotype in a heterozygote.

Question 15

Different forms of a gene are called

Accepted Answer

A)  traits. 
B)  phenotypes. 
C)  genotypes. 
D)  alleles. 
E)  None of the above

Question 16

Very few genes have been located on the Y chromosomes. Y-linked genes include a gene called testis-specific protein Y. A male with this gene will

Accepted Answer

A)  usually pass it to his sons, but occasionally also to a daughter. 
B)  only pass the gene to his sons. 
C)  only pass the gene to his daughters. 
D)  only pass the gene to his grandsons. 
E)  pass the gene to all of his children if the mother is a carrier.

Question 17

If a trait not expressed in the F1 generation reappears in the F2 generation, the inheritance of the trait in question is an example of

Accepted Answer

A)  codominance. 
B)  dominance and recessiveness. 
C)  incomplete dominance. 
D)  epistasis. 
E)  a sex-linked trait.

Question 18

Use the following to answer questions:
Cleft chin is an X-linked dominant trait. Assume that a man with a cleft chin marries a woman with a round chin.
-What percent of their male progeny will show the cleft chin trait?

Accepted Answer

A)  0 
B)  25 
C)  50 
D)  75 
E)  100

Question 19

True-breeding plants

Accepted Answer

A)  produce the same offspring when crossed for many generations. 
B)  have no mutations. 
C)  result from a monohybrid cross. 
D)  result from a dihybrid cross. 
E)  result from crossing over during prophase I of meiosis.

Question 20

Mendel's dihybrid crosses

Accepted Answer

A)  resulted in four different phenotypes. 
B)  produced recombinant phenotypes. 
C)  led to the formation of the law of independent assortment. 
D)  involved unlinked genes. 
E)  All of the above

Exam 12: Inheritance, Genes, and Chromosomes