Question 1

What is the best explanation for a BbCc × bbcc cross producing offspring in a 5:5:1:1 phenotypic ratio?

Accepted Answer

A)  linked genes 
B)  polygenic inheritance 
C)  incomplete dominance 
D)  codominance 
A)  linked genes 
B)  polygenic inheritance 
C)  incomplete dominance 
D)  codominance A

Question 2

A purebred plant that produces yellow seeds is crossed with a purebred plant that produces green seeds.The F₁ plants have yellow seeds.What is the expected phenotypic ratio of seed color of the offspring of an F₁ × F₁ cross?

Accepted Answer

A)  1:2:1 
B)  2:1 
C)  3:1 
D)  9:3:3:1 
A)  1:2:1 
B)  2:1 
C)  3:1 
D)  9:3:3:1 C

Question 3

Attached earlobes are recessive to free earlobes.What genotypic ratio is expected when an individual with attached earlobes mates with an individual heterozygous for free earlobes?

Accepted Answer

A)  2:1 
B)  1:1 
C)  1:2:1 
D)  3:1 
A)  2:1 
B)  1:1 
C)  1:2:1 
D)  3:1 B

Question 4

What is the key to the recognition of incomplete dominance?

Accepted Answer

A)  The phenotype of the heterozygote falls between the phenotypes of the homozygotes. 
B)  The trait exhibits a continuous distribution. 
C)  The alleles affect more than one trait. 
D)  The heterozygote expresses the phenotype of both homozygotes. 
A)  The phenotype of the heterozygote falls between the phenotypes of the homozygotes. 
B)  The trait exhibits a continuous distribution. 
C)  The alleles affect more than one trait. 
D)  The heterozygote expresses the phenotype of both homozygotes.

Question 5

Alleles are described as ________.

Accepted Answer

A)  homologous chromosomes 
B)  environmental factors that affect gene expression 
C)  alternate versions of a gene 
D)  alternate phenotypes 
A)  homologous chromosomes 
B)  environmental factors that affect gene expression 
C)  alternate versions of a gene 
D)  alternate phenotypes

Question 6

The recombination frequency between gene B and gene C is 11%.The recombination frequency between gene B and gene D is 5%.The recombination frequency between gene C and gene D is 15%.What would be the arrangement of these genes on a linkage map?

Accepted Answer

A)  CDB 
B)  DBC 
C)  BCD 
D)  More information is needed. 
A)  CDB 
B)  DBC 
C)  BCD 
D)  More information is needed.

Question 7

This hypothetical pedigree for a disease in humans illustrated inheritance that is

Accepted Answer

A)  autosomal recessive. 
B)  autosomal dominant. 
C)  sex-linked dominant. 
D)  carried on the Y chromosome. 
A)  autosomal recessive. 
B)  autosomal dominant. 
C)  sex-linked dominant. 
D)  carried on the Y chromosome.

Question 8

A couple has two female children.What is the probability that their next child will be male?

Accepted Answer

A)  25% 
B)  50% 
C)  33% 
D)  67% 
A)  25% 
B)  50% 
C)  33% 
D)  67%

Question 9

________ genes violate Mendel's principle of independent assortment.

Accepted Answer

A)  Codominant 
B)  Linked 
C)  Recessive 
D)  Pleiotropic 
A)  Codominant 
B)  Linked 
C)  Recessive 
D)  Pleiotropic

Question 10

Assume that having three nostrils is inherited as a sex-linked trait on the Y chromosome.A man with three nostrils has a daughter who has a son with a man who has only two nostrils.What is the probability that the three-nostriled man's grandson has three nostrils?

Accepted Answer

A)  0% 
B)  25% 
C)  50% 
D)  100% 
A)  0% 
B)  25% 
C)  50% 
D)  100%

Question 11

Experience with dog breeding has taught geneticists ________.

Accepted Answer

A)  that, given enough time, any desired trait can be bred into dogs 
B)  that purebred dogs have offspring with qualities identical to the parents, because all purebred dogs are alike genetically 
C)  that, while physical traits can be molded through artificial selection, behavioral traits cannot 
D)  that geographically isolated groups of dogs may be selected for quite different traits, resulting in a different dog breed 
A)  that, given enough time, any desired trait can be bred into dogs 
B)  that purebred dogs have offspring with qualities identical to the parents, because all purebred dogs are alike genetically 
C)  that, while physical traits can be molded through artificial selection, behavioral traits cannot 
D)  that geographically isolated groups of dogs may be selected for quite different traits, resulting in a different dog breed

Question 12

In humans,the inheritance of ________ is best explained as being polygenic.

Accepted Answer

A)  cystic fibrosis 
B)  height 
C)  blood type 
D)  sickle-cell disease 
A)  cystic fibrosis 
B)  height 
C)  blood type 
D)  sickle-cell disease

Question 13

The best definition of a purebred plant is one that ________.

Accepted Answer

A)  cannot be cross-fertilized 
B)  self-fertilizes to produce offspring identical to the parent 
C)  produces sterile offspring when cross-fertilized 
D)  self-fertilizes to produce hybrid offspring 
A)  cannot be cross-fertilized 
B)  self-fertilizes to produce offspring identical to the parent 
C)  produces sterile offspring when cross-fertilized 
D)  self-fertilizes to produce hybrid offspring

Question 14

In humans,the presence or absence of dimples is a trait controlled by a single gene.What is the genotype of an individual who is heterozygous for dimples?

Accepted Answer

A)  DD 
B)  Dd 
C)  dd 
D)  DI 
A)  DD 
B)  Dd 
C)  dd 
D)  DI

Question 15

Please read the following scenario to answer the following questions.
Widow's peak, a pointed hairline on the forehead, is a genetic trait caused by a dominant allele. It can be traced back through a family's history using pedigree analysis.
The pedigree shown here is of three generations of a family. Notice that some individuals (shown in gray) have a widow's peak (W = dominant allele and w = recessive allele).
  
-Janice's genotype is ________.

Accepted Answer

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

Question 16

An individual who is homozygous ________.

Accepted Answer

A)  expresses the dominant trait 
B)  carries two different alleles for a gene 
C)  carries two copies of the same allele for a gene 
D)  expresses the recessive trait 
A)  expresses the dominant trait 
B)  carries two different alleles for a gene 
C)  carries two copies of the same allele for a gene 
D)  expresses the recessive trait

Question 17

Achondroplasia is a form of dwarfism caused by a dominant allele.The homozygous dominant genotype causes death,so individuals who have this condition are all heterozygotes.If a person with achondroplasia mates with a person who does not have achondroplasia,what percentage of their children would be expected to have achondroplasia?

Accepted Answer

A)  0% 
B)  50% 
C)  75% 
D)  100% 
A)  0% 
B)  50% 
C)  75% 
D)  100%

Question 18

Which of these crosses will produce only heterozygous offspring?

Accepted Answer

A)  AA × aa 
B)  AA × Aa 
C)  Aa × Aa 
D)  Aa × aa 
A)  AA × aa 
B)  AA × Aa 
C)  Aa × Aa 
D)  Aa × aa

Question 19

In humans,free earlobes (E)are dominant to attached earlobes (e)and the presence of freckles (F)is dominant to the absence of freckles (f).If an individual heterozygous for both of these traits were to mate with an individual with attached earlobes and no freckles,what is the probability of having a child with attached earlobes and freckles?

Accepted Answer

A)  0% 
B)  25% 
C)  50% 
D)  100% 
A)  0% 
B)  25% 
C)  50% 
D)  100%

Question 20

Please read the following scenario to answer the following questions.
Widow's peak, a pointed hairline on the forehead, is a genetic trait caused by a dominant allele. It can be traced back through a family's history using pedigree analysis.
The pedigree shown here is of three generations of a family. Notice that some individuals (shown in gray) have a widow's peak (W = dominant allele and w = recessive allele).
  
-Mary has the genotype ________.

Accepted Answer

A)  WW 
B)  ww 
C)  Ww 
D)  More information is needed. 
A)  WW 
B)  ww 
C)  Ww 
D)  More information is needed.

Exam 9: Patterns of Inheritance

What is the best explanation for a BbCc × bbcc cross producing offspring in a 5:5:1:1 phenotypic ratio?

A purebred plant that produces yellow seeds is crossed with a purebred plant that produces green seeds.The F₁ plants have yellow seeds.What is the expected phenotypic ratio of seed color of the offspring of an F₁ × F₁ cross?

Attached earlobes are recessive to free earlobes.What genotypic ratio is expected when an individual with attached earlobes mates with an individual heterozygous for free earlobes?

What is the key to the recognition of incomplete dominance?

Alleles are described as ________.

The recombination frequency between gene B and gene C is 11%.The recombination frequency between gene B and gene D is 5%.The recombination frequency between gene C and gene D is 15%.What would be the arrangement of these genes on a linkage map?

This hypothetical pedigree for a disease in humans illustrated inheritance that is

A couple has two female children.What is the probability that their next child will be male?

________ genes violate Mendel's principle of independent assortment.

Assume that having three nostrils is inherited as a sex-linked trait on the Y chromosome.A man with three nostrils has a daughter who has a son with a man who has only two nostrils.What is the probability that the three-nostriled man's grandson has three nostrils?

Experience with dog breeding has taught geneticists ________.

In humans,the inheritance of ________ is best explained as being polygenic.

The best definition of a purebred plant is one that ________.

In humans,the presence or absence of dimples is a trait controlled by a single gene.What is the genotype of an individual who is heterozygous for dimples?

An individual who is homozygous ________.

Which of these crosses will produce only heterozygous offspring?

Introduction: Biology Today

Essential Chemistry for Biology

The Molecules of Life

A Tour of the Cell

The Working Cell

Cellular Respiration: Obtaining Energy from Food

Photosynthesis: Using Light to Make Food

Cellular Reproduction: Cells from Cells

The Structure and Function of DNA

How Genes Are Controlled

DNA Technology

How Populations Evolve

How Biological Diversity Evolves

The Evolution of Microbial Life

The Evolution of Plants and Fungi

The Evolution of Animals

An Introduction to Ecology and the Biosphere

Population Ecology

Communities and Ecosystems

Unifying Concepts of Animal Structure and Function

Nutrition and Digestion

Circulation and Respiration

The Body's Defenses

Hormones

Reproduction and Development

Nervous, Sensory, and Locomotor Systems

The Life of a Flowering Plant

The Working Plant

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