Question 1

In crosses involving complete dominance, the F₂ genotypic ratio is 1:2:1 and is expressed as a phenotypic ratio of ____________________.

Accepted Answer

3/4 dominant and 1/4 recessive or 3:1 ratio

Question 2

In Mendel's crosses, pure-breeding individuals were always in the ____________________ generation.

Accepted Answer

P₁

Question 3

Does the segregation or separation of members of a gene pair take place at one or both meiotic divisions? If not, which one? What evidence is there to support your answer?

Accepted Answer

The segregation or separation of members of a gene pair, also known as alleles, occurs during the first meiotic division, which is called meiosis I. Meiosis is a type of cell division that reduces the chromosome number by half, resulting in four daughter cells, each with half the number of chromosomes of the original cell. It consists of two successive divisions: meiosis I and meiosis II.

During meiosis I, homologous chromosomes pair up and exchange genetic material through a process called crossing over. This is followed by the alignment of these pairs at the metaphase plate and their subsequent separation during anaphase I. It is at this stage that the alleles for each gene are segregated into different cells. Each daughter cell receives one chromosome from each homologous pair, thus separating the alleles that were originally together in the diploid parent cell.

Meiosis II resembles a normal mitotic division, where the sister chromatids of each chromosome are separated and distributed to different daughter cells. However, since the alleles were already segregated during meiosis I, meiosis II does not involve the separation of gene pairs.

The evidence for this segregation comes from the observation of genetic inheritance patterns, as first described by Gregor Mendel in the 19th century. Mendel's law of segregation states that the two alleles for each trait separate during gamete formation, and each gamete receives only one allele. This law is a direct consequence of the segregation of homologous chromosomes during meiosis I.

Further evidence for the timing of allele segregation comes from cytogenetic observations under the microscope, where the behavior of chromosomes during meiosis can be directly visualized, and from modern genetic analysis techniques, such as gene mapping and sequencing, which confirm that the alleles are separated into different gametes during meiosis I.

Question 4

In all Mendel's crosses, it did not matter which phenotype was used as the male or as the female parent.

Accepted Answer

A) True 
 B)False

Question 5

Pedigrees _____.

Accepted Answer

A)  provide information on the patterns of inheritance of a trait 
B)  can identify those at risk for a disease 
C)  can identify those at risk for transmitting a disease 
D)  can be used to deduce the genotypes of parents 
E)  have all of these characteristics 
A)  provide information on the patterns of inheritance of a trait 
B)  can identify those at risk for a disease 
C)  can identify those at risk for transmitting a disease 
D)  can be used to deduce the genotypes of parents 
E)  have all of these characteristics

Question 6

In his monohybrid crosses, Mendel deduced that one trait was recessive because _____.

Accepted Answer

A)  that trait was not present in the F1 and did not reappear in the F2 
B)  that trait was present in the F1 and in the F2 
C)  that trait was not present in the F1 and reappeared in the F2 
D)  that trait was present only in the parents 
E)  that trait was present only in the F2 
A)  that trait was not present in the F1 and did not reappear in the F2 
B)  that trait was present in the F1 and in the F2 
C)  that trait was not present in the F1 and reappeared in the F2 
D)  that trait was present only in the parents 
E)  that trait was present only in the F2

Question 7

In a cross between a true-breeding plant bearing smooth, yellow seeds and a true-breeding plant with wrinkled, green seeds, the offspring were all smooth and yellow. What is the genotype of the F₁ plants?

Accepted Answer

A)  SSYY 
B)  ssyy 
C)  SsYy 
D)  ssYY 
E)  SSyy 
A)  SSYY 
B)  ssyy 
C)  SsYy 
D)  ssYY 
E)  SSyy

Question 8

If a dihybrid cross is begun with a P₁ generation of a plant that produces smooth and yellow peas, crossed with a plant that produces wrinkled green peas, the F₂ plants will have either smooth yellow peas or wrinkled green peas.

Accepted Answer

A) True 
 B)False

Question 9

Two heterozygous smooth-pea pea plants are crossed (Ss X Ss) and four peas from the cross are randomly selected for examination. The first three are smooth. Must the fourth one be wrinkled? Why or why not?

Accepted Answer

No, the fourth pea does not necessarily

Question 10

A cross between two individuals who differ with respect to two gene pairs is a ____________________ cross.

Accepted Answer

The answer of A cross between two individuals who differ...

Question 11

In a pedigree, a double line connecting a married couple indicates that the man and woman are ____________________.

Accepted Answer

The answer of In a pedigree, a double line connecting...

Question 12

In heterozygous crosses, the phenotypic and genotypic ratios differ for completely dominant traits but are the same for traits showing incomplete dominance.

Accepted Answer

A) True 
 B)False

Question 13

In the ABO multiple allele system, there are the following combinations of genotypes and phenotypes:

Accepted Answer

A)  4 genotypes, 4 phenotypes 
B)  4 genotypes, 6 phenotypes 
C)  6 genotypes, 6 phenotypes 
D)  6 genotypes, 4 phenotypes 
E)  3 genotypes, 4 phenotypes 
A)  4 genotypes, 4 phenotypes 
B)  4 genotypes, 6 phenotypes 
C)  6 genotypes, 6 phenotypes 
D)  6 genotypes, 4 phenotypes 
E)  3 genotypes, 4 phenotypes

Question 14

Heterozygotes and dominant homozygotes always have the same phenotype.

Accepted Answer

A) True 
 B)False

Question 15

The phenotype is _____.

Accepted Answer

A)  controlled by the genotype 
B)  the expression of a trait in an organism 
C)  the result of inheritance from both parents 
D)  never homozygous 
E)  all of these 
A)  controlled by the genotype 
B)  the expression of a trait in an organism 
C)  the result of inheritance from both parents 
D)  never homozygous 
E)  all of these

Question 16

In a cross involving incomplete dominance _____.

Accepted Answer

A)  the dominant phenotype is expressed in the F1 
B)  the recessive phenotype is expressed in the F1 
C)  Mendelian inheritance does not apply 
D)  the phenotypic ratio and genotypic ratio in the F2 are identical 
E)  heterozygotes have a phenotype like one of the parents 
A)  the dominant phenotype is expressed in the F1 
B)  the recessive phenotype is expressed in the F1 
C)  Mendelian inheritance does not apply 
D)  the phenotypic ratio and genotypic ratio in the F2 are identical 
E)  heterozygotes have a phenotype like one of the parents

Question 17

In a trait with multiple alleles, an individual carries ____________________ (how many?) alleles of the gene.

Accepted Answer

The answer of In a trait with multiple alleles, an...

Question 18

Mendel's principle of segregation is directly related to an event that occurs in ______ of meiosis.

Accepted Answer

A)  prophase I 
B)  metaphase I 
C)  anaphase I 
D)  prophase II 
E)  metaphase II 
A)  prophase I 
B)  metaphase I 
C)  anaphase I 
D)  prophase II 
E)  metaphase II

Question 19

A locus is best defined as _____.

Accepted Answer

A)  an alternate form of a gene 
B)  the chromosome location of the centromere 
C)  the location of a gene on a chromosome 
D)  a mutation of a gene to an alternate state 
E)  the site of crossing over 
A)  an alternate form of a gene 
B)  the chromosome location of the centromere 
C)  the location of a gene on a chromosome 
D)  a mutation of a gene to an alternate state 
E)  the site of crossing over

Question 20

In a monohybrid cross with complete dominance, the F₂ offspring should contain _____.

Accepted Answer

A)  two different phenotypes and two different genotypes 
B)  two different phenotypes and three different genotypes 
C)  three different phenotypes and two different genotypes 
D)  three different phenotypes and three different genotypes 
E)  none of these 
A)  two different phenotypes and two different genotypes 
B)  two different phenotypes and three different genotypes 
C)  three different phenotypes and two different genotypes 
D)  three different phenotypes and three different genotypes 
E)  none of these

In crosses involving complete dominance, the F₂ genotypic ratio is 1:2:1 and is expressed as a phenotypic ratio of ____________________.

In Mendel's crosses, pure-breeding individuals were always in the ____________________ generation.

Does the segregation or separation of members of a gene pair take place at one or both meiotic divisions? If not, which one? What evidence is there to support your answer?

In all Mendel's crosses, it did not matter which phenotype was used as the male or as the female parent.

Pedigrees _____.

In his monohybrid crosses, Mendel deduced that one trait was recessive because _____.

In a cross between a true-breeding plant bearing smooth, yellow seeds and a true-breeding plant with wrinkled, green seeds, the offspring were all smooth and yellow. What is the genotype of the F₁ plants?

If a dihybrid cross is begun with a P₁ generation of a plant that produces smooth and yellow peas, crossed with a plant that produces wrinkled green peas, the F₂ plants will have either smooth yellow peas or wrinkled green peas.

Two heterozygous smooth-pea pea plants are crossed (Ss X Ss) and four peas from the cross are randomly selected for examination. The first three are smooth. Must the fourth one be wrinkled? Why or why not?

A cross between two individuals who differ with respect to two gene pairs is a ____________________ cross.

In a pedigree, a double line connecting a married couple indicates that the man and woman are ____________________.

In heterozygous crosses, the phenotypic and genotypic ratios differ for completely dominant traits but are the same for traits showing incomplete dominance.

In the ABO multiple allele system, there are the following combinations of genotypes and phenotypes:

Heterozygotes and dominant homozygotes always have the same phenotype.

The phenotype is _____.

In a cross involving incomplete dominance _____.

In a trait with multiple alleles, an individual carries ____________________ (how many?) alleles of the gene.

Mendel's principle of segregation is directly related to an event that occurs in ______ of meiosis.

A locus is best defined as _____.

In a monohybrid cross with complete dominance, the F₂ offspring should contain _____.

A Perspective on Human Genetics

Cells and Cell Division

Pedigree Analysis in Human Genetics

Complex Patterns of Inheritance

Cytogenetics: Karyotypes and Chromosome Aberrations

Development and Sex Determination

DNA Structure and Chromosomal Organization

Gene Expression: From Genes to Proteins

From Proteins to Phenotypes

Mutation: the Source of Genetic Variation

Genes and Cancer

An Introduction to Genetic Technology

Biotechnology and Society

Genomes and Genomics

Reproductive Technology, Genetic Testing, and Gene Therapy

Genes and the Immune System

Genetics of Behavior

Population Genetics and Human Evolution

Filters

Exam 3: Transmission of Genes From Generation to Generation

In crosses involving complete dominance, the F₂ genotypic ratio is 1:2:1 and is expressed as a phenotypic ratio of ____________________.

In Mendel's crosses, pure-breeding individuals were always in the ____________________ generation.

Does the segregation or separation of members of a gene pair take place at one or both meiotic divisions? If not, which one? What evidence is there to support your answer?

In all Mendel's crosses, it did not matter which phenotype was used as the male or as the female parent.

Pedigrees _____.

In his monohybrid crosses, Mendel deduced that one trait was recessive because _____.

In a cross between a true-breeding plant bearing smooth, yellow seeds and a true-breeding plant with wrinkled, green seeds, the offspring were all smooth and yellow. What is the genotype of the F₁ plants?

If a dihybrid cross is begun with a P₁ generation of a plant that produces smooth and yellow peas, crossed with a plant that produces wrinkled green peas, the F₂ plants will have either smooth yellow peas or wrinkled green peas.

Two heterozygous smooth-pea pea plants are crossed (Ss X Ss) and four peas from the cross are randomly selected for examination. The first three are smooth. Must the fourth one be wrinkled? Why or why not?

A cross between two individuals who differ with respect to two gene pairs is a ____________________ cross.

In a pedigree, a double line connecting a married couple indicates that the man and woman are ____________________.

In heterozygous crosses, the phenotypic and genotypic ratios differ for completely dominant traits but are the same for traits showing incomplete dominance.

In the ABO multiple allele system, there are the following combinations of genotypes and phenotypes:

Heterozygotes and dominant homozygotes always have the same phenotype.

The phenotype is _____.

In a cross involving incomplete dominance _____.

In a trait with multiple alleles, an individual carries ____________________ (how many?) alleles of the gene.

Mendel's principle of segregation is directly related to an event that occurs in ______ of meiosis.

A locus is best defined as _____.

In a monohybrid cross with complete dominance, the F₂ offspring should contain _____.

A Perspective on Human Genetics

Cells and Cell Division

Pedigree Analysis in Human Genetics

Complex Patterns of Inheritance

Cytogenetics: Karyotypes and Chromosome Aberrations

Development and Sex Determination

DNA Structure and Chromosomal Organization

Gene Expression: From Genes to Proteins

From Proteins to Phenotypes

Mutation: the Source of Genetic Variation

Genes and Cancer

An Introduction to Genetic Technology

Biotechnology and Society

Genomes and Genomics

Reproductive Technology, Genetic Testing, and Gene Therapy

Genes and the Immune System

Genetics of Behavior

Population Genetics and Human Evolution

Filters