Question 1

A dihybrid cross produces 30 recombinant offspring out of a total of 1,000 offspring.What is the recombination frequency of the two gene pairs?
A)6%
B)3%
C)30%
D)1)5%

Accepted Answer

Recombinant offspring are those that exhibit a new combination of alleles from the parental pairs. The recombination frequency is calculated by taking the number of recombinant offspring divided by the total number of offspring and multiplying by 100. Therefore, the recombination frequency in this case is (30/1000) x 100 = 3%. Choice B is the only option that matches this calculation.

Question 2

What is the basis of Mendel's laws?
A)the behavior of chromosomes during prophase I of meiosis only
B)the behavior of chromosomes during mitotic anaphase
C)the behavior of chromosomes during prophase I and prophase II of meiosis
D)the behavior of chromosomes during metaphase I and anaphase I of meiosis

Accepted Answer

Mendel's laws are based on the behavior of chromosomes during metaphase I and anaphase I of meiosis, specifically the separation and independent assortment of homologous chromosomes. This is known as Mendel's Principle of Segregation and Mendel's Principle of Independent Assortment.

Question 3

What is key to recognition of a trait whose expression is determined by the effects of two or more genes (polygenic inheritance)?
A)A mating between a homozygous and a heterozygous individual produces more than the expected number of offspring expressing the dominant trait.
B)All of the alleles of the gene for that trait are equally expressed.
C)Pleiotropy occurs.
D)The trait varies along a continuum in the population.

Accepted Answer

Polygenic inheritance results in a trait that varies along a continuum in the population. This means that there is no clear distinction between individuals expressing the dominant or recessive trait. Instead, there is a range of expressions of the trait, with some individuals displaying intermediate characteristics. This is known as quantitative inheritance.

Question 4

Which of the following techniques is used to collect fetal cells during pregnancy for genetic testing?
A)testcross
B)dihybrid cross
C)amniocentesis
D)pedigree analysis

Accepted Answer

Amniocentesis is a medical procedure in which a small sample of amniotic fluid surrounding the fetus is extracted using a needle. This fluid contains fetal cells, which can then be analyzed for genetic defects or abnormalities. This technique is commonly used in prenatal genetic testing. The other options (testcross, dihybrid cross, pedigree analysis) are genetic analysis techniques that are not specifically used for collecting fetal cells during pregnancy.

Question 5

An individual heterozygous for cystic fibrosis ________.
A)cannot have children with cystic fibrosis
B)is a carrier
C)will have children who are all carriers of cystic fibrosis
D)has cystic fibrosis

Accepted Answer

Being heterozygous for cystic fibrosis means the individual has one normal copy of the CFTR gene and one mutated copy. This individual is a carrier of cystic fibrosis, but does not have the disease themselves. They have a 50% chance of passing on the mutated gene to their offspring, but as long as their partner does not carry the mutated gene, their children will not have cystic fibrosis.

Question 6

In humans,the inheritance of ________ is best explained as being polygenic.
A)cystic fibrosis
B)height
C)blood type
D)sickle-cell disease

Accepted Answer

Height is a complex trait that is influenced by multiple genes, making it a polygenic trait. Factors such as nutrition, environment, and lifestyle also play a role in determining an individual's height. Cystic fibrosis, sickle-cell disease, and blood type are inherited as single-gene traits.

Question 7

________ genes violate Mendel's principle of independent assortment.
A)Codominant
B)Linked
C)Recessive
D)Pleiotropic

Accepted Answer

Linked genes violate Mendel's principle of independent assortment because they are located near each other on the same chromosome and tend to be inherited together. This means that their inheritance is not independent, as required for independent assortment to occur. Codominant, recessive, and pleiotropic genes do not necessarily violate independent assortment.

Question 8

What is the key to the recognition of incomplete dominance?
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.

Accepted Answer

In incomplete dominance, the heterozygous phenotype is intermediate between the two homozygous phenotypes. This means that the heterozygote expresses a blended phenotype, rather than just one of the homozygous phenotypes. Therefore, the key to recognizing incomplete dominance is that the phenotype of the heterozygote falls between the phenotypes of the homozygotes.

Question 9

What is the best explanation for a BbCc × bbcc cross producing offspring in a 5:5:1:1 phenotypic ratio?
A)linked genes
B)polygenic inheritance
C)incomplete dominance
D)codominance

Accepted Answer

The 5:5:1:1 phenotypic ratio suggests that the genes are linked, meaning they are located close to each other on the same chromosome and tend to be inherited together, rather than assorting independently.

Question 10

Many human traits,such as our performance on intelligence tests or our susceptibility to heart disease,are ________.
A)determined only by our genes
B)influenced by both genes and the environment
C)determined by genes in some people and by the environment in other people
D)not affected by our genes

Accepted Answer

Most human traits are influenced by both genes and the environment. While genes play a significant role in determining traits, the environment can also have an impact on how these traits are expressed. For example, while intelligence has a genetic component, environmental factors such as education and experience can also influence our cognitive abilities. Similarly, while heart disease has a genetic component, lifestyle choices such as diet and exercise can also play a role in its development. Therefore, it is safe to say that genes and the environment both influence most human traits.

Question 11

An individual with (naturally)curly hair and an individual with (naturally)straight hair mate; all of their offspring have (naturally)wavy hair.If an individual with wavy hair mates with an individual with straight hair,what is the probability that their child will have curly hair?
A)0%
B)25%
C)50%
D)75%

Accepted Answer

The answer of An individual with (naturally)curly hair and an...

Question 12

What is the key to the recognition of codominance?
A)The phenotype of the heterozygote is intermediate 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.

Accepted Answer

The key to the recognition of codominance is that the heterozygote expresses the phenotype of both homozygotes. This means that neither allele is dominant or recessive, and both are expressed equally in the phenotype of the heterozygote. This is different from incomplete dominance, where the phenotype of the heterozygote is intermediate between the phenotypes of the homozygotes, and from polygenic inheritance, where multiple genes affect a single trait.

Question 13

Red-green color blindness is inherited as a sex-linked recessive trait.The gene is found on the X chromosome.Can a man with normal color vision father a daughter who is red-green color-blind?
A)Yes,if the woman with whom he mates is red-green color-blind.
B)Yes,if the man is heterozygous for red-green color blindness.
C)No,he can't (unless there is a mutation).
D)No,the expression of the trait skips a generation.

Accepted Answer

A man with normal color vision only carries one X chromosome, which he can only pass onto his daughters. Since the gene for red-green color blindness is found on the X chromosome, the daughter would inherit this gene only from her father. Therefore, if the man has normal color vision, he cannot pass on the gene for red-green color blindness to his daughter unless there is a new mutation.

Question 14

An individual with the blood group genotype Lᴹᴸᴺ has the phenotype MN.What is the relationship between the Lᴹ and Lᴺ alleles?
A)codominance
B)pleiotropy
C)Lᴺ is dominant
D)incomplete dominance

Accepted Answer

In codominance, both alleles are expressed equally in the phenotype. This is seen in individuals with the blood group genotype Lᴹᴸᴺ, who have both the M and N antigens expressed on their red blood cells, resulting in the MN phenotype.

Question 15

Marfan syndrome is the result of inheriting a single allele.Individuals with Marfan syndrome are tall and long-limbed,and have both cardiovascular and eye defects.Of what type of inheritance is the phenotype of Marfan syndrome an example?
A)codominance
B)homozygous recessive
C)pleiotropy
D)incomplete dominance

Accepted Answer

Marfan syndrome is an example of pleiotropy, where a single gene affects multiple phenotypic traits, such as height, limb length, cardiovascular, and eye defects.

Question 16

An individual with (naturally)curly hair and an individual with (naturally)straight hair mate; all of their offspring have (naturally)wavy hair.What is the relationship between the alleles for hair texture?
A)pleiotropy
B)incomplete dominance
C)wavy hair dominant to both straight and curly hair
D)codominance

Accepted Answer

The offspring having wavy hair indicates incomplete dominance between the alleles for curly and straight hair. This means that neither allele is dominant to the other, but instead, a blending of the two traits occurs in the offspring resulting in the intermediate wavy hair texture.

Question 17

Linked genes are usually ________.
A)found on the X chromosome
B)found on the Y chromosome
C)codominant
D)located close together on a chromosome

Accepted Answer

Linked genes are those that are located close together on a chromosome and tend to be inherited together. They can be found on any chromosome, not just the X or Y chromosomes. Codominance refers to a situation where both alleles of a gene are expressed equally in a heterozygote, and is not directly related to linkage.

Question 18

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

Accepted Answer

Since achondroplasia is caused by a dominant allele and the homozygous dominant genotype is lethal, individuals with achondroplasia must be heterozygous. When a heterozygous individual mates with someone who does not have the trait, the Punnett square shows that there is a 50% chance of their offspring inheriting the dominant allele and having achondroplasia. The other 50% would inherit the recessive allele and not have the trait.

Question 19

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

Accepted Answer

Since the trait is Y-linked, only males can inherit it. The daughter cannot pass the Y chromosome to her son, so the grandson cannot inherit the trait from his maternal grandfather.

Question 20

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

Accepted Answer

The answer of The recombination frequency between gene B and...

Quiz 9: Patterns of Inheritance

A dihybrid cross produces 30 recombinant offspring out of a total of 1,000 offspring.What is the recombination frequency of the two gene pairs?

What is the basis of Mendel's laws?

What is key to recognition of a trait whose expression is determined by the effects of two or more genes (polygenic inheritance) ?

Which of the following techniques is used to collect fetal cells during pregnancy for genetic testing?

An individual heterozygous for cystic fibrosis ________.

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

________ genes violate Mendel's principle of independent assortment.

What is the key to the recognition of incomplete dominance?

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

Many human traits,such as our performance on intelligence tests or our susceptibility to heart disease,are ________.

An individual with (naturally) curly hair and an individual with (naturally) straight hair mate; all of their offspring have (naturally) wavy hair.If an individual with wavy hair mates with an individual with straight hair,what is the probability that their child will have curly hair?

What is the key to the recognition of codominance?

Red-green color blindness is inherited as a sex-linked recessive trait.The gene is found on the X chromosome.Can a man with normal color vision father a daughter who is red-green color-blind?

An individual with the blood group genotype Lᴹᴸᴺ has the phenotype MN.What is the relationship between the Lᴹ and Lᴺ alleles?

Marfan syndrome is the result of inheriting a single allele.Individuals with Marfan syndrome are tall and long-limbed,and have both cardiovascular and eye defects.Of what type of inheritance is the phenotype of Marfan syndrome an example?

An individual with (naturally) curly hair and an individual with (naturally) straight hair mate; all of their offspring have (naturally) wavy hair.What is the relationship between the alleles for hair texture?

Linked genes are usually ________.

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?

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?