Question 1

Height is a trait that shows continuous variation in humans.In pea plants,on the other hand,the tall allele is dominant over the short allele and there are no intermediate heights.What is the best explanation for this difference?

Accepted Answer

Height in humans is influenced by multiple genes, each contributing a small amount to the overall height, which results in the continuous variation observed. This is the definition of a polygenic trait.

Question 2

The independent assortment of allele pairs is due to

Accepted Answer

The independent assortment of allele pairs is due to the independent segregation of homologous chromosome pairs during anaphase I, which allows for the random and independent segregation of different allele combinations into daughter cells. Choices A, C, and D refer to other aspects of meiosis that do not contribute to independent assortment, while choice B refers to the combination of gametes during fertilization, which is a separate process from independent assortment during meiosis.

Question 3

An extensive study was conducted on identical twins who were separated at birth.Among other things,the study showed that the individual from each pair who received better nutrition during childhood tended to score higher on standardized intelligence tests.This can best be described as an example of how

Accepted Answer

The study showed that the individual who received better nutrition (an environmental factor) during childhood tended to score higher on standardized intelligence tests. This demonstrates how the environment can alter the phenotype (expression of traits) of an individual.

Question 4

The allelic make up of a cell or individual is referred to as its

Accepted Answer

The allelic make up of a cell or individual is referred to as its genotype, which is represented by the combination of letters or symbols that represent each gene or allele. A blueprint refers to a plan or design, phenotype refers to the observable characteristics of an organism, and pedigree refers to a chart that shows the genetic relationships between individuals in a family.

Question 5

If a single gene has 3 or more alternative forms,this is called

Accepted Answer

When a single gene has three or more alternative forms, it means that there are multiple alleles for that gene. Pleiotropy refers to a gene that affects multiple traits, epistasis refers to the interaction of genes, blending inheritance was a discredited theory of inheritance, and codominance refers to both alleles being expressed in the phenotype. Therefore, the best choice for this scenario is multiple alleles.

Question 6

When Mendel crossed purple-flowered pea plants with white-flowered pea plants,he never got offspring with flowers that had an intermediate color.This was counter to the theory of

Accepted Answer

The theory of blending inheritance suggested that when two traits were crossed, their resulting offspring would be a blend of the two traits. Mendel's results countered this theory because he found that the traits remained distinct and didn't blend together.

Question 7

A person who has lost a large amount of blood but is still alive is found in a wrecked automobile under a highway bridge.Several people are helping the paramedics load the victim into the ambulance.After the ambulance has departed for the hospital,you overhear the following conversation from the persons who helped the paramedics."I am certain that when that guy gets to the hospital,they will transfuse him with any blood that they have in the blood bank since he has lost so much blood." The other person says,"Yeah,I bet you're right!" Having had a biology course,you know which blood could be safely given to anyone.Select it below.

Accepted Answer

Blood type O is the universal donor as it does not contain any surface antigens and will not be recognized as foreign by the recipient's immune system, making it safe to transfuse to anyone.

Question 8

The observable outward manifestation of the genes of an individual is referred to as its

Accepted Answer

Phenotype refers to the physical characteristics, behaviors, and traits that are observable or measurable in an individual, which are determined by the interaction of the individual's genotype (its genetic makeup) and the environment. The blueprint, genetic map, and pedigree refer to different ways of representing or understanding an individual's genetic information, but they do not directly describe the outward manifestation of that information.

Question 9

Based on his monohybrid crosses,Mendel's proposed which of the following? Check all that apply.

Accepted Answer

Mendel's monohybrid crosses led to the understanding that traits are determined by alleles, which separate during gamete formation, each with an equal chance of being passed on. Diploid organisms have two alleles for each trait. Independent assortment (D) is related to dihybrid crosses.

Question 10

Irene knows her blood type is A,but William does not know his blood type.However,William knows that his mother and father both had blood type B.Irene and William's first child is a boy with type O blood.Based on this information,William's blood type could be

Accepted Answer

Since the child has type O blood, both parents must carry the O allele. William's parents had type B blood, so they could have been BO genetically, allowing William to inherit an O allele. Thus, William could be BO (type B) or OO (type O).

Question 11

Let P = purple flowers and p = white,and T = tall plants and t = dwarf.If the uppercase letters represent the dominant alleles,what is the phenotype of a plant with the genotype PpTt?

Accepted Answer

P represents the dominant allele for purple flowers, therefore having one copy of P will result in purple flowers. T represents the dominant allele for tall plants, so having one copy of T will result in a tall plant. Therefore, PpTt will result in a plant with purple flowers and being tall.

Question 12

ABO blood group determination is an example of

Accepted Answer

ABO blood group determination is an example of multiple alleles, as there are three possible alleles (A, B, and O) that determine an individual's blood type.

Question 13

A cross where we follow the inheritance of 2 pairs of alleles is called

Accepted Answer

A cross where we follow the inheritance of 2 pairs of alleles is called a dihybrid cross. A dihybrid cross involves the study of inheritance patterns for two different traits simultaneously. For example, a cross between plants with yellow, round seeds (YYRR) and plants with green, wrinkled seeds (yyrr) would be a dihybrid cross.

Question 14

What type of cross is used to determine if an individual with the dominant form of a trait is homozygous or heterozygous?

Accepted Answer

A test cross is used to determine if an individual with the dominant form of a trait is homozygous or heterozygous. A test cross involves crossing the individual with an individual who is homozygous recessive for the same trait. If any offspring show the recessive trait, it indicates that the dominant individual was heterozygous. If all offspring show the dominant trait, it indicates that the dominant individual was homozygous dominant.

Question 15

Sometimes,when Mendel crossed two pea plants with each other,he obtained a phenotypic ratio of 3:1 purple-flowered pea plants to white-flowered pea plants.These results are consistent with which set of parents?

Accepted Answer

The 3:1 phenotypic ratio is characteristic of a monohybrid cross between two heterozygous individuals, where both parents carry one dominant allele (for purple flowers) and one recessive allele (for white flowers).

Question 16

Let P = purple flowers and p = white,and T = tall plants and t = dwarf.What are the genotypes of the gametes that are produced by a plant that is heterozygous for both traits?

Accepted Answer

When a plant is heterozygous for both traits, it has one dominant and one recessive allele for each trait. Therefore, the possible gametes are: PT, Pt, pT, and pt.

Question 17

Sometimes,one gene pair will interfere with the expression of a second gene pair in an interaction called

Accepted Answer

Epistasis occurs when one gene pair interferes with the expression of a second gene pair. This can result in masking of the phenotype of the second gene pair or modification of its expression. In contrast, incomplete dominance and codominance involve the blending or sharing of traits between two or more alleles. Blending inheritance refers to the mixing of traits from both parents to create a new phenotype, which is not related to epistasis. Pleiotropy occurs when one gene affects multiple traits, which is also not related to epistasis.

Question 18

If an individual allele has more than one effect on the phenotype,this is called

Accepted Answer

Pleiotropy refers to an allele that has multiple effects on different aspects of the phenotype. For example, a gene that controls pigmentation in skin and hair might also affect the function of certain organs or systems in the body. This can have complex and sometimes unexpected consequences for the individual's overall health and development.

Question 19

Mendel's Principle of Independent Assortment states that different pairs of

Accepted Answer

Mendel's Principle of Independent Assortment states that different alleles segregate independently of each other during the formation of gametes. This means that the inheritance of one allele does not affect the inheritance of another allele. This principle applies to genes located on different chromosomes as well as genes located on the same chromosome but far apart from each other. Therefore, choice D, "alleles segregate independently of each other," is the best choice.

Question 20

Let P = purple flowers and p = white,and T = tall plants and t = dwarf.Of the 16 possible gamete combinations in the dihybrid cross between 2 double heterozygotes,how many would produce the phenotype white,tall?

Accepted Answer

In a dihybrid cross between two double heterozygotes (PpTt x PpTt), the gametes produced by each parent can be PT, Pt, pT, and pt. To get a white, tall phenotype, we need the genotype to be ppT_. This means we need a p from one parent and a p from the other parent, and at least one T from either parent. There are 3 combinations that can produce this phenotype: pT x pT, pT x pt, and pt x pT.

Quiz 12: Patterns of Inheritance