Question 1

Some plants fail to produce chlorophyll,due to a recessive trait.If we locate a pea plant that is heterozygous for this trait,self-pollinate it,and harvest the seeds,what are the likely phenotypes of the resulting offspring?

Accepted Answer

This scenario is similar to a monohybrid cross, where the heterozygous parent (Gg) has a 50% chance of producing gametes with the dominant allele (G) and a 50% chance of producing gametes with the recessive allele (g). When these gametes combine during fertilization, the resulting offspring can be GG (green and chlorophyll producing), Gg (green and chlorophyll producing but carrying the recessive allele), or gg (white and lacking chlorophyll). Therefore, in this scenario, one-fourth of the offspring are likely to be gg and lack chlorophyll, while three-fourths are likely to be either GG or Gg and have chlorophyll.

Question 2

Which of the following is NOT correct concerning the law of independent assortment?

Accepted Answer

The law of independent assortment is not based on the observation that all maternal chromosomes end up in the egg. This statement is actually related to the process of meiosis and the law of segregation. The correct statement concerning the law of independent assortment is that it was the second law of heredity established by Mendel, stating that each pair of factors separates independently and all possible combinations of factors can occur in the gametes.

Question 3

If an albino (recessive)woman is married to a man with normal coloring and they have an albino child,what was the genotype of the man?

Accepted Answer

For the couple to have an albino child, the woman must be homozygous recessive (aa). The fact that they have an albino child means that the man contributed an "a" allele. This would make his genotype either heterozygous (Aa) or homozygous recessive (aa). As albino is a recessive trait, the man could not be homozygous dominant (AA).

Question 4

Since each child of two heterozygous parents has a 1/4 chance of receiving a recessive trait from each parent,

Accepted Answer

Each child of heterozygous parents independently has a 1/4 chance of being phenotypically recessive, regardless of the phenotype of any siblings.

Question 5

Which of the following would be considered a heterozygous dihybrid genotype?

Accepted Answer

A heterozygous dihybrid genotype would involve two different genes, each with two alleles. WwSs represents a genotype where the individual has one dominant and one recessive allele for both the Ww and Ss genes. A, B, and D all represent genotypes with only one gene being considered, and C represents a homozygous genotype for both genes.

Question 6

In 1940,two researchers named Weiner and Landsteiner discovered that about 85 percent of the human population sampled possessed a blood cell protein called the Rh factor.The presence of Rh factor was labeled Rh positive (Rh⁺)and was found to be dominant over the absence of the blood factor (Rh^-).Under normal Mendelian inheritance,which of the following statements is/are FALSE?

Accepted Answer

Two Rh⁻ parents cannot have an Rh⁺ child because they do not possess the Rh⁺ allele to pass on.

Question 7

If an individual with a dominant phenotype is crossed with an individual with a recessive phenotype,4 of their 9 offspring show the recessive phenotype.What is the genotype of the dominant parent?

Accepted Answer

If the dominant parent had a homozygous dominant genotype (AA), then all offspring would have the dominant phenotype. If the dominant parent had a heterozygous genotype (Aa), then there is a 1 in 4 chance for each offspring to inherit the recessive allele from both parents (resulting in a recessive phenotype). Therefore, the best choice for the genotype of the dominant parent is either Aa or AA. However, since 4 of the 9 offspring showed the recessive phenotype, it is more likely that the dominant parent was heterozygous (Aa) rather than homozygous dominant (AA).

Question 8

Computer simulations are sometimes used to demonstrate the outcome of monohybrid fruit fly crosses,where a student can run generation after generation of fruit flies with 100 offspring produced each generation,half male and half female,and a 3-to-1 phenotype ratio (or 75 to 25)in the F₁ generation.Compared to real genetics results,which of the following is NOT true?

Accepted Answer

It is highly unlikely to have exactly 100 offspring, an even split between males and females, and a precise 3-to-1 phenotypic ratio in real life. In real life, there may be variations in the number of offspring and sex ratios, which may result in slight deviations from the expected phenotypic ratios.

Question 9

If pairs of factors separate independently of other pairs of factors,you are dealing with

Accepted Answer

The law of independent assortment states that pairs of genes separate independently of other pairs of genes during gamete formation. This means that the inheritance of one gene does not affect the inheritance of another gene, as long as they are on different chromosomes, and they segregate randomly into gametes.

Question 10

In cattle,consider that the lack of horns is dominant to the presence of horns.A bull without horns is crossed with a horned cow.Of four offspring,one is horned and the other three lack horns.The bull is

Accepted Answer

The fact that one of the offspring is horned indicates that the bull cannot be homozygous dominant (AA), as in that case all offspring would lack horns. The fact that three of the offspring lack horns indicates that the bull cannot be homozygous recessive (aa), as in that case all offspring would also lack horns. Therefore, the bull must be heterozygous (Aa) and the horned offspring must have inherited the recessive allele from the bull's heterozygous genotype.

Question 11

A cross that involves two traits is called a ______ cross.

Accepted Answer

A dihybrid cross involves the analysis of inheritance patterns for two different traits.

Question 12

When crossing individuals with differing genotypes,in which kind of cross would you expect to have your actual results match the predicted results 100% of the time the cross is made?

Accepted Answer

Genetic crosses involve random assortment of alleles, and environmental factors can also influence phenotypic outcomes, so actual results may not always match predicted ratios exactly.

Question 13

A pheasant breeder starts with two birds in the P generation,one of which is AA and the other is aa.If he takes two of the birds from the F₁ generation and breeds them together,what can he expect in his F₂ offspring?

Accepted Answer

The F1 generation from AA and aa parents will all be Aa. Breeding two Aa individuals will result in an F2 generation with a genotypic ratio of 1:2:1, which includes AA, Aa, and aa.

Question 14

If the genotype of an organism is YySsTt,then yST would represent

Accepted Answer

yST represents a possible gamete of the parent organism with the given genotype YySsTt. Therefore, the correct answer is C, a gamete of the parent.

Question 15

Which of the following crosses will yield only homozygous recessive offspring?

Accepted Answer

In order to yield only homozygous recessive offspring, both parents must be heterozygous for the same trait. Therefore, in cross D, both parents are homozygous recessive (rryy), ensuring that all offspring will also be homozygous recessive for that trait.

Question 16

If the probability of event A is 3/4 and the probability of event B is 1/4,then the probability of both A and B occurring at the same time is

Accepted Answer

Since the events A and B are independent, the probability of both events occurring at the same time is equal to the product of their individual probabilities. Therefore, P(A and B) = P(A) x P(B) = (3/4) x (1/4) = 3/16.

Question 17

In humans,assume red hair is recessive to dark hair.What are the chances of a dark-haired couple having a red-haired child if each had a red-haired parent?

Accepted Answer

Each parent must be a carrier of the red hair allele (Rr) since they have a red-haired parent. The probability of both passing the recessive allele (r) to their child is 25%.

Question 18

Unattached earlobes (EE or Ee)are dominant over attached earlobes (ee).A couple both have unattached earlobes.Both notice that one of their parents on both sides have attached earlobes (ee).Therefore,they correctly assume that they are carriers for attached earlobes (Ee).If the couple proceeds to have four children,then

Accepted Answer

Since both parents are carriers for attached earlobes, they are each Ee. When they have children, each child has a 50% chance of inheriting an E allele and a 50% chance of inheriting an e allele. Therefore, the genotypes of their children can be any combination of EE, Ee, or ee. However, based on the laws of probability, the most likely outcome is two heterozygous (Ee), one homozygous dominant (EE), and one homozygous recessive (ee) child.

Question 19

A woman who can roll her tongue (presumably dominant)is married to a man who cannot.Two of their four children can roll their tongues and two cannot.If A = roll tongue and a = cannot roll tongue,then what is the genotype of the parents?

Accepted Answer

The woman must be heterozygous (Aa) to have children who cannot roll their tongues (aa), and the man must be homozygous recessive (aa) since he cannot roll his tongue.

Question 20

Both parents are heterozygous for Tay-Sachs disease (an autosomal recessive disorder).Three children in a row were born with Tay-Sachs disease.What is the chance that a fourth child will have Tay-Sachs disease?

Accepted Answer

The chance of a child inheriting Tay-Sachs disease when both parents are heterozygous is 25%, regardless of the outcomes of previous pregnancies.

Quiz 23: Patterns of Gene Inheritance

Some plants fail to produce chlorophyll,due to a recessive trait.If we locate a pea plant that is heterozygous for this trait,self-pollinate it,and harvest the seeds,what are the likely phenotypes of the resulting offspring?

Which of the following is NOT correct concerning the law of independent assortment?

If an albino (recessive) woman is married to a man with normal coloring and they have an albino child,what was the genotype of the man?

Since each child of two heterozygous parents has a 1/4 chance of receiving a recessive trait from each parent,

Which of the following would be considered a heterozygous dihybrid genotype?

If an individual with a dominant phenotype is crossed with an individual with a recessive phenotype,4 of their 9 offspring show the recessive phenotype.What is the genotype of the dominant parent?

If pairs of factors separate independently of other pairs of factors,you are dealing with

In cattle,consider that the lack of horns is dominant to the presence of horns.A bull without horns is crossed with a horned cow.Of four offspring,one is horned and the other three lack horns.The bull is

A cross that involves two traits is called a ______ cross.

When crossing individuals with differing genotypes,in which kind of cross would you expect to have your actual results match the predicted results 100% of the time the cross is made?

A pheasant breeder starts with two birds in the P generation,one of which is AA and the other is aa.If he takes two of the birds from the F₁ generation and breeds them together,what can he expect in his F₂ offspring?

If the genotype of an organism is YySsTt,then yST would represent

Which of the following crosses will yield only homozygous recessive offspring?

If the probability of event A is 3/4 and the probability of event B is 1/4,then the probability of both A and B occurring at the same time is

In humans,assume red hair is recessive to dark hair.What are the chances of a dark-haired couple having a red-haired child if each had a red-haired parent?

A woman who can roll her tongue (presumably dominant) is married to a man who cannot.Two of their four children can roll their tongues and two cannot.If A = roll tongue and a = cannot roll tongue,then what is the genotype of the parents?

Both parents are heterozygous for Tay-Sachs disease (an autosomal recessive disorder) .Three children in a row were born with Tay-Sachs disease.What is the chance that a fourth child will have Tay-Sachs disease?

Quiz 23: Patterns of Gene Inheritance

Some plants fail to produce chlorophyll,due to a recessive trait.If we locate a pea plant that is heterozygous for this trait,self-pollinate it,and harvest the seeds,what are the likely phenotypes of the resulting offspring?

Which of the following is NOT correct concerning the law of independent assortment?

If an albino (recessive) woman is married to a man with normal coloring and they have an albino child,what was the genotype of the man?

Since each child of two heterozygous parents has a 1/4 chance of receiving a recessive trait from each parent,

Which of the following would be considered a heterozygous dihybrid genotype?

If an individual with a dominant phenotype is crossed with an individual with a recessive phenotype,4 of their 9 offspring show the recessive phenotype.What is the genotype of the dominant parent?

If pairs of factors separate independently of other pairs of factors,you are dealing with

In cattle,consider that the lack of horns is dominant to the presence of horns.A bull without horns is crossed with a horned cow.Of four offspring,one is horned and the other three lack horns.The bull is

A cross that involves two traits is called a ______ cross.

When crossing individuals with differing genotypes,in which kind of cross would you expect to have your actual results match the predicted results 100% of the time the cross is made?

A pheasant breeder starts with two birds in the P generation,one of which is AA and the other is aa.If he takes two of the birds from the F1 generation and breeds them together,what can he expect in his F2 offspring?

If the genotype of an organism is YySsTt,then yST would represent

Which of the following crosses will yield only homozygous recessive offspring?

If the probability of event A is 3/4 and the probability of event B is 1/4,then the probability of both A and B occurring at the same time is

In humans,assume red hair is recessive to dark hair.What are the chances of a dark-haired couple having a red-haired child if each had a red-haired parent?

A woman who can roll her tongue (presumably dominant) is married to a man who cannot.Two of their four children can roll their tongues and two cannot.If A = roll tongue and a = cannot roll tongue,then what is the genotype of the parents?

Both parents are heterozygous for Tay-Sachs disease (an autosomal recessive disorder) .Three children in a row were born with Tay-Sachs disease.What is the chance that a fourth child will have Tay-Sachs disease?

A pheasant breeder starts with two birds in the P generation,one of which is AA and the other is aa.If he takes two of the birds from the F₁ generation and breeds them together,what can he expect in his F₂ offspring?