Question 1

Assuming that the trait represented by the filled symbols below is a rare inherited trait with complete penetrance due to a single gene with alleles A and a, what mode of inheritance does the pedigree suggest? 
A)dominant
B)recessive

Accepted Answer

The answer of Assuming that the trait represented by the...

Question 2

Imagine that you have crossed two types of peonies, one with purple flowers and long stems, and the other with white flowers and short stems. When you cross these flowers, you get the following numbers of progeny: 83 with purple flowers and short stems; 29 with purple flowers and long stems; 26 with white flowers and short stems; and 9 with white flowers and long stems. Based on these data, what can you say about genes that define flower color and stem length?
A)These genes are linked.
B)These genes sort independently.
C)You can make no statements about genes that define flower color and stem length.

Accepted Answer

The genes for flower color and stem length sort independently because the phenotypic ratio of the progeny is not consistent with the expected ratio for linked genes.

Question 3

Assuming that the trait represented by the filled symbols below is a rare inherited trait with complete penetrance due to a single gene with alleles A and a, what mode of inheritance does the pedigree suggest? 
A)dominant
B)recessive

Accepted Answer

The answer of Assuming that the trait represented by the...

Question 4

Recall that alleles of a single gene will segregate from each other during anaphase I. When do alleles for two different genes-located on two different chromosomes-segregate?
A)anaphase I
B)anaphase II
C)metaphase I
D)metaphase II
E)telophase I

Accepted Answer

Alleles for two different genes located on two different chromosomes segregate during anaphase I, following the law of independent assortment, as they are sorted into separate gametes independently of each other.

Question 5

Consider a gene with four alleles A₁, A₂, A₃, and A₄. In the cross A₁A₂ × A₃A₄, how many offspring genotypes are possible? A)2 B)3 C)4 D)5 E)6

Accepted Answer

To determine the number of possible genotypes in the offspring, we need to use the FOIL method. F = A₁, O = A₂, I = A₃, and L = A₄. Possible offspring genotypes are: FO, FOI, FOIL, OI, OIL, and IL. This gives us a total of 6 possible genotypes, so the correct answer is (C) 4.

Question 6

Consider a gene with four alleles A₁, A₂, A₃, and A₄. How many distinct homozygous genotypes are possible? A)2 B)3 C)4 D)5 E)6

Accepted Answer

Each allele can pair with itself to form a distinct homozygous genotype, resulting in 4 possible homozygous genotypes.

Question 7

Consider a gene with four alleles A₁, A₂, A₃, and A₄. If the cross A₁A₂ × A₃A₄ yields two offspring, what is the probability that both of them have the same genotype? A)1/8 B)1/4 C)1/3 D)1/2 E)3/4

Accepted Answer

The possible genotypes of the offspring are A₁A₃, A₁A₄, A₂A₃, and A₂A₄. The probability that two offspring have the same genotype is the probability of choosing one of these four possibilities twice, which is 1/4 or 25%. Therefore, the answer is B.

Question 8

Two individuals with the same genotype may not express the same phenotype because gene expression is influenced by:
A)other genes alone.
B)the environment alone.
C)a combination of genes and environment.
D)genes alone in some people and the environment alone in other people.
E)None of the answer options is correct

Accepted Answer

Phenotype is not only determined by the genotype but also by environmental factors. The expression of genes can be influenced by various factors, including temperature, nutrition, stress, and exposure to toxins, among other things. Therefore, two individuals with identical genotypes can still exhibit different phenotypes depending on their environmental experiences.

Question 9

Although Gregor Mendel's work was not originally considered by his contemporaries to be groundbreaking, Mendel's principles of segregation and independent assortment were "rediscovered" nearly two decades after his death.

Accepted Answer

This statement is true. Mendel's work was largely overlooked and not appreciated during his lifetime, but was later recognized for its key principles in genetics.

Question 10

Consider a gene with n alleles A₁, A₂, ..., A_n. How many distinct heterozygous genotypes are possible? A)n² B)n²/2 C)n(n -1) D)n(n - 1)/2 E)n(n + 1)/2

Accepted Answer

For each allele, there are (n-1) other alleles that can pair with it to form a heterozygous genotype. However, in counting these pairs, each pair has been counted twice since the order of the alleles does not matter. Therefore, the total number of distinct heterozygous genotypes is (n-1)/2, which is option D.

Question 11

Consider a gene with four alleles A₁, A₂, A₃, and A₄. In the cross A₁A₂ × A₃A₃, how many offspring genotypes are possible? A)2 B)3 C)4 D)5 E)6

Accepted Answer

The answer of Consider a gene with four alleles A₁,...

Question 12

Consider a gene with six alleles A₁, A₂, A₃, A₄, A₅, and A₆. How many distinct genotypes are possible, taking into account both homozygous and heterozygous genotypes? A)11 B)13 C)17 D)21 E)29

Accepted Answer

There are six possible alleles, which can be combined in pairs to form 15 possible heterozygous genotypes (6 choose 2). In addition, there are 6 possible homozygous genotypes. Therefore, the total number of distinct genotypes is 15 + 6 = 21.

Question 13

The ratio of white to colored chickens that occurs in the F₂ generation of a cross between White Leghorn and White Wyandotte chickens is the result of incomplete dominance and variable expressivity. These are the only explanations as to why a ratio would deviate from Mendel's expected 9:3:3:1 ratio.

Accepted Answer

Incomplete dominance and variable expressivity are not the only two explanations for a ratio to deviate from Mendel's expected ratio. Other factors such as linkage or epistasis can also affect the results of a genetic cross.

Question 14

Consider a gene with four alleles A₁, A₂, A₃, and A₄. If the cross A₁A₂ × A₃A₃ yields two offspring, what is the probability that both of them have the same genotype? A)1/8 B)1/4 C)1/3 D)1/2 E)3/4

Accepted Answer

The cross between A₁A₂ and A₃A₃ can produce offspring with genotypes A₁A₃ or A₂A₃. Each genotype has a 1/2 chance of occurring, so the probability that both offspring have the same genotype is 1/2.

Question 15

Consider a gene with four alleles A₁, A₂, A₃, and A₄. How many distinct genotypes are possible, taking into account both homozygous and heterozygous genotypes? A)6 B)7 C)8 D)9 E)10

Accepted Answer

For a gene with four different alleles, the number of possible genotypes can be calculated using the formula for combinations with repetition: n + r - 1 choose r, where n is the number of alleles and r is the number of genes in a genotype (which is 2 for diploid organisms). Here, n = 4 and r = 2, so the calculation is 4 + 2 - 1 choose 2 = 5 choose 2 = 10. This includes both homozygous (each allele paired with itself) and heterozygous combinations.

Question 16

Which of the following is TRUE regarding linked genes?
A)Linked genes are always located on different chromosomes.
B)Linked genes are located on the same chromosome.
C)Linked genes demonstrate independent assortment.
D)Linked genes do not follow patterns of independent assortment.
E)Linked genes are located in the same chromosome and do not follow patterns of independent assortment.

Accepted Answer

Linked genes are located on the same chromosome and tend to be inherited together because they do not follow the Mendelian principle of independent assortment, which applies to genes located on different chromosomes.

Question 17

Consider a gene with n alleles A₁, A₂, ..., A_n. How many distinct genotypes are possible, taking into account both homozygous and heterozygous genotypes? A)n² B)n²/2 C)n(n -1) D)n(n - 1)/2 E)n(n + 1)/2

Accepted Answer

The number of distinct genotypes for a gene with n alleles, considering both homozygous and heterozygous combinations, can be calculated using the formula n(n + 1)/2. This accounts for n homozygous genotypes (one for each allele) and n(n - 1)/2 heterozygous genotypes (since each pair of different alleles can form a unique heterozygous genotype, and each pair is counted only once).

Question 18

Consider a gene with six alleles A₁, A₂, A₃, A₄, A₅, and A₆. How many distinct heterozygous genotypes are possible? A)3 B)6 C)9 D)12 E)15

Accepted Answer

For a gene with six alleles, the number of distinct heterozygous genotypes can be calculated using the combination formula nC2, where n is the number of alleles. Here, n=6, so the calculation is 6C2 = (6*5)/(2*1) = 15.

Question 19

Consider a gene with six alleles A₁, A₂, A₃, A₄, A₅, and A₆. How many distinct homozygous genotypes are possible? A)2 B)3 C)4 D)5 E)6

Accepted Answer

Since there are six distinct alleles, and a homozygous genotype consists of two identical alleles, there are exactly six possible homozygous genotypes, one for each allele.

Question 20

You are examining a human pedigree for a trait. You notice that an offspring can be affected even if neither parent is affected. This immediately tells you that the trait is:
A)dominant.
B)recessive.
C)epistatic.
D)produced by multiple alleles.
E)incomplete penetrance.

Accepted Answer

If an offspring can be affected even if neither parent is affected, this suggests that the trait is recessive. This means that both parents are carriers of the trait, but do not express it themselves. When two carriers mate, there is a 25% chance that their offspring will inherit two copies of the recessive allele and therefore express the trait.

Quiz 16: Mendelian Inheritance

Assuming that the trait represented by the filled symbols below is a rare inherited trait with complete penetrance due to a single gene with alleles A and a, what mode of inheritance does the pedigree suggest?

Assuming that the trait represented by the filled symbols below is a rare inherited trait with complete penetrance due to a single gene with alleles A and a, what mode of inheritance does the pedigree suggest?

Recall that alleles of a single gene will segregate from each other during anaphase I. When do alleles for two different genes-located on two different chromosomes-segregate?

Consider a gene with four alleles A1, A2, A3, and A4. In the cross A1A2 × A3A4, how many offspring genotypes are possible?

Consider a gene with four alleles A1, A2, A3, and A4. How many distinct homozygous genotypes are possible?

Consider a gene with four alleles A1, A2, A3, and A4. If the cross A1A2 × A3A4 yields two offspring, what is the probability that both of them have the same genotype?

Two individuals with the same genotype may not express the same phenotype because gene expression is influenced by:

Although Gregor Mendel's work was not originally considered by his contemporaries to be groundbreaking, Mendel's principles of segregation and independent assortment were "rediscovered" nearly two decades after his death.

Consider a gene with n alleles A1, A2, ..., An. How many distinct heterozygous genotypes are possible?

Consider a gene with four alleles A1, A2, A3, and A4. In the cross A1A2 × A3A3, how many offspring genotypes are possible?

Consider a gene with six alleles A1, A2, A3, A4, A5, and A6. How many distinct genotypes are possible, taking into account both homozygous and heterozygous genotypes?

Consider a gene with four alleles A1, A2, A3, and A4. If the cross A1A2 × A3A3 yields two offspring, what is the probability that both of them have the same genotype?

Consider a gene with four alleles A1, A2, A3, and A4. How many distinct genotypes are possible, taking into account both homozygous and heterozygous genotypes?

Which of the following is TRUE regarding linked genes?

Consider a gene with n alleles A1, A2, ..., An. How many distinct genotypes are possible, taking into account both homozygous and heterozygous genotypes?

Consider a gene with six alleles A1, A2, A3, A4, A5, and A6. How many distinct heterozygous genotypes are possible?

Consider a gene with six alleles A1, A2, A3, A4, A5, and A6. How many distinct homozygous genotypes are possible?

You are examining a human pedigree for a trait. You notice that an offspring can be affected even if neither parent is affected. This immediately tells you that the trait is:

Consider a gene with four alleles A₁, A₂, A₃, and A₄. In the cross A₁A₂ × A₃A₄, how many offspring genotypes are possible?

Consider a gene with four alleles A₁, A₂, A₃, and A₄. How many distinct homozygous genotypes are possible?

Consider a gene with four alleles A₁, A₂, A₃, and A₄. If the cross A₁A₂ × A₃A₄ yields two offspring, what is the probability that both of them have the same genotype?

Consider a gene with n alleles A₁, A₂, ..., A_n. How many distinct heterozygous genotypes are possible?

Consider a gene with four alleles A₁, A₂, A₃, and A₄. In the cross A₁A₂ × A₃A₃, how many offspring genotypes are possible?

Consider a gene with six alleles A₁, A₂, A₃, A₄, A₅, and A₆. How many distinct genotypes are possible, taking into account both homozygous and heterozygous genotypes?

Consider a gene with four alleles A₁, A₂, A₃, and A₄. If the cross A₁A₂ × A₃A₃ yields two offspring, what is the probability that both of them have the same genotype?

Consider a gene with four alleles A₁, A₂, A₃, and A₄. How many distinct genotypes are possible, taking into account both homozygous and heterozygous genotypes?

Consider a gene with n alleles A₁, A₂, ..., A_n. How many distinct genotypes are possible, taking into account both homozygous and heterozygous genotypes?

Consider a gene with six alleles A₁, A₂, A₃, A₄, A₅, and A₆. How many distinct heterozygous genotypes are possible?

Consider a gene with six alleles A₁, A₂, A₃, A₄, A₅, and A₆. How many distinct homozygous genotypes are possible?