Question 1

In a Punnett square, the letters outside the little boxes represent ____.
A)offspring genotypes
B)parental genotypes
C)gametes
D)offspring phenotypes
E)parental phenotypes

Accepted Answer

The letters outside the boxes in a Punnett square represent the gametes, which are the reproductive cells carrying the alleles from each parent.

Question 2

The genes that code for blood typing are an example of ____. ​
A)sex-linkage
B)segregation
C)pleiotropy
D)independent assortment
E)co-dominance

Accepted Answer

The blood typing genes exhibit co-dominance, meaning that both alleles are expressed equally in heterozygous individuals. This is why someone with the genotype AB has blood type AB, displaying both A and B antigens on their red blood cells.

Question 3

If C is dominant to c, what fraction of offspring will be homozygous recessive when two heterozygous parents are crossed? ​
A)0/4
B)1/4
C)2/4
D)3/4
E)4/4

Accepted Answer

If C is dominant, then the heterozygous parents will both have the dominant allele (C) and the recessive allele (c). When they are crossed, there is a 1/4 chance of each offspring receiving two recessive alleles (cc) and expressing the recessive trait. Therefore, the fraction of offspring that are homozygous recessive is 1/4.

Question 4

In the cross Cc ´ Cc , gametes have a ____ chance of receiving either allele.
A)25 - 75
B)50 - 50
C)75 - 25
D)60 - 40
E)90 - 10

Accepted Answer

In a cross between two heterozygous individuals (Cc x Cc), each parent can produce two types of gametes: C or c. So, the four possible combinations of gametes are CC, Cc, cC, and cc. Since the alleles segregate independently during gamete formation, each gamete has an equal chance of receiving either allele. Therefore, the chance of receiving C is 50%, and the chance of receiving c is also 50%. Thus, gametes have a 50-50 chance of receiving either allele.

Question 5

If C is dominant to c, what fraction of offspring will show the recessive phenotype when two heterozygous parents are crossed?
A)0/4
B)1/4
C)2/4
D)3/4
E)4/4

Accepted Answer

When two heterozygous parents are crossed (Cc x Cc), they can produce four possible offspring genotypes: CC, Cc, cC, and cc. However, since C is dominant to c, both CC and Cc genotypes will show the dominant phenotype. Therefore, only the cc genotype will display the recessive phenotype. The chances of a heterozygous parent passing on the recessive allele to its offspring is 1/2. So, the probability of both parents passing on the recessive allele would be (1/2) x (1/2) = 1/4 or 25%. Therefore, 1/4 or 25% of the offspring will show the recessive phenotype.

Question 6

What fraction of the time will the cross of Aa Bb with Aa Bb produce an offspring that is aa bb ? ​
A)16/16
B)9/16
C)6/16
D)3/16
E)1/16

Accepted Answer

The cross of Aa Bb with Aa Bb can be analyzed by looking at each gene separately. For gene A, the chance of producing aa is 1/4 (since Aa x Aa gives AA, Aa, aa, Aa, with aa being one of the four possibilities). Similarly, for gene B, the chance of producing bb is also 1/4. Therefore, the combined probability of producing an offspring that is aa bb is 1/4 * 1/4 = 1/16.

Question 7

If short hair (L)is dominant to long hair (l), then what fraction of the offspring produced by a cross of Ll ´ ll will be homozygous dominant?
A)1/2
B)1/4
C)1/3
D)0
E)2/4

Accepted Answer

Homozygous dominant would require an offspring to have the genotype LL. However, since one parent is Ll and the other is ll, all offspring will either be Ll or ll, making it impossible to produce a homozygous dominant (LL) offspring from this cross.

Question 8

What fraction of the time will the cross of Aa Bb with Aa Bb produce an offspring that will express the dominant trait for one of the two alleles?
A)16/16
B)9/16
C)6/16
D)3/16
E)1/16

Accepted Answer

The cross Aa Bb x Aa Bb results in a 9:3:3:1 phenotypic ratio. The dominant trait for one allele (Aa or Bb) is expressed in 9 (both dominant) + 3 (dominant Aa, recessive Bb) + 3 (recessive Aa, dominant Bb) = 15 out of 16 cases. However, the question asks for expressing the dominant trait for only one of the two alleles, which is 3 (dominant Aa, recessive Bb) + 3 (recessive Aa, dominant Bb) = 6 out of 16 cases.

Question 9

In a Punnett square, the letters within the little boxes represent ____.
A)offspring genotypes
B)parental genotypes
C)parental genotypes.
D)offspring phenotypes.
E)parental phenotypes

Accepted Answer

The letters within the little boxes of a Punnett square represent the possible genotypes of the offspring resulting from a cross between two parental genotypes.

Question 10

If C is dominant to c, what fraction of offspring will be homozygous dominant when two heterozygous parents are crossed?
A)0/4
B)1/4
C)2/4
D)3/4
E)4/4

Accepted Answer

When two heterozygous parents (Cc x Cc) are crossed, the offspring genotypes follow a Punnett square distribution: CC, Cc, Cc, cc. Thus, 1 out of 4 offspring (1/4) will be homozygous dominant (CC).

Question 11

The process by which alleles in one gene move into gametes independent of alleles in other genes is known as ____.
A)independent segregation
B)independent separation
C)probability separation
D)probability assortment
E)independent assortment

Accepted Answer

Independent assortment refers to the random distribution of alleles from different genes into gametes. This occurs due to the random orientation of homologous pairs of chromosomes during meiosis I. As a result, alleles for different traits are inherited independently of one another, which contributes to the genetic diversity of offspring. The other choices, such as independent segregation/separation and probability separation/assortment, are not commonly used terms in genetics and do not accurately describe the phenomenon of independent assortment.

Question 12

If R is dominant to r , the offspring of the cross of RR with rr will ____.
A)be homozygous
B)display the same phenotype as the RR parent
C)display the same phenotype as the rr parent
D)have the same genotype as the RR parent
E)have the same genotype as the rr parent

Accepted Answer

The offspring from a cross between RR (dominant) and rr (recessive) will all inherit one R allele and one r allele, making them heterozygous (Rr). They will display the dominant phenotype, which is the same phenotype as the RR parent, because the presence of one R allele is enough to express the dominant trait.

Question 13

A graphic tool used to determine the probable outcome of genetic crosses is the ____.
A)Mendelian box
B)Archimedian triangle
C)Euclid box
D)Hardy-Weinberg graph
E)Punnett square

Accepted Answer

A Punnett square is a common graphic tool used in genetics to predict the possible offspring of a genetic cross between two individuals based on their genotypes. It is a simple grid that displays the possible combinations of alleles from each parent and the resulting genotype and phenotype frequencies of their offspring.

Question 14

The wide-ranging effect of a single gene is called ____.
A)homozygous
B)segregation
C)pleiotropy
D)independent assortment
E)co-dominance

Accepted Answer

Pleiotropy refers to the phenomenon where a single gene can have multiple effects on an organism's phenotype. This can include effects on traits that are seemingly unrelated, due to the gene's influence on various biochemical pathways. Examples include the sickle cell gene, which affects not only red blood cell shape but also susceptibility to certain diseases, and the PKU gene, which affects not only metabolism of phenylalanine but also neurological development.

Question 15

The genes that code for blood typing are an example of ____. ​
A)a multiple allele system
B)segregation
C)pleiotropy
D)independent assortment
E)sex-linkage

Accepted Answer

The genes that code for blood typing involve multiple alleles (A, B, and O), making it an example of a multiple allele system.

Question 16

If C is dominant to c, what fraction of offspring will be homozygous when two heterozygous parents are crossed?
A)0/4
B)1/4
C)2/4
D)3/4
E)4/4

Accepted Answer

When two heterozygous parents (Cc x Cc) are crossed, the possible genotypes of the offspring are CC, Cc, Cc, and cc. Out of these, two are homozygous (CC and cc), so the fraction is 2/4 or 1/2.

Question 17

What fraction of the time will the cross of Aa Bb with Aa Bb produce an offspring that will express the dominant trait for both alleles?
A)16/16
B)9/16
C)6/16
D)3/16
E)1/16

Accepted Answer

The cross of Aa Bb with Aa Bb will produce offspring with genotypes of AA, Aa, BB, Bb, AB, and ab, each with a probability of 1/4 (as there are four possible gamete combinations for each parent).

Of these genotypes, only AA (homozygous dominant) and AB (heterozygous dominant for both alleles) will express the dominant trait for both alleles.

Thus, the fraction of the time that the cross will produce an offspring with both dominant traits is the sum of the probabilities of these two genotypes: 1/4 (AA) + 1/4 (AB) = 1/2.

To simplify the fraction, we can convert 1/2 to 8/16, so the answer is 9/16 (the total possible outcomes).

Question 18

If tall (D)is dominant to dwarf (d), and two homozygous varieties DD and dd are crossed, then what kind of offspring will be produced?
A)all intermediate forms
B)all tall
C)all dwarf
D)1/2 tall, 1/2 dwarf
E)3/4 tall, 1/4 dwarf

Accepted Answer

When crossing DD and dd, all of the offspring will be heterozygous (Dd) and therefore tall, because the dominant allele will always be expressed over the recessive allele.

Question 19

If all offspring of a cross have the genotype Aa , the parents of the crosses would most likely be ____.
A)AA ´ aa
B)Aa ´ Aa
C)Aa ´ aa
D)AA ´ Aa
E)aa ´   aa

Accepted Answer

The correct cross to produce all Aa offspring is between an AA and an aa parent. This is because the AA parent can only contribute an A allele, and the aa parent can only contribute an a allele, resulting in offspring that are all Aa.

Question 20

If C is dominant to c, what fraction of offspring will show the dominant phenotype when two heterozygous parents are crossed? ​
A)0/4
B)1/4
C)2/4
D)3/4
E)4/4

Accepted Answer

If C is dominant to c, that means that if an individual inherits one copy of the dominant C allele and one copy of the recessive c allele, they will exhibit the dominant phenotype. When two heterozygous parents are crossed (Cc x Cc), they each have one copy of the dominant C allele and one copy of the recessive c allele. The Punnett square for this cross would produce offspring with the genotypes CC, Cc, cC, and cc. Out of these four possible genotypes, three of them (CC, Cc, and cC) would exhibit the dominant phenotype, while only one (cc) would exhibit the recessive phenotype. Therefore, the fraction of offspring that would show the dominant phenotype is 3/4 or 75%.

Quiz 19: Introduction to Genetics

In a Punnett square, the letters outside the little boxes represent ____.

The genes that code for blood typing are an example of ____.

If C is dominant to c, what fraction of offspring will be homozygous recessive when two heterozygous parents are crossed?

In the cross Cc ´ Cc , gametes have a ____ chance of receiving either allele.

If C is dominant to c, what fraction of offspring will show the recessive phenotype when two heterozygous parents are crossed?

What fraction of the time will the cross of Aa Bb with Aa Bb produce an offspring that is aa bb ?

If short hair (L) is dominant to long hair (l) , then what fraction of the offspring produced by a cross of Ll ´ ll will be homozygous dominant?

What fraction of the time will the cross of Aa Bb with Aa Bb produce an offspring that will express the dominant trait for one of the two alleles?

In a Punnett square, the letters within the little boxes represent ____.

If C is dominant to c, what fraction of offspring will be homozygous dominant when two heterozygous parents are crossed?

The process by which alleles in one gene move into gametes independent of alleles in other genes is known as ____.

If R is dominant to r , the offspring of the cross of RR with rr will ____.

A graphic tool used to determine the probable outcome of genetic crosses is the ____.

The wide-ranging effect of a single gene is called ____.

The genes that code for blood typing are an example of ____.

If C is dominant to c, what fraction of offspring will be homozygous when two heterozygous parents are crossed?

What fraction of the time will the cross of Aa Bb with Aa Bb produce an offspring that will express the dominant trait for both alleles?

If tall (D) is dominant to dwarf (d) , and two homozygous varieties DD and dd are crossed, then what kind of offspring will be produced?

If all offspring of a cross have the genotype Aa , the parents of the crosses would most likely be ____.

If C is dominant to c, what fraction of offspring will show the dominant phenotype when two heterozygous parents are crossed?

Quiz 19: Introduction to Genetics

In a Punnett square, the letters outside the little boxes represent ____.

The genes that code for blood typing are an example of ____. ​

If C is dominant to c, what fraction of offspring will be homozygous recessive when two heterozygous parents are crossed? ​

In the cross Cc ´ Cc , gametes have a ____ chance of receiving either allele.

If C is dominant to c, what fraction of offspring will show the recessive phenotype when two heterozygous parents are crossed?

What fraction of the time will the cross of Aa Bb with Aa Bb produce an offspring that is aa bb ? ​

If short hair (L) is dominant to long hair (l) , then what fraction of the offspring produced by a cross of Ll ´ ll will be homozygous dominant?

What fraction of the time will the cross of Aa Bb with Aa Bb produce an offspring that will express the dominant trait for one of the two alleles?

In a Punnett square, the letters within the little boxes represent ____.

If C is dominant to c, what fraction of offspring will be homozygous dominant when two heterozygous parents are crossed?

The process by which alleles in one gene move into gametes independent of alleles in other genes is known as ____.

If R is dominant to r , the offspring of the cross of RR with rr will ____.

A graphic tool used to determine the probable outcome of genetic crosses is the ____.

The wide-ranging effect of a single gene is called ____.

The genes that code for blood typing are an example of ____. ​

If C is dominant to c, what fraction of offspring will be homozygous when two heterozygous parents are crossed?

What fraction of the time will the cross of Aa Bb with Aa Bb produce an offspring that will express the dominant trait for both alleles?

If tall (D) is dominant to dwarf (d) , and two homozygous varieties DD and dd are crossed, then what kind of offspring will be produced?

If all offspring of a cross have the genotype Aa , the parents of the crosses would most likely be ____.

If C is dominant to c, what fraction of offspring will show the dominant phenotype when two heterozygous parents are crossed? ​

The genes that code for blood typing are an example of ____.

If C is dominant to c, what fraction of offspring will be homozygous recessive when two heterozygous parents are crossed?

What fraction of the time will the cross of Aa Bb with Aa Bb produce an offspring that is aa bb ?

The genes that code for blood typing are an example of ____.

If C is dominant to c, what fraction of offspring will show the dominant phenotype when two heterozygous parents are crossed?