Question 1

If all the offspring of a cross had the genotype Aa Bb , the parents of the cross would most likely be
A) AA BB x aa bb .
B) AA bb x aa BB .
C) Aa Bb x Aa Bb .
D) Aa bb x aa Bb .
E) both AA BB x aa bb and AA bb x aa BB .

Accepted Answer

The offspring genotype Aa Bb can result from either AA BB x aa bb or AA bb x aa BB, as both crosses would produce offspring with one dominant and one recessive allele for each gene.

Question 2

What fraction of the time will the cross of Aa Bb Cc with Aa Bb Cc produce an offspring of genotype aa bb cc ?
A) 1/64
B) 1/32
C) 3/64
D) 1/16
E) 9/64

Accepted Answer

Each gene pair (Aa, Bb, Cc) independently segregates with a 1/4 chance of producing a homozygous recessive genotype (aa, bb, or cc). Therefore, the probability of producing an offspring with the genotype aa bb cc is (1/4) * (1/4) * (1/4) = 1/64.

Question 3

What fraction of the time will a cross of Aa BB cc with Aa Bb CC produce an offspring of genotype Aa Bb CC ?
A) 1/32
B) 1/16
C) 3/32
D) 1/8
E) 0

Accepted Answer

The answer of What fraction of the time will a...

Question 4

What fraction of the time will the cross of Aa Bb Cc with Aa Bb Cc produce an offspring that expresses the dominant traits A and B and cc ( A _  B _ cc )?
A) 1/32
B) 3/64
C) 1/16
D) 9/64
E) 27/64

Accepted Answer

To express the dominant traits A and B, the offspring must have at least one dominant allele for each, which is 3/4 probability for A and 3/4 for B. For cc, the probability is 1/4. Multiply these probabilities: (3/4) * (3/4) * (1/4) = 9/64.

Question 5

Some dogs have erect ears; others have drooping ears. Some dogs bark when following scent; others are silent. Erect ears and barking are due to dominant alleles located on different chromosomes. If two dihybrids are crossed, A) the most common phenotype is drooping ears and barking. B) all droopy-eared, silent dogs are pure-breeding. C) the least common phenotype is drooping ears and barking. D) there will be no phenotypes or genotypes that resemble the original parents. E) there will be no offspring that resemble the F ₁ generation.

Accepted Answer

In a dihybrid cross, the least common phenotype is the one with both recessive traits. Droopy ears and silent behavior are recessive, so droopy-eared, silent dogs are homozygous recessive for both traits, making them pure-breeding.

Question 6

For monohybrid experiments, a testcross could result in which of the following ratios?
A) 1:1
B) 2:1
C) 9:3:3:1
D) 1:2:1
E) 3:1

Accepted Answer

A testcross in a monohybrid experiment involves crossing an individual with a homozygous recessive individual. This typically results in a 1:1 phenotypic ratio if the individual being tested is heterozygous.

Question 7

What fraction of the time will a cross of Aa Bb Cc with Aa BB cc produce an offspring of genotype Aa Bb Cc ?
A) 1/32
B) 1/16
C) 3/32
D) 1/8
E) none (no chance of this offspring)

Accepted Answer

The probability of Aa from Aa x Aa is 1/2, Bb from Bb x BB is 1/2, and Cc from Cc x cc is 1/2. Multiplying these probabilities gives 1/8.

Question 8

Independent assortment occurs during
A) meiosis.
B) mitosis.
C) morphogenesis.
D) segregation.
E) cell fission.

Accepted Answer

Independent assortment occurs during meiosis, specifically during metaphase I, where homologous chromosomes are randomly distributed to daughter cells, leading to genetic variation.

Question 9

The chance of producing an offspring of genotype Aa Bb cc from a cross of Aa BB Cc with Aa BB Cc is
A) 1/32.
B) 1/16.
C) 3/32.
D) 1/8.
E) none (no chance of this offspring)

Accepted Answer

The answer of The chance of producing an offspring of...

Question 10

If all the offspring of a testcross are alike and resemble the organism being tested, then that parent is
A) homozygous dominant.
B) homozygous recessive.
C) heterozygous.
D) recessive.
E) incompletely dominant.

Accepted Answer

In a testcross, an organism (whose genotype we want to determine) is crossed with a homozygous recessive individual. If all offspring resemble the tested parent, it indicates that the parent must be homozygous dominant, as only dominant alleles are present to be passed on, ensuring all offspring display the dominant phenotype.

Question 11

The principle of independent assortment states that
A) one allele is always dominant to another.
B) hereditary units from the male and female parents are blended in the offspring.
C) the two hereditary units that influence a certain trait segregate during gamete formation.
D) each hereditary unit on one chromosome is inherited separately from hereditary units on other chromosomes.
E) genes on the same chromosome travel separately.

Accepted Answer

The principle of independent assortment states that genes for different traits can segregate independently during the formation of gametes, meaning each hereditary unit (gene) on one chromosome is inherited separately from those on other chromosomes.

Question 12

When considering non-related traits, the fact that they may be inherited individually without any effect on one another is known as
A) segregation.
B) independent assortment.
C) synapsis.
D) independent segregation.
E) non-disjunction.

Accepted Answer

Independent assortment refers to the principle that genes for different traits can segregate independently during the formation of gametes, meaning they are inherited separately from one another.

Question 13

The chance of producing an offspring of genotype Aa BB cc from a cross of Aa Bb Cc with Aa Bb Cc is
A) 1/64.
B) 1/32.
C) 3/64.
D) 1/16.
E) 3/32.

Accepted Answer

The answer of The chance of producing an offspring of...

Question 14

Some dogs have erect ears; others have drooping ears. Some dogs bark when following a scent; others are silent. Erect ears and barking are due to dominant alleles located on different chromosomes. A dog homozygous for both dominant traits is mated to a droopy-eared, silent follower. The phenotypic ratio expected in the F ₁ is A) 9:3:3:1. B) 100 percent of one phenotype. C) 1:1. D) 1:2:1. E) 3:1.

Accepted Answer

The F1 generation will all be heterozygous for both traits, showing the dominant phenotype (erect ears and barking) because they inherit one dominant allele for each trait from the homozygous dominant parent.

Question 15

Assume short hair (L) is dominant to long hair (l) , and black hair (B) is dominant to brown (b) . If you found a black, short-haired animal, you could determine its genotype by crossing it to an animal with a genotype of
A) LL BB .
B) ll BB .
C) ll Bb .
D) ll bb .
E) LL bb .

Accepted Answer

To determine the genotype of a black short-haired animal (which shows dominant traits), you would cross it with an animal that has homozygous recessive traits for both characteristics (long brown hair, or ll bb). This would reveal whether the black short-haired animal carries recessive alleles, based on the phenotypes of the offspring.

Question 16

What fraction of the time will the cross of Aa Bb Cc with Aa Bb Cc produce an offspring that expresses the phenotype represented by the dominant gene C ( aa bb C_) ?
A) 1/32
B) 3/64
C) 1/16
D) 9/64
E) 27/64

Accepted Answer

The answer of What fraction of the time will the...

Question 17

What fraction of the time will the cross of Aa Bb Cc with Aa Bb Cc produce an offspring of genotype Aa bb CC ?
A) 1/64
B) 1/32
C) 3/64
D) 1/16
E) 9/64

Accepted Answer

The answer of What fraction of the time will the...

Question 18

What fraction of the time will the cross of Aa Bb Cc with Aa Bb Cc produce an offspring that is pure-breeding?
A) 3/64
B) 1/16
C) 1/8
D) 9/64
E) 27/64

Accepted Answer

The answer of What fraction of the time will the...

Question 19

What fraction of the time will the cross of Aa Bb Cc with Aa Bb Cc produce an offspring that expresses all three dominant genes?
A) 3/64
B) 1/16
C) 1/8
D) 9/64
E) 27/64

Accepted Answer

Each gene pair (Aa, Bb, Cc) follows Mendelian inheritance, with a 3/4 chance of expressing the dominant trait. The probability of expressing all three dominant traits is (3/4) * (3/4) * (3/4) = 27/64.

Question 20

A given chromosome and its genes may end up in any of ____ gametes.
A) 2
B) 4
C) 6
D) 8
E) 10

Accepted Answer

The answer of A given chromosome and its genes may...

Quiz 19: Introduction to Genetics

If all the offspring of a cross had the genotype Aa Bb , the parents of the cross would most likely be

What fraction of the time will the cross of Aa Bb Cc with Aa Bb Cc produce an offspring of genotype aa bb cc ?

What fraction of the time will a cross of Aa BB cc with Aa Bb CC produce an offspring of genotype Aa Bb CC ?

What fraction of the time will the cross of Aa Bb Cc with Aa Bb Cc produce an offspring that expresses the dominant traits A and B and cc ( A _ B _ cc ) ?

Some dogs have erect ears; others have drooping ears. Some dogs bark when following scent; others are silent. Erect ears and barking are due to dominant alleles located on different chromosomes. If two dihybrids are crossed,

For monohybrid experiments, a testcross could result in which of the following ratios?

What fraction of the time will a cross of Aa Bb Cc with Aa BB cc produce an offspring of genotype Aa Bb Cc ?

Independent assortment occurs during

The chance of producing an offspring of genotype Aa Bb cc from a cross of Aa BB Cc with Aa BB Cc is

If all the offspring of a testcross are alike and resemble the organism being tested, then that parent is

The principle of independent assortment states that

When considering non-related traits, the fact that they may be inherited individually without any effect on one another is known as

The chance of producing an offspring of genotype Aa BB cc from a cross of Aa Bb Cc with Aa Bb Cc is

Assume short hair (L) is dominant to long hair (l) , and black hair (B) is dominant to brown (b) . If you found a black, short-haired animal, you could determine its genotype by crossing it to an animal with a genotype of

What fraction of the time will the cross of Aa Bb Cc with Aa Bb Cc produce an offspring that expresses the phenotype represented by the dominant gene C ( aa bb C_) ?

What fraction of the time will the cross of Aa Bb Cc with Aa Bb Cc produce an offspring of genotype Aa bb CC ?

What fraction of the time will the cross of Aa Bb Cc with Aa Bb Cc produce an offspring that is pure-breeding?

What fraction of the time will the cross of Aa Bb Cc with Aa Bb Cc produce an offspring that expresses all three dominant genes?

A given chromosome and its genes may end up in any of ____ gametes.