Chapter 2: Mendel's Principles Of Heredity

Question 1

What type of cross described the mating of an individual expressing a dominant phenotype, but whose genotype is unknown, with an individual expressing the corresponding recessive phenotype?

Answer 1

Test cross

Question 2

A tall pea plant with purple flowers is crossed with a short pea plant with white flowers. What type of cross is this?

Answer 2

Di hybrid

Question 3

Which of the following statements are referring to genotypes?

1) the F1 generation offspring are Tt
2) the P generation has both tall and short plants
3) the parental plant in the P generation is TT
4) the F1 generation plants are tall

Answer 3

1 and 3

Question 4

An F1 hybrid plant from a cross between a heterozygous plant with round seeds and a plant with wrinkled seeds is allowed to self-fertilize. Each of the F2 plants with wrinkled seeds are then allowed to self-fertilize. What do you expect to see in the F3 generation?

Answer 4

100% wrinkled seeds

Question 5

The probability of producing a dwarf plant from two heterozygous parents is 1/4. What is the likelihood that these same parent plants will produce 3 dwarf plants?

Answer 5

1/64 or 1.6%

Question 6

If an organism has identical alleles for a given trait, it is said to be

Answer 6

Homozygous

Question 7

What is the purpose of performing a test cross?

Answer 7

To determine the genotype of an organism expressing the dominant phenotype.

Question 8

Two different genes will be randomly distributed into gametes during the formation of haploid cells. This statement summarizes which of Mendel’s laws?

Answer 8

Law of Independent Assortment

Question 9

A tall pea plant with axial flowers has the genotype TtAa. What are the gamete possibilities of this plant?

Answer 9

1/4 TA
1/4 Ta
1/4 tA
1/4 ta

Question 10

What are the possible gametes that could be formed from an organism with the genotype AaBb?

1) Aa
2) Ab
3) AaBb
4) AB
5) ab
6) aB
7) Bb

Answer 10

2, 4, 5, 6

Question 11

If a parent with the genotype AaBb mates with a parent who is aabb, what is the probability of an Aabb offspring?

Answer 11

1/4

Explanation: the probability of the offspring being heterozygous for the A gene is 1/2. The probability of the offspring being homozygous recessive recessive for the B gene is 1/2. Using the product rule, 1/2 x 1/2 = 1/4

Question 12

An organism’s genotype is RrYy and it produces gametes with the genotypes RY, Ry, rY, and ry with equal frequency. Which of Mendel’s laws explains this fact?

Answer 12

Law of independent assortment: different pairs of alleles segregate independently of each other.

Question 13

Purple flower color is dominant to white flower color in pea plants. Yellow seed color is dominant to green seed color. If you cross a heterozygous pea plant with purple flowers and yellow seeds to a pea plant with white flowers and green seeds, what is the expected genotypic ratio?

Answer 13

1/4 PpYy
1/4 Ppyy
1/4 ppYy
1/4 ppyy

Question 14

The genotype AAbbCCdd is

Answer 14

Homozygous

Question 15

A sheep breeder has a shed that is large (L) with soft wool (S). The breeder conducts a test cross to determine whether the sheep is homozygous or heterozygous for each of those dominant traits. If 1/4 of the offspring of the test toss are large with soft wool, what is the genotype of the breeder’s sheep?

Answer 15

Ll Ss

Question 16

Mating an organism expressing a dominant phenotype, but whose genotype is unknown, with an organism expressing the corresponding recessive phenotype is an example of a(n)

Answer 16

Testcross

Question 17

In a series of dihybrid crosses, pea plants with round, green seeds were crossed to plants with wrinkled, yellow seeds. All of the progeny had round, yellow seeds. What conclusions can be drawn from these data?

1) round is dominant to wrinkled and green is dominant to yellow
2) round is dominant to wrinkled and yellow is dominant to green
3) wrinkled is dominant to round and green is dominant to yellow
4) wrinkled is dominant to young and yellow is dominant to green

Answer 17

2

Question 18

A sheep breeder has a sheep that is large (L) with soft wool (S). The breeder conducts a test cross to determine whether the sheep is homozygous or heterozygous for each of these dominant traits. If all of the offspring of the test cross are large with soft wool, what is the genotype of the breeder’s sheep?

Answer 18

LL SS

Question 19

What is the probability of having three offspring that are male?

Answer 19

1/8

Question 20

Which of the following methods would best be applied to determine the probability of having 5 children, all female?

1) punnett square
2) product rule
3) sum rule

Answer 20

2

Question 21

What is a branched line diagram for?

Answer 21

To show all the possibilities for each gene in a sequence of columns

Question 22

What is a horizontal family pattern in a pedigree?What 2 things does a horizontal family pattern in a pedigree suggest?

Answer 22

Horizontal pattern:
Brothers and sisters in a sole generation are affected
1) the trait is recessive
2) the unaffected parents are heterozygous carriers, that they bear the recessive allele the would express the trait, but they have a dominant allele that masks it

Question 23

Which of the following are true for the inheritance of a recessive trait?

1) the trait often skips a generation
2) two heterozygotes will generally have affected offspring 25% of the time
3) affected individuals will inherit a dominant gene from at least one affected parent
4) the trait is usually present in every generation
5) all offspring of two affected individuals will be affected
5) all offspring of two affected individuals will be affected

Answer 23

1,2,5

Question 24

An inheritance pattern in which all offspring of two affected individuals are affected is most likely to be autosomal [blank] inheritance

Answer 24

Recessive

Question 25

A gamete only has one copy of each gene. Which of Mendel’s laws explains this fact?

Answer 25

Law of segregation

Question 26

What is a dihybrid?

Answer 26

An individual with two variant alleles for TWO SEPARATE TRAITS

Question 27

What does the Law of Independent Assortment say?

Answer 27

During gamete information, different pairs of alleles segregate independently of each other. For example, the inheritance of a gene for pea color is unaffected by the inheritance for pea shape, and vice versa.

Question 28

What does the law of segregation say?

Answer 28

Two alleles for each gene separate during gamete information, one allele goes to one gamete