Genetics [Module 2.1]

Question 1

In a species of birds, blue feather (B) are incompletely dominant to the gene for white feathers (b). Individuals that are heterozygous (Bb) have blue-tipped feathers.

A bird with blue-tipped feathers is crossed with a white bird.

What is the chance that the offspring will have blue feathers?

Answer 1

0%

This cross will only produce Bb and bb offspring.

Question 2

What type of non-Mendelian inheritance is depicted based on the phenotypic ratio below?

3:0

Answer 2

Lethal allele

Question 3

When white-coated cattle (W) are mated with red-coated cattle (R), the offspring are roan (WR), meaning their coats contain both white and red hairs.

A farmer breeds two roan cattle with one another.

What is the chance that their offspring will be roan?

Answer 3

50%

1/4 of the offspring will be white (WW), 1/4 of the offspring will be red (RR), and 2/4 of the offspring will be roan (WR).
2/4 WR = 1/2 = 50%

Question 4

P1 - White-coated cattle (W)
P2 - Red-coated cattle (R)
Offspring / F1 - Roan (WR)

What is the allelic interaction presented?

Answer 4

Codominance

Question 5

A black sheep is bred with a white sheep. All of their offspring have a phenotype of gray coats.

What is the most likely pattern of inheritance for coat color in sheep?

Answer 5

Incomplete dominance

Since the offspring have an intermediate phenotype (in between the colors black and white i.e. gray), this is an example of incomplete dominance.

Question 6

In humans, three alleles affect blood type. The A and B alleles are codominant, and the O allele is recessive.

An AB blood type father has children with an A blood type mother (genotype AO).

What are the chances that their children will have AB type blood?

Answer 6

25%

1/4 offspring will have AB blood type.
1/4 = 25%

Question 7

In humans, the gene for curly hair (H) is incompletely dominant to the gene for straight hair (h). Individuals that are heterozygous (Hh) have wavy hair.

Two wavy-haired heterozygous parents have a child.

What is the likeliness that the child will have wavy hair?

Answer 7

1/2

Question 8

In humans, three alleles affect blood type. Which of the following are true?

A. The A and B alleles are codominant because both alleles are simultaneously expressed in the heterozygote.

B. The O blood type is least common in the human population

C. Human blood type is an example of incomplete dominance.

D. Human blood type is an example of multiple allele inheritance.

Answer 8

D. Human blood type is an example of multiple allele inheritance.

Question 9

In camellia flowers, petal color is controlled by codominance. When a red flower is crossed with a white flower, all of the offspring are covered in both red and white petals.

A scientist crosses a red flower (RR) with a red-and-white (RW) flower.

What are the predicted phenotypes of their offspring?

Answer 9

50% - red
50% - red-and-white

Question 10

Pleiotropy is when one gene affects multiple characteristics (Cystic fibrosis).

True or False?

Answer 10

True

Question 11

A gene for corn has two alleles, one for yellow kernels and one for white kernels.

A farmer mates yellow and white corn. All of the offspring have a nearly even mix of yellow and white kernels.

What type of inheritance most likely explains the relationship between the two alleles?

Answer 11

Codominance

Because both alleles (yellow and white) are expressed, this is an example of codominance.

Question 12

Agouti - C - dominant
Black - Cb - dominant to albino
Albino - c - recessive

A scientist crosses a black mouse (CBc) with an agouti mouse (CCb).

What are the predicted phenotypes of their offspring?

Answer 12

50% of the offspring will have agouti coats, and 50% will have black coats.

2/4 offspring will have agouti coats (CCB or Cc) and 2/4 offspring will have black coats (CBCB or CBc).

Question 13

Hemophilia is an X-linked recessive trait that affects blood clotting. If a carrier woman (XX) and a hemophiliac man (XY) have a daughter, what is the percent chance that she will have hemophilia?

Answer 13

50%

Question 14

A group of students are studying flower color inheritance in the garden pea plant (Pisum sativum). They obtain a purple-flowered pea plant of unknown ancestry, allow it to self-pollinate, and collect 60 of its seeds. After planting the seeds, they observe the growth of 42 purple-flowered plants and 18 white-flowered plants.

Why are there white-flowered plants present?

Answer 14

White flower color is a trait recessive to purple flower color.

Question 15

Pattern of heredity in which one allele is not completely dominant over another

Answer 15

Incomplete dominance

Question 16

Pattern of heredity in which both alleles are simultaneously expressed in the heterozygote

Answer 16

Codominance

Question 17

A gene that is controlled by more than two alleles

Answer 17

Multiple alleles

Question 18

When one gene affects multiple characteristics

Answer 18

Pleiotropy

Question 19

Allele that results in the death of an individual

Answer 19

Lethal allele

Question 20

A section of DNA which encodes for protein

Answer 20

Gene

Question 21

The entire set of genes in an organism

Answer 21

Genome

Question 22

Specific type of variant of genes that occupy the same position on homologous chromosomes and that cover the same trait.

Answer 22

Alleles

Question 23

mother deroy, have mercy on us

Answer 23

amen

Question 24

This law states that in a heterozygote, one allele will conceal / hide the presence of another allele for the same gene governing a particular character or phenotype.

Answer 24

Law of Dominance

Question 25

The allele that conceals/hides the presence of the other allele.

Answer 25

Dominant allele

Question 26

The allele whose presence is concealed / hidden / masked is known as ___________.

Answer 26

Recessive allele

Question 27

During the formation of gametes, two alleles of a gene responsible for a character separate from each other as each sister chromatid separates during _________________.

Answer 27

Anaphase II

Question 28

The Punnett square is named after ______________.

Answer 28

Reginald Punnett

Question 29

It is a table that shows the genotypes the two individuals can produce when crossed.

Answer 29

Punnett Square

Question 30

A plant with round and yellow seeds is crossed with plant with wrinkled and green seeds. Round is dominant over wrinkled and is controlled by an allele R, while yellow flower color is dominant over white, controlled by an allele Y. All the resulting F1 progenies are heterozygous for the trait (RrYy)

If the F1 progenies are self-fertilized, what is the genotypic and phenotypic ratio of the F2 progenies?

Answer 30

9:3:3:1

Question 31

Pea plants can be tall (T) or short (t) and produce purple (R) and white (r) blossoms.

A pure-breeding tall plant with purple flowers (TTRR) is crossed with a pure-breeding short plant with white flowers (ttrr). What will the offspring look like?

Answer 31

All offspring will be tall with purple flowers (TtRr)

Question 32

Pea plants can be tall (T) or short (t) and produce purple (R) and white (r) blossoms.

A pure-breeding tall plant with purple flowers (TTRR) is crossed with a pure-breeding short plant with white flowers (ttrr).

If two of the hybrid (F1) plants are crossed, what offspring can they produce?

Answer 32

They can produce 9/16 tall purple plants, 3/16 short purple plants, 3/16 tall white plants, and 1/16 short white plants.

Question 33

It can help predict patterns of inheritance of traits in organisms and even diseases in family lines.

Answer 33

Probabilities

Question 34

The phenotypic measurements of F1 progeny exceed s or higher than compared to both parents is known as __________________.

Answer 34

Heterozygote advantage / Hybrid vigor

Question 35

An AB blood type mother has children with a B blood type father (genotype BO).

What are the chances that their children will have AB type blood?

Answer 35

25%

An AB x BO cross will produce:
- 1/4 AB
- 1/4 BB
- 1/4 BO
- 1/4 AO

Question 36

Bonus:

Hemophilia is an X-linked recessive disorder that causes problems with the blood clotting process. Hemophilia is caused by mutations in the F8 gene.

An affected female (XhXh) is paired with an unaffected male (XHY). They have 2 unaffected daughters and 2 affected sons.

What is the genotype of the unaffected daughters?

Question 37

It is a circumstance where the expression of one gene is masked, inhibited or suppressed by the expression of one or more other genes.

Answer 37

Epistasis

Question 38

There is complete dominance in both gene pair but one gene when homozygous recessive hides or mask the effect of the other gene.

Answer 38

Recessive Epistasis (9:3:4)

Question 39

There is complete dominance in both gene pair; but one gene, when dominant, hides or mask the effect of the other gene.

Answer 39

Dominant Epistasis (12:3:1)

Question 40

There is complete dominance in both gene pair, but either recessive homozygote is epistatic to the effects of the other gene.

Answer 40

Duplicate Recessive Epistasis (9:7)

Question 41

Dominant and Recessive epistasis

Answer 41

13:3

Question 42

Duplicate genes

Answer 42

15:1