Study Guide 5 Inheritance

Question 1

What is the difference between genotype and phenotype?

Answer 1

Genotype: the genetic makeup of an organism (the alleles it carries)

Phenotype: the traits it exhibits (its physical apperance)

-the phenotype is determined by the genotype and by the environment

Question 2

What is the difference between heterozygous and homozygous?

Answer 2

Heterozygous: having two different alleles for a given gene

Homozygous: two copies of the same allele

Question 3

If you know purple flower color is dominant over white flower color, is a white flower heterozygous or homozygous? explain your answer

Answer 3

to exhibit the recessive phenotype, the white flower must be homozygous recessive

Question 4

If you know purple flower color is dominant over white flower color, is a purple flower heterozygous or homozygous? explain your answer

Answer 4

the dominant phenotype is exhibited by both the homozygous dominant genotype and the heterozygous genotype. from the information, we cannot be sure of the genotype of this plant

Question 5

how does sexual reproduction contribute to genetic diversity in a population?

Answer 5

its important for maintain a healthy population and responding to new selective pressures

Question 6

how does independent assortment contribute to genetic diversity in a population?

Answer 6

‘shuffles’ whole genomes from two different individuals

Question 7

how does recombination contribute to genetic diversity in a population?

Answer 7

‘shuffles’ sets of chromosomes and allows an organism to make millions of genetically unique gametes

Question 8

why is genetic diversity important?

Answer 8

‘shuffles’ alleles on a given chromosome, creates new chromosome combinations different than what the organism inherited

Question 9

In squash, white flower color (allele R) is dominant over yellow glower color (allele r). draw a Punnett square demonstrating the cross below. include genotype and phenotype of the offspring.

RR x rr

Answer 9

Question 10

In squash, white flower color (allele R) is dominant over yellow glower color (allele r). draw a Punnett square demonstrating the cross below. include genotype and phenotype of the offspring.

Rr x rr

Answer 10

Question 11

In squash, white flower color (allele R) is dominant over yellow glower color (allele r). draw a Punnett square demonstrating the cross below. include genotype and phenotype of the offspring.

Rr x Rr

Answer 11

Question 12

For the example below, complete a Punnett Square for the cross described. All traits show complete dominance. Make sure to provide the genotypes and phenotypes of the offspring

a. A tall plant (TT) is crossed with a short plant (tt)

Answer 12

Question 13

For the example below, complete a Punnett Square for the cross described. All traits show complete dominance. Make sure to provide the genotypes and phenotypes of the offspring

b. A green pea (Gg) is crossed with a yellow pea (gg)

Answer 13

Question 14

For the example below, complete a Punnett Square for the cross described. All traits show complete dominance. Make sure to provide the genotypes and phenotypes of the offspring

c. A homozygous recessive tan mouse is crossed with a homozygous dominant brown mouse

Answer 14

Question 15

For the example below, complete a Punnett Square for the cross described. All traits show complete dominance. Make sure to provide the genotypes and phenotypes of the offspring

d. Two heterozygous white rabbits mate (brown is the recessive color)

Answer 15

Question 16

Many animals and plants bear recessive alleles for albinism, a condition in which homozygous individuals completely lack any pigments. If two normally-pigmented persons heterozygous for the albinism allele mate, what percentage of their offspring would you expect to be albino?

Answer 16

25%

Question 17

You cross a plant with red flowers and a plant with white flowers, expecting to get some red-flowered plants and some white-flowered plants. Instead, you get all pink-flowered plants. What happened? What were the genotypes of the initial plants?

Answer 17

You predicted the trait was simple dominant and the red-flowered plant was heterozygous, but the cross shows it’s incomplete dominant, and both plants were homozygous

Question 18

In tomatoes, the texture of the skin may be smooth or ‘hairy’ (like a peach). You cross a hairy-fruited plant with a smooth-fruited plant and produce an F1 generation of all smooth-fruited plants. A cross between these F1 offspring produces an F2 generation of 174 hairy fruited plants and 520 smooth
fruited plants. Which phenotype is dominant? What were the genotypes of the initial parents?

Answer 18

The fact that the entire F1 generation is smooth, and the F2 generation is ~3:1 smooth indicates that smooth is the dominant trait and that the initial parents were homozygous dominant and
homozygous recessive

Question 19

A brown mink is crossed with a silverblue mink, and all the offspring are brown. When these F1 brown minks mate, they produce 47 brown offspring and 15 silverblue offspring. Determine the genotypes of the original brown and silverblue mink, the genotypes of the F1 generation and the genotypes of the F2 generation. What fraction of the F2 individuals would you expect to be homozygous?

Answer 19

This pattern of inheritance (F1 all brown, F2 3 brown:1
silverblue) indicates that brown is the dominant phenotype
and the original parents were homozygous dominant and
homozygous recessive. The F1 offspring are all heterozygous
and we would expect the F2s to be 1 BB:2 Bb:1 bb. We
would expect 50% of the F2s to be homozygous (25%
homozygous dominant and 25% homozygous recessive)

Question 20

In pea plants, tall stems are dominant to short stems, and purple flower color is dominant to white flower color.

a. If a homozygous tall, white plant is crossed with a homozygous short, purple plant, what will be the phenotype of the F1 generation?

Answer 20

Parent genotypes are TTpp and ttPP, all F1 offspring will be TtPp, tall and purple

Question 21

In pea plants, tall stems are dominant to short stems, and purple flower color is dominant to white flower color.

b. If an F1 plant from this cross is then crossed with to a homozygous tall white plant, what will be the possible phenotypes of the offspring, and in what expected proportions?

Answer 21

Parent genotypes are TtPp and TTpp; Offspring will be 50% tall purple, 50% tall white

Question 22

Two plants that are heterozygous for seed color (yellow is dominant, green is recessive) and seed texture (smooth is dominant, wrinkled is recessive) are crossed.

a. What percentage of the offspring would you expect to have smooth green seeds?

Answer 22

3/16 or 18.75%

Question 23

Two plants that are heterozygous for seed color (yellow is dominant, green is recessive) and seed texture (smooth is dominant, wrinkled is recessive) are crossed.

b. What percentage of the offspring would you expect to have wrinkled yellow seeds?

Answer 23

3/16 or 18.75%

Question 24

Two plants that are heterozygous for seed color (yellow is dominant, green is recessive) and seed texture (smooth is dominant, wrinkled is recessive) are crossed.

c. What percentage of their offspring would you expect to be heterozygous for both traits?

Answer 24

4/16 or 25%

Question 25

In a certain type of flower, the dominant color is blue (B) and the recessive color is red (b). Two heterozygote blue flowers are crossed.

a. What are the potential genotypes of this cross?

Answer 25

BB, Bb, and bb

Question 26

In a certain type of flower, the dominant color is blue (B) and the recessive color is red (b). Two heterozygote blue flowers are crossed.

b. What are the potential phenotypes of this cross if this trait exhibits simple dominance?

Answer 26

BB and Bb are blue, bb is red

Question 27

In a certain type of flower, the dominant color is blue (B) and the recessive color is red (b). Two heterozygote blue flowers are crossed.

b. What are the potential phenotypes of this cross if this trait exhibits co-dominance?

Answer 27

BB is blue, bb is red, and Bb is blue and red stripes or splotches (both homozygous phenotypes are expressed)

Question 28

In a certain type of flower, the dominant color is blue (B) and the recessive color is red (b). Two heterozygote blue flowers are crossed.

b. What are the potential phenotypes of this cross if this trait exhibits intermediate dominance?

Answer 28

BB is blue, bb is red, and Bb is purple (homozygous phenotypes blended)