Punnett Square Practice Quiz & Answers To Learn

1. Tall is dominant to short. A homozygous tall plant is crossed with a short plant. What will be the phenotypes of the offspring?

100% tall (correct answer)
50% tall, 50% short
75% tall, 25% short
25% tall, 75% short

2. Green is dominant to yellow. Two heterozygous green plants are crossed. What are the genotypes of the offspring?

100% Gg
50% GG, 50% Gg
25% GG, 50% Gg, 25% gg(correct answer)
75% Gg, 25% gg

3. Purple is dominant to white. A heterozygous purple flower is crossed with a white flower. What are the genotypes and phenotypes of the offspring?

100% Pp (purple)
50% Pp (purple); 50% pp (white)(correct answer)
75% Pp (purple); 25% pp (white)
25% PP, 50% Pp, 25% pp
75% purple, 25% white

4. In humans, brown eyes are dominant over blue eyes. What would be the allele key you would make from this information?

B-brown b-blue(correct answer)
B-blue b-brown
BB-brown Bb-blue
bb-brown Bb-blue

5. If brown eyes are dominant over blue eyes, what would be the parent genotypes if two heterozygous brown-eyed persons were crossed?

BB and bb
BB and Bb
Bb and Bb(correct answer)
bb and Bb

6. If brown eyes are dominant to blue eyes, what would be the genotype of the offspring if a homozygous brown-eyed individual is crossed with a homozygous blue-eyed?

BB
bb
Bb(correct answer)
BB and bb

7. G = green, g = yellow The genotype for a yellow plant is…

GG
Gg
gg(correct answer)
all of the choices result in yellow

8. B = brown fur b = white fur In the punnett square, what is the probability for white fur?

0%
25%
50%(correct answer)
75%

9. Which of the following alleles is homozygous (purebred) recessive?

Tt
tt(correct answer)
TT
t

10. Aa is

homozygous (purebred)
heterozygous (hybrid)(correct answer)

11. Which of the following is a phenotype?

Aa
red hair(correct answer)
heterozygous
DNA

12. If Spongebob is homozygous for a yellow body (yellow dominant over blue), then his genotype would be …

Yy
yy
YY(correct answer)
Yb

13. In the punnett square shown, what must the genotype of the missing parent be?

BB
Bb(correct answer)
bb
Tt

14. In the punnett square shown, what is the genotypes of the two parents?

RW and RR
RW and WW
RR and WW(correct answer)
RW and RR

15. T = tall an t = short TT and Tt would result in the following phenotype

short
tall(correct answer)
both tall and short
neither tall or short

16. An allele whose trait only shows up when no dominant allele is present.

hidden allele
dominant allele
recessive allele(correct answer)
present allele

17. Two brown-eyed parents (Bb) have a baby. What is the chance the baby is blue-eyed?

0 %
25%(correct answer)
50%
75%

The trait that shows outwardly in the first (F1) generation (offspring).

Answer: dominant

The one trait that did not show outwardly but is still in the genes.

Answer: recessive

Codes for a trait. Each cell has two copies.

Answer: gene

Single copy of a gene. Each gene has two alleles.

Answer: allele

An individual who has two of the same alleles for a trait. Both capital or both lower case

Answer: homozygous

An individual with two different alleles for a trait. One capital and one lower case.

Answer: heterozygous

The set of genes (alleles) a person possesses.

Answer: genotype

The physical appearance that is determined by the genes.Phenotype

Answer: phenotype

Tall is dominant (T). Short is recessive (t). What is the phenotype of “Tt”?

Answer: tall

Tall is dominant (T). Short is recessive (t). What is the phenotype of “TT”?

Answer: tall

Tall is dominant (T). Short is recessive (t). What is the phenotype of “tt”?

Answer: short

Purple flowers are dominant (P). White flowers are recessive (p). What is the phenotype of “PP”?

Answer: purple

Purple flowers are dominant (P). White flowers are recessive (p). What is the phenotype of “Pp”?

Answer: purple

Purple flowers are dominant (P). White flowers are recessive (p). What is the phenotype of “pp”?

Answer: white

Yellow is dominant (Y). Green is recessive (y). What is the genotype of a heterozygous parent?

Answer: Yy

Yellow is dominant (Y). Green is recessive (y). What is the genotype of a homozygous dominant parent?

Answer: YY

Yellow is dominant (Y). Green is recessive (y). Create a Punnet Square to answer. What is the probability of an offspring of homozygous dominant parent and a heterozygous parent being yellow.

Answer: 1

Yellow is dominant (Y). Green is recessive (y). Create a Punnet Square to answer. What is the probability of an offspring of homozygous dominant parent and a heterozygous parent being green.

Answer: 0

Yellow is dominant (Y). Green is recessive (y). What is the genotype of a homozygous recessive parent?

Answer: yy

Round eye shape is dominant (R). Oval eye shape is recessive (r). What trait will be expressed (seen/phenotype) in a heterozygous parent?

Answer: round

Round eye shape is dominant (R). Oval eye shape is recessive (r).What trait will be expressed (seen/phenotype) in a homozygous recessive parent?

Answer: oval

Round eye shape is dominant (R). Oval eye shape is recessive (r).What trait will be expressed (seen/phenotype) in a homozygous dominant parent?

Answer: round

Round eye shape is dominant (R). Oval eye shape is recessive (r).What trait will be expressed in “Rr”?

Answer: round

Round eye shape is dominant (R). Oval eye shape is recessive (r).What trait will be expressed in “rr”?

Answer: oval

Round eye shape is dominant (R). Oval eye shape is recessive (r).What trait will be expressed in “RR”?

Answer: round

Which is the dominant allele? “Tt”

Answer: T

Which is the recessive allele? “Tt”

Answer: t

Is the allele pair heterozygous, homozygous dominant, or homozygous recessive? “OO”

Answer: homozygous dominant

Is the allele pair heterozygous, homozygous dominant, or homozygous recessive? “rr”

Answer: homozygous recessive

Is the allele pair heterozygous, homozygous dominant, or homozygous recessive? “Pp”

Answer: heterozygous

Traits represented by a lowercase letter (b).

Answer: recessive

Traits represented by a CAPITAL letter (B).

Answer: dominant

Genetics

Answer: Scientific study of heredity.

Trait

Answer: A characteristic that an organism can pass on to its offspring through its genes.

Cross-fertilization

Answer: Fertilization of a plant by pollen from a different plant

Hybrid

Answer: 2 different alleles

Monohybrid Cross

Answer: A cross between two individuals, concentrating on only one definable trait

Allele

Answer: An alternative form of a gene.

Homozygous

Answer: An organism that has two identical alleles for a trait

Heterozygous

Answer: An organism that has two different alleles for a trait

Dominant

Answer: Describes a trait that masks the other

Recessive

Answer: An allele for a trait that will be masked unless the organism is homozygous for this trait.

Punnett Square

Answer: A tool to predict the probability of certain traits in offspring that shows the different ways alleles

can combine

Phenotype

Answer: An organism’s physical appearance, or visible traits.

Genotype

Answer: An organism’s genetic makeup, or allele combinations.

Testcross

Answer: An individual of unknown genotype is crossed with a homozygous recessive individual

Dihybrid cross

Answer: Cross between two organisms where two distinct traits are being studied.

The principals of dominance, segregation, and independent assortment were described by _________________ .

Answer: Gregor Mendel

When chromosomes do not split correctly and can result in a genetic disorder, this is a cause of ___________________

Answer: Nondisjunction

Genetic diversity is a result of

Answer: Crossing over

A cross between homozygous purple-flowered and a homozygous white-flowered pea plants results in offspring with purple flowers. This demonstrates _________________

Answer: Dominance

Genotype

Answer: The genes of a organism that for one specific trait we use 2 letters to represent the genotype

Capital Letter

Answer: Represents the dominant form of a gene

Lower Case Letter

Answer: Abbreviation for the recessive form of the gene

Phenotype

Answer: Physical appearance of a trait in an organism

Alleles

Answer: Two forms of the same gene Alleles for a trait are located at corresponding positions on homologs chromosomes

Symbol Genotype Name Phenotype

Answer: RR Homozygous (Pure Dominat) Red Thoat

Symbol

Genotype Name

Phenotype

Answer: Rr

Heterogenous (Hybrid)

Red Thoat

Symbol

Genotype Name

Phenotype

Answer: rr

Homozygous (Pure Recessive)

Answer: White Thoat

Why do we use two codes for the same trait?

Answer: We use two forms of the same Capital and Lower Case Letter

What are the steps to accurately make a Punnett Square?

Answer: 1. Determine genotypes of the parent organisms

2. Write down cross

3. Draw a square

4. Split the letters of the genotype for each parent and put them outside the “P” square

5. Determine the possible genotypes of the offspring by filling in the “P” square

6. Summarize the results

What are the Parent Pea Plants?

Answer: P Generations

What is the Genotype for the Parent Pea Plants?

Answer: Tt x tt

What is the Phenotype for the Parent Pea Plants?

Answer: Tall x Short

What are the Offsprings?

Answer: F1 Generations

What is the Genotype for the Offsprings?

Answer: 50% (2/4) = Tt

50% (2/4) = tt

What is the Phenotype for the Offsprings?

Answer: 50% = Tall

50% = Short

Answer: Homozygous= Pure

Answer: Heterogenous= Hybrid

Answer: Homozygous= Pure

Hair texture exists at two alleles

Answer: One curly code; One straight code

aBcdeF

Answer: ABcDef

Each letter on the diagram stands for a allele gene

Answer: These are a pair of homologous chromosomes

Homologous Chromosomes

Answer: Same size and same genetic info

What can letters be?

Answer: Capital or Lower Case

Homozygous

Answer: Two of the same alleles in the genotype (2 big letters or 2 little letters)

Heterozygous

Answer: One allele in the genotype

Ex: Cc

Mendel’s First Law: Law of Dominance

Answer: Cross parents that are pure for contrasting traits, only one form of the trait will appear in the next generation. Offspring that are are hybrids for a trait will have only dominant trait in the phenotype

Mendel’s Second Law: Law of Segregation

Answer: During the formation of gametes, the two alleles responsible for a trait separate from each other. After, traits are recombined at fertilization producing the genotype for the traits off the offspring

Done after F1 offspring

Miosis

Answer: Sex cells each separate

Mendel’s Third Law: Law of Independent Assortment

Answer: Alleles for different traits are distributed to sex cells independently off of one another

Dyhybird Cross

Answer: Parents are hybrid for two different traits

RrGg x RrGg = dealing with two different traits

Law:

Parent Cross:

Offspring:

Answer: Dominance

TT x tt = Tall x Short

100% TT = Tall

Law:

Parent Cross:

Offspring:

Answer: Segregation

Tt x Tt = Tall x Tall

75% = Tall

25% = Short

Law:

Parent Cross:

Offspring:

Answer: Independent Assortment

RrGg x RrGg