Monohybrid Crosses Practice

Brown (B) is dominant over white (b). Which genotype is a purebred for brown fur?

• BB

• Bb

• bb

• All of the above

Tags

NGSS.HS-LS3-1

What is the genotypic ratio of the offspring?

• 3 AA : 1 aa

• 1 AA : 3 aa

• 1 AA : 2 Aa : 1 aa

• 2 AA : 2 aa

Tags

NGSS.HS-LS3-3

What are the phenotype percentages of the offspring?

• 50 % Brown fur and 50% White fur

• 25 % Brown fur and 75% White fur

• 75 % Brown fur and 25% White fur

• 0% Brown fur and 100% White fur

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

What allele combination should go in the missing box?

• AA

• Aa

• aa

• none of these

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

In Jessica's family gene pool, brown eyes are dominant, and blue eyes are recessive. Jessica is heterozygous for brown eyes and her husband is heterozygous for brown eyes. Complete the Punnett to show the possible genotypes for their baby.

e

f

g

d

c

a

b

bb

B (top)

BB

b (top)

B (side)

Bb

b (side)

Tags

112.34.c.6.F

What is the phenotypic ratio for the monohybrid cross between blue and brown eyes?

• 3:1

• 2:2

• 0:2:1

• 1:2:1

In a monohybrid cross between two heterozygous pea plants (Tt), what is the probability of producing a pea plant with tall stems (T-)? Scarlett and Kai are experimenting in their biology class to understand how traits are passed in pea plants. (T is dominant for tall stems, t is recessive for short stems.)

• 25%

• 50%

• 75%

• 100%

Answer explanation

The probability of producing a pea plant with tall stems (T-) in a monohybrid cross between two heterozygous pea plants is 75% because there is a 3/4 chance of getting the dominant allele for tall stems (T) in the offspring.

Tags

DOK Level 2: Skill/Concept

In cacti, long arms (A) are dominant to short arms (a).  Suppose 2 heterozygous cacti are crossed.  What percentage of their offspring are expected to have short arms?

• 0%

• 25%

• 75%

• 100%

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

NGSS.HS-LS3-3

having two of the same genes for the trait (sometimes called purebred).

• homozygous

• hetrozygous

• protein

• chromosome

Tags

NGSS.HS-LS3-1

Which of the following genotypes is a purebred?

• Bb

• Gg

• bb

• Dd