Monohybrid and Dihybrid Crosses

A __________ cross is cross between organisms that expressed two different traits.

• monohybrid

• multihybrid

• polyhybrid

• dihybrid

In a dihybrid cross

• one trait is crossed.
• two traits are crossed.
• four boxes are needed for the punnett square.
• mom's alleles are dominant.

What goes in box 3

• Aabb
• AABB
• AAbb
• aaBb

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

What goes in box 15

• aabb

• AABB

• aaBB

• AAbb

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

Members of the _____ generation in a Dihybrid cross showed the phenotypic ratio of 9:3:3:1

• F1

• F2

• F3

• F0

Tags

NGSS.HS-LS3-2

Cross Two Homozygous plants
(RRYY x rryy)
R = round seeds, r  = wrinkled seeds Y = yellow seeds, y = green seeds
What percent will have Round and Yellow seeds? 

• 0%
• 25%
• 50%
• 100%

Cross Two Heterozygous plants
(RrYy x RrYy)
R = round seeds, r  = wrinkled seeds Y = yellow seeds, y = green seeds
What percent will have Round and Yellow seeds? 

• 25%

• 50%

• 75%

• 100%

Tags

NGSS.HS-LS3-3

Cross Two Heterozygous plants
(RrYy x RrYy)
R = round seeds, r  = wrinkled seeds Y = yellow seeds, y = green seeds
What percent will have green seeds? 

• 25%

• 50%

• 75%

• 100%

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

NGSS.HS-LS3-3

Tomato plants usually have hairy stems. Hairless stems are present in tomato plants that are homozygous recessive for this trait. If the stem characteristics are determined by a single gene, what are the expected phenotype percentages for the offspring of a heterozygous hairy plant and a hairless plant?

• 100% hairy, 0% hairless
• 75% hairy, 25% hairless
• 50% hairy, 50% hairless
• 25% hairy, 75% hairless

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

In pea plants tall stems(T) are dominant over short stems(t) and round seeds(R) are dominant over wrinkled seeds(r). Consider the following cross: TtRr X Ttrr

a. Find the number of possible phenotypes

• 2

• 4

• 6

• 8

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2