Monohybrid Crosses and Punnett Squares

Monohybrid punnet squares

Learning objectives

SW learn how to create gametes on a four square Punnett square

SW identify genotypes and phenotypes in a Punnett square

SW identify genotypic and phenotypic rations

Multiple Choice

Heterozygous is when...

• the alleles are the same
• the alleles are different
• the alleles are absent
• the alleles are present

Multiple Choice

This type of allele masks the recessive allele and is capital ________________

• Dominant
• Homozygous
• Genotype
• Phenotype

Multiple Choice

What is a phenotype

• The genetic make up (code)
• The physical trait

Multiple Choice

What are different forms of a gene called?

• Alleles

• Chromosomes

• Factors

• Traits

Creating and Solving monohybrid Punnett squares

Please watch the directions twice and take notes- Questions to follow

Multiple Choice

What allele combination should go in the missing box?

• AA
• Aa
• aa
• none of these

Multiple Choice

T - tall and t = short
In the punnett square below, what belongs in the missing square

• tt
• Tt
• Bb
• TT

Multiple Choice

How many boxes would say BB?

• 1
• 2
• 4
• 0

Genotype and phenotype ratio and percentages

In four squares, each square represents 25% of the total or 1/4.

Multiple Choice

What are the chances that the offspring will have homozygous recessive traits?

• 1 in 4

• 3 out of 4

• 75%

• 50%

Multiple Choice

The dominant trait is

• yellow pea seeds
• green pea seeds
• there is no dominant seed
• Jolly green giant

Multiple Choice

The genotypic ratio here is

• 25% blue eye 75 % brown eye 
• BB = 25% Bb = 50% bb = 25%
• BB= 50 % bb = 50%
• All brown eye

Multiple Choice

What is the genotypic ratio represented by the punnett square?

• 1:1

• 3:1

• 1:3

• 1:2:1