Monohybrid Crosses

The physical expression of a genetic trait is called a

• mutation

• genotype

• crossing over

• phenotype

AA and Aa always show up as

• dominant
• recessive

What ratio of the offspring from the cross shown will be homozygous recessive for the  trait of tallness? 

• 0 in 4
• 1 in 4
• 2 in 4
• 4 in 4

In a heterozygous genotype, the ___________ allele takes over in the phenotype.

• recessive
• dominant
• lower case letter
• both 

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

• tt
• Tt
• Bb
• TT

B = brown eyes
b = blue eyes
What is true about these two brothers that have brown eyes?
One has genotype BB the other Bb.

• they have same phenotype and genotype
• they have different genotypes and phenotypes
• they have same phenotype but different genotypes
• they have same genotype but different phenotypes

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

• 0%
• 25%
• 50%
• 75%

In plants, tall (T) is dominant to short (t). Perform the following cross: Tt x Tt. What is the probability of producing a short plant?

• 0%
• 25%
• 50%
• 75%

What is the probability of heterozygous offspring?

• 25%
• 50%
• 0%
• 100%

What allele combination should go in the missing box?

• AA
• Aa
• aa
• none of these