Monohybrid and Dihybrid Crosses

Front

What is a monohybrid cross?

Back

A genetic cross that involves one trait, such as pod shape.

Front

What are alleles?

Back

Different versions of a gene.

Front

What are the possible genotypes for a monohybrid cross of Tt x Tt?

Back

TT=25%, Tt=50%, tt=25%.

Front

What does the Law of Dominance state?

Back

A recessive allele is only expressed when a dominant allele is not present.

Front

What does heterozygous mean?

Back

Having two different alleles for a trait, such as Tt.

Front

What is a dihybrid cross?

Back

A genetic cross that involves two traits, such as seed shape and seed color.

Front

What is the phenotype ratio for a dihybrid cross of RrYy x RrYy?

Back

9:3:3:1.

Front

What is the difference between homozygous and heterozygous?

Back

Homozygous means having two identical alleles (e.g., TT or tt), while heterozygous means having two different alleles (e.g., Tt).

Front

What is a test cross?

Back

A cross between an individual with an unknown genotype and a homozygous recessive individual to determine the unknown genotype.

Front

What is the genotype for a purebred tall plant?

Back

TT.