Flashcard #6 - Genetics & Punnett Squares

Front

What is a genotype?

Back

A genotype is the genetic makeup of an organism, represented by the alleles it possesses (e.g., BB, Bb, bb).

Front

What is the difference between homozygous and heterozygous?

Back

Homozygous means having two identical alleles for a trait (e.g., BB or bb), while heterozygous means having two different alleles (e.g., Bb).

Front

What does it mean for an allele to be dominant?

Back

A dominant allele is one that expresses its trait even when only one copy is present (e.g., T in Tt).

Front

What does it mean for an allele to be recessive?

Back

A recessive allele only expresses its trait when two copies are present (e.g., tt).

Front

How do you set up a Punnett square?

Back

A Punnett square is set up by placing one parent's alleles along the top and the other parent's alleles along the side, then filling in the squares to show possible offspring genotypes.

Front

What is the probability of producing a homozygous recessive offspring from a Tt x Tt cross?

Back

The probability is 25%.

Front

What are the possible genotypes from a Tt x Tt cross?

Back

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

Front

What is the phenotype of a plant with genotype Tt?

Back

The phenotype is tall, as tall (T) is dominant over short (t).

Front

What is the expected genotype ratio from a cross between a homozygous dominant (TT) and a homozygous recessive (tt) plant?

Back

The expected genotype ratio is 100% Tt.

Front

What is the expected phenotype ratio from a cross between Tt and tt?

Back

The expected phenotype ratio is 50% tall and 50% short.