Pre-Assessment: Mendelian Crosses

Front

What is a genotype?

Back

A genotype is the genetic makeup of an organism, represented by the alleles it possesses for a particular trait.

Front

What is a phenotype?

Back

A phenotype is the observable physical or biochemical characteristics of an organism, determined by its genotype.

Front

What does homozygous mean?

Back

Homozygous refers to having two identical alleles for a particular gene (e.g., BB or bb).

Front

What does heterozygous mean?

Back

Heterozygous refers to having two different alleles for a particular gene (e.g., Bb).

Front

What is the principle of dominance?

Back

The principle of dominance states that in a heterozygous genotype, one allele may mask the expression of another allele.

Front

What is a Punnett square?

Back

A Punnett square is a diagram used to predict the genotypes of offspring from a genetic cross.

Front

What is the expected phenotypic ratio from a cross between two heterozygous parents (Bb x Bb)?

Back

The expected phenotypic ratio is 3:1 (3 dominant: 1 recessive).

Front

What is the expected genotypic ratio from a cross between two heterozygous parents (Bb x Bb)?

Back

The expected genotypic ratio is 1:2:1 (1 BB: 2 Bb: 1 bb).

Front

What is the expected phenotype of offspring from a cross between a homozygous dominant (TT) and a homozygous recessive (tt) plant?

Back

The expected phenotype is 100% tall plants.

Front

What is the expected percentage of heterozygous offspring from a cross between a heterozygous parent (Dd) and a homozygous dominant parent (DD)?

Back

The expected percentage of heterozygous offspring is 50%.