Monohybrid Cross Worksheet

Monohybrid Cross Worksheet

Read each question carefully and answer to the best of your ability. Use Punnett squares where appropriate to show your work.

Complete the following sentences with the correct term.

1. A   is a cross involving a single pair of contrasting traits.

2. An organism with two identical alleles for a trait is said to be  .

3. The observable characteristics of an organism are referred to as its  .

4. The genetic makeup of an organism is called its  .

1. Which of the following describes a homozygous recessive genotype?

In pea plants, tall (T) is dominant over short (t). Cross a homozygous tall pea plant with a homozygous short pea plant.

1. What are the genotypes of the parent plants?

2. Draw a Punnett square for this cross.

3. What is the phenotypic ratio of the offspring?

4. What is the genotypic ratio of the offspring?

Indicate whether each statement is True or False.

1. A recessive allele will always be expressed if present in the genotype.

2. Mendel's Law of Segregation states that two alleles for a heritable character separate (segregate) during gamete formation and end up in different gametes.

In humans, having a widow's peak (W) is dominant over a straight hairline (w). A man with a homozygous dominant genotype for a widow's peak marries a woman with a straight hairline.

1. What are the genotypes of the parents?

2. What is the probability that their first child will have a straight hairline?

3. What is the probability that their first child will have a widow's peak?