Dominant and Recessive Traits (Part 5)

What You'll Learn

Dominant alleles are expressed when present, while recessive alleles are only expressed when two copies are present. A person with one dominant and one recessive allele shows the dominant trait.

Key Words

mitosis
meiosis
trait

Materials Needed

scissors
microscope (or magnifying glass)
slides
onion skin
iodine stain

Safety First

Tie back long hair before starting the experiment.
Protect your work surface with newspaper or plastic.

Steps

Step 1 — Read

Read and learn: Dominant alleles are expressed when present, while recessive alleles are only expressed when two copies are present. A person with one dominant and one recessive allele shows the dominant trait.

Step 2 — Do

Repeat the experiment two more times for accuracy.

Step 3 — Observe

Note any unexpected results.

Step 4 — Record

Share your findings with the class or a partner.

Check Your Understanding

Question 1

1 of 3

What is a dominant trait?