Dominant and Recessive Traits (Part 3)

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

recessive
life cycle
adaptation

Materials Needed

index cards
markers
ruler

Safety First

Wash hands after handling materials.
Be careful with scissors — ask an adult for help if needed.
Do not look directly at the sun or bright lights.

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?