Genetics for Kids: Dominant and Recessive Traits with Punnett Squares (Grade 7 Science)

Hi, I'm Luna from DoodleBeez. Today we are learning about genetics. Why do living things look a bit like their parents? The answer is hidden in tiny instructions called genes.

A trait is a feature, like flower color or seed shape. Traits are controlled by genes, which are made of DNA. For most genes, you get two copies, one from each parent.

Some versions of a gene are dominant. A dominant version shows up even if you have just one copy. A recessive version only shows up when you have two copies, so it can hide for generations.

Scientists use letters. A capital letter is dominant, and a small letter is recessive. In pea plants, purple flowers are dominant, so we write big P. White flowers are recessive, small p.

To predict offspring, we use a Punnett square. Say both parent plants are big P, small p. We write one parent's letters across the top, and the other parent's letters down the side.

Fill each box with one letter from the top and one from the side. We get one big P big P, two big P small p, and one small p small p. So three in four are purple, and one in four is white.

Now it's your turn. One parent is big P big P. The other is small p small p. What color will the offspring flowers be? Pause and try. All purple! Every box gets big P small p, and purple is dominant.

Great job! Remember, genes come in pairs, one from each parent. Dominant traits show with one copy, recessive traits need two, and a Punnett square helps predict offspring. Practice genetics in the Science Lab at doodlebeez.com. See you next time!