Resemble both, match neither
Show on a big screenTwo pea plants are crossed. Crossing means moving pollen from one plant to the other. The seeds are round and yellow. Neither parent was both round and yellow. Plants and seeds that come from a cross are its offspring.
- Parent A: round, green.
- Parent B: wrinkled, yellow.
- Every offspring seed is round, like Parent A.
- Every offspring seed is yellow, like Parent B.
- No seed matches either parent's whole look.
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Read the cross. Tap the parent that answers.
The rule
A gene is one unit of instruction for a trait. A trait is a feature, like seed shape or colour. Each trait has two gene copies, one from each parent. One copy can hide the other. A child may match one parent in shape. It may match the other in colour.
In the picture, the seed is round and yellow. Parent A gave a round copy. Parent B gave a yellow copy. Each parent also gave a copy that stays hidden. In shape, the round copy hides the wrinkled copy. In colour, the yellow copy hides the green copy.
Watch out!
A child is not a blend, like mixed paint. For each pea trait, a seed shows one parent's form. A seed is round or wrinkled, not half and half.
Try the lab to finish this lesson.