The laws in plain words
Three short rules explain the crosses in this chapter. Independently means one pair's sorting does not change the other's.
- Dominance: one form of a gene can hide another.
- Segregation: a pair separates, and each parent passes one gene.
- Independent assortment: two gene pairs sort into gametes independently.
- Together, the three rules predict a cross before it is grown.
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Read the two parents. Tap what their seeds grow into.
The rule
A gamete is a sex cell, like an egg or a sperm. The three rules, in plain words:
Dominance: one form of a gene can hide another. Segregation: a pair separates, and each parent passes one gene. Independent assortment: two gene pairs sort into gametes independently.
Try Tt × tt. This means a Tt plant is crossed with a tt plant. Segregation says the Tt parent passes T or t, half each. The tt parent passes t every time. T with t makes Tt. t with t makes tt. So the seeds are Tt, Tt, tt and tt. Dominance says Tt is tall, because T hides t. Two of four seeds grow tall. Two of four grow short.
You can predict a cross before planting one seed.