Biology / Unit 5 Bio 1045 short lesson, about 20 seconds
Lethal Alleles
Captions available
The idea
A lethal allele causes death, often in the homozygous state, before or shortly after birth, skewing an observed offspring ratio from its expected value.
In practice
A cross expected to produce a 1:2:1 genotype ratio can appear as 2:1 if the homozygous class dies before birth uncounted.
Where people slip
A skewed ratio is evidence to investigate, not evidence Mendelian inheritance failed — segregation still holds.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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