alleryStart learning →Two true-breeding pea plants with contrasting traits are cross-fertilised. What are all of the offspring?
AHeterozygous for the contrasting trait
BHomozygous for the recessive trait only
CHomozygous for the dominant trait only
DHalf homozygous and half heterozygous
Answer & Solution
Correct answer: A. Heterozygous for the contrasting trait
1. Each true-breeding parent is homozygous, so one can give only the dominant allele and the other only the recessive allele.
2. Every offspring therefore receives one of each, giving different alleles at that gene.
3. Different alleles at one gene is the definition of heterozygous.
4. No offspring can be homozygous, because neither parent can supply two of the same allele to one zygote.
5. That is why a half and half split is impossible from this pairing.
_Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 12 "Mendel's Experiments and Heredity", section 12.2 Characteristics and Traits_
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