本题目来源于试卷: Continuity and Change D.8 Inheritance，类别为 IB生物学
[单选题]
There are two alleles f l0f v kd,e4 .wq2yr6zbt3v1kfor flower colour96fhhoghbp * n40*jp6s,f fha in snapdragons. However, the result of a cross between two heterozygous plants yielded offsprinajof9,hf*b6 *6p0hf p hn4 hsgg with three different observed phenotypes, red, white and pink flowers. Which is the most likely explanation for this observation?
A. One allele is dominant to the other.
B. There is codominance between alleles.
C. There is incomplete dominance between alleles.
D. The alleles are sex-linked.
参考答案: C
本题详细解析:
If there are two alleles for a gene, but there are three possible phenotypes, this could suggest incomplete dominance (Choice C). This is when the dominant allele doesn’t completely suppress the effects of the recessive allele. Choice A is incorrect because if one allele was completely dominant over the other, then there would only be two possible phenotypes. Choice B is incorrect because if the alleles were codominant, then we would see both expressed in the phenotype. In this case, some petals would be white and others red, instead of the flower being pink. Choice D is incorrect because sex-linkage does not create an additional phenotype.
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