本题目来源于试卷: Continuity and Change D.8 Inheritance，类别为 IB生物学
[单选题]
Mendel observed that 3*gl5 ho. xbzxth1 w8sundzvb1h1psspc28mz *a u(fc 41 e seed shape in individual pea plants was either round or wrinkled. The results of an experimental cross yielded 315 offspring with round seeds and 105 offspring8cp8samhfz b 2wu1nc d(s1su *vz41p1 with wrinkled seeds.
Which row in the table below states the most likely genotypes of the parents?
A. Parent I is RR; Parent II is rr
B. Parent I is Rr; Parent II is rr
C. Parent I is Rr; Parent II is Rr
D. Parent I is Rr; Parent II is RR
参考答案: C
本题详细解析:
315:105 simplified is 3:1. In a monohybrid cross, 3:1 is the expected phenotypic ratio of offspring from two heterozygous parents (Choice C). Choice A is incorrect, because a cross between a homozygous dominant parent (RR) and a homozygous recessive parent (rr) would result in all offspring having smooth seeds. Choice B is incorrect, because a cross between a heterozygous parent (Rr) and homozygous recessive parent (rr) would produce the phenotypic ratio of 1:1 among offspring. Choice D is incorrect, because a cross between a heterozygous parent (Rr) and a homozygous dominant parent (RR) would result in all offspring having round seeds.
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