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 the seed s p yld91r-e2bohtu2(+y5m mwnhape in indicr f.qq zlu,,7vidual pea plants was either round or wrinkled. The results of an experimental cross yielded 7fq,q, zrlu.c315 offspring with round seeds and 105 offspring 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.
| 
