本题目来源于试卷: Continuity and Change D.5 Gene Expression，类别为 IB生物学
[单选题]
Ligers are the offspring of a m6g 3o7 btzv1jnale lion and a female tiger. Tigons are the of x,-jxtamqy +qd9me(3fspring of a female lion and a male tiger. Ligers tend to be much larger and heavier than their parents, while this is not usually seen with tigoqyta3m x+9, dqm-(xjens. What is the best explanation for the large size difference between a liger in comparison to the parents?
A. Variation in the epigenetic tags removed from genes prior to zygote formation
B. The Y chromosome suppresses the X chromosome
C. Tigons are always female while ligers are always male
D. The chromosome number is different between female and male lions
参考答案: A
本题详细解析:
Choice A is correct because genes of sperm and ova in tigers and lions undergo varying rates of epigenetic tag removal. Choice B is incorrect. Although in some species sex is partially determined by the Y chromosome suppressing the X chromosome, this is not the reason for ligers being larger than their parents. Choice C is incorrect because both tigons and ligons can be both male and female. Choice D is incorrect because female and male lions have the same number of chromosomes.
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