An insect species is discovered in which the heterogametic sex is unknown. An X-linked recessive mutation for reduced wing (rw) is discovered. Contrast the F₁ and F₂ generations from a cross between a female with reduced wings and a male with normal-sized wings when the male is the heterogametic sex.

Video transcript

Everyone. Let's take a look at this question together in the absence of any knowledge of hetero gammy, dick sex, what would be the expected sex ratio in the offspring of a cross between a male and female insect? So we know that the sex chromosomes determine the sex of the progeny, and we know that these sex chromosomes differ among species, meaning that depending on the species, the male or female can be the hetero comedic sex, for example, in fish and birds, it is the female, but in other species it could be the male. And since we have the absence of any knowledge of hetero comedic sects, and we do not know what the insect is, there's no way to determine what the expected sex ratio in the offspring of a cross between a male and a female insect would be. So, answer choice D. Cannot be determined is the correct answer, because the sex ratio cannot be predicted without knowledge of the specific insect species that is used in this cross. And so the expected sex ratio of their offspring cannot be determined. So answer choice D. Is the correct answer. I hope you found this video to be helpful. Thank you and goodbye.