Sex Chromosomes and Sex-Linked Genes — NEET Biology
📚 Practice ConceptMany genes were linked to sexes also, and called as sex-linked genes. The two sexes (male and female) were found to have a set of chromosomes which were common, and another set which were different. The chromosomes which were different in two sexes were named as sex chromosomes. The remaining set was named as autosomes. In humans, a normal female has 22 pairs of autosomes and a pair of sex chromosomes (XX). A male has 22 pairs of autosomes and a pair of sex chromosome as XY. In chicken, sex chromosomes in male are ZZ, and in females are ZY.
Which of the following statements are correct regarding chromosomal basis of sex determination and related inheritance patterns in human beings? S1. Human females are homogametic and produce only one type of gamete with respect to sex chromosomes. S2. Human males are heterogametic and produce two types of sperms differing in their sex chromosomes. S3. The probability of male or female child is determined at the time of fertilisation based on the type of sperm involved. S4. Mutations affecting genes on the Y chromosome can be inherited through both male and female lineages. S5. Sex-linked traits in humans are more commonly expressed in males due to their hemizygous condition for X-linked genes.
View solution & NCERT explanation
Correct answer: A — S1, S2, S3 and S5 are correct
In humans, sex determination follows the XX–XY type described by NCERT. S1 is correct because females are homogametic and produce only X-bearing ova. S2 is correct as males are heterogametic and produce X-bearing and Y-bearing sperms. S3 is correct since the fusion of either X- or Y-bearing sperm with the ovum determines the sex of the offspring at fertilisation. S4 is incorrect because genes on the Y chromosome are transmitted only from father to son and cannot pass through females. S5 is correct as males possess only one X chromosome, so recessive X-linked traits are expressed more frequently. Hence, option A correctly includes all true statements.
What does NCERT say about Many genes were linked?
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Through deep analysis of NEET and NTA, 176 of the 180 ReNEET 2026 (June 21) questions were already in the MedicNEET question bank before the exam.
176/180MedicNEET's Biology question bank is built from the same NCERT lines NTA picks repeatedly. Not random MCQs — questions crafted exactly like NTA crafts them.