Question in image

Question in image [58. W •ch of the following IS correct with respect to sex linked inheritance : other passes the sex linked trait to sons only (2) Dominant sex linked alleles express more in males (3) Sex linked allele can transmitted from father to son (4) Shows similar results for reciprocal crosses

Dear student, 
In sex linked inheritance, if the defect is in the X chromosome of mother, then expression in son is inevitable, irrespective of whether it is dominant or recessive. However the dominant gene in the mother can also express in daughter. Hence, option (1) is incorrect. 
Dominant sex linked alleles can be transferred to son or daughter from mother or father as dominant genes always express themselves in both. Option (2) is incorrect. 
Sex linked allele is transmitted from father to son in Y-chromosomes linked disorders as the son gets Y-chromosome only from father and there is only one copy of the gene. Option (3)is correct. 
Reciprocal crossing is when the female and male counterparts are exchanged. This does not work in sex-linked disorders as parents cannot be exchanged due to allosomal difference. Option (4) is incorrect. 
Regards. 

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