(a)Haemophilia and colour blindness are x-chromosome linked recessive disorder. Males have only one copy of x-chromosome and one y-chromosome. The genes on these chromommee do not have corresponding alleles. Therefore, the presence of only single defective x-chromoeome will result in these disorders. Women can develop these disorders only when they have both the defective copies of x-chromosomes, which is rare. Since, the father passes on only the ychromosome to the son a son is not haemophiliac.
(b) (i) (a) tRNA-It acts as an adaptor molecule that picks up a particular amino acid from cellular pool and takes the same over to A site of mRNA for incorporation in the polypeptide chain.
(b) It recognises the codon on mRNA by its anticodon.
(ii) (a) rRNA-It constitutes the ribosomal structure.
(b) It helps to form peptide bond.
