Turner’s syndrome is an example of:

The number of sex chromosomes is normal in

Read the following statements and choose the correct set of statements :
$(a)$ In sickle cell anaemia the mutant haemoglobin molecule undergoes polymerisation under high oxygen tension
$(b)$ Thalassemia is a qualitative problem
$(c)$ Turner's syndrome,Klinefelter's syndrome are common examples of chromosomal disorders.
$(d)$ Haemophilia is a sex-linked recessive disease

The formation of multivalents at meiosis in a diploid organism is due to

Down's syndrome is caused by the trisomy of which chromosome pair?

In which of the following disorders does an affected individual possess $47$ chromosomes?