Non-disjunction of X-chromosomes during meiosis in the formation of ovum leads to _________ syndrome.

Chromosomal basis of inheritance suggested by Sutton and Boveri is based on ________

Observe the given figure of Morgan's experiment for yellow body and white eyed female Drosophila crossed with brown body and red eyed male Drosophila. What will be the percentage of parental type in $F_2$ generation?

Choose the correct statement(s) with respect to Down's syndrome

i. Down's syndrome results from non-disjunction of $21^{\text {st }}$ chromosome during gamete formation.

ii. Down's syndrome is a sex chromosomal disorder observed in immature mothers who are below the age of 18 .

iii. These patients have mild mental retardation, poor skeletal development, flat hands, stubby fingers and palms are broader.

iv. The have 44 A with XO type of karyotype.

v. The risk of giving birth to a Down Syndrome child is more in mothers who are over 45 years of age.