A person who is trisomic for twenty first pair of chromosome suffers from
Klinefelter's syndrome
Down's syndrome
Turner's syndrome
None of the above
B.
Down's syndrome
Down's syndrome(45 + XXor45 + XY) is the case when there is one extra chromosome in 21st pair of autosome. It is also called trisomy 21 or trisomy-G. It is most common in children of over aged mothers (above 41 years). It is also called Mongolian syndrome.
Which of the following conditions represents a case of codominant genes
A gene expresses itself, suppressing the phenotypic effect of its alleles.
Genes that are similar in phenotypic effect when present separately, but when together interact to produce a different trait.
Alleles, both of which interact to produce a trait, which may or may not resemble either of the parental types.
Alleles, each of which produces an independent effect in a heterozygous condition.
If a plant having yellow or round seeds was crossed with another plant having green and wrinkled seeds then F, progeny are in the ratio
15 : 1
1 : 15
1 : 13
all yellow and round seeds
Which one of the following can help in the diagnosis of a genetical disorder?
ELISA
ABO blood group
PCR
NMR
When paternal and maternal chromosomes change their materials with each other in cell division this event is called
synapsis
crossing over
bivalent forming
dyad- forming
The children of a haemophilic man and a normal woman are
all haemophilic
only daughters are haemophilic
only sons are haemophilic
neither sons nor daughters are haemophilic
A man of blood group 'A', marries a woman of blood group 'B', both of them are heterozygous for blood group, chances of their first child having blood group AB will be
25%
50%
75%
100%