Principles of Inheritance and Variation

Assertion : Down's syndrome, Klinefelter's syndrome and Turner's syndrome are chromosomal disorders. Reason : In Klinefelter's syndrome, females are sterile.

Which of the following is a sex linked character?

Assertion : Phenylketonuria, haemophilia and sickle cell anaemia are genetic disorders. Reason : In phenylketonuria, the person lacks an enzyme for the conversion of phenylalanine into tyrosine.

Assertion : Accumulation of phenyl pyruvic acid in brain results in mental retardation in case of phenylketonuria. Reason: The affected individual lacks enzyme for the conversion of phenylalanine into tyrosine.

When red and white flowered Mirabilis plants are crossed all pink flowers are seen in $F_1$ generation. When $\mathrm{F}_1$ progeny is selfed, the expected phenotypic and genotypic ratios are

Assertion : The strength of linkage will be more when the distance between two genes is greater. Reason : Crossing over will be relatively less frequent for distantly located genes.

Assertion : A person may be a haemophilic, only if his mother is a carrier or colourblind. Reason: The male parent cannot pass on a sex-linked gene to his son.

Assertion : In humans, the gamete contributed by the male determines whether the child produced will be male or female. Reason: Sex in humans is a polygenic trait depending upon a cumulative effect of some genes on…

Which of the following disorders are caused due to recessive autosomal mutations?

Assertion : Chimpanzee is the closest relative of the present day humans. Reason : .The banding pattern in some autosomes of man and chimpanzee is remarkably similar.

Assertion : XX-XY type of sex determination mechanism is an example of female heterogamety and is found in Drosophila. Reason : Male heterogamety is seen in moths where males produce two different types of gamete.

Which of the following conditions represents a case of codominant genes?