Tag: bio-chemistry

Questions Related to bio-chemistry

Select the correct match.

  1. Sec-Limited trait: Colour blindness

  2. Sex-Limited trait: Express in both sex

  3. Sex-Influenced trait: More frequent in one sex than in the other

  4. Sex-influenced trait: Porcupine skin

Correct Option: A

Haemophilia is?

  1. Sex linked

  2. Sex limited

  3. Autosomal recessive

  4. Autosomal dominant

Correct Option: A

Haemophilia is a?

  1. X-linked dominant

  2. Autosomal dominant

  3. X-linked recessive

  4. Autosomal recessive

Correct Option: A

A daughter will not normally be colourblind, unless her mother is ...... and her father is ....

  1. Carrier, colour blind

  2. Colour blind, normal

  3. Colour blind, carrier

  4. Carrier, carrier

Correct Option: A

Daughters inherit x chromosomes of father & mother respectively since one x chromosome masks the effect of another x chromosome, a daughter will only be colourblind if her mother is a carrier & father is colorblind.

So, the correct option is 'Carrier, colour blind'.

Select the incorrect statement from the following :

  1. Baldness is a sex limited trait

  2. Linkage is an exception to the principle of independent assortment in heredity.

  3. Galactosemia is an inborn error of metabolism

  4. Small population size results in random genetic drift in a population

Correct Option: A

If both parents are bald and their first female child is normal, then the chances of baldness in their second male child is?

  1. $50$%

  2. $100$%

  3. $25$%

  4. $0$%

Correct Option: B

The most common type of haemophilia is due to congenital absence of

  1. Factor II

  2. Factor V

  3. Factor VIII

  4. Factor XI.

Correct Option: C

The possibility of a female becoming haemophilic is extremely rare because the mother of such a female has to be at least (i) and father should be (ii). 

  1. (i) Haemophilic, (ii) Carrier

  2. (i) Carrier, (ii) Haemophilic

  3. (i) Haemophilic, (ii) Normal

  4. (i) Haemophilic, (ii) Haemophilic

Correct Option: B

  • Haemophilia is genetically due to the presence of a $recessive$ sex-linked gene h, carried by the X chromosome. 
  • A female becomes haemophilic only when both Its X chromosomes carry the gene $(XhXh)$. However, such females (mothers) generally die before birth because the combination of these two recessive alleles is lethal. A female having only one allele for haemophilia $(XX^h)$ appears normal because of the allele for normal blood clotting present on the other X-chromosome is dominant. Such females are known as carriers. 
  • In the case of males, a single gene for the defect is able to express itself as the Y-chromosome is devoid of any corresponding allele $(Xh^Y)$.
  • Thus, the possibility of a human female becoming haemophilic is extremely rare because she has to be homozygous recessive for the trait, i.e., her father must be a haemophilic and mother must be at least a carrier.

Which one of the following is a genetically transmitted character?

  1. Colourblindness

  2. Hydrocephalus

  3. Haemophilia

  4. Muscular dystrophy

Correct Option: A

Correct pathway for synthesis of skin pigment is?

  1. Tyrosine - dopa - melanin - dopaquinone

  2. Tyrosine - dopaquinone - dopa - melanin

  3. Dopa - tyrosine - dopaquinone - melanin

  4. Tyrosine - dopa - dopaquinone - melanin

  5. Tyrosine - melanin - dopaquinone - dopa.

Correct Option: D