- Three alleles namely Ia, Ib and i control the blood grouping
in human beings. How many different genotypes are likely to
be present in the human population?
(a) 2 (b) 4
(c) 5 (d) 6
(e) 7 (Kerala PMT 2015)
- Identify the wrong statement.
(a) alleles b and c also produce sugar.
(b) alleles Ia and Ib produce sugars.
(c) When Ib and b or i are present only Ib is expressed.
(d) both Ia and Ib are present together and they express
because of co-dominance.
(Karnataka CET 2015)
- fruit colour in squash is an example of
(a) recessive epistasis
(b) dominant epistasis
(c) complementary genes
(d) inhibitory genes. (AIPMT 2014)
- In a dihybrid cross between two heterozygotes aabb × aabb,
if we get 3 : 1 ratio among the offsprings, the reason for this
may be
(a) polygenes (b) linked genes
(c) pleiotropic genes (d) hypostatic genes.
(AMU 2014)
- Multiple allelism is observed in
(a) flower colour in Snapdragon
(b) pod colour in Pisum sativum
(c) haemophilia in man
(d) sex determination in birds
(e) abO blood types. (Kerala PMT 2014)
- Two plants one with black flower and other with white
coloured flower were crossed in an experiment. In the next
generation grey coloured flowers were obtained. The reason
for the result is
(a) incomplete dominance
(b) pseudodominance
(c) codominance
(d) none of the above. (J & K 2014)
- Select the incorrect statement with regard to haemophilia.
(a) It is a dominant disease.
(b) a single protein involved in the clotting of blood is affected.
(c) It is a sex-linked disease.
(d) It is a recessive disease.
(NEET 2013)
- If two persons with ‘ab’ blood group marry and have
sufficiently large number of children, these children could be
classified as ‘a’ blood group: ‘ab’ blood group : ‘b’ blood group
in 1 : 2 : 1 ratio. Modern technique of protein electrophoresis
reveals presence of both ‘a’ and ‘b’ type proteins in ‘ab’ blood
group individuals. This in an example of
(a) partial dominance (b) complete dominance
(c) codominance (d) incomplete dominance.
(NEET 2013)
- With regard to the abO blood typing system, if a man who
has type b blood and a woman who has type O blood were
to have children, what blood types could the children have?
(a) a or O (b) b or O
(c) ab or O (d) a, b, ab or O
(Karnataka 2012)
Assertion & Reason
The following questions consist of two statements each : assertion
(a) and reason (r). To answer these questions, mark the correct
alternative as directed below :
(a) If both a and r are true and r is the correct explanation
of a.
(b) If both a and r are true but r is not the correct explanation
of a.
(c) If a is true but r is false.
(d) If both a and r are false.
- Assertion (A) : In intragenic interaction, two alleles of a
gene present on the same gene locus on the two homologous
chromosomes, interact in such a way so as to produce a different
phenotypic expression, e.g., incomplete dominance.
Reason (R) : In intergenic interaction, two or more independent
genes present on same or different chromosomes interact to
produce a different phenotypic expression, e.g., epistasis.
- Assertion (A) : Dominant lethal alleles rarely exist in a
population.
Reason (R) : for dominant lethal alleles to exist in a
population, the affected individual must reproduce before it
dies.
- Assertion (A) : f 2 phenotypic and genotypic ratios are 1 : 2 : 1
both in incomplete dominance as well as in codominance.
Reason (R) : In codominance, the two alleles of an allelic
pair interact to produce an intermediate phenotype, whereas
in incomplete dominance, the expressed phenotype is a
combination of the phenotypic traits produced by either of
the alleles in homozygous condition.
- Assertion (A) : Sex-linked allele of a trait is not usually
passed on from the father to his son.
Reason (R) : Human males have only one X-chromosome
which is transferred to the female offspring.
- Assertion (A) : Human skin colour and kernel colour in
wheat are the examples of polygenic inheritance.
Reason (R) : Polygenic inheritance is easily influenced by
environmental factors.
