- (i) Describe the characteristics of a cloning vector.
(ii) How is a bacterial cell made ‘competent’ to take up
recombinant DNA from the medium?
OR
(i) Name the source of Ta q polymerase. Explain the
advantage of its use in biotechnology.
(ii) Expand ADA. Why is it essential in the human body?
Suggest a gene therapy for its deficiency.
SOLUTIONS
- Binding of the sperm to the egg induces depolarization
of the egg plasma membrane. Depolarization causes fast
block to polyspermy, that checks additional sperms from
fusing with the egg’s plasma membrane. Immediately
after the fusion of sperm and egg plasma membrane,
the egg shows a cortical reaction to further check the
entry of more sperms. The cortical reaction functions as
the sure block to polyspermy. - Huntington’s disease is an autosomal dominant and
Gaucher’s disease is an autosomal recessive Mendelian
disorder. - hnRNA undergoes splicing in order to remove introns
which are intervening or non-coding sequences, and
exons are joined to form functional mRNA. - Tissue typing is determination of the HLA (human
leucocyte antigen) profiles of tissues to assess their
compatibility. It is the most important predictor of success
or failure of a transplant operation. - It is desirable to use unleaded petrol in the automobiles
fitted with catalytic converter, because lead in the petrol,
inactivates the catalyst metals like platinum-palladium
and rhodium, etc., present in the converter. - (i) Hieracium, a member of Family Asteraceae is a plant
where seeds develop without fertilization. This process
is called apomixis and is quite common in some families
like Asteraceae, Rosaceae etc.
(ii) Two ways by which seeds develop without fertilization
are as follows:
- In some species, the diploid (2n) egg cell is formed
without reduction division, and develops into an
embryo, without fertilization i.e., parthenogenesis. - In many varieties of Citrus and mango, some of
the nucellar cells surrounding the embryo sac start
dividing, protrude into the embryo sac and develop
into embryos i.e., adventive embryony.
7.(i) Tape worm and earthworm are hermaphrodite but tape
worm shows self fertilization whereas earthworm shows
cross fertilization.
(ii) In amphibians, syngamy takes place outside the body in
water and in reptiles syngamy takes place inside the body
of the organism. Thus, in amphibians external fertilization
takes place and in reptiles internal fertilization takes
place.
OR
Continued self pollination results in inbreeding de-
pression. So, flowering plants have developed following
devices to discourage self pollination and encourage
cross pollination. These are as follows:
(i) Dicliny : Flowers are unisexual so that self pollination
is not possible. The plants may be monoecious
(bearing both male and female flowers, e.g., maize)
or dioecious (male and female flowers present on
different plants, e.g., mulberry, papaya).
(ii) Dichogamy : Anthers and stigmas mature at
different times in a bisexual flower so as to prevent
self pollination. e.g., sunflower, Gloriosa.- The doctor must have used pedigree anlaysis which refers
to the analysis of distribution and movement of traits in
a series of generations of a family.
Since non-haemophilic parents gave birth to a
haemophilic child, their genotypes should be :
Father : XY (normal)
Mother : XXh (carrier/heterozygous, non-haemophilic)
Their progeny can consist of the following genotypes and
phenotypes :XX XXh XY XhY
Normal : Carrier, : Normal : Haemophilic
female non-haemo- male male
philic female
1 : 1 : 1 : 1