or foreign DNa is linked with the plasmid DNa, we
can multiply its number equal to the copy number of
the plasmid. This principle was used by eli Lilly, an
american company, to prepare human insulin.In 1983, eli Lilly, first prepared two DNa sequences
corresponding to a and b chains of human insulin
and introduced them in plasmids of E.coli to produce
insulin chains. The chains, a and b, were produced
separately, extracted and combined by creating disulfide
bonds to form human insulin (sold under trade name
of humulin).
- (i) X – Post reproductive stage
y – reproductive stage
Z – Pre-reproductive stage
(ii) a – expanding population
b – Stable population
C – Declining population
(iii) bell shaped age pyramid (Pyramid ‘b’ in the figure.)
- (i) Net primary productivity (NPP) refers to the
biomass available for the consumption to heterotrophs
(herbivores, carnivores and decomposers). It is equal to
the gross primary productivity (GPP) minus respiration
losses (r).
NPP = GPP – r
The annual net primary productivity of the whole
biosphere is approximately 170 billion tons (dry weight)
of organic matter.
(ii) The two reasons for less primary productivity (PP) in
temperate regions are :
(a) Temperate regions receive less amount of sunlight,
due to which photosynthesis is low. Hence PP, is
less in temperate regions (8 t ha–1 year–1), compared
to tropics (20 t ha–1 year–1).
(b) Temperate regions have cold climate, that severely
limits the PP.
- Inspite of the murdered man’s son repeatedly
accusing the servant, the forensic department will be
able to catch the real culprit with the aid of DNa
fingerprinting.
The major steps in DNa fingerprinting are :
(i) DNa is extracted from the cells in a high-speed
refrigerated centrifuge.
(ii) DNa is amplified by making many copies of it
using polymerase chain reaction.(iii) Digestion of DNa by restriction endonucleases is
carried out.
(iv) DNa fragments are separated by electrophoresis.
(v) Separated DNa fragments are transferred to
synthetic membranes, such as nitrocellulose or
nylon.
(vi) DNa hybridisation is done using VNTr probes.
(vii)Detection of hybridised DNa fragments by autoradio-
graphy gives a DNa fingerprint.
DNa fingerprints of suspects, i.e., murdered man’s
son and the servant, and from hair picked up from
crime scene are prepared and compared. The DNa
fingerprint of the person matching the one obtained
from sample of the crime scene will give a clue of the
actual criminal.- (i) X – Luteinising hormone (LH)
y – follicle stimulating hormone (fSH)
(ii) (a) Proliferative phase
(b) Ovulatory phase
(c) Luteal phase
(iii) During follicular phase (a), fSH stimulates the ovarian
follicle to secrete oestrogen. Oestrogen stimulates the
proliferation of the endometrium of the uterine wall.
During ovulatory phase (b), both LH and fSH attain a
peak level. rapid secretion of LH induces rupturing of
Graafian follicle and thereby the release of ovum.
During luteal phase (c), LH causes the remaining cells
of the ovarian follicles to develop corpus luteum.
OR
(i) Stages in the process of spermatogenesis in man can
be illustrated as follows: