they have to expend much energy to generate body heat
through metabolism. Greater body size reduces surface
area to volume ratio, and decreases heat loss, which is
very essential for surviving in cold polar regions.- (i) The differences between in situ conservation and
ex situ conservation are as follows :
In situ conservation Ex situ conservation
It is conservation and
protection of the whole
ecosystem and its biodiversity
at all levels in order to protect
the threatened species.
However, it is not economically
feasible to conserve all
biological wealth and all
the existing ecosystems. The
number of species required
to be saved from extinction
far exceeds the conservation
resources. Two alternate
methods are being used to
save biodiversity, hot spots
and protected areas.
It is conservation of
threatened plants/
animals in places
outside their natural
homes. Ex situ
conservation includes
offsite collections and
gene banks. The two
are also a source of
genetic material for
breeders and
genetic engineers.(ii) The measures for control of solid wastes are : Recovery
and recycling, source reduction, burning and dumping.
- (i) Polyblend is a fine powder of recycled modified plastic.
This mixture is mixed with bitumen that is used to lay
roads. Raw material is any plastic film waste.
(ii) Blends of polyblend and bitumen, when used to lay roads,
enhance the bitumen’s water repellant properties and
help to increase road life by a factor of three.
- (i) Height of the exhaust pipe for emitting smoke is
closer to the height of the children, that is why children
are more affected by vehicular exhaust. Manya is
justified in her actions as she shows her concern towards
environmental issues and health safety.
(ii) Bharat stage (BS) emission standards are instituted by
Central Pollution Control Board under the ministry of
Environment and Forests. They regulate the output of air
pollutants from internal combustion engine equipment,
including motor vehicles. Currently BS-IV is enforced in
13 major cities while BS III in rest of the country, which
are equivalent to Euro IV and Euro III norms respectively.
BS IV sticker on a vehicle implies that the vehicle fulfills
BS IV norms.
(iii) In catalytic converters, platinum - palladium and rhodium
are used as catalysts. As the exhaust passes through the
converter, unburnt hydrocarbons are converted into CO 2
and H 2 O. Carbon monoxide and nitric oxide are changed
into CO 2 and N 2 gas respectively. Vehicles fitted with such
equipment should run on unleaded petrol only, since lead
in petrol inactivates the catalysts.- DNA fingerprinting was invented by Alec Jeffreys in 1984.
It is a technique of determining nucleotide sequences of
certain areas of DNA called VNTRs which are unique to
each individual. DNA fingerprints can be prepared from
extremely minute amounts of blood, semen, hair bulb or
any other cells of the body.
The procedure of DNA fingerprinting includes the
following:
(i) Extraction - DNA is extracted from the cells in a
high-speed, refrigerated centrifuge.
(ii) Amplification - Many copies of the extracted DNA
are made by polymerase chain reaction if needed
such as in cases where sample size is very small.
(iii) Restriction digestion - DNA is cut into fragments
with restriction enzymes into precise sequences.
(iv) Separation of DNA sequences/restriction fragments-
The cut DNA fragments are separated using gel
electrophoresis.
(v) Southern blotting - The separated DNA sequences
are transferred on a nitrocellulose or nylon
membrane.
(vi) Hybridisation - The nylon membrane is immersed
in a bath and radioactive probes are added, these
probes target specific nucleotide sequences that are
complementary to them.
(vii) Autoradiography - The nylon membrane is pressed
on an X-ray film and dark bands develop at the
probe sites. The bands form a characteristic pattern
which varies from individual to individual.
From the patterns developed by the samples A and B it
can be confirmed whether they belong to one individual
or two different individuals. If the banding patterns are
similar they belong to the same individual but if banding
patterns are dissimilar then A and B are from different
individuals.
OR
Spermatogenesis is the process of formation of haploid
spermatozoa from diploid spermatogonia inside the
testes of the male.
It includes following three phases: