4. Modern plant tissue culture is performed under aseptic conditions underModern plant tissue culture is performed under aseptic conditions under
filtered air. Living plant materials from the environment are naturallyfiltered air. Living plant materials from the environment are naturally
contaminated on their surfaces (and sometimes interiors) withcontaminated on their surfaces (and sometimes interiors) with
microorganisms, so surface sterilization of starting materials (explants) inmicroorganisms, so surface sterilization of starting materials (explants) in
chemical solutions (usually Sodium or calcium hypochlorite or mercuricchemical solutions (usually Sodium or calcium hypochlorite or mercuric
chloride) is required. Mercuric chloride is seldom used as a plant sterilantchloride) is required. Mercuric chloride is seldom used as a plant sterilant
today, unless other sterilizing agents are found to be ineffective, as it istoday, unless other sterilizing agents are found to be ineffective, as it is
dangerous to use, and is difficult to dispose of. Explants are then usuallydangerous to use, and is difficult to dispose of. Explants are then usually
placed on the surface of a solid culture medium, but are sometimes placedplaced on the surface of a solid culture medium, but are sometimes placed
directly into a liquid medium, particularly when cell suspension culturesdirectly into a liquid medium, particularly when cell suspension cultures
are desired. Solid and liquid media are generally composed of inorganicare desired. Solid and liquid media are generally composed of inorganic
salts plus a few organic nutrients, vitamins and plant hormones. Solidsalts plus a few organic nutrients, vitamins and plant hormones. Solid
media are prepared from liquid media with the addition of a gelling agent,media are prepared from liquid media with the addition of a gelling agent,
usually purified agar.usually purified agar.

6. •True to the type of mother plant under well management.
•Pest and disease free seedlings.
•Uniform growth, increases yield.
•Early maturity of crop - maximum land use is possible in low land holding
country like India.
•Round the year planting possible as seedlings are made available
throughout the year.
•Two successive ratoons are possible in a short duration which minimizes
cost of cultivation.
•No staggered harvesting.
•95% - 98% plants bear bunches.
•New varieties can be introduced and multiplied in a short duration.

8. •The method in which explants that include a meristem
(viz. the shoot tips or nodes) are grown on appropriate
media supplemented with plant growth regulators to
induce proliferation of multiple shoots, followed by rooting
of the excised shoots to regenerate whole plants,
•The method in which totipotency of cells is realized in the
form of de novo organogenesis, either directly in the form
of induction of shoot meristems on the explants or
indirectly via a callus ( unorganised mass of cells resulting
from proliferation of cells of the explant) and plants are
regenerated through induction of roots on the resultant
shoots,
•Somatic embryogenesis, in which asexual adventive
embryos( comparable to zygotic embryos in their structure
and development) are induced directly on explants or
indirectly through a callus phase.