Download FAQs What is reproduction? Ans: Production of new individuals or

FAQs
What is reproduction?
Ans: Production of new individuals or offsprings by the
parents.
What
is
the
difference
between
asexual
and
sexual
reproduction?
Ans: Asexual reproduction does not involve the formation and
union of gametes whereas sexual reproduction involves the
formation and union of gametes by the process of fertilization,
resulting in the formation of a zygote.
What are bacteria?
Ans: Bacteria are smallest, most ancient, the simplest and,
generally one-celled microscopic organisms of prokaryotic type.
What are cyanobacteria?
Ans: Cyanobacteria, also known as blue-green algae, are Gram
negative
photosynthetic
bacteria.
Their
photosynthetic
pigments are chlorophyll a and phycobiliproteins. They may be
single-celled, colonial or filamentous.
Define binary fission?
Ans: Binary fission is the most common method of reproduction
found in bacteria in which the dividing cell elongates and the
protoplasmic mass then divides into two equal halves by a
transverse wall or constriction. The two daughter cells soon
grow to maturity and again divide within 20 minutes of their
formation.
What are akinetes?
Ans: Akinetes are thick-walled spore-like structures with
abundant food reserves, formed by certain cyanobacteria.
These akinetes are resistant to unfavorable environmental
conditions.
What are hormogonia?
Ans: Under favorable conditions, all filamentous Cyanobacteria
reproduce by fragmentation of their filaments (trichomes) at
more or less regular intervals to form short pieces each
consisting of 5-15 cells. These short pieces of filaments are
called hormogonia. The latter show gliding motility and
develop into new full-fledged filaments.
What are endospores and when are they formed?
Ans: Endospores are known as resting spores and represent
the resting stages of bacteria. The protoplast becomes round
and secretes a hard, resistant wall around it. They are formed
only in a few bacteria under adverse environmental conditions.
They are very resistant to temperatures as low as ice, and to
as high as boiling water.
What is a bacteriophage?
Ans: A virus that attacks bacteria or for which the host cell is
a bacterium.
Define lytic and lysogenic cycles?
Ans: In a Lytic cycle, a phage reproduces within the host and
destroys the host
cell completely and in a Lysogenic cycle
the phage chromosome integrates into the chromosome of the
host and replicates like any other segment of the host
chromosome.
What are the genotypic differences between F- cells, F+
cells and Hfr cells?
Ans: In F- cells, the F factor (F plasmid) is absent; in F+ cells, F
factor is present in an autonomous state; and in Hfr cells, F
factor is in the integrated state.
What
are
the
basic
differences
between
generalized
transduction and specialized transduction?
Ans: In generalized transduction, the transducing phages often
contain only host DNA and may carry any segment of the host
chromosome. Thus, all the host genes are transduced. In
specialized transduction, the transducing particles carry a
recombinant chromosome, which contains both phage and host
DNA. Only those genes that are adjacent to the prophage
integration site are transduced.
Define Fʹ plasmid?
Ans: An F plasmid or F factor that contains genes obtained
from the bacterial chromosome in addition to plasmid genes. It
is formed by aberrant excision of an integrated F factor, taking
along adjacent bacterial DNA.
What is sexduction?
Ans: The transfer of genetic material from Fʹ donor cell to the
F- recipient cell, results in the formation of partial diploids or
merozygotes. Recombination of this type, mediated by Fʹ
factors is called sexduction or F-duction.
Define transformation in bacteria
Ans: The conversion of the genotype of a bacterial cell by
exposing it to DNA isolated from bacteria with a different
genotype.