Biology Times (^19)
March
30.Sol: The ovule, where the funicle, chalaza, and
micropyle all lie in one, same vertical plane is
called as Orthotropous or Straight or atropous
ovule. The ovule in this type is erect. Such
a kind of ovule is found in species of family
Polygonaceae (cycas) and Piperaceae.
31.Sol: A meta female or superfemale is a condition
in which the ratio of X chromosomes to sets of
autosomes (A) exceeds 1.0 .Metafemales or
superfemales have 47 (44 +XXX) , 48 (44 +
XXXX) or 49 (44 + XXXXX) chromosomes
32.Sol: A transition is a point mutation which changes
a purine nucleotide to another purine (A G) or a
pyrimidine nucleotide to another pyrimidine
(CT). While, transversion mutations occurs when
a purine base substitutes for a pyrimidine base,
or vice versa; for example, when a (T = A) or
(CG ) pair replaces the (A=T) pair. 101.In man
which of the following genotypes and phenotypes
may be the correct result of aneuploidy in sex
chromosomes
(a) 22 pairs + XXXY females
(b) 22 pairs + Y females
(c) 22 pairs +XX females
(d) 22 pairs + XXY males
33.Sol: Aneuploidy is the presence of an abnormal
number of chromosomes in a cell. For example
a human cell will have 45 or 47 chromosomes
instead of the usual 46 in this condition. This
chromosomal disorder involves the loss or gain
of single chromosome. Klienefelter’s syndrome
condition is presented by genotype 22 pairs +
XXY males.
34.Sol: Lactose is the carbon source needed for the
growth of the bacteria. Lactose is transported
into the cells of bacterium through the action of
permease.
35.Sol: Frederick Griffith in 1928 reported through
his first experiment that bacteria are capable
of transferring genetic information through a
process known as transformation. Griffith while
experimenting with Diplococcus pneumonias
(now called Streptococcus pneumoniae) observed
that some colonies were shiny and smooth while
some were rough in appearance. He named , the
shiny colonies as ‘S strain’ and the rough colonies
as ‘R’ strain. Further he injected mice with the S
strain, which he found were encased, they died.
After this when he injected them with the R
strain, they didn’t die. To know the reason behind
this he killed the S bacteria with heat to destroy
the capsule. But when he injected mice with the
S strain bacteria that was killed by heat treatment,
they did not die. Though, if the heat-killed S
strain bacteria were mingled with harmless live
R strain bacteria of the same species and injected,
the mice would die. Principally living S strain
bacteria were found from the mice body. With
this he concluded that from the dead S strain
bacteria some substance passed to the R strain
bacteria, transmitting virulence and the ability to
form a capsule.
36.Sol: Mutations involve changes in the base
sequence of DNA. Substituting one base pair for
another is the a very common type of mutational
event. Therefore, when adenine is replaced
by guanine, it is a case of transition where
replacement of one purine by the other or that of
one pyrimidine by the other takes place.
37.Sol: In bolistics or gene gun the plant cells are
bombarded with high velocity micro-particles of
gold or tungsten coated with DNA. This method
is beneficial for constructing recombinant DNA
by joining with vectors.
38.Sol: The Ministry of Environment and Forests has
initiated Ganga action plan and Yamuna action
plan to save these major rivers of the country from
pollution. Under these plans, it is proposed to build
a large number of sewage plants.
39.Sol: During cellulose fermentation by anaerobic
bacteria in rumen and reticulum, Cellulose is
mainly changed into Volatile fatty acid.
40.Sol: Domestic sewage is composed of 99.9% water
and 0.1% of impurities like suspended solids,
colloidal material and dissolved materials.
41.Sol: T 4 DNA ligase is not a perquisite of PCR
because DNA ligase is not used in PCR.
42.Sol: The first restriction endonuclease type II, is
Hind II was isolated from Haemophillus influenza
bacterium.
43.Sol: Main objective of production of herbicide
resistant GM crops is to reduce herbicide
accumulation in food articles for health safety
45.Sol: “Bird flu” or “Avian influenza” is a viral
infection spread from bird to bird. H5N1 IS
the most common form of bird flu. It is deadly
to birds and can easily affect humans and other
animals that come in contact with carrier.
singke
(singke)
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