\q== 0 .. 0001 001
Now, p + q = 1
\ p = 0.99
So, the frequency of carriers of albinism in the population
i.e., 2pq, is
2 pq = 2 × 0.99 × 0.01
= 0.0198 0.02
22
100pq= or 15 / 0Thus, in the given population, 1 person in every 50
individuals would be carrier of albinism.
OR
(i) In angiosperms, one of the male gametes fuses with
the egg cell to form the zygote (syngamy) and the other
male gamete fuses with the two polar nuclei to produce
a triploid primary endosperm nucleus (triple fusion). Since
two types of fusion, syngamy and triple fusion take place
in an embryo sac, the phenomenon is termed as double
fertilization.
(ii) L.S. of an endospermous monocot seed (maize grain) is
drawn as follows:
- (i) DNA molecule is a more stable genetic material than
RNA because of the following reasons :
(a) The 2′-OH group present at every nucleotide in RNA
is a reactive group and makes RNA labile and easily
degradable.
(b) DNA is chemically less reactive and structurally more
stable as its nucleotides are not exposed except
when they are to express their effect.
(c) Presence of thymine at the place of uracil also
confers additional stability to DNA.
(d) RNA mutates at a much faster rate and there is
no repairing system whereas DNA is capable of
undergoing slow mutations and has power of
repairing.
(ii) “Unambiguous” means that one codon codes for only
one amino acid.
“Degenerate” means that the same amino acid is coded
by more than one codon.
“Universal” means that the same code would code for
same amino acid from bacteria to human.- Natural selection is the process by which those organisms
that are best suited for their environment survive and
reproduce. One of the most striking examples which
demonstrates the action of natural selection in the wild,
is the case of peppered moth, Biston betularia that lives
in all parts of England.
Due to industrial smoke and soot, the pale tree trunks
became more and more blackened. As a result, the light
moths stood out in contrast to its background, increasing
the possibility of being easily detected and eaten by their
predators, such as birds, in much greater number than
the dark melanic variety. Decrease in the number of
light moths and increase in the number of dark variety
was the ultimate result. Therefore, evolution favoured
the melanic moths to reproduce more successfully due
to their adaptation to the polluted areas of England.
Evolution of the darker form, in response to industrial
pollution is known as industrial melanism. - (i) Evolution is not a directed process in the sense of
determinism. It is a stochastic process based on chance
events in nature and chance mutations in the organisms.
Anthropogenic actions also leads to evolution. For
example:
(a) Excess use of heribicides and pesticides has resulted
in selection of resistant varieties.
(b) Resistant varieties of microbes develop against
which, antibiotics are applied.
(ii) Differences between divergent and convergent evolution
are given below :
Divergent
evolution
Convergent evolution- Origin of a variety of
species from a common
ancestral form.
Independent development of
similar form and features by
unrelated organisms usually
as an adaptation to similar
environment.- Homologous organs
result from divergent
evolution e.g. evolution
of pouched mammals.
Analogous organs result from
convergent evolution.
e.g. Similar streamlined body
form, fins in fish and whale.