becomes thicker.
- (d) Sea weeds include multicellular algaes
and they are too soft to fossilize. - (a)
- (b) Gene pool is the set of all genes (genetic
information) of a single species in any
population. - (d) Heterozygotic condition is when one
gene is dominant and another gene is the
recessive. In such conditions lethal gene
will be recessive and dominant gene will
express itself. The recessive gene can be
expressed in the next generation and
selection cannot eliminate lethal recessive
allele from large population of diploid
organisms. Recessive lethals produce
effect only in homozygous condition, their
heterozygotes are normal. - (a) Potential damage to a population that
has been greatly reduced in number is loss
in its genetic variability (Bottle neck effect) - (c)
- (d)
Allelic frequencies:
p (IA) = 0.1
q (IB) = 0.3
r (IO) = 0.6
B blood type is found in people with the
genotypes IBIB and IBIO.
Frequency of IBIB = q2 = 0.3 x 0.3 = 0.09
Frequency of IBIO = 2qr = 2 x 0.3 x 0.6 =
0.36
Frequency of B type = 0.09+0.36 = 0.45
This is an application question based on
the Hardy-Weinberg equation mentioned
on Page - (a) Each individual has two alleles. Each
Rh-negative individual (dd) has two ‘d’
alleles. Each heterozygous Rh-positive
individual (Dd) has one ‘d’ allele. Therefore
Frequency of recessive allele (q)- (b) Theory of pangenesis was given
by Darwin to explain the inheritance of
characters from parents to off springs.
Haeckel gave a biogenetic Law stating
‘‘Ontogeny recapitulates phylogeny’’.
In modern synthetic theory, the unit
of evolution is population Weismann’s
theory of germplasm rejected the Darwin’s
pangenesis theory.
Mutations are random and direction less
i.e., they may result in loss or gain of
characters. - (b)
- (d) Higher mortality of large adult fish
(compared to small adult fish) leads to
decreased reproductive success of larger
fish. The mean size of the fish body would
gradually decrease over generations. This
is directional selection which eliminates
one extreme phenotype from an array of
phenotypes. - (c) The cradle of human evolution is Africa.
So, Homo sapiens arose in Africa and
moved to different continents to develop
into distinct races.
Agriculture came around 10,000 years ago,
and human settlement started.
Modern Homo sapiens arose between
75000-10000 years ago Neanderthal man
was present in central and eastern Asia
between 100,000 -40,000 years back. It has
a brain size of around 1400 CC. - (d) 35. (b) 36. (d)