1) A Mendelian experiment consisted
of breeding tall pea plants bearing violet flowers with short pea plants
bearing white flowers. The progeny all bore violet flowers, but almost half of
them were short. This suggests that the genetic make-up of the tall parent can
be depicted as-
of breeding tall pea plants bearing violet flowers with short pea plants
bearing white flowers. The progeny all bore violet flowers, but almost half of
them were short. This suggests that the genetic make-up of the tall parent can
be depicted as-
(a)
TTWW
TTWW
(b)
TTww
TTww
(c)
TtWW
TtWW
(d)
TtWw
TtWw
ANSWER :-(c)
TtWW
TtWW
2) An example of homologous organs
is-
is-
(a) our
arm and a dog’s fore- leg.
arm and a dog’s fore- leg.
(b) our
teeth and an elephant’s tusks.
teeth and an elephant’s tusks.
(c)
potato and runners of grass.
potato and runners of grass.
(d) all
of the above.
of the above.
ANSWER:-(b)
our teeth and an elephant’s tusks.
our teeth and an elephant’s tusks.
3) In
evolutionary terms, we have more in common with
evolutionary terms, we have more in common with
(a) a
Chinese school-boy.
Chinese school-boy.
(b) a
chimpanzee.
chimpanzee.
(c) a
spider.
spider.
(d) a
bacterium.
bacterium.
ANSWER:-(a)
a Chinese school-boy.
a Chinese school-boy.
3) A study found that
children with light-coloured eyes are likely to have parents with
light-coloured eyes. On this basis, can we say anything about whether the light
eye colour trait is dominant or recessive? Why or why not?
children with light-coloured eyes are likely to have parents with
light-coloured eyes. On this basis, can we say anything about whether the light
eye colour trait is dominant or recessive? Why or why not?
ANSWER:-For considering a trait as dominant
or recessive, we need data of at least three generations. This data is about only
two generations.
or recessive, we need data of at least three generations. This data is about only
two generations.
5) How
are the areas of study – evolution and
classification – interlinked?
are the areas of study – evolution and
classification – interlinked?
ANSWER:-Classification
involves grouping of organism into a formal system based on similarities in
internal and external structure or evolutionary history. Two species are more
closely related if they have more characteristics in common. And if two species
are more closely related, then it means they have a more recent ancestor.
involves grouping of organism into a formal system based on similarities in
internal and external structure or evolutionary history. Two species are more
closely related if they have more characteristics in common. And if two species
are more closely related, then it means they have a more recent ancestor.
6) Explain
the terms analogous and homologous organs with examples.
the terms analogous and homologous organs with examples.
ANSWER:-Homologous
organs are those organs which have the same basic structural design and origin
but have different functions.
organs are those organs which have the same basic structural design and origin
but have different functions.
Analogous
organs are those organs which have the
different basic structural design and origin but have similar functions.
organs are those organs which have the
different basic structural design and origin but have similar functions.
7.
Outline a project which aims to find the dominant coat
colour in dogs.
Outline a project which aims to find the dominant coat
colour in dogs.
ANSWER:-Dogs have a variety
of genes that govern coat colour. There are at least eleven identified gene
series (A, B, C, D, E, F, G, M, P, S, T) that influence coat colour in dog. A
dog inherits one gene from each of its parents. The dominant gene gets
expressed in the phenotype. For example, in the B series, a
dog can be genetically black or brown. Let us assume that one parent is
homozygous black (BB), while the other parent is homozygous
brown (bb)
of genes that govern coat colour. There are at least eleven identified gene
series (A, B, C, D, E, F, G, M, P, S, T) that influence coat colour in dog. A
dog inherits one gene from each of its parents. The dominant gene gets
expressed in the phenotype. For example, in the B series, a
dog can be genetically black or brown. Let us assume that one parent is
homozygous black (BB), while the other parent is homozygous
brown (bb)
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8)Explain
the importance of fossils in deciding
evolutionary relationships.
the importance of fossils in deciding
evolutionary relationships.
ANSWER:-Fossil provides us
evidence about:
evidence about:
→ The organisms that lived long ago such as the time period
during which they lived, their structure etc.
during which they lived, their structure etc.
→ Evolutionary development of species i.e. line of their
development.
development.
→ Connecting links between two groups.
→ Which organisms evolved earlier and which later.
9) What
evidence do we have for the origin of life from inanimate matter?
evidence do we have for the origin of life from inanimate matter?
ANSWER:-The evidence for
the origin of life from inanimate matter, was provided through an experiment,
conducted in 1953, by Stanley L. Miller and
Harold C. Urey. In experiment, they assembled an atmosphere containing
molecules like ammonia, methane and hydrogen sulphide, but no
oxygen, over water. This was similar to atmosphere that thought
to exist on early earth.This was maintained at a temperature just below 100°C and sparks were passed through
the mixture of gases to simulate lightning. At
the end of a week, 15% of the carbon from methane had been converted to simple
compounds of carbon including amino acids which make up protein molecules and
support the life in basic form. Thus, amply suggesting that life arose
afresh on earth.
the origin of life from inanimate matter, was provided through an experiment,
conducted in 1953, by Stanley L. Miller and
Harold C. Urey. In experiment, they assembled an atmosphere containing
molecules like ammonia, methane and hydrogen sulphide, but no
oxygen, over water. This was similar to atmosphere that thought
to exist on early earth.This was maintained at a temperature just below 100°C and sparks were passed through
the mixture of gases to simulate lightning. At
the end of a week, 15% of the carbon from methane had been converted to simple
compounds of carbon including amino acids which make up protein molecules and
support the life in basic form. Thus, amply suggesting that life arose
afresh on earth.
10)Explain
how sexual reproduction gives rise to more viable variations than a sexual
how sexual reproduction gives rise to more viable variations than a sexual
reproduction.
How does this affect the evolution of those organisms that reproduce sexually?
How does this affect the evolution of those organisms that reproduce sexually?
ANSWER:-In
sexual reproduction, two individuals having different variations combine their
DNA to give rise to a new individual. Therefore, sexual reproduction allows
more variations, whereas in asexual reproduction, chance variations can only
occur when the copying of DNA is not accurate. Additionally, asexual reproduction
allows very less variations because if
there are more variations, then the resultant DNA will not be able to
survive inside the inherited cellular apparatus. However, in sexual
reproduction, more variations are allowed and the resultant DNA is also able to survive,
thus making the variations viable.
sexual reproduction, two individuals having different variations combine their
DNA to give rise to a new individual. Therefore, sexual reproduction allows
more variations, whereas in asexual reproduction, chance variations can only
occur when the copying of DNA is not accurate. Additionally, asexual reproduction
allows very less variations because if
there are more variations, then the resultant DNA will not be able to
survive inside the inherited cellular apparatus. However, in sexual
reproduction, more variations are allowed and the resultant DNA is also able to survive,
thus making the variations viable.
Variation and Evolution:
Variants help the species to survive in all the conditions.
Variants help the species to survive in all the conditions.
Environmental conditions
such as heat, light, pests, and food availability can change suddenly at only
one place. At that time, only those variants resistant to these conditions
would be able to survive. This will slowly lead to the evolution of a
better adapted species.
such as heat, light, pests, and food availability can change suddenly at only
one place. At that time, only those variants resistant to these conditions
would be able to survive. This will slowly lead to the evolution of a
better adapted species.
11) How
is the equal genetic contribution of male and female parents ensured in the
progeny?
is the equal genetic contribution of male and female parents ensured in the
progeny?
ANSWER:-In human beings,
equal genetic contribution of male and a female parent is ensured
in the progeny through inheritance of equal number of chromosomes from both
parents. There are 23 pairs of chromosomes All human chromosomes are not paired.
equal genetic contribution of male and a female parent is ensured
in the progeny through inheritance of equal number of chromosomes from both
parents. There are 23 pairs of chromosomes All human chromosomes are not paired.
Out of these 23 pairs, the
first 22 pairs are known as autosomes and the remaining one pair is
known as sex chromosomes represented as X and Y. Females have a perfect pair of
two X sex chromosomes and males have a mismatched pair of one X and one Y
sex chromosome. During the course of reproduction, as fertilization process
takes place, the male gamete (haploid) fuses with the
female gamete (haploid) resulting in formation of
the diploid zygote. The zygote in the progeny receives an
equal contribution of genetic material from the parents. Out of 23 pairs
of chromosomes in progeny, male parent contributes 22 autosomes and one X or Y
chromosome and female parent contributes 22 autosomes and one X-chromosome.
first 22 pairs are known as autosomes and the remaining one pair is
known as sex chromosomes represented as X and Y. Females have a perfect pair of
two X sex chromosomes and males have a mismatched pair of one X and one Y
sex chromosome. During the course of reproduction, as fertilization process
takes place, the male gamete (haploid) fuses with the
female gamete (haploid) resulting in formation of
the diploid zygote. The zygote in the progeny receives an
equal contribution of genetic material from the parents. Out of 23 pairs
of chromosomes in progeny, male parent contributes 22 autosomes and one X or Y
chromosome and female parent contributes 22 autosomes and one X-chromosome.
12) Only
variations that confer an advantage to an
individual organism will survive in
a population. Do you agree
with this statement? Why or
why not?
variations that confer an advantage to an
individual organism will survive in
a population. Do you agree
with this statement? Why or
why not?
ANSWER:-We agree with the
statement that only variations that confer an advantage to an individual
organism will survive in a population. All the variations do not
have an equal chance of surviving in the
environment in which they find themselves. The chances of surviving
depend on the nature of variations.
statement that only variations that confer an advantage to an individual
organism will survive in a population. All the variations do not
have an equal chance of surviving in the
environment in which they find themselves. The chances of surviving
depend on the nature of variations.