Individuals with a particular trait may increase in a population as a result of the following: (i) Natural selection: When that trait offers some survival advantage. (ii) Genetic drift: When some genes governing that trait become common in a population. (iii) When that trait gets acquired during theRead more
Individuals with a particular trait may increase in a population as a result of the following:
(i) Natural selection: When that trait offers some survival advantage.
(ii) Genetic drift: When some genes governing that trait become common in a population.
(iii) When that trait gets acquired during the individual’s lifetime.
In human beings, the females have two X chromosomes and the males have one X and one Y chromosome. Therefore, the females are XX and the males are XY. The gametes, as we know, receive half of the chromosomes. The male gametes have 22 autosomes and either X or Y sex chromosome. Type of male gametes:Read more
In human beings, the females have two X chromosomes and the males have one X and
one Y chromosome. Therefore, the females are XX and the males are XY.
The gametes, as we know, receive half of the chromosomes. The male gametes have 22
autosomes and either X or Y sex chromosome.
Type of male gametes: 22+X OR 22+ Y.
However, since the females have XX sex chromosomes, their gametes can only have X
sex chromosome.
Type of female gamete: 22+X
Thus, the mother provides only X chromosomes. The sex of the baby is determined by the
type of male gamete (X or Y) that fuses with the X chromosome of the female.
No. This information is not sufficient to determine which of the traits - blood group A or O - is dominant. This is because we do not know about the blood group of all the progeny. Blood group A can be genotypically AA or AO. Hence, the information is incomplete to draw any such conclusion. For moreRead more
No. This information is not sufficient to determine which of the traits – blood group A or
O – is dominant. This is because we do not know about the blood group of all the progeny.
Blood group A can be genotypically AA or AO. Hence, the information is incomplete to draw
any such conclusion.
Mendel crossed pea plants having round green seeds (RRyy) with pea plants having wrinkled yellow seeds (rrYY).Since the F1 plants are formed after crossing pea plants having green round seeds and pea plants having yellow wrinkled seeds, F1 generation will have both these characters in them. However,Read more
Mendel crossed pea plants having round green seeds (RRyy) with pea plants having
wrinkled yellow seeds (rrYY).Since the F1 plants are formed after crossing pea plants having green round seeds and
pea plants having yellow wrinkled seeds, F1 generation will have both these characters in
them. However, as we know that yellow seed colour and round seeds are dominant
characters, therefore, the F1 plants will have yellow round seeds.
Then this F1 progeny was self-pollinated and the F2 progeny was found to have yellow
round seeds, green round seeds, yellow wrinkled seeds, and green wrinkled seeds in the
ratio of 9:3:3:1. In the above cross, more than two factors are involved, and these are independently inherited.
Mendel selected true breeding tall (TT) and dwarf (tt) pea plants. Then, he crossed these two plants. The seeds formed after fertilization were grown and these plants that were formed represent the first filial or F1 generation. All the F1 plants obtained were tall. Then, Mendel self-pollinated theRead more
Mendel selected true breeding tall (TT) and dwarf (tt) pea plants. Then, he crossed these
two plants. The seeds formed after fertilization were grown and these plants that were
formed represent the first filial or F1 generation. All the F1 plants obtained were tall.
Then, Mendel self-pollinated the F1 plants and observed that all plants obtained in the F2
generation were not tall. Instead, one-fourth of the F2 plants were short.
From this experiment, Mendel concluded that the F1 tall plants were not true breeding.
They were carrying traits of both short height and tall height. They appeared tall only
because the tall trait is dominant over the dwarf trait.
Sometimes for a species, the environmental conditions change so drastically that their survival becomes difficult. For example, if the temperature of water increases suddenly, most of the bacteria living in that water would die. Only few variants resistant to heat would be able to survive. If theseRead more
Sometimes for a species, the environmental conditions change so drastically that their
survival becomes difficult. For example, if the temperature of water increases suddenly,
most of the bacteria living in that water would die. Only few variants resistant to heat
would be able to survive. If these variants were not there, then the entire species of
bacteria would have been destroyed. Thus, these variants help in the survival of the
species.
However, not all variations are useful. Therefore, these are not necessarily beneficial for
the individual organisms.
In asexual reproduction, the reproducing cells produce a copy of their DNA through some chemical reactions. However, this copying of DNA is not accurate and therefore, the newly formed DNA has some variations. It can be easily observed in the above figure that in asexual reproduction, very few variaRead more
In asexual reproduction, the reproducing cells produce a copy of their DNA through some
chemical reactions. However, this copying of DNA is not accurate and therefore, the newly
formed DNA has some variations.
It can be easily observed in the above figure that in asexual reproduction, very few
variations are allowed. Therefore, if a trait is present in only 10% of the population, it is
more likely that the trait has arisen recently. Hence, it can be concluded that trait B that
exists in 60% of the same population has arisen earlier than trait A.
In species, variations that offer survival advantages are naturally selected. Individuals adjust to their environments with the help of these selected variations and consequently these variations are passed on to their progeny. Evolution of organisms occurs as a result of this natural selection. HowRead more
In species, variations that offer survival advantages are naturally selected. Individuals
adjust to their environments with the help of these selected variations and consequently
these variations are passed on to their progeny. Evolution of organisms occurs as a result
of this natural selection.
However, there can be some other variations, which do not offer any survival advantage
and arise only accidentally. Such variations in small populations can change the frequency
of some genes even if they are not important for survival.
This accidental change in the frequency of genes in small populations is referred to as
genetic drift.
Thus, genetic drift provides diversity (variations) without any survival advantage.
In human beings, every somatic cell of the body contains 23 pairs of chromosomes. 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 two X chromosomes and males have one X and one Y chromosome.Read more
In human beings, every somatic cell of the body contains 23 pairs of chromosomes. 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 two X chromosomes and males have one X and one Y chromosome. The
gamete receives half of the chromosomes. Therefore, the male gametes have 22
autosomes and either X or Y chromosome.
The female gamete, on the other hand, has 22 autosomes and X chromosome.
During reproduction, the male and female gametes fuse and thus the progeny receives 22
autosomes and one X or Y chromosome from male parent and 22 autosomes and one X
chromosome from the female parent.
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, asexRead more
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.
Variation and Evolution: 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.
Thus, variation helps in the evolution of sexually reproducing organisms.
What are the different ways in which individuals with a particular trait may increase in a population?
Individuals with a particular trait may increase in a population as a result of the following: (i) Natural selection: When that trait offers some survival advantage. (ii) Genetic drift: When some genes governing that trait become common in a population. (iii) When that trait gets acquired during theRead more
Individuals with a particular trait may increase in a population as a result of the following:
(i) Natural selection: When that trait offers some survival advantage.
(ii) Genetic drift: When some genes governing that trait become common in a population.
(iii) When that trait gets acquired during the individual’s lifetime.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-9/
How is the sex of the child determined in human beings?
In human beings, the females have two X chromosomes and the males have one X and one Y chromosome. Therefore, the females are XX and the males are XY. The gametes, as we know, receive half of the chromosomes. The male gametes have 22 autosomes and either X or Y sex chromosome. Type of male gametes:Read more
In human beings, the females have two X chromosomes and the males have one X and
one Y chromosome. Therefore, the females are XX and the males are XY.
The gametes, as we know, receive half of the chromosomes. The male gametes have 22
autosomes and either X or Y sex chromosome.
Type of male gametes: 22+X OR 22+ Y.
However, since the females have XX sex chromosomes, their gametes can only have X
sex chromosome.
Type of female gamete: 22+X
Thus, the mother provides only X chromosomes. The sex of the baby is determined by the
type of male gamete (X or Y) that fuses with the X chromosome of the female.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-9/
A man with blood group A marries a woman with blood group O and their daughter has blood group O. Is this information enough to tell you which of the traits – blood group A or O – is dominant? Why or why not?
No. This information is not sufficient to determine which of the traits - blood group A or O - is dominant. This is because we do not know about the blood group of all the progeny. Blood group A can be genotypically AA or AO. Hence, the information is incomplete to draw any such conclusion. For moreRead more
No. This information is not sufficient to determine which of the traits – blood group A or
O – is dominant. This is because we do not know about the blood group of all the progeny.
Blood group A can be genotypically AA or AO. Hence, the information is incomplete to draw
any such conclusion.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-9/
How do Mendel’s experiments show that traits are inherited independently?
Mendel crossed pea plants having round green seeds (RRyy) with pea plants having wrinkled yellow seeds (rrYY).Since the F1 plants are formed after crossing pea plants having green round seeds and pea plants having yellow wrinkled seeds, F1 generation will have both these characters in them. However,Read more
Mendel crossed pea plants having round green seeds (RRyy) with pea plants having
wrinkled yellow seeds (rrYY).Since the F1 plants are formed after crossing pea plants having green round seeds and
pea plants having yellow wrinkled seeds, F1 generation will have both these characters in
them. However, as we know that yellow seed colour and round seeds are dominant
characters, therefore, the F1 plants will have yellow round seeds.
Then this F1 progeny was self-pollinated and the F2 progeny was found to have yellow
round seeds, green round seeds, yellow wrinkled seeds, and green wrinkled seeds in the
ratio of 9:3:3:1. In the above cross, more than two factors are involved, and these are independently inherited.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-9/
How do Mendel’s experiments show that traits may be dominant or recessive?
Mendel selected true breeding tall (TT) and dwarf (tt) pea plants. Then, he crossed these two plants. The seeds formed after fertilization were grown and these plants that were formed represent the first filial or F1 generation. All the F1 plants obtained were tall. Then, Mendel self-pollinated theRead more
Mendel selected true breeding tall (TT) and dwarf (tt) pea plants. Then, he crossed these
two plants. The seeds formed after fertilization were grown and these plants that were
formed represent the first filial or F1 generation. All the F1 plants obtained were tall.
Then, Mendel self-pollinated the F1 plants and observed that all plants obtained in the F2
generation were not tall. Instead, one-fourth of the F2 plants were short.
From this experiment, Mendel concluded that the F1 tall plants were not true breeding.
They were carrying traits of both short height and tall height. They appeared tall only
because the tall trait is dominant over the dwarf trait.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-9/
How does the creation of variations in a species promote survival?
Sometimes for a species, the environmental conditions change so drastically that their survival becomes difficult. For example, if the temperature of water increases suddenly, most of the bacteria living in that water would die. Only few variants resistant to heat would be able to survive. If theseRead more
Sometimes for a species, the environmental conditions change so drastically that their
survival becomes difficult. For example, if the temperature of water increases suddenly,
most of the bacteria living in that water would die. Only few variants resistant to heat
would be able to survive. If these variants were not there, then the entire species of
bacteria would have been destroyed. Thus, these variants help in the survival of the
species.
However, not all variations are useful. Therefore, these are not necessarily beneficial for
the individual organisms.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-9/
If a trait A exists in 10% of a population of an asexually reproducing species and a trait B exists in 60% of the same population, which trait is likely to have arisen earlier?
In asexual reproduction, the reproducing cells produce a copy of their DNA through some chemical reactions. However, this copying of DNA is not accurate and therefore, the newly formed DNA has some variations. It can be easily observed in the above figure that in asexual reproduction, very few variaRead more
In asexual reproduction, the reproducing cells produce a copy of their DNA through some
chemical reactions. However, this copying of DNA is not accurate and therefore, the newly
formed DNA has some variations.
It can be easily observed in the above figure that in asexual reproduction, very few
variations are allowed. Therefore, if a trait is present in only 10% of the population, it is
more likely that the trait has arisen recently. Hence, it can be concluded that trait B that
exists in 60% of the same population has arisen earlier than trait A.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-9/
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?
In species, variations that offer survival advantages are naturally selected. Individuals adjust to their environments with the help of these selected variations and consequently these variations are passed on to their progeny. Evolution of organisms occurs as a result of this natural selection. HowRead more
In species, variations that offer survival advantages are naturally selected. Individuals
adjust to their environments with the help of these selected variations and consequently
these variations are passed on to their progeny. Evolution of organisms occurs as a result
of this natural selection.
However, there can be some other variations, which do not offer any survival advantage
and arise only accidentally. Such variations in small populations can change the frequency
of some genes even if they are not important for survival.
This accidental change in the frequency of genes in small populations is referred to as
genetic drift.
Thus, genetic drift provides diversity (variations) without any survival advantage.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-9/
How is the equal genetic contribution of male and female parents ensured in the progeny?
In human beings, every somatic cell of the body contains 23 pairs of chromosomes. 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 two X chromosomes and males have one X and one Y chromosome.Read more
In human beings, every somatic cell of the body contains 23 pairs of chromosomes. 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 two X chromosomes and males have one X and one Y chromosome. The
gamete receives half of the chromosomes. Therefore, the male gametes have 22
autosomes and either X or Y chromosome.
The female gamete, on the other hand, has 22 autosomes and X chromosome.
During reproduction, the male and female gametes fuse and thus the progeny receives 22
autosomes and one X or Y chromosome from male parent and 22 autosomes and one X
chromosome from the female parent.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-9/
Explain how sexual reproduction gives rise to more viable variations than asexual reproduction. How does this affect the evolution of those organisms that reproduce sexually?
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, asexRead more
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.
Variation and Evolution: 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.
Thus, variation helps in the evolution of sexually reproducing organisms.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-9/