1. 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.

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  2. 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.

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  3. 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.

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  4. 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.

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  5. 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.

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