Tag: sex determination in humans

Questions Related to sex determination in humans

Choose the correct answer from the alternatives given.


A couple has six daughters, What is the possibility of their having a girl next time?

biology mendel's law of inheritance determination of sex sex determination sex determination in humans

  1. 10%

  2. 50%

  3. 90%

  4. 100%

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Correct Option: B
Explanation:

The possibility of having a girl or boy child is equal Le., 50% as 50% male gametes are Y type and 50% are X type. Fusion of egg with X type sperm will produce a girl child. 

If the first seven children born to a particular pair of parents are all males, what is the probability that the eighth child will also be a male?

biology mendel's law of inheritance determination of sex sex determination sex determination in humans

  1. $\dfrac{1}{2}$

  2. $\dfrac{1}{4}$

  3. $\dfrac{1}{8}$

  4. $\dfrac{1}{16}$

Show answer
Correct Option: A
Explanation:
The sex of an individual depends on the combination of sex chromosomes in its cells, that is, the combination of X and Y chromosomes. An embryo with XX genotype would develop into a female, while an embryo with an XY would develop into a male. The mother has a genotype and would always produce gametes with an X chromosome. The father, however, would produce half the gametes having an X chromosome and half carrying a Y chromosome. The sex of the embryo in humans would hence depend on the chromosome present in the gamete of the father. For every child conceived, there is an equal probability of the child being a male or a female, as the gamete received from the father has a 50% chance of carrying an X chromosome and  50% chance of carrying a Y chromosome.
So, the correct answer is $\dfrac{1}{2}$

In human beings, the gametes from the .......... decides the sex of the baby.

biology mendel's law of inheritance determination of sex sex determination sex determination in humans

  1. Male parent

  2. Female parent

  3. Both A and B

  4. None of the above

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Correct Option: A
Explanation:
Sex is determined by two chromosomes, X and Y. A female is XX, a male is XY. Since women completely lack the Y chromosome, they always contribute an X chromosome to the baby. The sex is determined by whether the sperm that fertilizes the egg is carrying another X or a Y.
The generally accepted theory is that males determine the sex because males can donate both an X chromosome or Y chromosome, while females can only donate an X chromosome to their offspring, making their contribution constant and the male's contribution the variable which, under normal circumstances, determines the offspring's genetic sex.

A son inherits an X chromosome from 

biology mendel's law of inheritance determination of sex sex determination sex determination in humans

  1. Mother

  2. Father

  3. Both A and B

  4. Grandparents

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Correct Option: A
Explanation:
A child will inherit Y chromosome from father to become a boy. In human being, Y is the factor of maleness.
Male parent:  XY     x      Female parent: XX
Gametes:      X, Y            X
Offspring:     XX (Female child), XY  (Male child)

A child who inherits an Y chromosome from father will be a girl.

biology mendel's law of inheritance determination of sex sex determination sex determination in humans

  1. True

  2. False

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Correct Option: B
Explanation:
A child will inherit Y chromosome from father to become a boy and X chromosome to become a girl. In human being, Y is the factor of maleness.
Male parent:  XY     x     Female parent: XX
Gametes:      X, Y           X
Offspring:     XX (Female child) , XY  (Male child)

Mother is responsible for the sex of a baby.

biology mendel's law of inheritance determination of sex sex determination sex determination in humans

  1. True

  2. False

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Correct Option: B
Explanation:

The sex of the child is completely dependent on the father and not mother. This is because men are XY and women are XX. This means that the woman can only donate one X chromosome to her child, while the father can either donate an X or a Y. If the father donates the X to the child, it will be XX and become a female, if the father donates a Y to the child, it will be XY and will become a male.

The sex chromosomes of .......... determine the sex of an unborn baby.

biology mendel's law of inheritance determination of sex sex determination sex determination in humans

  1. Male

  2. Female

  3. Grand parent

  4. None of the above

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Correct Option: A
Explanation:
The sex of a human baby is determined by the composition of its sex chromosomes (a single distinct pair among humans 23 pairs of chromosomes). Females possess two copies of the same chromosome (referred to as the 'X' chromosome); males have one copy of the X chromosome and one copy of the smaller, hook-shaped Y chromosome.
When fertilization occurs, the new gamete (the initial cell from which a fetus grows) always inherits one of the mother's X chromosomes, and either a X or a Y from the father, depending on which chromosome the fertilizing sperm cell happened to inherit. One could say, then, that the father—or, at least, his sperm—determines the sex of the child. 

The given statement is true or false. Sex of baby mainly depends on male.

biology mendel's law of inheritance determination of sex sex determination sex determination in humans

  1. When X chromosome containing sperm fuses with ovum, male foetus develops.

  2. When Y chromosome containing sperm fuses with ovum, male foetus develops.

  3. When X chromosome containing sperm fuses with ovum, female foetus develops.

  4. Both B and C

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Correct Option: D
Explanation:

The chromosome in the human female is XX while that in the male is XY.
If a sperm carrying X chromosome fertilizes an ovum or egg, which carries X chromosome, then the child born will be a girl (female). This is because the child will have XX combination of sex chromosomes.
If a sperm carrying Y chromosome fertilizes an ovum, which carries X chromosome, then the child will have XY combination of sex chromosome and hence it will be a male child.
Thus, the correct answer is the option (D), 'Both B and C.'.

A zygote which has inherited a Y chromosome from the father will develop into

biology mendel's law of inheritance determination of sex sex determination sex determination in humans

  1. A boy

  2. A girl

  3. Anyone of the above

  4. None of the above

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Correct Option: A
Explanation:

XY type of sex determination is seen in humans. Genetic makeup of female is XX and that of male is XY. A female ovum always carries a X chromosome and male sperm can carry either X or Y chromosome.

The human which has an XX pair of chromosomes is called 

biology mendel's law of inheritance determination of sex sex determination sex determination in humans

  1. Male

  2. Female

  3. Hybrid

  4. Pure breed

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Correct Option: B
Explanation:

Humans have X and Y sex chromosomes. A human with 22 pairs of autosomes and two copies of X chromosomes as sex chromosomes are females while those with 22 pairs of autosomes and XY chromosomes as sex chromosomes are males. A pure breed refers to individual that have a pair of identical alleles for a particular locus while a hybrid carries unlike alleles for a particular locus. The correct answer is B.