Tag: sex determination in humans

Questions Related to sex determination in humans

In humans, the composition of a zygote that will develop into a female is

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

  1. $44A + XX$

  2. $44A + XY$

  3. $22 + X$

  4. $23A$

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Correct Option: A
Explanation:

A zygote is diploid. Hence it will have 44 autosomes. A sperm can have either of the two sex chromosomes X or Y while the egg has only one sex chromosome X. If the sperm containing the X chromosome fuses with the egg, the child born will be a female. If the sperm containing the Y chromosome fuses with the egg the child born will be a male. Thus the correct answer is option A.

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

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

  1. Boy

  2. Girl

  3. X chromosome does not determine the sex of a child

  4. Either boy or girl

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Correct Option: B
Explanation:

XX chromosomal pair determines that a child is a female. XY combination determines that the child is a male. Thus, an egg of a female will always contain and X chromosome. 50% of the sperms contain X chromosome and 50% of sperms contain Y chromosome. Thus when an egg is fertilized by a sperm containing X chromosome, the combination of XX is paired thus giving birth to a girl child.

Structure present in a cell which is responsible for determination of the sex of a baby is

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

  1. Cytoplasm

  2. Cell membrane

  3. Nucleus

  4. Chromosome

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Correct Option: D
Explanation:

In humans, males and females have differences in sex chromosomes. Human cells are having two types of chromosomes: autosomes and allosomes. Allosomes present in a male is XY and those present in a female are XX. There are no differences in the cytoplasm or membrane. The chromosome is present inside a nucleus, so you can think of the nucleus also as the correct answer but when a chromosome is given as an option, it is a better choice.

The human offspring can be of two types with XX and .......... chromosomes.

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

  1. XY

  2. XX

  3. XXX

  4. YY

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Correct Option: A
Explanation:
The sex of an individual is determined by which paternal sex chromosome (X or Y) is inherited during fertilization. Eggs and sperm, as reproductive cells, each contain only one of the two sex chromosomes as a result of having undergone meiosis, a form of cell division that produces daughter cells containing only one member of each chromosome pair. All eggs therefore, contain an X chromosome, but half of the sperms contain an X chromosome and the other half a Y chromosome. 
If an egg is fertilized by a sperm carrying an X chromosome, an XX or female embryo will result, while fertilization of the egg by a Y-bearing sperm will produce an XY or male embryo. In some organisms, including birds, the female contains the unlike pair of sex chromosomes. Thus, in these cases, the mother determines the sex of the offspring.
Thus, the offspring can be of two types, XX and XY.

Sex of the child is determined by the type of ................ provided by the father.

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

  1. Sperm

  2. Ovum

  3. Embryo

  4. Placenta

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Correct Option: A
Explanation:

A human female produces only one type of ovum having half the number of autosomes and one X chromosome. However, a male produces two types of sperms having half the number of autosomes and either an X or a Y chromosome. In case, the sperm with X type of chromosome fertilizes ovum then a female child is produced and if the sperm with a Y chromosome fertilizes the ovum a male child is produced. Hence, the type of sperm that actually fertilizes the ovum determines the sex of the baby.

Which of the following statement is true?

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

  1. Mother determines the sex of the child.

  2. Father inherits the character to the son only.

  3. Father inherits the character to daughter only.

  4. None of the above.

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Correct Option: D
Explanation:
  • Father determines the sex of the child as there are two types of sperms ( 23+XX and 23+XY) while all eggs are same (23+XX).
  • Father inherits the character to both son and daughter as each offspring whether boy or girl receives half of their genome from mother and another half from father.
  • So, the correct option is 'None of the above'.

In human beings, the statistical probability of getting either a male or a female child is 50:50. Which of the following is the cause behind it?

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

  1. The sex of an infant is determined by the type of sex chromosome contributed by the male gamete.

  2. The ratio of male gametes containing X chromosome and those containing Y chromosome is 50:50.

  3. Both A and B.

  4. None of these

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Correct Option: C
Explanation:
  • The sex of an infant is determined by the type of sex chromosome contributed by the male gamete. A male produces two types of sperms, one type bears 22+X composition and the other, 22+Y. Therefore, a male has 50% sperms with X chromosomes and the other 50% with Y chromosomes.
Anyone of the two types of the sperms can fertilize the egg. If a Y bearing sperm fertilizes the egg, the zygote will be a male (XY) and when X bearing sperm fertilizes the egg, the resulting zygote will be female (XX). Since the ratio of the X chromosome and the Y chromosome in a male gamete is 50:50. The statistical probability of male or female infants is also 50:50.