Determination of sex - class-XII

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. 

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 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.'.

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.

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.

Each pregnancy has a 50% chance of resulting in a boy or girl and this does not include the possibility of multiples. Having 3 daughters previously does not affect the chances of any resulting pregnancy. The chance of having a boy remains at 50%. Thus, the correct answer is option C. 

Human follows XX- XY mechanism of sex determination. Human females have 46 chromosomes arranged in 22 homologous and homomorphic autosomes and two copies of X chromosomes as sex chromosomes (44+XX). Males have 22 homomorphic pairs and one heteromorphic pair, the XY pair (44+XY). During meiosis, all the gametes produced by females contain only the X chromosome (22 + X), whereas males produce two kinds of gametes, 1/2 gametes with X- and 1/2 with Y-chromosome (22 + X and 22 + Y). Fertilization of egg (22 + X) with sperm carrying 22+X chromosomes results in female child (44 + XX). Fertilization of egg (22 + X) with the sperm carrying 22+Y chromosomes results in a male child (44A + XY) as the zygote is a diploid structure and consists of two complete sets of chromosomes. Thus, the correct answer is option A.

Sex determination seen in humans is XY sex determination. Ovum carries X chromosome, whereas sperm can carry either X or Y chromosome. The genetic makeup of a female is XX and genetic makeup of male is XY. Therefore, if the zygote is formed by receiving the X chromosome from the father, the resulting zygote will be a female. 

The karyotype of a normal human contains 22 pairs of autosomal chromosome and one pair of sex chromosome called as allosomes. Female contains 2 X chromosomes and 46 autosomes and male contains 1 X and 1 Y chromosome and 46 autosomes.

In human, the genetic makeup of female is XX and that of male is XY. Female ovum carries X chromosome, whereas the male sperm may carry either X chromosome or a Y chromosome. Therefore, if the sperm is carrying Y chromosome fertilizes an egg with X chromosome, the zygote develops into a male child.

Humans have 22 pairs of chromosome of which one pair of sex chromosome is not always a perfect pair. Women have a perfect pair of X chromosome but, men have a mismatched pair of X and Y chromosome. Therefore, (c) is the correct answer.

All animals do not contain chromosomes. In some cases, sex is determined by environmental variables (such as temperature) or social variables (e.g. the size of an organism relative to other members of its population). Therefore, (d) is the correct answer.

There is one X chromosome present in a male. Sex pair of chromosome XY represents the male human.

There are two X chromosomes present in a female. Sex pair of chromosome XX represents the female human.

When a sperm containing Y chromosome fertilises an egg with X chromosome, the zygote develops into a male child with XY as the sex chromosome. Because Y chromosome is only found in males.

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.

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.

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.

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.

• 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'.