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प्रश्न
How is sex determined in human beings?
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उत्तर
The XX-XY chromosomal pattern determines sex in humans. Humans possess 22 pairs of autosomes and one pair of sex chromosomes. The female has two homomorphic sex chromosomes called XX. The males have two heteromorphic sex chromosomes, XY. Female oocytes have equivalent chromosomal types (22 + X). As a result, girls are homogametic. Human males produce two types of male gametes or sperm: gynosperms (22 + X) and androsperms (22 + Y). Human males are hence heterogametic. The gender of the offspring is determined at fertilisation. Fertilisation of the egg (22 + X) with a gynosperm (22 + X) results in a female child (44 + XX), whereas fertilisation with an androsperm (22 + Y) results in a male child (44 + XY). Because the two types of sperm are produced in equal quantities, there is an equal possibility of having a male or female child in a given pairing. The Y-chromosome, which defines an individual’s male sex, is also known as the androsome.
संबंधित प्रश्न
Answer the following questions related to sex determination in human beings:
i. What is sex chromosome?
ii. How many pairs of chromosomes are present in human beings?
iii. How is the sex of the human offspring determined?
iv. Draw a diagram depicting sex determination in man.
Differentiate between ‘ZZ’ and ‘XY’ type of sex-determination mechanisms.
A new born child has an XY pair of chromosmes. Will it be a baby boy or a baby girl?
In a human, how many chromosmes are present in a brain cell?
The number of pair(s) of sex chromosomes in the zygote of humans is ______.
A couple with a newborn baby is troubled that the child does not resemble either of them. Suspecting that a mixup occurred at the hospital, they check the blood type of the infant. It is type O. Because the father is type A and the mother type B, they conclude that a mixup has definitely occurred. Are they correct? Give reason for your answer.
Name two animals which have nineteen pairs of chromosomes.
________ shows haplo-diploid type of sex-determination.
Define the following:
Sex-linked characters
Write a short note on sex determination in man.
Write the functional activity of the following structure:
Heterosomes
From the following which option correctly represents the normal genetic constitution of a ovum?
Which of the following develops through parthenogene is?
Sex is determined in human beings ______.
A man with blood group A marries a woman having blood group O. What will be the blood group of the child?
A zygote which has an X-chromosome inherited from the father will develop into a
A woman has only daughters. Analyse the situation genetically and provide a suitable explanation.
The belief that the mother is completely responsible for the sex of the child is wrong because the child
Structures present in a cell which is responsible for determination of the sex of a baby is ______.
The chromosomal constitution of a human female can be written as ______
In humans, males are heterogametic and females are homogametic. Explain. Are there any examples where males are homogametic and females heterogametic?
Name the two types of gametes produced by men.
All human chromosomes ate not paired. Most human chromosomes have a maternal and a paternal copy, and we have 22 such pairs. But one pair called the sex chromosomes, is odd in not always being a perfect pair. Women have a perfect pair of sex chromosomes. But men have a mismatched pair in which one is normal sized while the other is a short one.
(a) In humans, how many chromosomes are present in a Zygote and in each gamete?
(b) A few reptiles rely entirely on environmental cues for sex determination. Comment.
(c) "The sex of a child is a matter of chance and none of the parents are considered to be responsible for it." Justify it through flow chart only.
OR
(c) Why do all the gametes formed in human females have an X chromosome?
What is the probability of a girl or a boy being born into a family? Justify your answer.
How is the sex of a newborn individual determined in different species of animals? Give three examples to support your answer.
In the ZW–ZZ sex determination system, which sex is heterogametic?
In the haplodiploidy system observed in honeybees, fertilized eggs develop into which type of individual?
