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प्रश्न
Write a short note on sex determination in man.
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उत्तर
The difference between two individuals of the same species with respect to heredity is known as sex. So, an individual can either be a male or female in normal circumstances. Scientists have discovered that sex is transmitted by definite sex determination, also called heterosomes. The human body cells have two sex- chromosomes. A woman has two X- chromosomes while a man has one X- chromosome and one Y-chromosome.
Therefore, an egg cell has one X- chromosome and a sperm cell have either an X- or a Y-chromosome. This means that the sex of a baby is determined by the type of sperm cell fertilizing the egg. If an egg, fused with a sperm having Y-chromosome, then the male zygote will develop and when fused with a sperm having an X-chromosome then a female zygote will develop.
संबंधित प्रश्न
Define the following:
Sex-linked characters
Give Reason:
Why X-linked recessive diseases are more common among males than females.
Explain the haplo-diploid method of sex determination in the honey bee.
From the following which option correctly represents the normal genetic constitution of a ovum?
Grasshopper is an example of XO type of sex determination in which the males have ______.
Some dinosaurs had feathers although they could not fly but birds have feathers that help them to fly. In the context of evolution this means that
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?
In the XX–XO sex determination system, what does the 'O' represent?
In the ZW–ZZ sex determination system, which sex is heterogametic?
