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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.
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संबंधित प्रश्न
Write the types of sex-determination mechanisms the following crosses show. Give an example of each type.
(i) Female XX with Male XO
(ii) Female ZW with Male ZZ
Which combination of genes in the zygote will produce children with blue eyes?
Explain the mechanism of sex determination in humans with a suitable chart.
Which of the following is incorrect regarding ZW-ZZ type of sex determination?
What is haplodiploidy?
Explain the mode of sex determination in honeybees.
Match the items of Column I with Column II:
| Column I | Column II | ||
| i. | XX-XO method of Sex Determination | a. | Turner syndrome |
| ii. | XX-XY method of Sex Determination | b. | Female heterog ametic |
| iii. | karyotype-45 | c. | Grasshopper |
| iv. | ZW-ZZ method of Sex Determination | d. | Female homogametic |
The two versions of a trait (character) which are brought in by the male and female gametes are situated on
Also describe as to, who determines the sex of an unborn child? Mention whether temperature has a role in sex determination.
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?
