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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.
उत्तर
i. The sex chromosome is a chromosome involved in sex determination.
ii. 23 pairs of chromosomes are present in human beings. Of these, 22 pairs are of the autosomes and 1 pair is of the sex chromosomes.
iii. Determination of sex in human offspring:
- In human beings, the male possesses 44 autosomes and a pair of heteromorphic sex chromosomes, XY, while the female possesses 44 autosomes and a pair of homomorphic sex chromosomes, XX.
- At the time of gamete formation, meiosis occurs.
- The male parent produces X-bearing and Y-bearing gametes or sperms. The female parent produces only X-bearing gametes or eggs.
- During reproduction, the combination of one X-bearing gamete from the male with one X-bearing gamete from the female results in offspring with the genetic constitution XX. The child produced is a female or a daughter.
- The combination of a Y chromosome from the male with one X chromosome from the female results in an offspring with genetic constitution XY. The child produced is a male or a son.
- The offspring produced are always in equal proportion, and hence, the chance of having a daughter or a son is 50%.
iv. Sex determination in man:
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संबंधित प्रश्न
Differentiate between 'ZZ' and 'XY' type of sex-determination mechanisms.
How is the sex of the child determined in human beings?
Which of the two, sperm or ovum, decides the sex of the child?
In a human, how many chromosmes are present in a sperm in the testes?
The exchange of genetic material takes place in :
(a) vegetative reproduction
(b) asexual reproduction
(c) sexual reproduction
(d) budding
The number of pair(s) of sex chromosomes in the zygote of humans is :
(a) one
(b) two
(c) three
(d) four
The person A has only B chromosomes in all its gametes. On the other hand, another person C has chromosome D in half of gametes and chromosome E in the other half of gametes. When chromosomes B and D combine during fertilisation, a female zygote results. On the other hand, combination of B and E chromosomes produces a male zygote.
(a) What are chromosomes (i) B (ii) D, and (iii) E?
(b) Out of B, D and E, which two chromosomes are of the same type?
(c) Which chromosome is smaller in size?
(d) What is the general name of chromosomes such as B and E?
(e) Out of the two persons A and C, which one is (i) male, and (ii) female?
________ shows haplo-diploid type of sex-determination.
In which livings, female decides the sex? Give two examples.
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 |
Diploid larvae which get royal jelly as food develops into ____________ and other develops into workers (sterile females).
ZZ / ZW type of sex determination is seen in ______.
Haplodiploidy is found in ______.
In XO type of sex determination ______.
In human males all the chromosomes are paired perfectly except one. This/these unpaired chromosomes is/are ______.
- large chromosome
- small chromosome
- Y-chromosome
- X-chromosome
Human offspring’s sex is determined ______
Female heterogamy is shown by
