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प्रश्न
Trace the events from copulation to zygote formation in a human female.
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उत्तर
- When coitus (copulation) occurs, the penis releases semen into the vagina (insemination).
- The motile sperms travel quickly past the cervix, penetrate the uterus, and finally reach the fallopian tube's ampullary area.
- The ovary's ovum is also transferred to the ampullary area, where fertilisation occurs.
- Fertilisation can take place only if the ovum and sperms are transferred to the ampullary region at the same time. This is why not all copulations result in fertilisation and pregnancy.
- The process of fusion of a sperm with an ovum is called fertilisation.
- During fertilisation, a sperm comes into contact with the ovum's zona pellucida layer, causing alterations in the membrane that prevent further sperm from entering. As a result, only one sperm can fertilise an ovum.
- The acrosome's secretions aid sperm entry into the cytoplasm of the ovum via the zona pellucida and plasma membrane.
- This causes the secondary oocyte's meiotic division to be completed.
- The second meiotic division is also uneven, producing a second polar body and a haploid ovum (ootid).
- Soon, a diploid zygote is created when the haploid nuclei of the sperm and the ovum fuse together.
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संबंधित प्रश्न
A large number of married couples the world over are childless. It is shocking to know that in India the female partner is often blamed for the couple being childless.
- Why in your opinion the female partner is often blamed for such situations in India? Mention any two values that you as a biology student can promote to check this social evil.
- State any two reasons responsible for the cause of infertility.
- Suggest a technique that can help the couple to have a child where the problem is with male partner.
The highly sophisticated procedure of directly injecting a sperm into an egg is called ______.
The test-tube baby programme employs which one of the following techniques?
The test-tube baby programme employs which one of the following techniques?
Males in whom testes fail to descend to the scrotum are generally infertile. Why?
What are the Assisted Reproductive Techniques practised to help infertile couples? Describe any three techniques.
Given below are Column A with a list of certain Assisted Reproductive Technologies (ART) and in Column B the procedures followed during ART:
| Column A | Column B | ||
| S. No. | Names of ART | S. No. | Procedures |
| (A) | GIFT | (i) | Transfer of ovum from a donor into the fallopian tube of another female. |
| (B) | ICSI | (ii) | Transfer of semen from the donor into the vagina of the female. |
| (C) | ZIFT | (iii) | Injecting sperm directly into the ovum. |
| (D) | IUI | (iv) | Transfer of early embryos into the fallopian tube. |
Choose the option where ART correctly matches with the procedure.
The ______ is also called the womb.
Name any two Cu-ions releasing IUDs.
Which one of the following choices reflects the correct number of chromosomes in the zygote and in the second polar body of Drosophila melanogaster?
| Zygote | Meiocytes | |
| I | 08 | 08 |
| II | 04 | 08 |
| III | 08 | 04 |
| IV | 04 | 04 |
