Question
- Explain the process of spermatogenesis in humans.
- Draw a human sperm and label acrosome and middle piece. Mention their functions.
✓
Answer
- Spermatogenesis is the process of the production of sperms from the immature germ cells in males. It takes place in seminiferous tubules present inside the testes. During spermatogenesis, a diploid spermatogonium (male germ cell) increases its size to form a diploid primary spermatocyte. This diploid primary spermatocyte undergoes first meiotic division (meiosis I), which is a reductional division to form two equal haploid secondary spermatocytes. Each secondary spermatocyte then undergoes second meiotic division (meiosis II) to form two equal haploid spermatids. Hence, a diploid spermatogonium produces four haploid spermatids. These spermatids are transformed into spermatozoa (sperm) by the process called spermiogenesis.
- Acrosome: It is flat, oval in shape and composed of a large haploid nucleus and a small anterior cap-like structure, called acrosome. The acrosome lies at the tip of the nucleus and is formed from the Golgi complex. It contains hydrolytic enzymes and is used to contact and penetrate the egg (ovum) during fertilisation.
- Middle piece: It is cylindrical in shape and known as powerhouse of the sperm. It possesses many mitochondria to produce energy for the movement of the tail that facilitates sperm motility essential for fertilization.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
Smita was working in a garage with the doors closed and automobiles engine running. After some time she felt breathless and fainted. What would be the reason? How can she be treated
OR
While working with the car engine in a closed garage, John suddenly felt dizzy and fainted what is the possible reason?
OR
While working with the car engine in a closed garage, John suddenly felt dizzy and fainted what is the possible reason?
Particulate air pollutants.
Shreyas went to a garden on a wintry morning. When he came back, he found it difficult to breath and stated wheezing. What could be the possible condition and how can he be treated?
Gene expression can be controlled with the help of RNA. Explain the method with an example.
Complete the following table by placing the categories and the given signs + : Benefited ; – : Inhibited ; 0 : Not affected
| Interactions | Species | |
| A | B | |
| 1. Neutralism – ………………….. | ||
| 2. Negative interactions ………………………… | ||
| 3. Positive interactions ……………………. | ||
| 4. Both positive and negative interactions ………………………….. | ||
Describe the T.S. of anther. ### Sketch and label the T.S. of undehisced anther.
What essential features must be present in a cloning vector?
Himani while watching a TV programme based on life in polar region observed that all animals in polar regions possess larger size. Also, smaller animals are not found in that region. She asked about this surprising fact to her teacher.
- Why smaller animals (e.g. humming birds) are rarely found in polar regions?
- What are the adaptations shown by polar animals?
- What are the chief characteristics of polar region animals?
- What values are shown by Himani?
Describe in details different types of mycorrhizae.
What is blood clotting? How and when does it occur?