| List-I | List-II |
|---|---|
| A. Head | I. Enzymes |
| B. Middle piece | II. Sperm motility |
| C. Acrosome | III. Energy |
| D. Tail | IV. Genetic material |
To solve this matching question, we must analyze the structural components of a human sperm and their specific physiological roles:
Matching these pairs leads us to A-IV, B-III, C-I, D-II, which corresponds to option (C).
The human sperm (spermatozoon) is a microscopic, motile male gamete produced through the process of spermatogenesis in the seminiferous tubules of the testes. Its structure is highly specialized for one singular purpose: reaching and penetrating the female gamete (ovum).
A mature sperm is composed of a head, neck, middle piece, and a tail. The entire body of the sperm is enveloped by a plasma membrane.
The head contains the haploid nucleus. The dense packing of chromatin ensures that the genetic material is protected during its journey. At the tip of the head lies the Acrosome. Derived from the Golgi apparatus, the acrosome acts like a "chemical drill." It contains proteolytic enzymes, collectively called sperm lysins (e.g., hyaluronidase and acrosin), which dissolve the zona pellucida and corona radiata of the egg.
The neck is very short and contains two centrioles: the proximal centriole (which plays a role in the first cleavage of the zygote) and the distal centriole (which gives rise to the axial filament of the tail).
The middle piece contains 25–30 spiral-shaped mitochondria (nebenkern). These mitochondria utilize fructose from the seminal fluid to generate the ATP required for the tail's movement. Without a functional middle piece, the sperm would be stationary (immotile) and incapable of fertilization.
The tail is the longest part of the sperm. It consists of a central axial filament (axoneme) surrounded by a thin layer of cytoplasm. The whip-like movements of the tail provide the necessary thrust for the sperm to swim through the female reproductive tract at a rate of approximately 1–4 mm per minute.
During ejaculation, a human male releases about 200 to 300 million sperm. For normal fertility, at least 60 percent of these sperm must have normal shape and size, and at least 40 percent of them must show vigorous motility.
Spermatogenesis and sperm maturation are controlled by hormones. Luteinizing Hormone (LH) acts on Leydig cells to produce testosterone, while Follicle Stimulating Hormone (FSH) acts on Sertoli cells to stimulate spermiogenesis and the secretion of factors essential for maturation.
1. What is the main function of the acrosome?
The acrosome contains enzymes that dissolve the protective layers of the ovum to allow penetration.
2. Why does the middle piece contain so many mitochondria?
To provide the high amount of ATP (energy) needed for the sperm to swim a long distance.
3. Where is the genetic material located in the sperm?
It is located in the haploid nucleus within the head of the sperm.
4. What determines sperm motility?
Motility is provided by the movement of the tail, powered by energy from the middle piece.
5. What is the role of the proximal centriole?
It enters the egg during fertilization and helps in the formation of the first mitotic spindle for the zygote.
6. How many sperm are usually present in one ejaculation?
Approximately 200 to 300 million sperm.
7. What is the cap-like structure on the sperm head called?
It is called the acrosome.
8. From which cell organelle is the acrosome derived?
It is derived from the Golgi apparatus during spermiogenesis.
9. What sugar provides energy to the sperm?
Fructose, which is secreted by the seminal vesicles.
10. What is a spiral arrangement of mitochondria called?
It is known as the nebenkern.