34. Eukaryotic cell containing flagella is
(A) cell lining the fallopian tube
(B) sperm
(C) Paramecium
(D) cell lining the respiratory tract
Eukaryotic Cells Containing Flagella
Introduction
Cell movement is one of the most fascinating aspects of cell biology. In eukaryotic organisms, specialized cellular extensions known as cilia and flagella enable cells or surrounding fluids to move. Although both structures possess the characteristic 9+2 arrangement of microtubules and are powered by dynein motor proteins, they differ significantly in their length, number, and function.
Flagella are usually long and few in number, functioning primarily in locomotion of the entire cell. Cilia, on the other hand, are shorter, numerous, and beat in a coordinated manner to move fluids or particles across the cell surface. In humans, the sperm cell is the only normal somatic cell that possesses a true flagellum, whereas epithelial cells of the respiratory tract and fallopian tube contain motile cilia. Protozoans such as Paramecium also move using numerous cilia rather than flagella.
Correct Answer
Correct Option: (B) Sperm
Detailed Explanation
The sperm cell is the classic example of a eukaryotic cell possessing a single flagellum. The sperm flagellum is responsible for propelling the sperm through the female reproductive tract toward the ovum. Structurally, the flagellum contains a 9+2 microtubule axoneme, basal body, outer dense fibers, mitochondrial sheath, and dynein motor proteins that generate bending movements using ATP.
Cells lining the fallopian tube are not flagellated. Instead, they possess numerous motile cilia, which beat rhythmically to move the ovum from the ovary toward the uterus. Similarly, epithelial cells lining the respiratory tract contain abundant motile cilia that continuously transport mucus, dust particles, and microorganisms toward the pharynx, helping maintain respiratory health.
Paramecium is also not flagellated. It is a unicellular ciliate protozoan covered with thousands of short cilia that coordinate their movement to propel the organism through water and direct food particles toward the oral groove.
Therefore, among the given options, only the sperm cell possesses a true eukaryotic flagellum.
Explanation of Each Option
Option (A): Cell Lining the Fallopian Tube
This statement is incorrect. The epithelial cells of the fallopian tube possess numerous motile cilia that facilitate the movement of the ovum toward the uterus. They do not contain flagella.
Option (B): Sperm
This statement is correct. Human sperm contains a single long flagellum that generates propulsion through whip-like movements powered by dynein ATPase.
Option (C): Paramecium
This statement is incorrect. Paramecium belongs to the phylum Ciliophora and moves using thousands of coordinated cilia rather than flagella.
Option (D): Cell Lining the Respiratory Tract
This statement is incorrect. Respiratory epithelial cells are covered with motile cilia that remove mucus and trapped particles from the airways. They do not possess flagella.
Why Option (B) is Correct
The sperm cell contains a single flagellum specialized for locomotion. This flagellum is structurally composed of a microtubule-based axoneme arranged in the characteristic 9+2 pattern and is powered by dynein motor proteins. It is the only option representing a true flagellated eukaryotic cell.
Why the Other Options are Incorrect
Why Option (A) is Incorrect
Fallopian tube epithelial cells contain motile cilia that transport the ovum, not flagella.
Why Option (C) is Incorrect
Paramecium is classified as a ciliate protozoan because its entire surface is covered with cilia.
Why Option (D) is Incorrect
Respiratory epithelial cells use coordinated ciliary beating to remove mucus and inhaled particles rather than flagellar movement.
Comparison of All Options
| Option | Cell Type | Locomotory Structure | Correct or Incorrect |
|---|---|---|---|
| A | Fallopian Tube Cell | Cilia | Incorrect |
| B | Sperm | Flagellum | Correct |
| C | Paramecium | Cilia | Incorrect |
| D | Respiratory Epithelial Cell | Cilia | Incorrect |
Differences Between Cilia and Flagella
| Feature | Cilia | Flagella |
|---|---|---|
| Length | Short | Long |
| Number per Cell | Numerous | Usually One or Few |
| Movement | Coordinated Power Stroke | Whip-like Movement |
| Main Function | Move Fluid or Particles | Move the Entire Cell |
| Human Example | Respiratory Epithelium, Fallopian Tube | Sperm Cell |
Examples of Eukaryotic Cells with Cilia and Flagella
| Organism or Cell | Cilia | Flagella |
|---|---|---|
| Human Sperm | No | Yes |
| Fallopian Tube Cell | Yes | No |
| Respiratory Epithelial Cell | Yes | No |
| Paramecium | Yes | No |
| Euglena | No | Yes |
Structure of a Eukaryotic Flagellum
| Component | Function |
|---|---|
| Axoneme | Core microtubule structure with 9+2 arrangement |
| Dynein Arms | Generate sliding movement using ATP |
| Basal Body | Anchors the flagellum to the cell |
| Outer Dense Fibers | Provide mechanical support |
| Mitochondrial Sheath | Supplies ATP for motility |
Biological Significance of Flagella
Flagella enable efficient cellular locomotion and play a critical role in reproduction by allowing sperm to reach and fertilize the ovum. Defects in flagellar structure or dynein motor proteins can lead to male infertility and disorders such as Primary Ciliary Dyskinesia (Kartagener syndrome), where impaired movement of both cilia and flagella affects respiration and fertility.
Final Answer
Correct Option: (B) Sperm
The sperm cell is the only option that contains a true eukaryotic flagellum, which propels the sperm toward the ovum during fertilization. The cells lining the fallopian tube and respiratory tract, as well as Paramecium, possess cilia rather than flagella.
