Biology · Locomotion and Movement · NEET
It is flagellar movement. NCERT clearly states that flagellar movement helps in the swimming of spermatozoa (sperm). The single long tail of the sperm is a flagellum, and its beating drives the cell forward. This is a very common NEET single-line question.
Both are hair-like outgrowths of the cell membrane with the same internal 9+2 microtubule core, but they differ in number and length. Cilia are short and many, and work like oars. A flagellum is long and usually few (a sperm has only ONE). Because the sperm moves using its single long tail, we call it flagellar movement.
NCERT lists three examples of flagellar movement: swimming of spermatozoa, maintenance of the water current in the canal system of sponges, and locomotion of protists like Euglena. Remember these three, as NEET often asks for examples of flagellar movement.
The flagellum is covered by the plasma membrane and its core is called the axoneme. The axoneme has the 9+2 arrangement: nine doublets of peripheral microtubules arranged radially plus two central microtubules. These are made of the protein tubulin, and the flagellum arises from a basal body.
The three cell movements NCERT lists for the human body are amoeboid, ciliary and muscular. Flagellar movement is discussed alongside them because sperm cells show it, but in the strict three-type classification of human body cell movements, sperm swimming is often grouped under the flagellar type. Read the NCERT line carefully as NEET tests this exact wording.
Sperm motility is due to ___________.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
The beating of the sperm's single long tail, which is a flagellum. This is called flagellar movement.
A flagellum. It is long and there is only one per sperm, which fits the definition of a flagellum, not a cilium.
The axoneme is the core of the flagellum. It has the 9+2 arrangement of microtubules made of tubulin protein, running along the length of the tail.
Swimming of spermatozoa, maintenance of water current in the canal system of sponges, and locomotion of protists like Euglena.
NEET asks direct one-line questions such as 'Sperm motility is due to' and expects you to pick flagellar movement. Mixing it up with ciliary movement is a common mistake that loses easy marks.
