Question

Which of these is absent in human sperm?

• A. Nucleus
• B. Mitochondria
• C. Centriole
• D. Endoplasmic reticulum

Answer 1

The correct option is D Endoplasmic reticulum

The endoplasmic reticulum is present in all other cells except sperms. Testis is the primary sex organ in males which produce gametes i.e., sperms. Mature sperm cell consists of a head, a neck, a middle piece and a tail. A plasma membrane envelops the whole body of sperm. The sperm head contains a very little cytoplasm, an elongated haploid nucleus, the anterior portion of which is covered by a cap-like structure, acrosome. The short neck contains two distinct granules - the proximal and distal centrioles. The proximal centriole plays a crucial role during the first cleavage of the fertilized ovum. The distal centriole gives rise to the axial filament of the long tail of the sperm. The middle piece of mammalian sperm cell possesses numerous mitochondria. These mitochondria are 25 to 30 in number which are spirally arranged. They produce energy for the movement of the sperm cell.
Thus, mitochondria, nucleus, and centriole are present in the sperm and E.R. is absent in the human sperm.