Correct option is B
Explanation -
Option a - Transient rise in Ca²⁺ is necessary for egg activation in mammals.
This is true. A temporary increase in intracellular calcium is a well-established trigger for egg activation after fertilization.
Option b - Sperm induces egg activation and does not involve Ca²⁺.
This is false. Sperm-induced egg activation does involve a calcium signal (Ca²⁺ oscillations). Hence, this is the INCORRECT statement.
Option c - In many organisms, eggs secrete diffusible molecules that attract and activate sperm.
This is true for species like sea urchins and some marine organisms, where chemotaxis guides sperm to the egg.
Option d - Capacitated mammalian sperm can penetrate the cumulus and bind the zona pellucida.
This is also true. Capacitation is a process that prepares the sperm to interact with and penetrate the protective layers of the egg.
Since, option b is the only incorrect statement among all the other that makes it a correct answer
Option b: Sperm induces egg activation and does not involve Ca²⁺.
