Secondary nucleus is also called as

• (a) Generative nucleus
• (b) Tube nucleus
• (c) Definitive nucleus
• (d) Primary endosperm nucleus

The secondary nucleus is commonly referred to as the **definitive nucleus**. This term is used in the context of plant reproduction, particularly during the process of double fertilization in angiosperms (flowering plants). To clarify this concept further, let’s delve into the roles and characteristics of the secondary nucleus and its significance in plant development.

Understanding the Role of the Secondary Nucleus

In flowering plants, fertilization involves two sperm cells from the pollen grain. One sperm cell fertilizes the egg cell, forming the zygote, while the other sperm cell fuses with the two polar nuclei located in the central cell of the ovule. This fusion results in the formation of the definitive nucleus, which ultimately develops into the endosperm.

Key Functions of the Definitive Nucleus

• Endosperm Formation: The definitive nucleus is crucial for the formation of the endosperm, which serves as a nutrient-rich tissue that supports the developing embryo.
• Support for Embryo Development: The endosperm provides essential nutrients, allowing the embryo to grow until it can establish its own photosynthetic capabilities.
• Double Fertilization Process: This process is unique to angiosperms and is vital for successful reproduction, ensuring that both the embryo and the endosperm are formed simultaneously.

Comparing the Terms

To further clarify why the secondary nucleus is called the definitive nucleus, let’s look at the other options you mentioned:

• Generative Nucleus: This refers to the nucleus that divides to form the two sperm cells during pollen development.
• Tube Nucleus: This is the nucleus that directs the growth of the pollen tube, facilitating the delivery of sperm cells to the ovule.
• Primary Endosperm Nucleus: This term is sometimes used interchangeably with definitive nucleus, but it specifically refers to the initial stage of the endosperm before it matures.

Conclusion

In summary, the secondary nucleus is best identified as the definitive nucleus due to its role in forming the endosperm, which is essential for nurturing the developing embryo in flowering plants. Understanding these terms and their functions helps clarify the complex processes involved in plant reproduction and development.