11. During double fertilization in plants, one sperm fuses with the egg cell and the other sperm fuses with
    (1) synergid cell (2) central cell
    (3) antipodal cell (4) nucellar cell

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Introduction

Double fertilization is a defining feature of flowering plants, involving two sperm cells released from the pollen tube into the female gametophyte. In this process, one sperm fertilizes the egg cell leading to embryo formation, while the second sperm fuses with the central cell containing two polar nuclei, resulting in the formation of triploid endosperm. This process ensures coordinated development of the embryo and its nutritive tissue.

Mechanism of Double Fertilization

• Upon reaching the ovule, the pollen tube penetrates the embryo sac (female gametophyte) and delivers two sperm cells.

• The first sperm fuses with the haploid egg cell, restoring diploidy and forming the zygote, which develops into the embryo.

• The second sperm moves to the central cell, which contains two haploid polar nuclei that fuse with the sperm nucleus to produce the triploid primary endosperm nucleus.

• The endosperm nourishes the developing embryo and forms the tissue that later supports the seedling.

Roles of Other Cells in the Embryo Sac

• Synergid cells (Option 1) aid in pollen tube guidance but do not fuse with sperm.

• Antipodal cells (Option 3) are located at the opposite end of the embryo sac and generally degenerate without fusing with sperm.

• Nucellar cells (Option 4) belong to the sporophytic tissue surrounding the embryo sac and are not directly involved in fertilization.

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Summary Table: Key Events in Double Fertilization

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Conclusion

Double fertilization involves one sperm fusing with the egg cell to form the zygote and the other sperm fusing with the central cell to produce the endosperm. Hence, the correct answer is the central cell.