Double fertilization is unique to …......

Correct option is D

The correct answer is (d) Angiosperms

Double fertilization is a distinctive feature of angiosperms (flowering plants) and is not observed in other plant groups. This process involves two separate fertilization events within the embryo sac.

Key Features of Double Fertilization in Angiosperms:

Two Fertilization Events:

• One sperm cell fuses with the egg cell to form the diploid zygote (fertilization).

• The other sperm cell fuses with the two polar nuclei to form a triploid cell, which develops into the endosperm.

Formation of Zygote and Endosperm: The zygote develops into the embryo, while the endosperm provides nourishment for the developing seed.

Significance: Ensures efficient utilization of resources by forming the nutritive tissue (endosperm) only after fertilization occurs.

Additional Information:

Pteridophytes:

• Pteridophytes are vascular plants that reproduce via spores instead of seeds or flowers.

• Examples: Ferns, horsetails, and club mosses.

• Reproductive Features:

• Sporophyte Dominance: The dominant phase in their life cycle is the sporophyte, which produces spores.

• Water-Dependent Fertilization: Sperm from the male gametophyte swims to the egg in the female gametophyte for fertilization.

• Unique Traits:

• First plants to develop vascular tissue (xylem and phloem).

• Do not exhibit seed formation or double fertilization.

Bryophytes:

• Bryophytes are non-vascular plants, meaning they lack xylem and phloem.

• Examples: Mosses (e.g., Funaria), liverworts (e.g., Marchantia), and hornworts.

• Reproductive Features:

• Gametophyte Dominance: The dominant phase is the gametophyte, which produces gametes.

• Water-Dependent Fertilization: Sperm from the male antheridia swims through water to reach the female archegonia for fertilization.

• Reproduction results in a sporophyte attached to the gametophyte, which produces spores.

• Unique Traits:

• Found in moist and shaded environments.

• Lack true roots, stems, and leaves; instead, they have structures like rhizoids.

Gymnosperms:

• Gymnosperms are seed-producing plants that do not produce flowers or fruits.

• The term "gymnosperm" means "naked seed," as their seeds are exposed on the surface of cones.

• Examples: Pines, firs, spruces, and cycads.

• Reproductive Features:

• Sporophyte Dominance: The dominant phase is the sporophyte.

• Male and Female Cones: Male cones produce pollen grains, and female cones produce ovules.

• Fertilization occurs when pollen grains are carried by wind to the ovule.

• Endosperm in gymnosperms is haploid (n), unlike the triploid (3n) endosperm in angiosperms.

• Unique Traits:

• Adapted to dry conditions with needle-like leaves and thick cuticles.

• Do not exhibit double fertilization.