Question

Double fertilization occurs in
A. Riccia
B. Pteridium
C. Cycas
D. Capsella

Answer 1

Hint: Double fertilization is the characteristic feature of angiosperm plants. In this process, the two male gametes undergo two fertilization processes, in which one fuses with the egg cell or ovum to form the zygote, while the other fuses with the two polar nuclei present in the ovary to produce the endosperm.

Complete answer:
Capsella is a biennial and a herbaceous plant present in Brassicaceae of the Mustard family. The plant belongs to the angiosperms class. Double fertilization is the unique feature to angiosperms. Thus the process of double fertilization occurs in Capsella. In double fertilization, the pollen deposited on the stigma germinates through the style to reach the ovule. The pollen contains two cells; the pollen tube cell and the generative cell. The pollen tube cell grows through the style and reaches the ovule through the micropyle. Of the two sperm cells, one sperm fertilizes the egg cell, forming a diploid zygote; the other sperm fuses with the two polar nuclei, forming a triploid cell that develops into the endosperm. The other sperm fuses with the two polar nuclei, forming a triploid cell that develops into the endosperm. Together, these two fertilization events in angiosperms are known as double fertilization.
i. Riccia belongs to the division Bryophyta. It belongs to the class of liverworts. Double fertilization is not a feature of bryophytes. The sexual reproduction in these species occurs by the fertilization of male and female gametes and production of the zygote.
ii. Pteridium belongs to division Pteridophyta and is commonly known as ferns. The reproduction in these species occurs through spores.
iii. Cycas is a gymnosperm plant, where the fertilized seeds are not enclosed with a fruit. Sexual reproduction in these species does not include double fertilization.
Hence, the correct answer is option D.

Note: The reproductive process in gymnosperms is different from that of angiosperms. The gametes are present in reproductive organs known as cones. There are both male and female cones, which carry male and female gametes respectively. The pollination occurs through wind and fertilizes to form the zygote.