Question

When the fern plant is developed from its prothallus without fertilization. This phenomenon is an example of
A. Parthenocarpy
B. Apogamy
C. Apospory
D. Organogenesis

Answer 1

Hint: Pteridophytes are the first terrestrial plant having vascular system. Ferns come under Pteridophytes. Leaves in ferns are megaphylls, i.e. they have large leaves. In ferns, the main part of the body is the sporophyte. Sporophyte has true root, stem and leaves. It has a sporangium subtended by a leaf-like structure called sporophylls.

Complete step by step answer: In ferns, sporangia produce spores. It is produced as a result of meiosis in mother cells. Spores germinate and give rise to a structure called prothallus. Prothallus is small, multicellular, mostly photosynthetic thalloid gametophytes. It bears both male and female sex organs that produce gametes. When a fern is developed from its gametophytes without fertilisation, this phenomenon is known as apogamy. Apogamy results in 1n sporophyte. It is an asexual method of reproduction. Apogamy is a related term that has had various meanings over time. In plants with independent gametophytes (notably ferns), the term is still used interchangeably with "apomixis", and both refer to the formation of sporophytes by parthenogenesis of gametophyte cells.
i. Parthenocarpy: In parthenocarpy, flowers after fertilisation develop into a fruit and ovules into seeds. But in some cases, the fruit is formed without fertilisation. This process is known as parthenocarpy. Banana is an example of parthenocarpy as it is produced without fertilisation.
ii. Apospory: When the non-reproductive cell of sporophyte develops into 2n gametophytes without meiosis and spore formation, it is known as apospory.
iii. Organogenesis: It is a phase when ectoderm, endoderm and mesoderm formation takes place. It begins after gastrulation and it is part of the embryonic development.
Hence, the correct answer is option B.

Note: Mostly in ferns, the gametophyte antheridia (male sex organ) and archegonia (female sex organ) produce gametes. Male and female gametes fertilised and formed a zygote. The zygote then produces a sporophyte which is the dominant phase of ferns.