Question

Calyptra develops from
A. Venter wall of archegonium
B. Outgrowth of gametophyte
C. Neck wall of archegonium
D. Paraphysis of the archegonial branch.

Answer 1

Hint: The protective covering around the eggs/sporophytes present inside the archegonium is known as Calyptra. As the egg is present in the swollen part of the archegonium which is a flask shaped structure the cells of the swollen part will make calyptra.

Complete answer:
Calyptra is also known as hood, covering or a lid. It is a maternal gametophytic structure which is small and covers the capsule which contains the eggs/ embryonic sporophytes. As the sporophytes are released from the capsule that is present in the center of the archegonium, calyptra disappears. It is considered to be a haploid tissue that grows in close association with the sporophytes in case of bryophytes and gymnosperms.

Functions of Calyptra –
-Secrets hormones for sporophyte differentiation.
-Provides mechanical support to the developing capsule which contains sporophytes.
-Prevents the loss of water from the apex of sporophyte.
-Lowers the rate of sporophytic transpiration.
-Protects the undifferentiated region of the capsule physically.

Archegonia which is the female reproductive organ is a flask shaped organ having neck region and swollen venter region which contains the capsule of sporophyte and the calyptra is present there in the center region. So calyptra will develop from the venter wall of the archegonium.

Hence, the correct answer is option (A).

Additional information:
-Some studies in Funaria showed that Calyptra is important for the formation of a sporophyte capsule that is why it forms before the capsule is formed.
-In some species capsule formed without calyptra but they didn’t elongate much and this was considered to be because of the lack of calyptra.
-In the absence of calyptra transpiration by the sporophyte increases that accelerates the upward movement of water in the plant body.
-Paraphysis is a sterile hair-like projection which might contain pigments. They are support structures present in the reproductive organs of plants of lower organisation.

Note: Calyptra is important in the developing sporophyte as it protects it from early desiccation due to excess transpiration and water loss from the undifferentiated apical region of the sporophyte.