Question

A sterile jacket around gametangia is found among __________.
A) Bryophytes
B) Lichens
C) Algae
D) Fungi

Answer 1

Hint:Gametangia (singular-gametangium) is a cell or organ in many multicellular protists, fungi, algae and the gametophytes in plants where gametes are produced. The gametangium is a haploid structure and the gamete formation in it takes place via mitosis and not meiosis.

Complete answer:
The male gametangium is called antheridium whereas the female gametangium is called archegonium. The jacket or sheath around the reproductive organs in plants are found only in higher order angiosperms; similarly, amongst organisms reproducing through spore formation, bryophytes and pteridophytes are of the highest order. Therefore, the sterile jacket is found around the gametangia is present only in the aforementioned class of organisms.
Let us look at each option one by one.
>Bryophytes are higher order spore producing organisms and therefore contain a jacket made of sterile cells surrounding the gametangia. Therefore, this is the correct option.

>Lichens are composite organisms which grow in symbiosis with some cyanobacteria, fungi or algae. These organisms also reproduce via spores produced in their hyphae but are very primitive in nature and do not contain jacketed gametangia. Therefore, this option is incorrect.

>Algae are eukaryotic aquatic organisms that are capable of photosynthesis. While some small algae reproduce asexually, larger algae are known to reproduce sexually usually by means of spore formation. Since algae are also classified as primitive life forms, they do not contain jacketed gametangia. Therefore, this option is incorrect.

>Fungi are multicellular eukaryotes that are heterotrophic in nature. They play important roles in nutrient cycling in the environment. While some fungi reproduce asexually, others reproduce sexually via spore formation. Since fungi are primitive organisms, they do not have jacketed gametangia. Therefore, this option is incorrect.

Thus, the correct answer is option (A) Bryophytes.

Note:The evolution of jacketed gametangia was observed in response to protecting the primitive plants against the harsh conditions of the environment. Later, these jacketed gametangia evolved to form seeds that protect the embryo in higher order plants.