Question

Auxospores are formed by
A. Diatoms
B. Euglenoids
C. Dinoflagellates
D. Bacteria

Answer 1

Hint:- In general, spores are haploid as well as unicellular and are formed in the sporangium of a diploid sporophyte by meiosis. The spore will grow into a new organism through mitotic division during favourable conditions, creating a multicellular gametophyte that eventually produces gametes.

Complete step-by-step solution:-
In diatoms, the size is restored by a special cell called the 'auxospore '(meaning development or growing spore). In the usual sense, this is not a spore. It is not a dispersal unit like moss or fern or mushroom spores, nor is it a resistant or dormant process like the Zygnema or Spirogyra, Green Algae Zygospores. Instead, regenerating the maximum size and characteristic shape of that particular diatom is its principal function. The initial cell has a modified morphology relative to the subsequently developed vegetative cells since it is formed within the auxospore, rather than within another vegetative cell.
By means of cell division, in which euglenoids divide through their length, Euglena reproduces asexually and some species develop dormant cysts which can tolerate drying.
Dinoflagellates reproduce asexually by means of predominantly binary or multiple fission reproduction.
Bacterias reproduce by binary division, where the mother cell divides into two identical daughter cells.
So, the correct answer is option (A).

Note:- Usually the auxospore is a zygote and is thus almost always diploid. It is not nude, but has a special organic wall or a composite wall consisting of organic elements and silica. As in the diagram, the growth of the auxospore can be isodiametric or it can be limited by harder, less elastic parts of its wall, forming bipolar or multipolar shapes.