Question

Dinomitosis occurs in which of the following?
A) Prokaryotes
B) Mesokaryotes
C) Eukaryotes
D) Akaryotes

Answer 1

Hint: Dinomitosis is seen in an organism belonging to Kingdom Protista.

Complete answer:
Dinoflagellates are aquation, marine, photosynthetic and unicellular eukaryotes. In dinoflagellates division occurs in an unique way, during division the nuclear membrane and nucleolus persist, no spindle formation takes place and they are replaced by cytoplasmic microtubules, and this is known as dinomitosis. The nucleus is large and known as a mesokaryon. These organisms are therefore referred to as mesokaryotes.

Additional Information:
The Kingdom Protista can be divided into three categories, autotrophic protists/photosynthetic protists (diatoms and dinoflagellates), consumer decomposer protists (slime molds), and protozoan protists.
The general features of organisms belonging to dinoflagellates are as follows:
a) The cell is covered by a theca or lorica, which are stiff cellulosic plates. The cellulosic plates have a sculptured look and therefore they are known as armored dinoflagellates.
b) Two grooves are present, one is known as transverse cingulum or girdle or annulus, and the other groove is known as the longitudinal sulcus.
c) Two flagella are present which are different therefore are known as heterokont.
d) The two flagella are at an angle of ninety degrees to each other and show a unique type of movement, hence dinoflagellates are also called whirling whips.
e) They contain pigments like chlorophyll a, chlorophyll b, fucoxanthin rich carotenoids in structures known as chromatophores.
f) Reserved food is stored as starch and oil.
g) Only the asexual mode of reproduction is seen in them.
h) Some dinoflagellates show the property of bioluminescence and therefore known as fire algae, examples are Noctiluca, Pyrocystis.
i) Excessive growth of some dinoflagellates makes seawater reddish in appearance and so they are called red algae.

So, the correct answer is, ‘Dinomitosis occurs in the Mesokaryotes’.

Note: It should be remembered that both dinoflagellates and diatoms are known as chrysophytes and both of them are autotrophic, unicellular protists but only dinoflagellates are known as mesokaryotes and not diatoms.