Question

Which of the following statements is not true in the case of Paramecium?
(A)Macro nucleus is involved in reproduction
(B)Micronucleus controls cellular metabolism
(C)Micronucleus controls reproduction
(D)All of the above

Answer 1

Hint: Paramecium are unicellular organisms that carry out most of their external functions with the help of cilia but they possess a unique dual nuclear Apparatus with a larger macronucleus and a diploid micronucleus. They both have certain distinguished structures and functions.

Complete answer:
The macronucleus in Paramecium is involved in reproduction.
Paramecium shows a dual nuclear apparatus which consists of a polyploid macronucleus and one or more diploid micronucleus. The macronucleus controls cellular functions whereas the micronucleus is involved in reproduction as it is generative or germline and contains genetic material that is passed along from one generation to another.

Additional information:
Paramecium is unicellular ciliates and is found in the freshwater, brackish, and marine environments. The cell is enclosed by a stiff but elastic structure known as pellicle which consists of the outer cell membrane, a layer of alveoli, and an inner membrane called the periplasm. They move with the help of cilia and their specialized movements. Paramecium mainly feeds on microorganisms like bacteria, yeast, and algae and gathers these foods with the help of cilia. Some of the species of paramecium live in symbiosis with other organisms like green algae, bacteria, etc.
They reproduce asexually and mainly by binary fission in which the macronucleus splits by amitosis and the micronucleus undergoes mitosis. This results in the cell dividing Transversely and each new cell gains a micronucleus as well as the macronucleus. In the case of spontaneous fission, either self-fertilization or conjugation takes place during which compatible mating types fuse temporarily and exchange genetic material. During this process, the micronucleus divides by meiosis and passes from one cell to the other. Later the gametes of each organism fuse and make the diploid micronuclei.

So, the correct answer is "macro Nucleus is involved in reproduction".

Note: Paramecium is widely used in classrooms and laboratories for their property of being easily induced to conjugate and divide. They are, in fact, the first ciliates that were observed by a microscope. The cells of this organism are ovoid, elongated, foot, or cigar-shaped and are almost 50 to 330 micrometers in length.