Question

The sexual reproduction in protozoa is caused by
A. Binary fission
B. Conjugation
C. Fragmentation
D. None of the above

Answer 1

Hint: From basic unicellular prokaryotes to multicellular eukaryotes, reproduction is the most fundamental characteristic of all living organisms. It is a mechanism by which the parent and offspring create new individual species. This mode of reproduction occurs in most of the ciliates.

Complete answer: Conjugation is a sexual phase in which a temporary union of two lower organisms of the same genus, such as bacteria, protozoa, algae and fungi, etc. exchange their nuclei and its material. They completely pass the content of one organism to the other or fuse together to form one organism. The nucleus that results after the fusion is diploid. Different forms that are involved in conjugation are known as mating styles. In scale, shape, or motility, forms may or may not resemble each other. Some physiological or genetic features are distinct. In Protozoa, it is found in ciliates and sporozoans. Conjugation takes place via a structure called pilus in bacteria.
a) The rest two, viz. binary fission and fragmentation are means of asexual reproduction, where there is no involvement of gametes.
Hence, option B is the correct answer.

Note: In a living organism, reproduction is a simple biological mechanism. Sexual and asexual reproduction are two kinds of the reproduction process. A gamete is produced in sexual reproduction, and it is a bi-parental process, while during asexual reproduction, no gamete is formed and it can occur via a single parent. In asexual reproduction, the offspring are genetically identical to the parent, whereas, in sexual reproduction, the offspring inherits traits from both parents.