Question

Hologamy is observed in

• A. Plasmodium
• B. Trichonympha
• C. Vorticella
• D. Paramecium

Hint:

Hologamy is a primitive form of sexual reproduction where the entire organism acts as a gamete and fuses with another entire organism. It is distinct from conjugation (genetic exchange without complete fusion) or anisogamy (fusion of differentiated gametes).

Answer 1

The Correct Option is B

Step 1: Define Hologamy. Hologamy is a type of sexual reproduction found in some lower organisms, typically unicellular ones. In hologamy, the entire mature organism (which acts as a gamete) fuses with another entire mature organism. Essentially, the individuals themselves act as gametes and fuse completely. Step 2: Evaluate the options based on the definition of Hologamy and the reproductive methods of each organism. \begin{itemize} \item (1) Plasmodium: \textit{Plasmodium} (the malaria parasite) undergoes sexual reproduction involving the fusion of distinct male and female gametes (anisogamy) in the mosquito gut. It does not exhibit hologamy where the entire mature organism fuses. \item This option is incorrect. \item (2) Trichonympha: \textit{Trichonympha} is a flagellate protozoan that lives symbiotically in the gut of termites and cockroaches, helping them digest cellulose. Some species of \textit{Trichonympha} are known to exhibit hologamy, where two mature individuals fuse completely to form a zygote. \item This option is correct. \item (3) Vorticella: \textit{Vorticella} is a ciliate protozoan. It reproduces primarily by binary fission (asexual reproduction). It also engages in sexual reproduction through conjugation, where two individuals exchange genetic material, but they do not fuse completely as in hologamy. They separate after conjugation. \item This option is incorrect. \item (4) Paramecium: \textit{Paramecium} is another well-known ciliate protozoan. Like \textit{Vorticella}, \textit{Paramecium} reproduces asexually by binary fission and sexually by conjugation. In conjugation, two \textit{Paramecium} individuals temporarily fuse, exchange micronuclear material, and then separate. This is not hologamy, as the entire organisms do not permanently fuse. \item This option is incorrect. \end{itemize} Step 3: Conclude the correct option. Based on the reproductive strategies, hologamy is observed in \textit{Trichonympha} among the given options. The final answer is $\boxed{\text{Trichonympha}}$.