Question

Transverse binary fission occurs in -
a. Euglena
b. Amoeba
c. Hydra
d. Paramecium

Answer 1

Hint: Fission is the division of a single cell into two or more parts, and after regeneration, resembling the parent cell. Fission can be binary (single organism produces two parts) or multiple (single organism produces multiple parts). It is a form of asexual reproduction. It is a primary mode of reproduction in the prokaryotes.

Complete answer:
- The mode of reproduction in Euglena is Longitudinal Binary fission.
- The mode of reproduction in Amoeba is normal binary fission.
- Hydra reproduces asexually by budding or fragmentation.
- Transverse binary fission takes place in ciliates. This is observed in Paramecium.
- The cytoplasm separates transversely between two pairs of nuclei, forming two unrelated individuals.
- The splitting into two occurs by pinching off in the middle of the long axis of the organism.
- The macronucleus does not divide by mitosis, instead, it elongates and then splits in two, and the micronuclei undergo mitosis. This type of reproduction involves no exchange of genetic material and is a type of asexual reproduction, known as fission.

Hence, the correct answer is option (D).

Additional information:
Different types of Binary fission:
> Longitudinal Binary fission- In this, cytokinesis takes place along the longitudinal axis. e.g. in flagellates like Euglena.
> Oblique Binary fission-In this, binary fission cytokinesis occurs obliquely.
> Transverse Binary fission- Cytokinesis takes place along the transverse axis. e.g. in ciliated protozoans like Paramecium.

Note: Binary fission is a method of asexual reproduction, there is a separation of the parent cell into two daughter cells that resembles the parent cell. This process begins with the division and duplication of the parent’s genetic components into two parts such that each daughter cell receives one copy of its parent DNA. Paramecium is a unicellular organism found in the freshwater environment.