Reproduction in paramecium is by

Analyze the question: The question asks how Paramecium reproduces. Paramecium is a single-celled (unicellular) protozoan that lives in freshwater and has cilia for movement.

Explain the concept:

• Binary fission is when one cell divides into two identical daughter cells. Paramecium does this asexually, and the division is transverse (across the body).
• Budding is when a small outgrowth forms on the parent and detaches. Yeast and Hydra do this.
• Spore formation is common in fungi (e.g. Mucor, Rhizopus) and ferns.
• Fragmentation is when the body breaks into pieces, each growing into a new organism. Spirogyra and planarians do this.

Step-by-step solution:

1. Paramecium is unicellular, so it has no complex body to bud or fragment.
2. Under favourable conditions, its micronucleus divides by mitosis and the macronucleus elongates and divides.
3. The cell then constricts across the middle and splits into two daughter paramecia.
4. Paramecium can also exchange genetic material through conjugation, which is sexual. This is not a true reproduction method because it does not increase the number of cells. It only brings variation.

So the main method of reproduction is binary fission.

Answer: A. binary fission.

Exam tip: Match each organism with its method:

• Paramecium, Amoeba, bacteria → binary fission
• Yeast, Hydra → budding
• Mushroom, Mucor → spores
• Spirogyra, planarians → fragmentation

Remember "Paramecium and Amoeba divide into two."