Auxospores are formed by -

Options

A. Diatoms
B. Euglenoids
C. Dinoflagellates
D. bacteria

Answer

**Step-by-Step Solution:**

1. **Understanding Auxospores**: Auxospores are specialized reproductive structures that are formed during the sexual reproduction of certain organisms. They play a crucial role in restoring the size of the organism after a period of asexual reproduction.

2. **Identifying the Organisms**: The question provides four options: diatoms, jugulanoids, xanoflagellates, and bacteria. We need to determine which of these organisms is known for forming auxospores.

3. **Diatoms and Their Reproduction**: Diatoms are a group of microalgae characterized by their unique silica cell walls, which consist of two halves known as frustules. During asexual reproduction, diatoms divide, and each daughter cell receives only one of the two frustules, leading to a gradual decrease in cell size over generations.

4. **Transition to Sexual Reproduction**: When diatoms reach a minimum size limit due to successive asexual divisions, they switch to sexual reproduction. In this phase, they produce gametes that are isogamous, meaning they are morphologically similar.

5. **Formation of Auxospores**: The fusion of these gametes results in the formation of a zygote, which then develops into an auxospore. This auxospore is larger than the parent cells and helps restore the original size of the diatom.

6. **Conclusion**: Based on the characteristics of diatoms and their reproductive cycle, it is clear that auxospores are specifically formed by diatoms.

**Final Answer**: Auxospores are formed by diatoms.

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