Which of the following is correct about heterospory?

Options

A. Selaginella and salvinia are heterosporous
B. heteroporous pteridophytes have mcro (large) and micro (small) spores
C. The development of zygote within female gametophyte is the precursor to the seed habit
D. All of the aabove

Answer

**Step-by-Step Text Solution:**

1. **Understanding Heterospory**: Heterospory refers to the production of two distinct types of spores by a plant. These spores are categorized as macrospores (large) and microspores (small). This is in contrast to homospory, where only one type of spore is produced.

2. **Identifying Examples**: The question mentions Sleginella and Salvinia. Both of these are examples of pteridophytes that exhibit heterospory. This means they produce both macrospores and microspores.

3. **Characteristics of Spores**: In heterosporous plants, the macrospores develop into female gametophytes, while the microspores develop into male gametophytes. This differentiation is crucial for the reproductive process.

4. **Development of Zygote**: In heterosporous plants, the zygote develops within the female gametophyte. This process is significant as it is considered a precursor to the seed habit, which is an important evolutionary step leading to the development of seeds in higher plants.

5. **Conclusion**: Since all statements regarding heterospory, including the examples of Sleginella and Salvinia being heterosporous, the distinction between macro and micro spores, and the development of the zygote within the female gametophyte being a precursor to seed habit, are correct, the answer is that all of the above statements are true.

**Final Answer**: The correct option is "all of the above."

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