Length of pollen tube depends on the distance between

Options

A. pollen grain and upper surface of stigma
B. pollen grain on upper surface of stigma and ovule
C. pollen grain in anther and upper surface of stigma
D. upper surface of stigma and lower part of style

Explanation

**Step-by-Step Solution:**

1. **Understanding the Pollen Tube Function**: The pollen tube is responsible for transporting male gametes from the pollen grain to the ovule for fertilization.

2. **Identifying Key Structures**: The key structures involved in this process are:
- Pollen grain
- Stigma (the upper surface of the pistil where pollen lands)
- Style (the structure that connects the stigma to the ovary)
- Ovule (located within the ovary)

3. **Analyzing the Options**:
- **Option A**: Pollen grain and upper surface of stigma - This does not account for the distance to the ovule.
- **Option B**: Pollen grain and upper surface of stigma and ovule - This includes both the stigma and the ovule, which is essential for the pollen tube's length.
- **Option C**: Pollen grain on the anther and upper surface of stigma - The anther is not relevant to the length of the pollen tube.
- **Option D**: Upper surface of stigma and lower part of style - This does not include the ovule.

4. **Determining the Correct Answer**: The length of the pollen tube is determined by the distance from the stigma to the ovule, which is located in the ovary. Therefore, the correct answer is **Option B**: pollen grain and upper surface of stigma and ovule.

5. **Conclusion**: The length of the pollen tube depends on the distance between the pollen grain (which germinates on the stigma) and the ovule (located in the ovary).

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