Given below are five statements (i-v) regarding constrivances to ensure cross - pollination is plants
(i) Dicliny - Anthers stigmas mature at different times in a bisexual flower.
(ii) Dichogamy - Flowers are unisexual.
(iii) Prepotency - Pollen grains of the same flower germinate more rapidly over the stigma than the pollen grains another flower.
(iv) Heterostyly - Two or three types of flowers with different heights of styles.
(v) Herkogamy - A mechanical device to prevent self - pollination
which of the above statement are correct ?

Options

A. (i) and (ii)
B. (i), (ii) and (iii)
C. (iii) , (iv) and (v)
D. (iv) and (v)

Answer

To determine which of the five statements regarding contrivances to ensure cross-pollination in plants are correct, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement (i): Dicliny - Anthers and stigmas mature at different times in a bisexual flower.**
- **Analysis**: This statement is incorrect. Dicliny refers to the condition where flowers are unisexual, meaning that either the male or female reproductive organs are present in a flower, but not both. Therefore, this statement does not correctly define dicliny.

2. **Statement (ii): Dichogamy - Flowers are unisexual.**
- **Analysis**: This statement is also incorrect. Dichogamy is a mechanism where the male and female parts of a flower mature at different times, but it can occur in bisexual flowers. Thus, this statement misrepresents the concept of dichogamy.

3. **Statement (iii): Prepotency - Pollen grains of the same flower germinate more rapidly over the stigma than the pollen grains of another flower.**
- **Analysis**: This statement is incorrect. Prepotency refers to the phenomenon where pollen from a different flower (cross-pollen) germinates faster than the self-pollen from the same flower. Hence, this statement does not accurately describe prepotency.

4. **Statement (iv): Heterostyly - Two or three types of flowers with different heights of styles.**
- **Analysis**: This statement is correct. Heterostyly refers to the presence of flowers with styles of different lengths within the same species, which helps promote cross-pollination by ensuring that pollen from one flower type is less likely to fertilize its own type.

5. **Statement (v): Herkogamy - A mechanical device to prevent self-pollination.**
- **Analysis**: This statement is correct. Herkogamy involves the spatial arrangement of the anthers and stigma in such a way that it minimizes the chances of self-pollination, thereby promoting cross-pollination.

### Conclusion:
Based on the analysis:
- **Correct Statements**: (iv) Heterostyly and (v) Herkogamy.
- **Incorrect Statements**: (i) Dicliny, (ii) Dichogamy, and (iii) Prepotency.

### Final Answer:
The correct statements are (iv) and (v).

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