Germ pores in pollen grains are

Options

A. prominent apertures in exine where sporopollenin is absent
B. prominent apertures in intine where sporopollenin is absent
C. prominent apertures where exine is absent
D. prominent apertures where intine is absent

Answer

**Step-by-Step Solution:**

1. **Understanding Pollen Grain Structure**:
- Pollen grains have two main layers: the outer layer called the exine and the inner layer called the intine. The exine is composed of a tough substance known as sporopollenin.

2. **Identifying Germ Pores**:
- Germ pores are specific areas on the pollen grain where the exine is absent, allowing for the formation of a germ tube during the process of pollination.

3. **Function of Germ Pores**:
- The primary function of germ pores is to facilitate the emergence of the germ tube. When pollen lands on a compatible stigma, the germ tube grows out through these pores to reach the ovule for fertilization.

4. **Characteristics of Sporopollenin**:
- Sporopollenin is highly resistant to degradation, which allows pollen grains to survive in various environmental conditions (high temperatures, acidic or alkaline pH). This resilience is crucial for the pollen's longevity and ability to reach the ovule.

5. **Conclusion**:
- Germ pores are essentially prominent apertures in the exine where sporopollenin is absent, allowing the germ tube to form and grow during pollination.

**Final Answer**: Germ pores in pollen grains are prominent apertures in the exine where sporopollenin is absent.

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