Preparing for the practical or lab-based questions in the Botany optional subject requires a combination of theoretical knowledge and hands-on experience. Here are some strategies to help you effectively prepare for these types of questions:

1. Understand the syllabus:
- Familiarize yourself with the detailed syllabus provided by the UPSC for the Botany optional subject.
- Identify the specific practical or lab-based topics that are covered in the syllabus.

2. Study the theoretical concepts:
- Gain a thorough understanding of the theoretical concepts related to the practical or lab-based topics.
- Use standard Botany textbooks and study materials to strengthen your theoretical knowledge.
- Take notes and create summaries of the important concepts for quick revision.

3. Practice in the laboratory:
- Regularly visit the laboratory and perform experiments related to the practical or lab-based topics.
- Familiarize yourself with the various laboratory equipment, techniques, and procedures.
- Pay attention to safety precautions and handling of chemicals and specimens.

4. Observe and document:
- Develop the habit of keen observation during practical experiments.
- Take detailed notes on the observations, results, and interpretations.
- Maintain a laboratory notebook to record your experiments, including the procedure followed and the outcomes.

5. Analyze sample questions:
- Solve previous years' question papers and sample question papers specifically focusing on practical or lab-based questions.
- Analyze the patterns and types of questions that are commonly asked.
- Identify the areas where you need more practice or improvement.

6. Collaborate with peers:
- Engage in group study sessions or discussions with classmates who are also preparing for the Botany optional subject.
- Share your knowledge and experiences related to practical experiments.
- Discuss and solve practice questions together to enhance your understanding.

7. Seek guidance from experts:
- Consult your professors or subject matter experts for guidance on practical or lab-based topics.
- Clarify any doubts or queries you may have about specific experiments or concepts.
- Attend workshops or seminars related to Botany to gain additional insights.

8. Revise and review:
- Regularly revise the theoretical concepts and practical aspects of the topics covered in the syllabus.
- Review your laboratory notes and observations to refresh your memory.
- Solve mock tests or attempt model answers for practical or lab-based questions to improve your answering skills.

By following these strategies, you can effectively prepare for the practical or lab-based questions in the Botany optional subject and increase your chances of scoring well in the UPSC examination.