Unfortunately, I cannot browse the internet or access specific websites like EduRev. However, I can provide you with general information about previous year question papers for Paper I of the UPSC Zoology Optional subject.

Previous year question papers are a valuable resource for UPSC aspirants as they give an insight into the exam pattern, types of questions asked, and the level of difficulty. They help candidates understand the syllabus and focus on important topics. Solving these papers also helps in time management and improving problem-solving skills.

Here is a general outline of how you can find previous year question papers for UPSC Zoology Optional subject:

1. UPSC Official Website:
- Visit the official website of the Union Public Service Commission (UPSC).
- Navigate to the "Examination" section.
- Look for the previous year question papers for the Zoology Optional subject.
- UPSC often provides question papers of the past few years, which can be downloaded in PDF format.

2. UPSC Preparation Websites:
- Several websites dedicated to UPSC preparation offer previous year question papers.
- Look for reputable and reliable websites that provide authentic question papers.
- Check if the website has a specific section for UPSC Zoology Optional subject question papers.
- Download the question papers in PDF format from these websites.

3. Coaching Institutes and Study Materials:
- Many coaching institutes provide study materials and question papers for UPSC preparation.
- Enroll in a reputable coaching institute that offers Zoology Optional subject coaching.
- They often provide their students with previous year question papers as part of their study materials.
- Alternatively, you can also check if the coaching institute sells question paper sets separately.

Remember to use these previous year question papers as a supplementary resource and not solely rely on them for your preparation. It is important to cover the entire syllabus and refer to other study materials, textbooks, and reference books to enhance your understanding of the subject.