Understanding and answering questions related to animal physiology in Paper I of UPSC Zoology Optional subject can be challenging but with the right approach, it can be tackled effectively. Here are some specific tips to help you comprehend and respond to these questions:

1. Thoroughly study the syllabus: Familiarize yourself with the syllabus for Paper I of UPSC Zoology Optional subject. Understand the topics and subtopics that fall under animal physiology and ensure you have a strong foundation in these areas.

2. Read and analyze the question carefully: Before attempting to answer a question, read it attentively. Identify the keywords and understand what the question is asking for. Pay attention to the specific animal or physiological process mentioned in the question.

3. Review the relevant concepts: Once you have understood the question, recall the relevant concepts and theories related to animal physiology. Make sure you have a clear understanding of the topic being asked.

4. Organize your answer: Plan your answer and organize it in a logical manner. Break down your response into an introduction, main body, and conclusion. Use bullet points or numbered lists to present your ideas clearly.

5. Use diagrams and illustrations: Animal physiology often involves complex processes and structures. Utilize diagrams, flowcharts, and illustrations to explain your points effectively. These visual aids can enhance the clarity and understanding of your answer.

6. Provide examples and case studies: To support your answer, include relevant examples and case studies. These can help illustrate your understanding of the topic and demonstrate your ability to apply theoretical knowledge to practical situations.

7. Stay updated with current research: Animal physiology is a dynamic field with ongoing research and discoveries. Stay updated with the latest advancements and findings in the field. This will not only enhance your understanding but also add depth to your answers.

8. Practice previous year question papers: Solve previous year question papers to get familiar with the pattern and types of questions asked in the exam. This will help you understand the level of detail required in your answers and improve your time management skills.

Remember, practice and thorough understanding of the subject are key to performing well in Paper I of UPSC Zoology Optional subject.