There are several important keywords and phrases that you should include in your answers for Paper II of the UPSC Zoology Optional Subject. These keywords and phrases will help you demonstrate your understanding of the subject matter and showcase your knowledge to the examiner. Here are some key points to remember:

1. **Scientific Terminology**: Incorporate relevant scientific terms and vocabulary in your answers to showcase your understanding of the subject. For example, when discussing animal behavior, use terms such as ethology, innate behavior, or operant conditioning.

2. **Classification and Taxonomy**: When discussing different animal groups, include their scientific classification and taxonomic hierarchy. For instance, when talking about birds, mention their class (Aves), order (Passeriformes), and family (Turdidae).

3. **Evolutionary Concepts**: Include keywords related to evolutionary concepts such as natural selection, adaptation, speciation, or convergent evolution. These terms will demonstrate your understanding of the evolutionary processes and mechanisms.

4. **Life Cycles and Reproduction**: When discussing life cycles or reproductive strategies of animals, use terms such as metamorphosis, sexual selection, brood parasitism, or viviparity. These keywords will highlight your knowledge of different reproductive strategies and life history traits.

5. **Ecological Interactions**: Incorporate keywords related to ecological interactions, such as predation, competition, mutualism, or symbiosis, to demonstrate your understanding of the dynamics between organisms and their environment.

6. **Conservation Biology**: Use phrases such as habitat loss, species extinction, endangered species, or conservation measures when discussing conservation biology. This will showcase your understanding of the importance of preserving biodiversity and protecting ecosystems.

7. **Research Techniques and Methodology**: Include keywords related to research techniques and methodologies used in zoology, such as DNA sequencing, mark-recapture, transect sampling, or radio telemetry. These terms will highlight your familiarity with scientific methodologies used in zoological research.

Remember to integrate these keywords and phrases seamlessly into your answers, ensuring that they contribute to the overall coherence and clarity of your response. Using these keywords will help you showcase your knowledge and understanding of zoology to the examiner effectively.