Investigatory projects in biology for class 12

Hi Monikashoo,
It's not obvious to me how you can answer this question except from reading about advanced research. Investigations tend to be focused around a very narrow question, which this is not. I can try to help you set up an experimental design, but you need to formulate a testable hypothesis. Let's by your telling me what specific question you want to answer? If you are not sure, I recommend you do some reading about caffeine, and then come back here.

EDIT: Also, please see the sticky and check out Science Buddies, which is specifically designed to help students do good science projects.

Caffeine - Wikipedia, the free encyclopedia
en.wikipedia.org/wiki/CaffeineCaffeine is found in varying quantities in the seeds, leaves, and fruit of some plants, ... Beverages containing caffeine, such as coffee, tea, soft drinks, and energy drinks, ... 1.3 Psychological; 1.4 Caffeine intoxication; 1.5 Addiction, tolerance and ..... Robiquet was one of the first to isolate and describe the properties of pure ...

biology investigatory projects topics???