I also graduated from JMSS, and also helped out in the interview process last year.
Firstly congratulations to everyone who got an interview!
Quotes from the information night could be useful, but make sure you use it to explain what made the school appeal to you, or in other words what you found attractive about the school.
My top advise for the interview is to explain in detail WHY you like Science, HOW it has affected you in the past (if it has, if it hasn't it's okay) and WHAT your hopes are in the future, as a result of your passion for Science.
I think it'll really help if you have an example about when you thought Science was cool, when you got excited about things you saw in a prac, or maybe when you realized knowing a simple scientific fact changed the way you see things. Like, when you learned that everything is made up of atoms, you realized everything you see are huge clusters of really tiny tiny atoms, and you thought that was really cool. Ideally a more detailed example is better if you can think of any, but the idea is sharing an example of what you thought about Science will get you a long way
Also, not sure if they are doing this year but if you have a group discussion interview, where you sit with other students and discuss a topic, try to say something, anything, no matter how obvious your ideas are. You will almost always get some marks for saying something.
Finally, just wanted to say that it's totally okay to be nervous, I was so so so nervous on the day as well, I hardly remember anything
The JMSS students assisting and the teachers are usually nice too
Good luck guys!!