PLEASE HELP ITS FOR FINALS!

Of your good in bio kusing a series of preliminary observations; pstate a problem developed from these observations, formulate a hypothesis, design an experiment to test the hypothesis

(select all the correct choose each statement that is scientific. - the opinions of randomly selected participants in a survey prove the idea that global temperatures are not increasing on earth. - the universe's average temperature and rate of expansion support the idea that it began as one super-dense and hot mass 13.8 billion years ago. - ocean tides are caused by the uneven gravitational pulls of the moon and sun on different parts of earth. - human life is more valuable than other forms of life on earth because humans are more intelligent than other organisms.

What substance acts to prevent sudden ph changes in bodily fluids?