Why must a scientists hypothesis be testable

To be able to do the experiment, and like that being able to find the correct answer to your hypothesis by testing it

  Because you can't prove something is true you can only prove that you can't prove it is false. You can't conduct the infinite number of experiments needed to prove that something always happens but its easy to conduct the one experiment that proves it doesn't always happen.hope this helpped

No that answer is wrong. you have written the function of mitochondria in chloroplast and function of chloroplast in mitochondria.

Very minute and important evidence needs to be collected in order together detail and figure out what had happened