Thomas discovered cathode rays when he was working with electrons. He was performing experiments with electrons when one of them became electrically charged and a beam of light came from it, this creating a cathode ray.
It’s either not testable since hypothesis need to be able to be tested or it could be not likely tho second option it has been poorly written
Cardiovascular system( im so sorry if it was wrong)
Choloroplasts are unique to plant cells.
They are used to absorb light energy, which animals don’t.
Therefore plants contain chloroplasts and animals don’t.