4. Scientists are studying photosynthesis in a forest ecosystem that has plants, animals, and
decomposers (which consume dead things). Which group or groups of organisms in the forest
carry out photosynthesis?

The independent variable is the type of music.the dependent variable is the pulse rate.the intervening variable is the age of the subject.if the mother does not like rock, her pulse is likely to not increase.the same might be true for the sister.the friend may like rap and gets excited.to establish cause/effect relationship, all of the subjects must be consistent.hope i .