Aside from direct harm, what secondary issue do invasive species present? They may be able to eat all kinds of native organisms.

They might introduce other organisms like viruses and bacteria.

They might damage the habitat that other organisms rely on.

They may not have any predators.

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 .