Which is the best definition of a cellular membrane

49 ! how are energy cycles and growth cycles related?

Males of different species of the fruit fly drosophila that live in the same parts of the hawaiian islands have different elaborate courtship rituals. these rituals involve fighting other males and making stylized movements that attract females. what type of reproductive isolation does this represent?

Since color is not a very useful way to identify a mineral what other article property or properties can be used