A/an blank exists when different concentrations of a substance exist on either side of a membrane?

Which of the following is true of photosynthesis? a)carbon dioxide is a reactant b)water is a product c)most reactions within this process are exothermic d)oxygen is a reactant

Consider the skeleton. which skeletal system is represented by the shaded portion of the skeleton? spongy skeleton compact skeleton axial skeleton appendicular skeleton

Apaleontologist finds a plant fossil that shows that the plant had seeds. what can the paleontologist conclude?