How many independent variables should exist in a well designed experiment

The fruit of a certain plant is sweet and fleshy. the seeds of this plant have a seed coat that is fairly tough. the seeds germinate better if they are exposed to acid, or scarification. what is the most likely type of dispersal for this seed? water animal wind

What do your cells need to live? a. carbon dioxide b. carbon c. air d. oxygen

Technology can bring both good and bad things. pesticides can make crops more resistant to insects (good) but can harm humans if they are used improperly (bad). give examples of both the good and bad