PLEASE HELP (Over Due)

Mario performed an experiment to determine if photosynthesis was affected by the amount of light that a plant received. what could he have done to increase the validity of his data? reduce the number of plants. remove the 1 hour group. add a 0 hours control. measure the oxygen in liters

Apopulation of black bears depends on salmon from a stream for food. if a drought causes the stream to run dry one year, how will this likely impact the black bear population?

When a gasoline engine burns gasoline, what type of chemical reaction is occurring?