Answer:
Acid rain is a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. These substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain. It could cause serious troubles in pollution. Note that acid rain only occurs when near a high power plant do to the high levels of dioxide and nitrogen oxides are released into the air.
Sorry if I miss understood the question or didn't get it right I tried. :)
Animal cells dont have a cell wall or chloroplasts
I think this is true because the species evolved and adapted to the natural environments so perfectly that when a geological change such as global warming, the asteroid that hit earth etc. all affected climate, food or water.
A direct observation usually refers to observing a behavior and knowing exactly what is happening. For example, if I see a pigeon peck at some bread, I have observed it pecking. With direct observation, I cannot assume it is eating, that it is hungry, that it has any intention whatsoever. All I know is that it pecks.
A certain gene is only used for certain functions, and if that gene is always going, your body cant turn certain functions on and off, which can ultimately lead to a lot of health problems.
