1. An amoeba is a unicellular organism.
What characteristics?

Some things consist of only one cell. They are called unicellular organisms. One of the simplest living things, an amoeba, is made of only one cell. Amoebas (sometimes spelled amoebas or amoebae) are too small to be seen without a microscope, but they are commonly found in ponds and lakes.

sulfur dioxide

explanation: acid rain is caused by 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.

answer///multiple alleles;