Which of the following human activities can cause an increase in carbon dioxide (CO2) in the atmosphere? large amounts of trees being cut down and burned

factories being built

automobiles being used

all of the above

The body is protected against harmful flu viruses by

What is a limitation of using a chemical formula, such as c6h1206, to represent a compound? the chemical formula does not show the types of elements that make up the compound. the chemical formula does not show how the atoms are connected to one another the chemical formula does not show the number of atoms of each element in a molecule. the chemical formula does not show the chemical symbols of the elements in the compound

What does polymerase chain reaction (pcr) do? o a. separates dna fragments by size o b. cuts a dna sample into fragments o c. provides an overall picture of a person's chromosomes o d. makes more copies of a sample of dna