Which statement is true for single-celled organisms?
a.
they are often harmless.
b.
they always cause disease.
c.
they only live inside humans.
d.
they reproduce in a complicated process.

In dna, only the_ varies from one nucleotide to another. base phosphate sugar amino acid

Many organs are involved in the processes of keeping the blood and the body clean. when poisonous or harmful substances are in the blood, they are absorbed by the and released in a less harmful form. when wastes are present in the blood, they are filtered out and removed from the body by the

What is the name of the two satelites on mars