Which gland stimulates the immune system?
a. thymus
b. thyroid
c. pineal
d. testes
-apex

What are the characteristics of living things

Which set of characteristics best describes sedimentary rock? a) largest type of rock, made of organic matter, hardest type of rock b) often contains layers, forms near sources of water, contains fossils c) least abundant type of rock, made of other rocks, made mostly of minerals d) most abundant type in earth's crust, made of magma/lava, contains no fossils

Which enzyme is responsible for “unzipping" the dna by breaking the hydrogen bonds between the nucleotides?