How many different amino acids can be used in the construction of a protein

An enzyme lowers the energy of activation. what does that mean?

Select the correct answer from each drop-down menu. in an experiment, dr. travis examined the effects of calcium intake on osteoporosis, a condition that causes an increased risk of bone fractures. the amount of calcium is variable. the risk of bone fractures .

Which plate boundary causes plates to collide forming mountain ranges, volcanoes, and island arcs? give an example of this type of plate boundary. 2. at which plate boundary do rifts and mid-oceans ridges form? give an example of this type of plate boundary. 3. at which plate boundary do plates slide past each other while moving in opposite directions? give an example of this type of boundary.