Which of the following is correct about the flatworm's muscular system ?
a. it's muscles are attached to a center bone.
b. it consists of two layers of muscle.
c. its muscles are all involuntary.
d. it contains three types of muscle tissue.

How are tumors cells different from normal cells

Which level of consumer had access to the smallest apply of energy

Which best describes the nucleus of an atom a. it is where all of the particle s of the atom are located b. it is the negatively charged part of the atom c. it is where the electrons and the protons are located d. it is the part of the atom with the greatest mass