Which layer of the heart is made of muscle tissue and pumps the blood through the system?

Which of the following is an oxidation-reduction reaction? (pictured below)

Which must be kept in mind when determining if an explanation is correct? check all that apply. which must be kept in mind when determining if an explanation is correct? check all that apply.

The blue particles in this image are able to cross the cell membrane through simple diffusion. how will they be transported? outside the cell inside the cell o a. the substances will move directly across the membrane from outside the cell to inside the cell. b. the substances will move through channels in the membrane proteins from outside the cell to inside the cell. o c. the substances will move through channels in the membrane proteins from inside the cell to outside the cell. o d. the substances will move directly across the membrane from inside the cell to outside the cell.