Author Question: When a substance must attach to another molecule, called a carrier, to move into or out of a cell, ... (Read 48 times)

soccerdreamer_17 · **on:** Jul 23, 2018

When a substance must attach to another molecule, called a carrier, to move into or out of a cell, it is called what?

A) Active transport
B) Osmosis
C) Passive transport
D) Facilitated diffusion

Question 2

What process is used by the large intestine to evacuate waste products from the body?

A) Rectal stimulation
B) Basic electrical rhythm
C) Segmentation
D) Mass movement

alvinum · **Reply #1 on:** Jul 23, 2018

Answer to Question 1

D
Feedback:
Sometimes a substance cannot move freely on its own in or out of a cell. Such a substance may attach to another kind of molecule, called a carrier, to be diffused. This form of diffusion, known as facilitated diffusion, does not require energy, only the presence of the carrier. Active transport requires energy to move the substance against the concentration gradient. Osmosis is a special form of diffusion where water moves across a semipermeable membrane from an area low in solutes to one that is higher in solutes to dilute solutes. Passive transport does not require energy to move solutions across a semipermeable membrane and includes diffusion, osmosis, and facilitated diffusion.

Answer to Question 2

D
Feedback:
The large intestine uses a process of mass movement with an occasional peristaltic wave. When the beginning segment of the large intestine is stimulated, it contracts and sends a massive peristaltic movement throughout the entire large intestine. The end result of the mass movement is usually excretion of waste products. Segmentation occurs in the small intestine. The nerve plexus maintains a basic electrical rhythm (BER), much like the pacemaker rhythm in the heart. Rectal stimulation is not normally required for a bowel movement.