Plasma membranes of the cell are permeable to molecules that pass through the phospholipid bilayer easily, namely small nonpolar molecules. Due to this specificity in permeability, membrane proteins are often required to transport molecules across the bilayer. Simple diffusion occurs when a substance passes through a membrane without the aid of an intermediary. All forms of facilitated transport, along with active transport, require the aid of specific membrane proteins. Thus, simple diffusion is the correct answer.

The sodium-potassium pump serves to move three sodium ions out of the cell and two potassium ion into the cell.  These ions both have a plus one charge, so when the pump functions, it creates an environment where there are more solutes on the outside of the cell.  if it stopped working, the cell would stop moving sodium out, and since it is a polar molecule, it can't cross the cell membrane on its own.  There would be more solutes inside the cell than on the outside, and water would flow into the cell towards the higher solute concentration, causing the cell to swell and lyse.

Active transport most correctly describes this type of movement, as it uses ATP as an energy source. In contrast, the other four choices are all different types of passive transport, constituting types of movement where no energy source is needed. Diffusion is simply the net movement of particles down their concentration gradient. Facilitated diffusion is a similar concept, but uses specialized transport proteins. Osmosis describes the movement of water, and lastly, filtration is the movement of both solute and water molecules.

To answer this question you need to know the directionality of the sodium-potassium pump and the number of ions pumped each cycle. Remember that each cycle of the sodium-potassium pump moves three sodium ions to the outside of the cell and two potassium ions to the inside of the cell. The amount of sodium ions outside the cell will increase by three and the amount of potassium ions inside the cell will increase by two.

The final result after one cycle of the sodium-potassium pump will be 33 sodium ions outside the cell and 22 potassium ions inside the cell.

When a membrane channel, such as the sodium-potassium pump, requires energy (ATP) to transport molecules it means that the channel is moving molecules against their concentration gradient. This mode of transport is called active transport.

Recall that the sodium-potassium pump moves three sodium ions out of the cell and two potassium ions into the cell per cycle. Since it uses active transport, the sodium-potassium pump must move both sodium and potassium ions against their respective concentration gradients. This means that the concentration of sodium ions is greater outside the cell and the concentration of potassium ions is greater inside the cell.

Note that symporters exist in which facilitated diffusion of one ion is used to pull a second ion against its concentration gradient without the use of ATP. In this manner, ATP is not always necessary to transport an ion against its concentration gradient. When both ions are moving against their gradients, however, or when only one ion is being transported, ATP will be needed.

Antiporters are proteins that carry molecules in opposite directions, whereas symporters are proteins that carry molecules in the same direction. The sodium-potassium pump transports sodium ions out of the cell and potassium ions into the cell. The movement of ions occurs in opposite directions; therefore, the sodium-potassium pump is classified as an antiporter.

An electrochemical gradient is a gradient that is created by concentration differences of ions between the inside and the outside of the cell. If the concentration of molecules is equal on both sides of the cell, then the electrochemical gradient is depleted.

An electrochemical gradient will also involve electric potential, since the concentration discrepancy involves ion gradients. Recall that electric potential is dependent on the charges of molecules; therefore, an electrochemical gradient is only created when there is an unequal amount of ions present on both sides of the cell, not neutral molecules.

An electrochemical gradient acts as a driving force to move molecules from a region of high concentration (high potential) to a region of low concentration (low potential). This movement is observed in simple diffusion and facilitated diffusion. In active transport, however, molecules move from an area of low concentration to an area high concentration. This means that active transport is not driven by the electrochemical gradient and that molecules move against the electrochemical gradient in active transport.

Proton motive force is the main driving force that pumps protons from the intermembrane space to the matrix of a mitochondrion. This pumping is coupled with ATPase (the enzyme that synthesizes ATP); therefore, the proton motive force drives the synthesis of ATP in mitochondria. The proton motive force arises from an electrochemical gradient of hydrogen ions (protons). During the electron transport chain, protons are pumped into the intermembrane space. This leads to an increase in the concentration of protons and, subsequently, the electric potential in the intermembrane space. The electrochemical gradient created from this phenomenon drives the protons from a region of high electric potential (intermembrane space) to a region of low electric potential (matrix); therefore, proton motive force comes from an electrochemical gradient.

Paracellular transport moves material between cells, while transcellular transport moves things through cells; thus, this is an example of paracellular transport.

Facilitated diffusion, pinocytosis, and passive transport all involve the entrance of a substance into a cell. Monocytes are transferring location, but are not entering another cell in the process.

The core of the lipid bilayer of all eukaryotic cells contains lipid; therefore, transmembrane proteins have a hydrophobic-rich series of residues in the area that spans the membrane.

The major components of the plasma membrane of an animal cell are lipids and proteins, with a small amount of carbohydrate components. The major lipid components are glycerophospholipids, sphingolipids, and some cholesterol. The amount of cholesterol varies depending upon certain factors, such as temperature, and helps maintain the fluidity of the membrane. Thus, the correct answer is phospholipids, sphingolipids, cholesterol, and protein, with some carbohydrate.