Cell Transport Systems

Question 1

Molecules move randomly from areas of higher concentration to lower concentration. This is because in areas where there are more molecules, the number of collisions among molecules increases until they reach an evenly distributed state of equilibrium.

In membranes, small uncharged molecules such as CO2, O2, and H2O can easily diffuse through the membrane through simple diffusion

Answer 1

Simple Diffusion

Question 2

However, some molecules such as large polar molecules and ions, do not easily pass through the membrane. In the case of large polar molecules, they are not soluble in the hydrophobic layer of the lipid bilayer. As such, these molecules may pass through the membrane through channel or transport proteins. These structures either act as pores /openings or assist in the movement across the lipid bilayer so that they do not come into contact with the hydrophobic layer of the membrane. This type of transport, much like simple diffusion, does not require any energy input from the cell and moves from a higher concentration to a lower concentration.

Answer 2

Facilitated Diffusion

Question 3

Water easily passes through cellular membranes. The
movement of water through a selectively permeable
membrane is called ?, which is a special type of
diffusion.

Answer 3

Osmosis

Question 4

is the relative concentration of solutes in the water inside and
outside the cell.

Answer 4

Tonicity

Question 5

the concentration of solutes inside and outside the cell is
the same.

Answer 5

Isotonic Solution

Question 6

In a ? solution, the concentration of solutes is higher outside the cell than inside the cell.

Answer 6

Hypertonic Solution

Question 7

In a ?, the concentration of solutes is higher inside the cell than
outside the cell.

Answer 7

Hypotonic Solution

Question 8

when water pressure forcibly moves molecules across a membrane. These molecules are the small uncharged molecules that can readily pass through the membrane.
However, in filtration, this process is sped up by water pressure or by an externally applied force, like blood pressure.

Answer 8

Filtration

Question 9

? uses energy (usually in the form of ATP) to move materials across the membrane against the concentration gradient—i.e. from lower concentration to higher concentration. Cells usually undergo this process when they need an additional amount of materials that cannot be supplied by passive transport

Answer 9

Active transport

Question 10

moves many molecules into and out of the cell at the same
time.

Answer 10

Bulk Transport

Question 11

is the movement of many molecules into the cell. The membrane creates an inward
pocket and then buds off inside the cell, forming a vesicle with the materials inside.

Answer 11

Endocytosis

Question 12

There are three types of endocytosis:

Answer 12

pinocytosis, phagocytosis, and receptor-mediated endocytosis.

Question 13

(e. “cell-drinking”) is the uptake of small droplets of extracellular (outside of cell) fluid.

Answer 13

Pinocytosis

Question 14

(e. “cell-eating”) is the uptake of solid material into the cell. This can be observed by macrophages, a type of white blood cell, ‘eating’ bacteria.

Answer 14

Phagocytosis

Question 15

This involves a receptor protein in the membrane
that ‘recognizes’ a material (usually a molecule called a ligand) and binds with it. This results in the formation of a vesicle into the cell.

Answer 15

Receptor-mediated endocytosis.

Question 16

can be interpreted as the opposite pathway of
endocytosis. Instead of materials going into the cell,
materials are going out of the cell. Here, materials,
especially ones produced by the endomembrane system,
are packaged into vesicles and are released into the
environment. This process also replenishes the
membranes lost by endocytosis.

Answer 16

Exocytosis