Cells & Homeostasis

Question 1

Cells

Answer 1

The basic, living, structural, and functional units of the body

Question 2

Plasma membrane

Answer 2

Forms the cell’s flexible outer surface, separating the cell’s internal environment from the external environment. It is a selective barrier that regulates the flow of materials into and out of a cell. It also plays a key role in communication among cells and between cells and their external environment

Question 3

Lipid bilayer

Answer 3

Two back-to-back layers made up of three types of lipid molecules— phospholipids (75%), cholesterol (20%), and glycolipids (5%)

Question 4

Amphipathic

Answer 4

Molecules that have both polar and nonpolar parts. The polar part is the phosphate-containing head, which is hydrophilic. The nonpolar parts are the fatty acid tails, which are hydrophobic

Question 5

Diffusion

Answer 5

A passive process in which the random mixing of particles in a solution occurs because of the particles’ kinetic energy.

If a particular solute is present in high concentration in one area of a solution and in low concentration in another area, solute molecules will diffuse toward the area of lower concentration

Question 6

Factors in the diffusion rate of substances across plasma membranes

Answer 6

Steepness of the concentration gradient
Temperature
Mass of the diffusing substance
Surface Area
Diffusion distance

Question 7

Simple diffusion

Answer 7

A passive process in which substances move freely through the lipid bilayer without the help of membrane transport proteins

Question 8

Facilitated diffusion

Answer 8

An integral membrane protein assists a specific substance across the membrane. The integral membrane can either form a channel or function as a carrier