Week 2 Lab Objective

Question 1

Diffusion

Answer 1

Diffusion is the movement of molecules from a region of their higher concentration to a region of their lower concentration. The driving force for diffusion is the kinetic energy of the molecules, the speed of diffusion depends on molecular size and temperature. Smaller molecules move faster, and molecules move faster as temperature increases. Diffusion is an important transport process for every cell in the body.

Question 2

Concentration gradient

Answer 2

A concentration gradient is present when molecules are unevenly disturbed, resulting in an area of higher concentration and an area of lower concentration.

Question 3

Molecular mass and rate of diffusion

Answer 3

The relationship between the molecular weight and the rate of diffusion can be examined easily by observing the diffusion of two different types of dye molecules through an agar gel. The dyes used in this experiment are methylene blue, which has a molecular weight of 320 and is deep blue in color, and potassium permanganate, a purple dye with a molecular weight of 158. Although the agar gel appears quite solid, it is primarily (98.5%) water and allows the dye molecules to move freely through it.

Question 4

Osmosis

Answer 4

The flow of water across a selectively permeable membrane is called osmosis. During osmosis, water moves its concentration gradient. The concentration of water is inversely related to the concertation of solutes. If the solutes can diffuse across the membrane, both water and solutes will move down their concentration gradients through the membrane. If the molecules in the solution are nonpenetrating solutes (prevented from crossing the membrane), water alone will move by osmosis and in doing so will cause changes in the volume of the compartments on either side of the membrane.

Question 5

Selectively permeable membrane

Answer 5

Valuable cell proteins and other substances are kept within the cell, and excreta or wastes pass to the exterior. This property is known as selective or differential permeability. The unassisted diffusion of solutes (dissolved substances) through a selectively permeable membrane is called simple diffusion.

Question 6

Hypertonic

Answer 6

Cells lose water by osmosis and shrink in a hypertonic solution (contains a higher concentration of nonpenetrating solutes than are present inside the cells).

A solution surrounding a cell is hypertonic if it contains more nonpenetrating solute particles than the interior of the cell. Water moves from the interior of the cell into a surrounding hypertonic solution by osmosis.

Question 7

Hypotonic

Answer 7

Cells take on water by osmosis until they become bloated and burst (lyse) in a hypotonic solution (contains a lower concentration of nonpenetrating solutes than are present in cells).

A solution surrounding a cell is hypotonic if it contains fewer nonpenetrating solute particles than the interior of the cell. Water moves from a hypotonic solution into the cell by osmosis.

Question 8

Isotonic

Answer 8

Cells retain their normal size and shape in isotonic solutions (same solute/water concentration as inside cells, no net osmosis)

Question 9

Epithelial tissue characteristics

Question 10

Apical surface

Question 11

Basal surface

Question 12

Basement membrane

Question 13

Avascular

Question 14

Epithelial tissue classification

Question 15

-Layers

Question 16

Simple

Question 17

Stratified

Question 18

-Shape

Question 19

Squamous

Question 20

Cuboidal

Question 21

Columnar

Question 22

Epithelial tissue components

Question 23

Goblet cell

Question 24

Cilia

Question 25

Lumen

Question 26

Simple epithelium

Question 27

Simple squamous epithelium

Question 28

Simple cuboidal epithelium

Question 29

Simple columnar epithelium

Question 30

Pseudostratified ciliated columnar epithelium

Question 31

Stratified epithelium

Question 32

Stratified squamous epithelium

Question 33

Transitional epithelium/Urothelium epithelium