Unit 2 - Ch 5 - Biological Transport

Question 1

Water Potential Definition

Answer 1

amount of free energy in water or energy avialable to do work

Question 2

Water potential causes

Answer 2

• from gravity (adds to W.P.)
• and/or pressure (add or decrease or no effect on W.P)
• and/or solute (decreases w.p. or no effect - no solute)

Question 3

Water Movement

Answer 3

water moves from high to low water potentials

Question 4

Bulk Flow Definition

Answer 4

• overall movement of a substance caused by gravity and/or pressure - movement is all in one direction

= Circulatory system - moves blood via pressure

Question 5

Diffusion definition

Answer 5

movement of a substance from high concentration to low concentration (there may be a membrane)

Question 6

Diffusion Cause

Answer 6

random molecular motion

• requires no energy
• passive transport

Question 7

Dynamic equilibrium

Answer 7

eventually occurs, diffusion ceases, molecular motion continues

Question 8

Diffusion Rates are influenced by:

Answer 8

1. Concentration Gradient - high gradients diffuse faster
2. Solute Weight - lighter solute weights diffuse faster
3. Solvent Viscosity - thickness - highly viscous diffuse slower
4. Temperature - increased temp. increases diffusion rates (temp. is a measure of molecular motion)

Question 9

Osmosis definition and cause:

Answer 9

A. Definition - diffusion of water across a semi-permeable membrane that excludes solute

B. Cause - random molecular motion - no energy required - passive

Question 10

Tonicity

Answer 10

refers to the solute concentration

Question 11

Isotonic

Answer 11

equal solute concentration; equal h2o concentration

Question 12

Hypertonic

Answer 12

higher solute concentration; lower h2o concentration

Question 13

Hypotonic

Answer 13

lower solute concentration; higher h2o concentration

Question 14

Animal cell in Isotonic Solution

Answer 14

• h2o potential on both sides is equal
• water crosses both ways
• no net h2o flow

= Injections/Cell Cultures - normal saline (.85% NaCl) - osmotic balance

Question 15

Animal cell in Hypertonic Solution

Answer 15

• > .85% NaCl
• cell is hypotonic
• net h2o loss from the cell
• crenation occurs

Question 16

Crenation

Answer 16

In an animal cell, volume decreases when placed in a hypertonic solution

Question 17

Animal cell in hypotonic solution

Answer 17

The cell is hypertonic
- net h2o gain into cell

Lysis will occur in deionized water (no solute, 100% h2o)
= hemolysis of red blood cells

Question 18

Lysis

Answer 18

refers to the breaking down of the cell, often by viral, enzymic, or osmotic mechanisms that compromise its integrity

Question 19

Plasmolysis

Answer 19

due to osmosis in plants, the cell membrane tears away from cell wall
= over fertilize lawn

Question 20

Turgor Pressure

Answer 20

cell increases in volume up to the limits of the cell wall

• equilibrium occurs due to water potential
• provides rigidity in the stems of herbaceous plants (non-woody; grasses and forbs)

Question 21

Osmotic Potential

Answer 21

reduction in the free energy of water due to solute presence

• the more solute, the more negative the osmotic potential
• no solute, no osmotic potential

Question 22

In osomosis, net H2O movement occurs from:

Answer 22

• higher to lower water concentration
• higher to lower water potential
• lower to higher solute concentration
• hypotonic to hypertonic solutions
• less negative to more negative osmotic potentials

Question 23

Describe the factors that influence the permeability of materials to a cell.

Answer 23

1. Lipid solubility - nonpolar substances often pass through the bilayer = o2 gas, co2
2. Ionization - ions tend to be excluded by the bilayer
3. Size - large molecules pass slower or are excluded by the bilayer = glucose

Question 24

Carrier Proteins purpose and specificity

Answer 24

A. Purpose - allow passage of impermeable molecules

B. Specificity - high degree of specificity due to tertiary structure

Question 25

Facilitated Transport OR Carrier Facilitted Diffusion

Answer 25

• diffusion through a carrier protein - no energy required (passive transport)
• transport in or out of cells depending upon the gradient

Question 26

Active Transport

Answer 26

• passage of a substance through a carrier protein against the gradient - requires ATP
• Irreversible - pumps in or pumps out
• Na+/K+ pump - pump Na+ out of cells - pumps K+ into cells - counteracts facilitated transport

Question 27

Exocytosis

Answer 27

Transport of material outside of cells via a vesicle

• common in secretory cells
• active (requires energy)

Question 28

Endocytosis. Definition and types

Answer 28

Definition - movement of material into a cell via a vesicle formation - requires energy

A. Phagocytosis

B. Pinocytosis

C. Receptor-Mediated

Question 29

Phagocytosis

Answer 29

cells transport solid material into cells

= amoebe, white blood cells

Question 30

Pinocytosis

Answer 30

cells transport liquid matrial into cells

= capillaries, small intestine

Question 31

Receptor-Mediated endocytosis

Answer 31

a specific substance binds to a receptor protein on the cell surface and initiates endocytosis = cholesterol transport

Question 32

Desmosomes

Answer 32

Cell junctions formed from proteins anchored into intermediate filaments within cells - found in tissues that stretch
= skin, stomach

Question 33

Tight Junctions

Answer 33

protein strands that “stitch” cells together
- forms a semi-permeable sheet of cells
= small intestine

Question 34

Gap Junctions

Answer 34

cell to cell connection in animal cells
- allow for rapid cellular communication via chemical stimuli
- formed from proteins
= cardiac muscle

Question 35

Plasmodesmata

Answer 35

cell to cell connections in plants

- allow for rapid cellular communication via chemical signals