bio lab quiz osmosis and cellular membrane

2. What is the fluid mosaic model?

A membrane is a fluid structure with a "mosaic" of various proteins embedded in it

3. What organism did you as a model to investigate the effect of different ranges of temperature on plasma membrane integrity?

A section from beetroot

8. What is osmosis?

Diffusion of water across a differentially permeable membrane

4. When you put the dyes in the petri plate what did the halos indicate? What does a larger halo mean?

How far the solute had traveled, the largest halo had the lowest molecular weight

10.What are hypotonic, isotonic, and hypertonic solutions?

Hypotonic- solute inside is greater than what's outside of cell (more salt in cell than out), more water will go in, than will go out. The cell will swell and burst causing "lysis" • Isotonic- (equal strength) the amount of water going in is the same going out. No shape changes in cell, no gain or loss in water • Hypertonic- solute outside is greater than what's in the cell (more salt outside the cell than what's inside of it). Water moves out faster than in, this will cause cell to shrivel or "crenate"

9. What is the difference between osmosis and diffusion?

Osmosis always refers to water, the principal solvent in cells

2. What is diffusion? In which direction do molecules diffuse?

Passive directional movement of molecules; molecules move from area of high concentration, heat or pressure to areas of low concentration, heat or pressure

1. What is Brownian movement?

Rapid, erratic motion of particles in a liquid or gas (random movement)

7. What does iodine react with?

Starch - blue color

4. How did you determine what effect temperature had on the membranes?

The amount of leakage from the beetroot (betacyanin)

5. What is phenolphthalein? What color is it in basic solution?

a pH indicator turns basic solutions pink

3. What affects the rate of diffusion?

mass of the solute, the temperature of the environment, the solvent density, and the distance traveled. (temperature and pressure gradient)

1. What are the functions of biological membrane?

• Acts as a barrier to diffusion • Prevents entrance of certain molecules • House receptors • Provide site for active and passive transport • Provide surface for chemical reactions • Help maintain cell shape • Contains phospholipid bilayer • Contains proteins (channels/transporters/receptors) • Contains carbohydrates (which are bound to lipids and proteins)

11.For procedure 9.5, you should know which bags should have gained water, lost water, or had no net loss or gain of water. Why? • Bag A (1% sucrose in bag, 10% in water) • Bag B (1% sucrose in bag, 1% in water) • Bag C (10% sucrose in bag, 1% in water) • Bag D (20% sucrose in bag, 1% in water)

• Bag A (1% sucrose in bag, 10% in water) water moves out of bag, bag loses water • Bag B (1% sucrose in bag, 1% in water) no change • Bag C (10% sucrose in bag, 1% in water) water moves into bag, bag gains water • Bag D (20% sucrose in bag, 1% in water) water moves into bag, bag gains water

6. Why is extreme heat or cold damaging to the membrane? Why?

• Extreme heat causes violent molecular collisions that destroy a membrane (break down of biological molecules) • Freezing temperatures causes the formation of crystals which causes the rupture in the cell membrane from the expansion of water inside the cell.

13.What happens to red blood (animal cells) when you put them in isotonic, hypertonic, and hypotonic solutions. Under which conditions do cells crenate or undergo lysis?

• Hypotonic causes the red blood cells to expand and burst (lysis), this was also the only one you were able to read through • Isotonic causes no change • Hypertonic causes red blood cells to shrivel (crenate)

What happens to Elodea (plant cells) when you put them in isotonic, hypertonic, and hypotonic solutions. What did you observe under the microscope when you added water or salt to Elodea cells? Under which conditions to cells become turgid or undergo plasmolysis?

• Hypotonic- solute inside is greater than what's outside of cell (more salt in cell than out), more water will go in, than will go out. This is the "normal" state of the plant, also called turgid (firm). The cell wall prevents the cell from bursting as vacuole increases with water • isotonic- (equal strength) the amount of water going in is the same going out. The plant will become flaccid or limp and the plant may wilt • hypertonic- solute outside is greater than what's in the cell (more salt outside the cell than what's inside of it). Water moves out faster than in, and organelles move away from cell wall and collect in the center, this is called plasmolysis and is usually lethal for the plant

12.For procedure 9.6, you should know which potato cylinders should have gained water, lost water, or had no net loss or gain of water. Why did this happen? Which solution is isotonic to plant? • potato in the 0% salt solution • potato in the 0.9% salt solution • potato in the 5-15% salt concentration

• The 0% salt solution gained the most weight (water moved into the potato) • The 0.9% salt solution stayed the same (the salt in the potato and in the water were the same) this is the solution that was isotonic • The 5-15% salt concentration lost the most amount of weight (water moved out of the potato)

6. Why did the bags change color in procedure 9.3 and which molecules and ions crossed the membrane?

• The bag with the starch suspension turned blue, the iodine that was in the beaker traveled into the bag tuning it blue. The iodine molecules were small enough to pass through the bag and the starch molecules were too big making them stay in place (Iodine passed - starch in bag stayed) • The bag with the phenolphthalein eventually turned pink, the hydroxide that was in the beaker passed into the bag turning it pink. (hydroxide passed - phenolphthalein stayed in bag)

5. Which temperature damaged the membrane the most? Which the least? How do you know?

• The high heat (70 degrees C) had the second to most damage, the lowest heat (-5 degrees C) had the most damage. • The least amount of damage was done by the 20 degree C. • This was determined by ranking the color and viewing absorbance