Bio lab review #4

In simple diffusion, molecules move from an area of ____ concentration to an area of ____ concentration.

high to low

The figure below reflects how animal and plant cells would respond in a(n) _______ environment.

hypertonic

A(n) _______ solution has the same concentration of water as the cell placed in the solution.

isotonic

When a person requires intravenous administration of fluids, which type of fluid do you expect to be most commonly used?

isotonic

What effect does corn syrup concentration have on the movement of water in this simulation?

more water is drawn up into the thistle tube with higher concentrations of corn syrup.

1st - Glucose test strip

negative - light blue

Did diffusion across the membrane occur for the starch solution?

no

What is your strategy?

I will place Elodea into solutions with different tonicities and I will examine the appearance of the cells under a microscope to see if the cells change.

What is your strategy?

I will place iodine on one side of the dialysis tubing and glucose and starch on the other. I will then test to determine if diffusion has occurred

What is your strategy?

I will place red blood cells into solutions with different tonicities, and I will examine the appearance of the cells under a microscope to see if the cells change.

conclusion:

In the blood and 10% NaCl solution, what happened to the cells to cause them to shrink? Due to the hypertonic solution, water left the cells. In the blood and 0.9% NaCl solution, what happened to the cells since there seems to be no change? Since the solution is isotonic, there was no net movement of water. In the blood and distiled water solution, why did blood become clear? Because distilled water is hypotonic, the cells burst and no longer block light passing through the fluid. What is happened to the cells placed into various solutions? The cells exchanged water with the solutions based on tonicity because the cells have selectively permeable membranes.

What is your prediction for this experiment

Iodine and glucose will be able to diffuse across the dialysis tubing membrane, but not starch due to its molecular size

What does it mean for a membrane to be semipermeable?

Only certain things can get through.

What is your prediction for this experiment

Red blood cells placed in an isotonic solution will shrink because osmosis will draw water out of the cells, causing their volume to decrease.

In the blood and 0.9% NaCl solution, what happened to the cells since there seems to be no change?

Since the solution is isotonic, there was no net movement of water.

When Elodea leaves were placed in 10% NaCl, what was the result?

The cell membrane shrank away from the cell wall because the solution was hypertonic.

What is happened to the cells placed into various solutions?

The cells exchanged water with the solutions based on tonicity because the cells have selectively permeable membranes.

A(n) _______ solution has a higher concentration of water and lower concentration of solute than the cell placed in the solution.

hypotonic

Did diffusion across the membrane occur for the glucose solution?

yes

Did diffusion across the membrane occur for the iodine solution?

yes

When testing tonicity in Elodea cells, once Elodea cells were placed in distilled water, what did you observe? Select all that apply.

- Cell membranes pressed tightly against the cell walls. - Full central vacuoles.

How are you going to determine if iodine and/or starch diffuse across the dialysis tubing?

- In this situation the iodine would diffuse from the beaker into the dialysis tubing with the starch. - If both starch and iodine are able to diffuse across the dialysis tubing they would mix on both sides of the membrane turning both solutions dark purple.

Select all that apply: Tonicity of a solution

- is related to solute content. - gives information about potential changes in cell volume when cells are placed in that solution. - is related to membrane permeability to solutes.

lab 1

....

lab 2

....

Complete the table by dragging each structure name or description into the appropriate place.

1.- Organelle: Golgi apparatus- Function(s): creates vesicles to enclose materials to be secreted; produces lysosomes- Structure: stacked, flat, single-membrane sacs- Plant or Animal: animal and plant 2.- Organelle: Ribosome- Function(s): location of protein synthesis- Structure: two subunits of RNA and protein synthesized in the nucleus of eukaryotic cells- Plant or Animal: animal and plant 3.- Organelle: Smooth ER (endoplasmic reticulum)- Function(s): synthesizes lipids; detoxifies drugs and poisons- Structure: a single membrane network- Plant or Animal: animal and plant 4.- Organelle: Rough ER (endoplasmic reticulum)- Function(s): produces proteins destined for secretion from the cell- Structure: a single membrane network covered with ribosomes- Plant or Animal: animal and plant

Complete the table by dragging each structure name or description into the appropriate place.

1.- Organelle: Golgi apparatus- Function(s): creates vesicles to enclose materials to be secreted; produces lysosomes- Structure: stacked, membranous, flat, single-membrane sacs- Plant or Animal: animal and plant 2.- Organelle: lysosome- Function(s): breaks down and recycles components of food, cellular debris, and captured pathogens- Structure: sac containing digestive enzymes; surrounded by single membrane- Plant or Animal: animals and some plants 3.- Organelle: Smooth ER (endoplasmic reticulum)- Function(s): synthesizes lipids; detoxifies drugs and poisons- Structure: a single-membrane network- Plant or Animal: animal and plant 4.- Organelle: mitochondrion- Function(s): releases energy from food using cellular respiration- Structure: double-membrane organelle containing DNA and ribosomes; inner membrane is folded into enzyme-studded cristae- Plant or Animal: animal and plant

Corn Syrup Concentration

10% = 3 20% = 7 30% = 12

Lab Data...

10% NaCI -Cloudy -Crenated -Hypertonic 0.9% NaCI -Cloudy -Normal -Isotonic Distilled Water -Clear -Burst -Hypotonic

2nd - Glucose test strip

2; 2,000 or more - dark brown

In the blood and distilled water solution, why did blood become clear?

Because distilled water is hypotonic, the cells burst and no longer block light passing through the fluid.

Why is this called a selectively permeable membrane?

Because it allows small molecules, such as water, to pass through but not larger molecules, such as those in corn syrup.

What can you conclude about the diffusion of iodine, glucose and starch across the selectively permeable permeable dialysis tubing membrane?

Diffusion occurred based on molecular size. Iodine and glucose are much smaller molecules than starch; therefore, they were able to diffuse.

Lab Data

Distilled Water -Hypotonic -Cells have swollen with chloroplasts along the edge of the cell. 10% NaCl -Hypertonic -Cells that have shrunk because of osmosis with chloroplasts balled up on center of cell.

What is happening to the Elodea cell that is causing it to shrink?

Due to the hypertonic solution, water is leaving the cell.

conclusion:

Due to the hypertonic solution, water is leaving the cell.

In the blood and 10% NaCl solution, what happened to the cells to cause them to shrink?

Due to the hypertonic solution, water left the cells.

What happened to the cell to cause it to swell?

Due to the hypotonic solution, water is entering the cell.

what is your prediction for this experiment?

Elodea placed in a hypertonic solution will shrink because osmosis will draw water out of the cells, causing their volume to decrease.

A defining characteristic that distinguishes prokaryotic and eukaryotic organisms is the lack of a cell membrane in prokaryotes.

False

In osmosis, water is actively transported across a cell membrane.

False

Lab 4

Tonicity in Elodea Cells

Lab 3

Tonicity in Red Blood Cells

The osmotic pressure of a solution is usually a factor in tonicity.

True

When testing tonicity of red blood cells, if the solution became opaque after adding blood cells, you could assume

You could determine that the cells remained intact, but you could not determine whether the solution was isotonic or hypertonic without looking at the cells under the microscope.

Since the cell membrane allows some molecules to pass through it and will not allow others, it can be described as

selectively permeable.

A membrane allows water through but will not allow any solutes to pass. What type of membrane is this?

semipermeable

Tonicity in cells refers to the concentration of solute in a solution outside of a cell, relative to

the solute concentration of the cytoplasm inside the cell.

When testing tonicity of red blood cells, if the solution became transparent after adding blood cells, you could assume

the solution was hypotonic and the cells had burst.

Proteins do not pass through plasma membranes because

they are very large molecules.