BIO short answer

diffusion characterisitcs

-movement of molecules -not for water -can occur in any type of medium

osmosis characteristics

-movement of water -requires a semi-permeable membrane -equilibrium in the free energy of solvent molecules is never achieved

osmosis n diffusion similarities

-passive transport -high to low concentration -through semi-permeable membrane

Please list and briefly describe the three types of proteins found in the membrane. Be sure you explain their functions thoroughly and give an example of each.

Transport proteins- allow molecules to cross through the membrane Receptor proteins- transfer information from one side to the other Marker proteins- provide identification for the cell

Why would water molecules need a transport protein to move rapidly and in large quantities across a membrane?

Water is a polar molecule and it can not go through the membrane because of the non polar fatty acid tails. It needs help from a transport protein to get through the membrane.

If something happened to a paramecium that caused its contractile vacuole to stop contracting, what would you expect to happen? Would this result occur more quickly if the paramecium was in water with a high salt concentration or in water with a low salt concentration? Explain your answer in terms of what you know about osmosis and solutions.

Water would collect inside the paramecium and it would burst because the cell wouldn't be able to hold all of the water. It would occur more rapidly if the paramecium were in water with a low salt concentration because the water would accumulate quicker then if it were in a high salt solution.

In the supermarket, produce is often sprayed with water. Explain why this makes vegetables look crisp.

When the produce is sprayed with water there would be more solute in the plant then there would be outside of it. The produce would be in a hypertonic solution so the water on the plants would diffuse by osmosis to reach an equilibrium which would make the vegetables look crisper.

The biologist concludes that the molecule moves cross the cell membrane by facilitated diffusion. Do you agree with his conclusion? Use the above information to explain your reasons for agreeing or disagreeing.

I agree that 1 and 2 are facilitated diffusion but 3 and 4 do not use facilitated diffusion. When molecules move high to low it is against the current and you would need ATP. When you need ATP that means it is active transport. In 4 the cell was using energy so that means it is active transport.

What are the effects of cells when they are placed in a hypotonic solution, hypertonic solution, and isotonic solution?

In a hypotonic solution the cell will swell and maybe lyse open. In a hypertonic solution the cell would shrink. In an isotonic solution the cell would remain the same shape and size.

Can humans drink salt water for hydration?

No, humans cannot drink salt water because they would become dehydrated.

List and describe the role of the three molecules that cell membranes are composed of.

Phosphate heads: negatively-charged polar head and also is hydrophilic Fatty acid tails: non polar and hydrophobic Glycerol: backbone of the membrane lipids

a. How can you explain the observed relationship between salt concentration and rate of contractile vacuole contractions in terms of what you know about osmotic solutions?

The lower the concentration of salt solution in the water the more water there is. When there is more water then there is more of a chance that the water will enter the Paramecium by osmosis. If there is more water that enters by osmosis then the contractile vacuole will have to fill up and then empty out more often.

Predict what will happen to the red blood cells in Beaker C (0.2) and explain why using your science vocabulary.

The red blood cell is hypertonic to the solution and the cell will shrink because the water will move out of the cell.

Predict what will happen to the red blood cells in Beaker B (1.3) and explain why using your science vocabulary.

The red blood cell is hypotonic to the solution and the water will go into the cell and the cell will swell and it could lyse open.

Predict what will happen to the red blood cells in Beaker A (o.8) and explain why using your science vocabulary.

The red blood cell will stay the same shape because it is isotonic solution. In an isotonic solution the water moves in and out at the same rate.

What is the major limitation that cells face? Discuss how volume versus surface area impacts a cell's ability to function efficiently in an organism.

The volume gets bigger faster then the surface area. If the volume gets to big to quick the cell cannot be efficient and bring enough nutrients into the cell. The cell cannot be too small either or else the nutrients will not fit.

c. What has happened to the water level in the U-tube? Explain your answer.

The water will go to side 1 because water always follows solute.

How many grams of substance A will be in solution on side 1 of the U-tube? How many grams of substance A will be on side 2 of the U-tube. Explain your answer.

There will be 30 grams of A on both sides of the U-Tube. The substance A ttys to reach an equilibrium. It is permeable to the membrane so it can cross over.

How many grams of substance B will be in solution on side 1 of the U-tube? How many grams of substance B will be on side 2 of the U-tube? Explain your answer.

There will be 40 grams of B on side 1 and 10 grams of B on side 2. Substance B can not cross over because it is not permeable to the membrane.

11. How are molecules moved that are too big to fit through membrane proteins? How are molecules moved into and out of the cell? Describe both processes in terms of a cell membrane.

They are moved through the endocytosis and exocytosis if they are to big. Molecules are moved into and out of the cell by passive transport and active transport. Passive transport does not use energy and it goes from high to low concentration gradient. Active transport requires energy and moves molecules against concentration gradient.