exercise 2

Question 1

Define diffusion and identify physiological examples of diffusion

Answer 1

Passive random movement of molecules with their concentration gradient. Respiratory gasses (oxygen and carbon dioxide) and ions move by diffusion. Glucose moves into cells by facilitated diffusion (requires insulin)

Question 2

How does the diffusion of a gas like oxygen differ from the diffusion of an ion like sodium

Answer 2

Oxygen is lipid soluble so it passes through the phospholipid barrier without the help of a carrier or ion channel

Question 3

Define osmosis and identify physiological examples of osmosis

Answer 3

The passive movement of Water molecules through a porous membrane with their concentration gradient (from hypotonic region) all movement of water Into and out of individual cells is by osmosis. Movement out of kidney tubules back into blood stream is by osmosis

Question 4

Define filtration and identify physiological examples of filtration

Answer 4

Movement of molecules through a porous membrane using hydrostatic forces. Molecules leave capillaries by filtration

Question 5

Why is it possible to demonstrate diffusion osmosis and filtration in experiments that do not include living tissue

Answer 5

doesnt need cellular energy in the form of atp

Question 6

How does the experiment demonstrate diffusion

Answer 6

Potassium permanganate passively moved with concentration gradient

Question 7

The result of this experiment suggests the two agar plates have different permeability. What would make membranes in your body have different permeability

Answer 7

The type and distribution of ion channels present

Question 8

How does this experiment demonstrate the influence of time on the rate of osmosis

Answer 8

Connect change in volume gain and rate of volume change decreased as time passed. Because the gradient gradually decreased

Question 9

Could this experiment also demonstrate the influence of the size of the concentration gradient on the rate of osmosis explain

Answer 9

Yes as water moved into the dialysis bag the contents became more diluted which decreased the gradient

Question 10

Because the salt molecules cannot pass through the dialysis tubing, the concentration of the solutions on each side of the dialysis to being can never be the same but a state of equilibrium can still be achieved explain

Answer 10

Because water molecules are in random motion some water molecules are also leaving the dialysis bag. Some point the same volume of water will move into the dialysis bag as exits and the net change in volume will be zero

Question 11

Summarize the results of this experiment

Answer 11

When blood cells are placed in a relatively hypotonic solution they take on water from the surroundings and swell. Enlarged or perhaps ruptured cells block less light increasing transmittance plateau on upper left. Conversely when blood cells are placed in a relatively hypertonic solution they lose volume to the surroundings and shrink. the shrunken cells block more light decreasing transmittance plateau on lower right. cells placed in a relatively isotonic solution exchange water with their surroundings but don’t swell or shrink vertical section of tracing

Question 12

Import C was a solution in the beaker’s hypertonic hypotonic or isotonic to the solution in the dialysis bags

Answer 12

Hypotonic. Water always moves with its concentration gradient from the relatively hypotonic region towards a relatively hypertonic region

Question 13

How does this experiment demonstrate filtration

Answer 13

A solution was passed through a selective membrane by hydrostatic pressure. The water and small sugar particles passed through the membrane while the larger charcoal pieces and starch molecules were trapped by the membrane

Question 14

list two reasons why it is necessary to test both the original solution and the filtrate for sugar and starch

Answer 14

To confirm that you know how to perform the tests and that all reagents are working properly

To have a positive control test for comparison of your unknown results

Question 15

Was charcoal present in the filtrate explain how you came to this conclusion

Answer 15

No the charcoal can’t be seen with the naked eye. Crackle was present in the filtrate it was all trapped by the filter paper

Question 16

Was sugar present in the filtrate explain how you came to this conclusion

Answer 16

yes The Benedict’s test changed color. It was positive for sugar because it turned green yellow or red

Question 17

Was starch present in the filtrate explain how you came to this conclusion

Answer 17

No the iodine test didn’t change color. It was negative because it didn’t turn purple dark green or black

Question 18

Explain why the above experiments and activities demonstrate good experimental design

Answer 18

Experiment B C and D had one variable examined elapsed time initial concentration gradient or NaCl Into which blood cells are placed. experiment E how to control that was performed lacked repetition that is why we are averaging

Question 19

A family went for vacation to the beach and spent a day swimming and playing in the ocean. Children noticed that unlike when she went to the swimming pool at home her fingers and toes weren’t all wrinkly when she got out of the water explain

Answer 19

The ocean contains saltwater which is a hypertonic solution to the skin. The water left her skin from a higher concentration to a lower concentration to the ocean. Cells shrink.

In a swimming pool the water is a hypotonic solution to the skin in this case cells take on water and increase in size

Question 20

Diseases like emphysema tuberculosis and pneumonia reduce the surface area available for gas exchange in the lungs explain the effect this will have on diffusion

Answer 20

The less surface area equals slower diffusion. Patients may need oxygen therapy to increase the concentration gradient to compensate for the loss of surface area

Question 21

The kidneys are where substances are filtered out of your blood and some of these substances are removed from your body in the urine. If your blood pressure increases what will happen to filtration in the kidneys? Glucose molecules are relatively small and are very important as an energy source to the body. Is relatively large molecule and can be removed from the body only through urination. Which will be filtered? explain

Answer 21

Increasing the driving force or hydrostatic pressure equals increasing the rate of filtration. Blood pressure is the driving force behind filtration. Filtration is selected by size only not need so glucose will filter where penicillin will not