Thursday, September 25, 2008

New videos and info for Chapter 7

I am posting videos, images, and sample questions for Chapter 7 as extra info and as a review!


An overview video on the structure of the plasma membrane: Click on the link below:
http://www.youtube.com/watch?v=ULR79TiUj80&feature=related



Passive vs. Active Transport

A video on Osmosis, click on link:
http://www.youtube.com/watch?v=sdiJtDRJQEc



Cotransport



Diffusion models

For those of you who were questioning how exocytosis and endocytosis affected the size of the plasma membrane, this animation should answer your question.

http://www.youtube.com/watch?v=4gLtk8Yc1Zc

A few questions to ponder:

1. The internal solute concentration of a plant cell is about 0.8 M. To demonstrate plasmolysis, it would be necessary to suspend the cell in what solution?

a.distilled water b. 0.4 M c. 0.8 M d. 1.0 M e. none of the above


2. If a red blood cell and a plant cell were placed in seawater, what would happen to the two types of cells?

a. The red blood cell would burst, and the plant cell would shrink.
b. Both cells would lose water; the red blood cell would shrivel, and the plant plasma membrane would pull away from the cell wall.
c. Seawater is isotonic to both cells. There will be no change in water content of the cells.
d. Both cells would gain water by osmosis; the red blood cell would burst, and the plant cell would increase in turgor pressure.
e. The red blood cell would shrink, and the plant cell would gain water.



3. Imagine two solutions separated by a selectively permeable membrane that allows water to pass, but not sucrose or glucose. The membrane separates a 0.2-molar sucrose solution from a 0.2-molar glucose solution. With time, how will the solutions change?

a. Nothing happens because the two solutions are isotonic to one another.
b. Water enters the sucrose solution because the sucrose molecule is a disaccharide and thus larger than the monosaccharide glucose.
c. Water leaves the sucrose solution because the sucrose molecule is a disaccharide and thus larger than the monosaccharide glucose.
d. The sucrose solution is hypertonic and will gain water because the total mass of sucrose is greater than that of glucose.
e. After the sucrose dissociates to two monosaccharides, water will be osmotically drawn to that side of the membrane.


4. A nursing infant is able to obtain disease-fighting antibodies, which are large protein molecules, from its mother's milk. These molecules probably enter the cells lining the baby's digestive tract via which process?

a. osmosis b. passive transport c.exocytosis
d.active transport e. endocytosis



1 comment:

Meghan Colip said...

Thanks Mrs Lyon! The videos were really helpful! :) What are the answers to 2 and 3?