Question 2

This question is about membrane structure and function. Carry out the matching using the best answer. Note that for the name of the function, alternative names are also given. Any of those could be used in conversation about how membranes work. Not all functions will be used.

The lipid bilayer creates a hydrophobic barrier between the outside world and the inside world of the cell. This could be said to provide this function of the membrane.

Some proteins are shaped like tubes or tunnels and span the entire thickness of the membrane to enable this function.

For some tissues to form, cells have to be able to form sheets together that hold together to create tissue barriers (like our skin). This function provided by the membranes of those cells is called this.

When one of our immune system cells encounters another one of our own cells, it should know not to attack. It should also know that it should attack if it encounters a foreign cell. This function of membranes is
 D. identification of self (or ID recognition)
A cell in the bone of a child encounters growth hormone and begins to divide. This is an example of this function.

All Answer Choices
A. signal transduction (or recognize and respond, communicate, etc.)
B. protection
C. transport (which could also be called selective permeability, letting some things in/out, etc.)
D. identification of self (or ID recognition)
E. adhesion (or attachment, sticking, etc.)
F. compartmentalization (which could also be called separation, isolation, etc.)
G. shape (or structure)

Question 3

Use this image that shows what is in higher concentration on each side of the membrane to answer these questions. That doesn’t mean that these items are not also on the opposite side of the membrane… it is just that they are in higher concentration where shown. If you find this difficult to do, make sure to complete the transport activity provided in Module 3. That should help you learn this well, and this topic is essential for success in this class.

For these first questions, just consider whether the concentration gradient is into or out of the cell.  The concentration gradient on sodium ions (Na+) would be  into the cell. The concentration gradient on calcium ions (Ca2+) would be  into the cell. The concentration gradient on potassium ions (K+) would be [3]. The concentration gradient on carbon dioxide gas (CO2) would be [4]. The concentration gradient on chloride ions (Cl-) would be [5]. The concentration gradient on oxygen gas (O2) would be [6]. And the concentration gradient on lipid would be [7] while the concentration gradient on protein would be [8].

The concentration gradient is the driving force for [9]. (select diffusion or osmosis)

For the next questions, you will need to select one of the following specific methods of transport:

simple diffusion

facilitated diffusion

osmosis

active transport using pumps

active transport using vesicles (endocytosis and exocytosis) The drawing doesn’t show any water, but if water were to cross this membrane it would cross by [10]. If sodium ions were to enter the cell, they would be crossing the membrane via [11]. If sodium ions were to exit the cell they would do so by [12].

If oxygen gas was to enter the cell, it would do so by [13]. If carbon dioxide gas was to exit the cell it would do so by [14].

If protein were to exit the cell, it would do so by [15], while if lipid were to enter the cell it would do so by [16]. If potassium ions were to enter the cell they would do so by [17].  If potassium ions were to exit the cell they would do so by [18]. Finally, if calcium ions were to enter the cell they would do so by [19].  And if calcium ions were to exit the cell they would do so by [20].

All Answer Choices

into the cell
out of the cell
diffusion
osmosis
simple diffusion
facilitated diffusion
active transport using pumps
active transport using vesicles

Question 4

The fluidity of membranes lets them pinch and fuse. At any given time, a cell will have lots (hundreds or thousands) of little vesicles and some larger vesicles (called vacuoles) in them. Match the descriptions with the best term.

Any time something large is brought into the cell, this term can be used to describe it.
 E. endocytosis
When a cell transports really large, undissolved materials into it, that is typically called this.

When a cell secretes materials like hormones or sweat in vesicles, it uses this.

When a cell brings in large materials (like starch) that are dissolved so that they are not visible even in the electron microscope, that is considered this.

Any time any cell transports something too large to fit through a protein transporter, whether it brings that item into the cell or kicks that item out of the cell, it has to use this method.

All Answer Choices
A. phagocytosis
B. pinocytosis
C. active transport using vesicles
D. exocytosis
E. endocytosis

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