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AP Biology - Chapter 6/7 Extra
Essay Questions and Graph
21
Biology
11/16/2009

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Term
Why is facilitated diffusion considered passive transport?
Definition
Transports substances down the concentration gradient without using energy by using a carrier molecule.
Term
carrier molecule
Definition
creates a channel that certain substances can travel through the plasma membrane with
Term
The Na(+) - K(+) pump, the major electrogenic pump in animal cells, exchanges sodium ions for potassium ions, both of which are cations. How does this exchange generate a membrane potential?
Definition
The exchange is unequal, with more positive going out than in, this creates a relatively positive change on the outside (membrane potential)
Term
How is cholesterol, which is used for synthesis of other steroids and membranes, transported into human cells?
Definition
Through receptor mediated endocytosis. Cholesterol fits onto receptors on the membrane of the cell and the cell engulfs them, creating an internal vesicle that contains them.
Term
a sac made of membrane in the cytoplasm
Definition
vesicle
Term
receptor mediated endocytosis
Definition
the movement of specific molecules into a cell by the inward budding of membranous vesicles containing receptor sites specific to the molecules being taken in
Term
Explain why cholesterol accumulates in the blood of individuals with the disease familial hypercholesteremia.
Definition
Causes people to have missing LDL receptor sites, so the cholesterol cannot undergo receptor mediated endocytosis and remains in the blood.
Term
Explain the fluid mosaic model of the plasma membrane.
Definition
There is a phospholipid bilayer with a hydrophobic interior and hydrophilic exterior. In it, proteins are embedded. Integral proteins go through the membrane whereas peripheral proteins aren't embedded directly into the bilayer.
Term
What types of molecules have difficulty crossing the plasma membrane? Why?
Definition
Large polar molecules and ions cannot cross plasma membranes easily. The inner hydrophobic section of the membrane impedes the movement of these molecules.
Term
List the three parts of the cell theory.
Definition
1. All living things are made of cells.
2. All cells come from preexisting cells.
3. Cells are the basic units of structure and function of living things.
Term
pressure potential (Ψp) in an open environment =
Definition
0
Term
water potential (Ψ) =
Definition
solute potential (Ψs) + pressure potential (Ψp)
Term
solute potential (Ψs) =
Definition
-iCRT
Term
i =
Definition
ionized constant (1.0 for sucrose)
Term
Molar concentration =
Definition
C
Term
pressure constant (0.0831) =
Definition
R
Term
T =
Definition
Temperature degrees kelvin (273+degrees C)
Term
On a graph, always label:
Definition
Title, x-axis, y-axis, and units
Term
Where the line of best fit crosses the 0% change in mass, that is the ______
Definition
molar concentration of the thing being tested
Term
hypertonic
Definition
has more solutes, and therefore less water potential (water will move to it)
Term
hypotonic
Definition
has less solutes, and therefore more water potential (water will leave it)