BIO 107 EXAM 2 QUESTIONS WITH
CORRECT ANSWERS
Describe and label a diagram of the Fluid-Mosaic Model of membrane structure;
Indicate the hydrophobic and hydrophilic regions of the membrane - Correct Answers -
Hydrophilic region = phosphate head
Hydrophobic region = fatty acid tails
Phospholipid bilayer with embedded proteins
Define the term selectively permeable and relate it to cell function - Correct Answers -
Selectively permeable - allows only some substances to cross more easily than others
Cell membranes are selectively permeable, allowing only small or non-polar molecules
to permeate the phospholipid bilayer. Other large or polar molecules must transfer using
proteins.
Compare and contrast hypotonic, isotonic, and hypertonic solutions - Correct Answers -
cell in hypotonic solution
- animal cell bursts because high level of water wants to move into cell with lower level
of water
- plant cell wall can hold water, cell wall gets stiff - good
cell in isotonic solution
- dynamic equilibrium
- no net flow
- animal cell is happy
,- plant cell is flaccid (wilted)
cell in hypertonic sollution
- water of cell moves out of the cell b/c low level of concentration of water outside the
cell
- animal cell shrivels
- plant cell shrivels (plasmolyzed)
- cell membrane pulls away from the cell wall
Given a hypothetical scenario involving tonicity draw and describe water movement into
and out of solutions and cells - Correct Answers -A hypotonic solution will cause water
to move into the cell because there is a lower amount of solute levels outside of the cell
than inside the cell. The cell has high solute levels and low water levels, causing water
to move from high to low into the cell.
A hypertonic solution will cause water to move out of the cell because there is a higher
amount of solute levels outside of the cell than inside the cell. The cell has low solute
levels and high water levels, causing water to move from high to low out of the cell.
Compare and contrast diffusion and osmosis; Relate both terms to the phrase
"concentration gradient" - Correct Answers -Diffusion
- vibrational motion
- rotational motion
- translational motion
- all molecules/particles have kinetic energy
- molecules are always in motion!
- molecules continue to diffuse until the reach dynamic equilibrium, where there is no
net change in concentration
Osmosis
- special kind of diffusion - diffusion of water and water across a membrane
- more solute we have, the less solvent we have
- more solute and less water on right side
- less solute and more water on left side
- result = water moves from the left to the right because water moves from high level of
concentration to low level of concentration
Both processes cause the molecules to move with their concentration gradient, from
high to low.
Compare and contrast the transport mechanisms listed below, including the direction of
movement and the energy source:
a) Passive Transport
b) Facilitated diffusion
c) Active Transport
d) Exocytosis
, e) Endocytosis - Correct Answers -*Diffusion*
High -> low
No energy from cell
Passive
No protein facilitator
*Facilitated diffusion*
High -> low
No energy from cell
Passive
Protein facilitator required
*Active transport*
Low -> high
Energy required from cell
Active
Protein facilitator required
*Exocytosis*
Movement of materials out of a cell by the fusion of vesicles with the plasma membrane
*Endocytosis*
Cellular uptake of molecules or particles via formation of new vesicles from the plasma
membrane
Define the term "energy" and describe its importance to living organisms - Correct
Answers -Energy = the capacity to do work or ability to cause change
Cells transform energy as they perform work
- humans can transfer chemical energy to kinetic energy
- plants can transfer light energy to chemical energy
Compare and contrast potential energy and kinetic energy, and provide or recognize
examples of them - Correct Answers -Energy associated with Location = Potential
Energy
- very ordered
- chemical energy
* relevant to biology
* there is order to a molecule like water
* order is associated with location; atoms have to be in a specific location to be part of
a molecule
* location also equals the location of the electrons in relation to the nucleus
- gravitational energy
* EX: object's potential energy converts to kinetic energy when falling
- stored mechanical energy
- nuclear energy
CORRECT ANSWERS
Describe and label a diagram of the Fluid-Mosaic Model of membrane structure;
Indicate the hydrophobic and hydrophilic regions of the membrane - Correct Answers -
Hydrophilic region = phosphate head
Hydrophobic region = fatty acid tails
Phospholipid bilayer with embedded proteins
Define the term selectively permeable and relate it to cell function - Correct Answers -
Selectively permeable - allows only some substances to cross more easily than others
Cell membranes are selectively permeable, allowing only small or non-polar molecules
to permeate the phospholipid bilayer. Other large or polar molecules must transfer using
proteins.
Compare and contrast hypotonic, isotonic, and hypertonic solutions - Correct Answers -
cell in hypotonic solution
- animal cell bursts because high level of water wants to move into cell with lower level
of water
- plant cell wall can hold water, cell wall gets stiff - good
cell in isotonic solution
- dynamic equilibrium
- no net flow
- animal cell is happy
,- plant cell is flaccid (wilted)
cell in hypertonic sollution
- water of cell moves out of the cell b/c low level of concentration of water outside the
cell
- animal cell shrivels
- plant cell shrivels (plasmolyzed)
- cell membrane pulls away from the cell wall
Given a hypothetical scenario involving tonicity draw and describe water movement into
and out of solutions and cells - Correct Answers -A hypotonic solution will cause water
to move into the cell because there is a lower amount of solute levels outside of the cell
than inside the cell. The cell has high solute levels and low water levels, causing water
to move from high to low into the cell.
A hypertonic solution will cause water to move out of the cell because there is a higher
amount of solute levels outside of the cell than inside the cell. The cell has low solute
levels and high water levels, causing water to move from high to low out of the cell.
Compare and contrast diffusion and osmosis; Relate both terms to the phrase
"concentration gradient" - Correct Answers -Diffusion
- vibrational motion
- rotational motion
- translational motion
- all molecules/particles have kinetic energy
- molecules are always in motion!
- molecules continue to diffuse until the reach dynamic equilibrium, where there is no
net change in concentration
Osmosis
- special kind of diffusion - diffusion of water and water across a membrane
- more solute we have, the less solvent we have
- more solute and less water on right side
- less solute and more water on left side
- result = water moves from the left to the right because water moves from high level of
concentration to low level of concentration
Both processes cause the molecules to move with their concentration gradient, from
high to low.
Compare and contrast the transport mechanisms listed below, including the direction of
movement and the energy source:
a) Passive Transport
b) Facilitated diffusion
c) Active Transport
d) Exocytosis
, e) Endocytosis - Correct Answers -*Diffusion*
High -> low
No energy from cell
Passive
No protein facilitator
*Facilitated diffusion*
High -> low
No energy from cell
Passive
Protein facilitator required
*Active transport*
Low -> high
Energy required from cell
Active
Protein facilitator required
*Exocytosis*
Movement of materials out of a cell by the fusion of vesicles with the plasma membrane
*Endocytosis*
Cellular uptake of molecules or particles via formation of new vesicles from the plasma
membrane
Define the term "energy" and describe its importance to living organisms - Correct
Answers -Energy = the capacity to do work or ability to cause change
Cells transform energy as they perform work
- humans can transfer chemical energy to kinetic energy
- plants can transfer light energy to chemical energy
Compare and contrast potential energy and kinetic energy, and provide or recognize
examples of them - Correct Answers -Energy associated with Location = Potential
Energy
- very ordered
- chemical energy
* relevant to biology
* there is order to a molecule like water
* order is associated with location; atoms have to be in a specific location to be part of
a molecule
* location also equals the location of the electrons in relation to the nucleus
- gravitational energy
* EX: object's potential energy converts to kinetic energy when falling
- stored mechanical energy
- nuclear energy
