LSU BIO 1201 EXAM 2 QUESTIONS &
ACCURATE COMPLETE SOLUTIONS
why are membranes called phospholipid bilayers? - Correct Answer ✔✔ phospholipids
have hydrophilic head and hydrophobic tail, hydrophobic face inside of cell making 2
layers
what is meant by fluid mosaic? - Correct Answer ✔✔ Mosaic of proteins drifting laterally
in fluid bilayer of phospholipids
how are membranes adjusted for different temperatures? - Correct Answer ✔✔
membrane fluidity adjusted by changing the ratio of unsaturated to saturated fatty acids
how do the relative amounts of saturated and unsaturated fats change? - Correct
Answer ✔✔ if you are in a cold environment you want more saturated fats for your
membranes to be fluid; warm environment you want more saturated fats to make your
membranes more solid
what is meant by membrane fluidity? - Correct Answer ✔✔ not too solid, not too fluid
why is fluidity an important property? - Correct Answer ✔✔ preserves membrane
function
Henrique and Hanson performed experiments with pigs and examined the effects on the
relative amounts of saturated and unsaturated fats. What did they find? - Correct
Answer ✔✔ found that membrane fluidity can acclimate to temperature; pigs raised
wearing underwear in a hot room had subcutaneous fats with higher melting point
what types of molecules can move easily across the membrane? - Correct Answer ✔✔
small nonpolar molecules, gases, steroid hormones, and water
what is simple diffusion? - Correct Answer ✔✔ down the concentration gradient; does
not require supplied energy; does not use a carrier molecule
what is facilitated diffusion? - Correct Answer ✔✔ down the concentration gradient;
employs carrier molecule; does not require supplied energy
what is active transport? - Correct Answer ✔✔ work must me done; must use supplied
energy; employs carrier molecule
for which transport processes are carrier molecules involved? - Correct Answer ✔✔
facilitated diffusion and active transport
, which transport processes require the input of additional energy? - Correct Answer ✔✔
active transport
what is a semi-permeable barrier? - Correct Answer ✔✔ only some types of molecules
pass through
when equilibrium is reached in diffusion: does movement of molecules stop? - Correct
Answer ✔✔ no
when equilibrium is reached in diffusion: does the net movement of molecules stop? -
Correct Answer ✔✔ yes
what is meant by hypertonic? - Correct Answer ✔✔ lower water potential; more solutes
dissolved; tend to gain water via osmosis
what is meant by hypertonic? - Correct Answer ✔✔ higher water potential; fewer solutes
dissolved; will tend to lose water via osmosis
isotonic - Correct Answer ✔✔ equivalent water potential; equal number of solutes; no
note movement of water
in which direction does water flow? - Correct Answer ✔✔ osmosis and the direction of
net water movement
what are aquaporins? - Correct Answer ✔✔ channel proteins which facilitate water
diffusion through the membrane
marine bony fish are...? - Correct Answer ✔✔ hypotonic to seawater
how do enzymes work? - Correct Answer ✔✔ they position the reactants in a
conformation more favorable for the chemical reaction to occur
what aspects of the energetics do enzymes change? - Correct Answer ✔✔ enzymes
lower activation energy barrier ΔG⧧
what aspects of energetics do enzymes not affect? - Correct Answer ✔✔ they do not
reverse an energetically unfavorable reactions; they do not make a reaction go uphill
how are substrates lured into the active site? - Correct Answer ✔✔ positively charged
arginine sidechain lures the negatively charged substrate into the active site
what are the analogs to these characters in the binding of substrates to enzymes? -
Correct Answer ✔✔ Siren song= positively charged arginine sidechain
Negatively charged substrate= Odysseus' men
Circe= active site
ACCURATE COMPLETE SOLUTIONS
why are membranes called phospholipid bilayers? - Correct Answer ✔✔ phospholipids
have hydrophilic head and hydrophobic tail, hydrophobic face inside of cell making 2
layers
what is meant by fluid mosaic? - Correct Answer ✔✔ Mosaic of proteins drifting laterally
in fluid bilayer of phospholipids
how are membranes adjusted for different temperatures? - Correct Answer ✔✔
membrane fluidity adjusted by changing the ratio of unsaturated to saturated fatty acids
how do the relative amounts of saturated and unsaturated fats change? - Correct
Answer ✔✔ if you are in a cold environment you want more saturated fats for your
membranes to be fluid; warm environment you want more saturated fats to make your
membranes more solid
what is meant by membrane fluidity? - Correct Answer ✔✔ not too solid, not too fluid
why is fluidity an important property? - Correct Answer ✔✔ preserves membrane
function
Henrique and Hanson performed experiments with pigs and examined the effects on the
relative amounts of saturated and unsaturated fats. What did they find? - Correct
Answer ✔✔ found that membrane fluidity can acclimate to temperature; pigs raised
wearing underwear in a hot room had subcutaneous fats with higher melting point
what types of molecules can move easily across the membrane? - Correct Answer ✔✔
small nonpolar molecules, gases, steroid hormones, and water
what is simple diffusion? - Correct Answer ✔✔ down the concentration gradient; does
not require supplied energy; does not use a carrier molecule
what is facilitated diffusion? - Correct Answer ✔✔ down the concentration gradient;
employs carrier molecule; does not require supplied energy
what is active transport? - Correct Answer ✔✔ work must me done; must use supplied
energy; employs carrier molecule
for which transport processes are carrier molecules involved? - Correct Answer ✔✔
facilitated diffusion and active transport
, which transport processes require the input of additional energy? - Correct Answer ✔✔
active transport
what is a semi-permeable barrier? - Correct Answer ✔✔ only some types of molecules
pass through
when equilibrium is reached in diffusion: does movement of molecules stop? - Correct
Answer ✔✔ no
when equilibrium is reached in diffusion: does the net movement of molecules stop? -
Correct Answer ✔✔ yes
what is meant by hypertonic? - Correct Answer ✔✔ lower water potential; more solutes
dissolved; tend to gain water via osmosis
what is meant by hypertonic? - Correct Answer ✔✔ higher water potential; fewer solutes
dissolved; will tend to lose water via osmosis
isotonic - Correct Answer ✔✔ equivalent water potential; equal number of solutes; no
note movement of water
in which direction does water flow? - Correct Answer ✔✔ osmosis and the direction of
net water movement
what are aquaporins? - Correct Answer ✔✔ channel proteins which facilitate water
diffusion through the membrane
marine bony fish are...? - Correct Answer ✔✔ hypotonic to seawater
how do enzymes work? - Correct Answer ✔✔ they position the reactants in a
conformation more favorable for the chemical reaction to occur
what aspects of the energetics do enzymes change? - Correct Answer ✔✔ enzymes
lower activation energy barrier ΔG⧧
what aspects of energetics do enzymes not affect? - Correct Answer ✔✔ they do not
reverse an energetically unfavorable reactions; they do not make a reaction go uphill
how are substrates lured into the active site? - Correct Answer ✔✔ positively charged
arginine sidechain lures the negatively charged substrate into the active site
what are the analogs to these characters in the binding of substrates to enzymes? -
Correct Answer ✔✔ Siren song= positively charged arginine sidechain
Negatively charged substrate= Odysseus' men
Circe= active site
