BIOLOGY 160 EXAM #2 Questions With All
Correct Answers
selective permeability Correct answer-allows some substances to cross more easily than others
phospholipids Correct answer-key ingredient of biological molecules
spontaneously self-assemble into simple membranes
diffusion Correct answer-tendency for particles of any substance to spread out into available space
concentration gradient Correct answer-diffuses down it when net movement from more
concentrated to less concentrated side
equilibrium Correct answer-molecules still move back and forth; no net change in concentration on
either side
passive transport Correct answer-when molecules diffuse across membrane
polar molecules diffusion Correct answer-diffuse across hydrophobic interior if theyre moving
down concentration gradient and have transport proteins
nonpolar molecules diffusion Correct answer-diffuse easily across phospholipid bilayer
osmosis Correct answer-diffusion of water across selectively permeable membrane
tonicity Correct answer-refers to ability of a surrounding solution to cause a cell to gain or lose
water
animal cell in isotonic solution Correct answer-volume remains constant
animal cell in hypotonic solution Correct answer-cell gains water; swells and may burst
animal cell in hypertonic solution Correct answer-cell shrivels and can die from water loss
osmoregulation Correct answer-control of water balance
plant cell in hypotonic Correct answer-turgid (firm)
healthy state
turgor pressure Correct answer-prevents cell from taking in too much water and bursting
plant cell in isotonic Correct answer-no net movement of water into cell, cell is flaccid (limp)
plant cell in hypertonic Correct answer-loses water, shrivels, plasma membrane pulls away from
cell wall
plasmolysis Correct answer-causes plant to wilt and can be lethal in hypertonic solution
bacteria and fungi also plasmolyze
, facilitated diffusion Correct answer-assisted transport; type of passive transport bc no energy
needed
driving force is concentration gradient
used by sugars, amino acids, ions, and water
aquaporins Correct answer-allow only water molecules to pass thru them
found in bacteria, plants, and animals
active transport Correct answer-cell must expend energy to move solute against concentration
gradient
ATP supplies the energy
allows cells to maintain internal concentrations of small molecules and ions that are different from
surroundings
model of active transport system Correct answer-1. solute molecule on cytoplasmic side attach to
specific binding sites on transport protein
2. energy provided by ATP, transport protein changes shape in a way that solute is released on other
side of membrane
3. transport protein returns to original shape, ready for next passengers
exocytosis Correct answer-export BULKY materials like proteins and polysaccharides
-transport vesicle filled with large molecules comes from golgi apparatus to plasma membrane
-vesicle fuses with plasma membrane and vesicles contents spill out of cell when vesicle membrane
becomes part of plasma membrane
endocytosis Correct answer-process thru which cell takes in LARGE molecules
phagocytosis (type of endocytosis) Correct answer-"cellular eating"
-cell engulfs particle by wrapping extensions (pseudopodia) around it and packaging it within a
vacuole
-vacuole fuses with lysosome
-hydrophilic enzymes digest contents of the vacuole
used by protists and white blood cells
receptor-mediated endocytosis (other type of endocytosis) Correct answer--enables a cell to
acquire specific solutes
-receptor proteins are embedded in regions of the membrane lined by layer of coat proteins
-plasma membrane indents to form coated pit, receptor proteins pick up particular molecules from
extracellular fluid
-coated pit pinches closed to form a vesicle, which releases molecules into the cytoplasm
-our cells use it to take in cholesterol from the blood for making membranes a precursor for other
steroids
LDL's Correct answer-low density lipoproteins
bind to receptor proteins and enter cells by endocytosis
cholesterol uses it to circulate in blood
energy Correct answer-the capacity to cause change or perform work
kinetic Correct answer-energy of motion
Correct Answers
selective permeability Correct answer-allows some substances to cross more easily than others
phospholipids Correct answer-key ingredient of biological molecules
spontaneously self-assemble into simple membranes
diffusion Correct answer-tendency for particles of any substance to spread out into available space
concentration gradient Correct answer-diffuses down it when net movement from more
concentrated to less concentrated side
equilibrium Correct answer-molecules still move back and forth; no net change in concentration on
either side
passive transport Correct answer-when molecules diffuse across membrane
polar molecules diffusion Correct answer-diffuse across hydrophobic interior if theyre moving
down concentration gradient and have transport proteins
nonpolar molecules diffusion Correct answer-diffuse easily across phospholipid bilayer
osmosis Correct answer-diffusion of water across selectively permeable membrane
tonicity Correct answer-refers to ability of a surrounding solution to cause a cell to gain or lose
water
animal cell in isotonic solution Correct answer-volume remains constant
animal cell in hypotonic solution Correct answer-cell gains water; swells and may burst
animal cell in hypertonic solution Correct answer-cell shrivels and can die from water loss
osmoregulation Correct answer-control of water balance
plant cell in hypotonic Correct answer-turgid (firm)
healthy state
turgor pressure Correct answer-prevents cell from taking in too much water and bursting
plant cell in isotonic Correct answer-no net movement of water into cell, cell is flaccid (limp)
plant cell in hypertonic Correct answer-loses water, shrivels, plasma membrane pulls away from
cell wall
plasmolysis Correct answer-causes plant to wilt and can be lethal in hypertonic solution
bacteria and fungi also plasmolyze
, facilitated diffusion Correct answer-assisted transport; type of passive transport bc no energy
needed
driving force is concentration gradient
used by sugars, amino acids, ions, and water
aquaporins Correct answer-allow only water molecules to pass thru them
found in bacteria, plants, and animals
active transport Correct answer-cell must expend energy to move solute against concentration
gradient
ATP supplies the energy
allows cells to maintain internal concentrations of small molecules and ions that are different from
surroundings
model of active transport system Correct answer-1. solute molecule on cytoplasmic side attach to
specific binding sites on transport protein
2. energy provided by ATP, transport protein changes shape in a way that solute is released on other
side of membrane
3. transport protein returns to original shape, ready for next passengers
exocytosis Correct answer-export BULKY materials like proteins and polysaccharides
-transport vesicle filled with large molecules comes from golgi apparatus to plasma membrane
-vesicle fuses with plasma membrane and vesicles contents spill out of cell when vesicle membrane
becomes part of plasma membrane
endocytosis Correct answer-process thru which cell takes in LARGE molecules
phagocytosis (type of endocytosis) Correct answer-"cellular eating"
-cell engulfs particle by wrapping extensions (pseudopodia) around it and packaging it within a
vacuole
-vacuole fuses with lysosome
-hydrophilic enzymes digest contents of the vacuole
used by protists and white blood cells
receptor-mediated endocytosis (other type of endocytosis) Correct answer--enables a cell to
acquire specific solutes
-receptor proteins are embedded in regions of the membrane lined by layer of coat proteins
-plasma membrane indents to form coated pit, receptor proteins pick up particular molecules from
extracellular fluid
-coated pit pinches closed to form a vesicle, which releases molecules into the cytoplasm
-our cells use it to take in cholesterol from the blood for making membranes a precursor for other
steroids
LDL's Correct answer-low density lipoproteins
bind to receptor proteins and enter cells by endocytosis
cholesterol uses it to circulate in blood
energy Correct answer-the capacity to cause change or perform work
kinetic Correct answer-energy of motion
