AP Biology Cells Exam Questions and
Answers7
Countercurrent Exchange - ANSWERS -Diffusion of substances between two regions in which
they are moving by bulk flow in oposite directions
Active Transport - ANSWERS -Movement of solutes against a gradient, requiring the expenditure
of energy
Exocytosis - ANSWERS -Vesicles fuse with the plasma membrane and release their contents to
the outside
Endocytosis - ANSWERS -The plasma membrane engulfs a substance and enters the cytoplasm
in a vesicle; phagocytosis (undissolved, solid material) and pinocytosis (dissolved, liquid
material), receptor-mediated (specific molecules bind to receptors)
Cell - ANSWERS -Basic functional unit of all living things
Cytoplasm - ANSWERS -Consists of specialized bodies (organelles) suspended in a fluid matrix
(cytosol)
Plasma Membrane - ANSWERS -Separates internal metabolic events from the external
environment; controls the movement of materials into and out of the cell (selective
permeability); lipid bilayer with hydrophilic heads and hydrophobic tails, proteins, cholesterol to
provide some rigidity, and a glycocalyx of glycolipids (lipids + oligosaccharides) and
glycoproteins (proteins + oligosaccharides)
, Peripheral Proteins - ANSWERS -Proteins that attach to the inner or outer surface of the
membrane
Integral Proteins - ANSWERS -Proteins that extend into the membrane
Transmembrane Proteins - ANSWERS -Integral proteins that span completely through the
membrane; held in place by hydrophilic/hydrophobic regions
Fluid Mosaic Model - ANSWERS -Describes structure of the plasma membrane; scattered
proteins within a flexible matrix of phospholipids
Channel Proteins - ANSWERS -Provide open passageways through the membrane
Ion Channels - ANSWERS -Allow the passage of ions across the membranes; gated channels
open and close in response to specific stimuli i.e. Na+ and K+
Porins - ANSWERS -Allow the passage of certain ions and small polar molecules; aquaporins
increase the passage rate of water molecules
Carrier Proteins - ANSWERS -Bind to specific molecules, undergo a change in shape, and then
transfer the molecules across the membrane; i.e. the passage of glucose
Transport Proteins - ANSWERS -Use ATP to transport materials through active transport; i.e.
sodium-potassium pump maintaining higher sodium and potassium concentrations on opposite
sides of the membrane
Recognition Proteins - ANSWERS -Give each cell type a unique identification so it can distinguish
between "self" and "foreign" cells
Answers7
Countercurrent Exchange - ANSWERS -Diffusion of substances between two regions in which
they are moving by bulk flow in oposite directions
Active Transport - ANSWERS -Movement of solutes against a gradient, requiring the expenditure
of energy
Exocytosis - ANSWERS -Vesicles fuse with the plasma membrane and release their contents to
the outside
Endocytosis - ANSWERS -The plasma membrane engulfs a substance and enters the cytoplasm
in a vesicle; phagocytosis (undissolved, solid material) and pinocytosis (dissolved, liquid
material), receptor-mediated (specific molecules bind to receptors)
Cell - ANSWERS -Basic functional unit of all living things
Cytoplasm - ANSWERS -Consists of specialized bodies (organelles) suspended in a fluid matrix
(cytosol)
Plasma Membrane - ANSWERS -Separates internal metabolic events from the external
environment; controls the movement of materials into and out of the cell (selective
permeability); lipid bilayer with hydrophilic heads and hydrophobic tails, proteins, cholesterol to
provide some rigidity, and a glycocalyx of glycolipids (lipids + oligosaccharides) and
glycoproteins (proteins + oligosaccharides)
, Peripheral Proteins - ANSWERS -Proteins that attach to the inner or outer surface of the
membrane
Integral Proteins - ANSWERS -Proteins that extend into the membrane
Transmembrane Proteins - ANSWERS -Integral proteins that span completely through the
membrane; held in place by hydrophilic/hydrophobic regions
Fluid Mosaic Model - ANSWERS -Describes structure of the plasma membrane; scattered
proteins within a flexible matrix of phospholipids
Channel Proteins - ANSWERS -Provide open passageways through the membrane
Ion Channels - ANSWERS -Allow the passage of ions across the membranes; gated channels
open and close in response to specific stimuli i.e. Na+ and K+
Porins - ANSWERS -Allow the passage of certain ions and small polar molecules; aquaporins
increase the passage rate of water molecules
Carrier Proteins - ANSWERS -Bind to specific molecules, undergo a change in shape, and then
transfer the molecules across the membrane; i.e. the passage of glucose
Transport Proteins - ANSWERS -Use ATP to transport materials through active transport; i.e.
sodium-potassium pump maintaining higher sodium and potassium concentrations on opposite
sides of the membrane
Recognition Proteins - ANSWERS -Give each cell type a unique identification so it can distinguish
between "self" and "foreign" cells
