Bio 2 U2S3: membrane structure and function homework
Some protozoans have special organelles called contractile vacuoles that continually eliminate excess water from the cell. The presence of these organelles tells you that the environment
is hypotonic to the protozoan
The ideal osmotic environment for an animal cell is a __________ environment.
isotonic
a plant cell surrounded by a __________ solution will be flaccid (limp)
isotonic
which of the following statements regarding membrane protein function is false?
membrane proteins produce phospholipids
The plasma membrane is selectively permeable. Which of the following can pass freely through the membrane w no assistance?
oxygen and carbon dioxide
Diffusion does not require the cell to expend ATP. Therefore, diffusion is considered a type of....
passive transport
the process of a white blood cell engulfing a bacterium is
phagocytosis
Most of the functions of a cell membrane, including transport and enzymatic function, are performed by
proteins
the molecules responsible for membrane transport are
proteins
which statement best describes phagocytosis?
a cell engulfs a particle by wrapping pseudopodia around it and packaging it within a vacuole
which of the following substances would have the most trouble crossing a biological membrane by diffusing through the lipid bilayer?
Na+
which of the following processes can move a solute against its concentration gradient?
active transport
which of the following statements regarding active transport is false?
active transport is driven by the concentration gradient
Membrane phospholipids
are able to drift about in the plasma membrane
a plant cell in a hypotonic solution
becomes turgid because of an inflow of water
how do fatty acids travel through a cell membrane?
carrier proteins
Fluidity of an animal cell plasma membrane is enhanced by __________.
cholesterol molecules
Osmosis can be defined as
diffusion of water
The fluid mosaic model describes the plasma membrane as consisting of ...
diverse proteins embedded in a phospholipid bilayer
what controls the net direction of molecules, such as oxygen, involved in passive transport?
the direction of the oxygen concentration gradient
Plasma membranes are selectively permeable. This means...
the plasma membrane allows some substances to enter or leave a cell more easily than others.
When two aqueous solutions that differ in solute concentration are placed on either side of a semipermeable membrane and osmosis is allowed to take place, the water will
exhibit a net movement to the side with lower free water concentration
The cholesterol associated with animal cell membranes
helps to keep phospholipids from being too close to one another
A plant cell placed in a ___________ solution will lose water and plasmolyze
hypertonic
there is a net diffusion of water out of an animal cell when it is placed in a ___________ solution.
hypertonic
An animal cell placed in a ______________ solution will gain water, swell, and possibly burst
hypotonic
The ideal osmotic environment for a plant cell is a _________ environment
hypotonic
Facilitated diffusion across a biological membrane requires ________ and moves a substance ________ its concentration gradient.
transport proteins : down
In the figure below, working from the inside out, what would be the order of components observed?
water, hydrophilic head, hydrophobic tail, hydrophobic tail, hydrophilic head, water
