Title: Cell Membranes
Course: Question Banks

Q: In order to pass through the ________, some materials require a specialized structure, like a protein channel.
- ribosome (Incorrect. Ribosomes do not have protein channels and materials do not pass through them.)
- nuclear membrane (Incorrect. Nuclear membranes do not have protein channels; they have pores.)
- cell membrane (Correct. The cell membrane controls transit of some materials using protein channels.)
A: cell membrane

Q: Choose the best explanation of why the cell membrane is a "fluid mosaic."
- It is composed of chemically and physically similar parts that move freely in and out of the phospholipid bilayer. (Incorrect. Similar parts do not make a ‘mosaic’.)
- It is composed of distinct parts that flow continuously between it and the cytoplasm. (Incorrect. Components of the membrane do not regularly move into and out of the cytoplasm.)
- It is composed of physically and chemically different parts that move throughout and around the phospholipid bilayer. (Correct. The cell membrane has many different components which move around the membrane bilayer.)
A: It is composed of physically and chemically different parts that move throughout and around the phospholipid bilayer.

Q: The recognition of self facilitated by the cell membrane plays an important role in ________.
- a cell’s physical defense (Incorrect. Recognition of self does not play a role in physical defense.)
- cell adhesion (Incorrect. Recognition of self is not required for cell adhesion.)
- the immune response (Correct. The immune response must be controlled so it does not attack its ‘own’ cells.)
A: the immune response

Q: ________ form specialized sites on the cell surface that allow cells to recognize each other.
- Phospholipids (Incorrect. Phospholipids do not play a direct role in recognition of self.)
- Cholesterols (Incorrect. Cholesterols do not play a role in recognition of self.)
- Carbohydrates (Correct. Carbohydrates bound to the plasma membrane allow for recognition of self.)
A: Carbohydrates

Q: The surface of the plasma membrane is ________ due to the ________.
- hydrophobic; phospholipids (Incorrect. The surface of the plasma membrane is not hydrophobic.)
- fluid; cholesterol (Incorrect. Cholesterol does not keep the surface of the plasma membrane fluid.)
- hydrophilic; phospholipids (Correct. The surface of the plasma membrane is hydrophilic due to the phosphate-glycerol heads of the phospholipids.)
A: hydrophilic; phospholipids

Q: Integral proteins ________.
- are found on only one side of the plasma membrane (Incorrect. Peripheral proteins are found on only one side of the plasma membrane.)
- do not necessarily span all or part of the membrane (Incorrect. Integral proteins must span all or part of the membrane.)
- span all or part of the membrane (Correct. Integral proteins span all or part of the plasma membrane.)
A: span all or part of the membrane

Q: The presence of ________ regulates the fluidity of a membrane in animal cells.
- proteins (Incorrect. Proteins are not involved in fluidity of the membrane.)
- phospholipids (Incorrect. Phospholipids do not regulate the fluidity of the membrane.)
- cholesterol (Correct. In animal cells cholesterol regulates fluidity of the membrane.)
A: cholesterol

Q: Passive transport ________.
- does require energy input (Incorrect. Passive transport does not require energy input.)
- requires and burns up energy (Incorrect. Passive transport does not burn energy.)
- does not require any energy input (Correct. Passive transport requires no external energy.)
A: does not require any energy input

Q: The driving force behind ________ is a concentration gradient from high to low molecule concentration.
- active transport (Incorrect. The driving force behind active transport is energy.)
- reverse transport (Incorrect. No cellular transport process is called ‘reverse transport’.)
- passive transport (Correct. The concentration gradient difference is what allows passive transport to proceed with no energy.)
A: passive transport

Q: ________ is a special type of diffusion that moves water from an a more diluted area to one with a greater solute concentration.
- Facilitated transport (Incorrect. Facilitated transport is not the diffusion of water.)
- Active transport (Incorrect. Active transport works from areas of low concentration to higher.)
- Osmosis (Correct. Osmosis is the term for diffusion of water down its concentration gradient.)
A: Osmosis

Q: A solution is ________ when there is low osmolarity outside a cell and overall water moves into the cell.
- hypertonic (Incorrect. A hypertonic solution has higher osmolarity outside the cell.)
- isotonic (Incorrect. An isotonic solution has equal osmolarity with the cell.)
- hypotonic (Correct. A hypotonic solution has lower osmolarity outside the cell.)
A: hypotonic

Q: Facilitated transport requires ________ to proceed.
- ATP (Incorrect. Facilitated transport does not require energy.)
- osmotic pressure (Incorrect. A concentration gradient still drives facilitated transport, not osmotic pressure.)
- transport proteins (Correct. Facilitated transport is just passive transport using a protein channel.)
A: transport proteins

Q: ________ is used to move ions across a membrane.
- Passive transport (Incorrect. Passive transport cannot move ions across the hydrophobic regions of the membrane.)
- Osmosis (Incorrect. Osmosis is simply the diffusion of water.)
- Facilitated transport (Correct. Ions are hydrophilic and hence cannot pass through the hydrophobic tails by themselves.)
A: Facilitated transport

Q: Active transport must function continuously because ________.
- diffusion is constantly moving solutes to areas of high concentration (Incorrect. This is not how diffusion works.)
- facilitated transport opposes active transport (Incorrect. Facilitated transport is simply passive transport using a channel, not an opposition to active transport.)
- diffusion is constantly moving solutes to areas of low concentration (Correct. Solutes naturally move down their concentration gradient. Active transport must work to overcome this.)
A: diffusion is constantly moving solutes to areas of low concentration

Q: In ________, the energy required is provided by an electrochemical gradient.
- primary active transport (Incorrect. Primary active transport uses energy from ATP.)
- facilitated transport (Incorrect. Facilitated transport does not require energy of any kind.)
- secondary active transport (Correct. An electrochemical gradient is set up in advance; when a channel protein opens, sodium (and other molecules) are then pulled through the membrane.)
A: secondary active transport

Q: An ________ arises from an ion’s combined concentration gradient and electrical charge.
- cellular gradient (Incorrect. This is not the correct term.)
- electrochemical pressure (Incorrect. This is not the correct term.)
- electrochemical gradient (Correct. An electrochemical gradient is the electrical charge and concentration of an ion.)
A: electrochemical gradient

Q: ________ requires transporter proteins.
- Passive transport (Incorrect. Passive transport requires not transporters.)
- Facilitated transport (Incorrect. Facilitated transport requires a channel, not a transporter.)
- Active transport (Correct. Active transport requires transporter proteins.)
A: Active transport

Q: All types of endocytosis include ________.
- an electrochemical gradient (Incorrect. Endocytosis is not based on an electrochemical gradient.)
- the formation of a plasma membrane channel specific to the target (Incorrect. Endocytosis does not utilize channels to bring material into cells.)
- the formation of a plasma membrane pocket around the target (Correct. All types of endocytosis require the plasma membrane to invaginate around the target.)
A: the formation of a plasma membrane pocket around the target

Q: ________ is the process of a cell taking in large particles.
- Pinocytosis (Incorrect. Pinocytosis is “cell drinking,” or taking in small molecules including water, from the extracellular matrix.)
- Receptor-mediated endocytosis (Incorrect. Receptor-mediated endocytosis is not determined by size.)
- Phagocytosis (Correct. This is the term for endocytosis of a large particle.)
A: Phagocytosis

Q: During ________, the inward facing portion of the membrane is stabilized by clathrin.
- pinocytosis (Incorrect. Clathrin has no role in pinocytosis.)
- exocytosis (Incorrect. Clathrin has no role in exocytosis.)
- phagocytosis (Correct. Clathrin is used to stabilize the portion of the membrane that will pinch off during phagocytosis.)
A: phagocytosis

Q: ________ is the process of a cell taking in needed molecules from the extracellular fluid.
- Receptor-mediated endocytosis (Incorrect.)
- Phagocytosis (Incorrect. This is the term for endocytosis of a large particle.)
- Pinocytosis (Correct. Pinocytosis is “cell drinking”, or taking in small molecules including water, from the extracellular matrix.)
A: Pinocytosis

Q: ________ brings in only a specifically targeted substance.
- Phagocytosis (Incorrect. Phagocytosis is the term for endocytosis of a large particle.)
- Pinocytosis (Incorrect. Pinocytosis is “cell drinking”, or taking in small molecules including water, from the extracellular matrix.)
- Receptor-mediated endocytosis (Correct. Receptor-mediated endocytosis is a targeted variation of endocytosis.)
A: Receptor-mediated endocytosis

Q: What happens to the membrane of a vesicle after exocytosis?
- It leaves the cell. (Incorrect. The only material that leaves after exocytosis is the material being expelled.)
- It is disassembled by the cell. (Incorrect. Cells are the ultimate recyclers so they rarely disassemble components unless absolutely necessary.)
- It fuses with and becomes part of the plasma membrane. (Correct. Just as endocytosis removes portions of the plasma membrane to become vesicles, exocytosis reabsorbs vesicles into the membrane.)
A: It fuses with and becomes part of the plasma membrane.

Q: What cell process does this statement describe?

Waste material is enveloped inside a vesicle, and the vesicle merges with the cell membrane and releases the waste outside the cell.
- Endocytosis (Incorrect. Endocytosis brings material into a cell.)
- Phagocytosis (Incorrect. Phagocytosis is a type of endocytosis.)
- Exocytosis (Correct. Exocytosis is the process of expelling waste outside the cell.)
A: Exocytosis

Q: Synaptic vesicles are used for ________ of neurotransmitters.
- endocytosis (Incorrect. Neurotransmitters need to be released outside the cell.)
- phagocytosis (Incorrect. Neurotransmitters need to be released outside the cell.)
- exocytosis (Correct. Neurotransmitters must be released outside the cell; this is done by exoctyosis.)
A: exocytosis