Biological Membranes quiz #2 Flashcards
Biological Membranes quiz #2
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The role of the cell membrane is most like the job of which person?
The cell membrane acts like a security guard, controlling what enters and exits the cell. Which of the following factors does not affect membrane permeability? A) Temperature B) Cholesterol content C) Phospholipid composition D) Color of the membrane
D) Color of the membrane What does selectively permeable mean?
Selectively permeable means the membrane allows certain molecules to pass through while blocking others. Which molecule has both hydrophilic and hydrophobic properties and is found in plasma membranes?
Phospholipids have both hydrophilic and hydrophobic properties and are found in plasma membranes. How does the 'fluid mosaic model' describe the structure of the plasma membrane?
The fluid mosaic model describes the plasma membrane as a semi-fluid structure with proteins and cholesterol embedded in a phospholipid bilayer. What is the definition of selective permeability?
Selective permeability is the ability of a membrane to regulate the passage of substances, allowing some to pass while blocking others. Which group of molecules forms the core of all biological membranes?
Phospholipids form the core of all biological membranes. Why do phospholipids tend to spontaneously orient themselves into something resembling a membrane?
Phospholipids spontaneously orient into a bilayer because their hydrophilic heads face water while hydrophobic tails avoid it. Which of the following will pass through a cell membrane most easily? A) Large proteins B) Small nonpolar molecules C) Ions D) Polysaccharides
B) Small nonpolar molecules Which of the following is a principle of the fluid mosaic model of cell membrane structure? A) Static arrangement B) Rigid structure C) Dynamic and flexible D) Uniform composition
C) Dynamic and flexible What is a selectively permeable membrane?
A selectively permeable membrane allows certain substances to pass while restricting others. Which of the following statements is correct about a biological membrane that is fluid? A) It is rigid and immobile B) It allows lateral movement of molecules C) It is impermeable to all substances D) It is composed solely of proteins
B) It allows lateral movement of molecules Which of the following is a defining feature of biological membranes? A) Uniform composition B) Selective permeability C) Lack of proteins D) Static structure
B) Selective permeability Which of the following statements best describes the fluid mosaic model of the plasma membrane?
The fluid mosaic model describes the plasma membrane as a dynamic structure with proteins and lipids moving within a phospholipid bilayer. What is the primary function of the cell membrane?
The primary function of the cell membrane is to regulate the passage of substances in and out of the cell. Why is a cell membrane described as a fluid mosaic?
A cell membrane is described as a fluid mosaic because it is composed of various molecules that can move laterally within the bilayer. Which of the following statements best describes the fluid-mosaic model of membrane structure?
The fluid-mosaic model describes the membrane as a flexible layer with proteins embedded in or attached to a phospholipid bilayer. Which statement best describes the role of the cell membrane in this model?
The cell membrane acts as a selective barrier, controlling the entry and exit of substances. Which statement best describes the plasma membrane of a living plant cell?
The plasma membrane of a living plant cell is a selectively permeable barrier composed of a phospholipid bilayer with embedded proteins. Which type of lipid forms the bilayer that makes up cell membranes?
Phospholipids form the bilayer that makes up cell membranes. What does it mean that the cell membrane is selectively permeable?
It means the cell membrane allows certain molecules to pass while blocking others. Which example is a function of the selectively permeable membrane of a cell?
Regulating the passage of ions and nutrients into and out of the cell. What part of cell membranes gives flexibility to the structure?
The fluid nature of the phospholipid bilayer gives flexibility to the cell membrane. Which is true of the fluid mosaic model of membrane structure?
The fluid mosaic model describes the membrane as dynamic, with proteins and lipids able to move within the bilayer. Why do phospholipids form a bilayer in the plasma membrane?
Phospholipids form a bilayer because their hydrophilic heads face water while hydrophobic tails avoid it. What is the role of the cell membrane in both prokaryotic and eukaryotic cells?
The cell membrane regulates the passage of substances and provides structural support. Which of the following does not impact membrane permeability? A) Temperature B) Lipid composition C) Membrane thickness D) Membrane color
D) Membrane color Which part of a phospholipid would be facing the cytoplasm and extracellular fluids?
The hydrophilic head of a phospholipid faces the cytoplasm and extracellular fluids. How is a cell wall different than a cell membrane?
A cell wall provides structural support and protection, while a cell membrane regulates the passage of substances. Which of the following statements about biological membranes is false? A) They are composed of a phospholipid bilayer B) They are static and rigid C) They contain embedded proteins D) They are selectively permeable
B) They are static and rigid How is the reaction center positioned in the membrane?
The reaction center is typically embedded within the membrane, interacting with both the lipid bilayer and proteins. Which of the following contributes to the fluid mosaic model? A) Rigid lipid structure B) Embedded proteins C) Uniform composition D) Lack of cholesterol
B) Embedded proteins As a membrane surface area increases, what happens to its permeability?
As membrane surface area increases, permeability may increase due to more space for transport proteins and channels. How do unsaturated fatty acids help keep any membrane more fluid at lower temperatures?
Unsaturated fatty acids prevent tight packing of lipids, maintaining fluidity at lower temperatures. What is the job of a cell’s selectively permeable membrane?
The job of a cell’s selectively permeable membrane is to regulate the passage of substances in and out of the cell. What is the function of a cell’s selectively permeable plasma membrane?
The function is to control the entry and exit of molecules, maintaining homeostasis. Which of the following does not describe a biological membrane? A) Dynamic B) Rigid C) Selectively permeable D) Composed of lipids and proteins
B) Rigid What is the function of the cell membrane’s selective permeability?
Selective permeability allows the cell to maintain homeostasis by regulating substance passage. The cell membrane is made up of which type of biomolecule?
The cell membrane is primarily made up of phospholipids, proteins, and cholesterol. Why is the plasma membrane considered selectively permeable? Why is this important?
The plasma membrane is selectively permeable to regulate the internal environment, crucial for maintaining homeostasis.
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