BackBiological Membranes quiz #2
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1/39BackSkip to main contentBackThe 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 factor does not affect membrane permeability?
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 type of molecule passes through a cell membrane most easily?
B) Small nonpolar molecules What is a principle of the fluid mosaic model of cell membrane structure?
Dynamic and flexible What is a selectively permeable membrane?
A selectively permeable membrane allows certain substances to pass while restricting others. What is true about a biological membrane that is fluid?
It allows lateral movement of molecules What is a defining feature of biological membranes?
Selective permeability How does the fluid mosaic model describe 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. How does the fluid-mosaic model describe 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. What factor does not impact membrane permeability?
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. 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. What contributes to the fluid mosaic model of membrane structure?
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. What characteristic does not describe a biological membrane?
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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