This set of Cell Biology Multiple Choice Questions & Answers (MCQs) focuses on “Cellular Membranes – History and Overview”.
1. One of the main functions of plasma membranes is to enclose the contents of _____________
Explanation: The main function of the plasma membrane is compartmentalization, to enclose all the organelles of the cell and thereby separate them from external hydrophilic environment.
2. Cytosol is the same as cytoplasm.
Explanation: Cytoplasm is the collective name of the inner fluid of the cell which is surrounded by a plasma membrane. The soluble part of the cytoplasm is called cytosol, which is not held by any of the cell organelles.
3. Which of the following is allowed in context with a plasma membrane?
Explanation: Plasma membrane is responsible for transportation of solutes across itself. It is a selectively permeable membrane that allows the transport of a number of molecules and prevents it for others.
4. Which type of molecules are involved in responding to external signals received by the cell?
b) Nucleic acids
Explanation: Receptors present on the plasma membrane face outwards in the extracellular environment and are responsible for responding to signals received by cell. These signals are received in the form of small molecules that bind to the receptor consequently generating an orchestration of intracellular action.
5. The specific molecules that bind to receptors are _____________
Explanation: Receptors present on the cellular membrane are responsible for receiving the signals that come from extracellular environment. These signals are received and the corresponding action is generated upon binding of specific molecules called ligands on the receptors. The ligands have complementary structure with the receptors.
6. Energy transduction is the underlying process of which of the following?
Explanation: Energy transduction is the conversion of one form of energy to another. In photosynthesis, the energy in sunlight is absorbed by the membrane bound photosynthetic pigments, converted into chemical energy and then stored as carbohydrates.
7. The first insights into the chemical nature of plasma membranes date back to __________
Explanation: The first insights into the chemical nature of cell membrane came from Ernst Overton of the University of Zürich during the 1890s. He stated that a substance entering the cell would first have to dissolve in the boundary layer of the cell.
8. Which material was used by Overton in his experiments to conclude the lipid nature of plasma membrane?
c) plant root hair
d) animal root hair
Explanation: Overton placed plant root hair in different solutions containing different solutes. He concluded that more lipid-soluble the solute, more rapidly it would enter the root hair cells.
9. The fluid mosaic model was proposed in the year __________
Explanation: The fluid mosaic model proposed in 1972 by S. Jonathan Singer and Garth Nicolson of the University of California, San Diego. This model has served as the central dogma of membrane biology for over three decades.
10. According to the fluid mosaic model, the membrane is _____________
Explanation: The fluid mosaic model states that the membrane is a lipid bilayer of fluid nature in which the lipid components are free to move about.
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