Membrane Structure And Function(Biochemistry ) Questions and Answers

Question 1. Cholesterol is essential for normal membrane functions because it
  1.    plugs up the cardiac arteries of older men
  2.    cannot be made by higher organisms
  3.    spans the thickness of the bilayer
  4.    keeps membranes fluid.
Explanation:-
Answer: Option D. -> keeps membranes fluid.
Question 2. In active transport, the membrane structure that functions is
  1.    hydrophobic molecules
  2.    cholesterol
  3.    carbohydrates
  4.    integral proteins
Explanation:-
Answer: Option D. -> integral proteins
Question 3. Bacteriorhodopsin
  1.    contains primarily alpha-helical residues
  2.    absorbs light and pumps protons
  3.    All of these
  4.    is an integral membrane protein
Explanation:-
Answer: Option C. -> All of these
Question 4. Cholesterol is somewhat amphipathic due to
  1.    the five-methyl groups along with the hydrocarbon chain
  2.    the three six-membered rings along with the single five-membered ring
  3.    the long branched hydrocarbon along with the four hydrocarbon rings
  4.    the single hydroxyl along with the hydrocarbon nature of the remainder of the molecule
Explanation:-
Answer: Option D. -> the single hydroxyl along with the hydrocarbon nature of the remainder of the molecule
Question 5. The model that is now known to be correct for the structure of biological membrane is
  1.    Page's model
  2.    Fluid mosaic model
  3.    Lock and Key model
  4.    Lac Operon model
Explanation:-
Answer: Option B. -> Fluid mosaic model
Question 6. In Fluid mosaic model, the biological membrane can be viewed as
  1.    three dimensional solutions of oriented lipids and carbohydrate
  2.    three dimensional solutions of oriented lipids and globular proteins
  3.    two dimensional solutions of oriented lipids and carbohydrate
  4.    two dimensional solutions of oriented lipids and globular proteins
Explanation:-
Answer: Option D. -> two dimensional solutions of oriented lipids and globular proteins
Question 7. Pinocytosis occurs in
  1.    all prokaryotic cells
  2.    mitochondria of all cells
  3.    all eukaryotic cells
  4.    none of these
Explanation:-
Answer: Option C. -> all eukaryotic cells
Question 8. Exocytosis is the secretion of proteins
  1.    out of the cell across the plasma membrane into the extracellular space
  2.    out of the cell across the plasma membrane into the intracellular space
  3.    is the uptake of macromolecules from the intracellular space into the cell across the plasma membrane
  4.    is the uptake of macromolecules from the extracellular space into the cell across the plasma membrane
Explanation:-
Answer: Option A. -> out of the cell across the plasma membrane into the extracellular space
Question 9. Membrane lipids are
  1.    hydrophilic
  2.    hydrophobic
  3.    ampiphillic
  4.    none of these
Explanation:-
Answer: Option A. -> hydrophilic
Question 10. The membrane proteins that catalyze active transport reactions differ from soluble enzymes as
  1.    the substrates of the reaction are all outside the cell
  2.    the products of the reaction move in a specific direction
  3.    they are permanently changed during the reaction
  4.    they do not enhance the rates of reaction
Explanation:-
Answer: Option B. -> the products of the reaction move in a specific direction
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