Question 1
Which Of The Following Statements About Phospholipids Is False?
a) Membrane surfaces that face the interior and exterior of the cell are hydrophobic. The interior of the cell membrane is hydrophilic.
b) The hydrophobic membrane-spanning regions of integral proteins interact with the hydrophobic region of the phospholipid bilayer.
c) Carbohydrates are found on the exterior surface of cells and are bound either to proteins, or to lipids.
d) Phospholipids tend to become arranged with their hydrophobic tails facing each other and their hydrophilic heads facing out.
Question 2
Which of the following statements regarding phospholipids is false?
A. A phospholipid has nearly the same structure as a triglyceride.
B. All of these statements are true.
C. A cell membrane is a bilayer of phospholipids and glycolipids.
D. Phospholipids are common in the cell membrane.
E. Unlike triglycerides, phospholipids have a polar region.
Question 3
A. A phospholipid has nearly the same structure as a triglyceride. TRUE
Triglycerides are the esters of glycerol and consist of three fatty acids. This same structure is found in phospholipids but with the substitution of phosphoric residue for one of the fatty acids.
B. All of these statements are true. FALSE
Since statement C is false, not all of these statements are true.
C. A cell membrane is a bilayer of phospholipids and glycolipids. FALSE
Aside from phospholipids and glycolipids, the cell membrane is also embedded with proteins, glycoproteins, and other carbohydrates.
D. Phospholipids are common in the cell membrane. TRUE
The cell membrane is mainly a bilayer of phospholipids.
E. Unlike triglycerides, phospholipids have a polar region. TRUE
The phosphate head gives phospholipids its polar region which is absent in triglycerides.
Answer to question 1
The answer to the above question is option a i.e membrane surfaces that face the interior and exterior of the cell are hydrophobic. The interior of the cell membrane is hydrophilic. This statement is a false statement.
The cell membrane is present surrounding the cell which contains proteins and other macromolecules in it. It is made up of lipids especially phospholipids and proteins that remain embedded in the bilayer. Phospholipid molecules are amphipathic in nature i.e they have a polar or hydrophilic phosphate head and non-polar or hydrophobic fatty acid tails. These hydrophobic tails face the interior of the cell and the hydrophilic part is present towards the exterior. Thus the interior becomes hydrophobic in nature and the exterior i.e the membrane surfaceis hydrophilic in nature. The integral proteins are embedded into this interior region which is hydrophobic with respect to the phospholipid bilayer. Carbohydrates are found on the exterior of the surface in the form of glycolipids and glycoproteins.
Thus only the first statement is a false statement. Rest all are true.
Answer to question 2
A. A phospholipid has nearly the same structure as a triglyceride. TRUE
Triglycerides are the esters of glycerol and consist of three fatty acids. This same structure is found in phospholipids but with the substitution of phosphoric residue for one of the fatty acids.
B. All of these statements are true. FALSE
Since statement C is false, not all of these statements are true.
C. A cell membrane is a bilayer of phospholipids and glycolipids. FALSE
Aside from phospholipids and glycolipids, the cell membrane is also embedded with proteins, glycoproteins, and other carbohydrates.
D. Phospholipids are common in the cell membrane. TRUE
The cell membrane is mainly a bilayer of phospholipids.
E. Unlike triglycerides, phospholipids have a polar region. TRUE
The phosphate head gives phospholipids its polar region which is absent in triglycerides.
Answer to question 3
The features of phospholipids are not associated with membrane budding. So, membrane budding does not require transient breakages in the case of bilayer sheath. This is described as the surrounding membrane that encompasses the contents of the cytoplasm.
Therefore, the correct answer is b. membrane budding requires transient breakages in the bilayer membrane.
Please note that:
Option a. is incorrect as this bilayer acts as an obstruction that works by splitting the cell from the exterior environment.
Option c. is incorrect as the interior side of the phospholipid bilayer possesses a hydrophobic environment.
Option d. is incorrect as the chemical properties of this bilayer results in the spontaneous formation of bilayers.