1. Energy transduction is the underlying process of which of the following?
a) DNA
b) Transcription
c) Translation
d) Photosynthesis
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.
2. The first insights into the chemical nature of plasma membranes date back to __________
a) 1700
b) 1790
c) 1800
d) 1890
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.
3. Which material was used by Overton in his experiments to conclude the lipid nature of plasma membrane?
a) bacteria
b) yeast
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
4. The fluid mosaic model was proposed in the year __________
a) 1942
b) 1972
c) 2002
d) 1872
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.
5. According to the fluid mosaic model, the membrane is _____________
a) rigid
b) discontinuous
c) sheet-like
d) fluid-like
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
6. Fluidity and viscosity are the same.
a) True
b) False
Explanation: Fluidity and viscosity are not the same and they are inversely related. Fluidity is a measure of ease of flow and viscosity is the resistance to flow
7. Which of the following attributes of the membrane is most affected at the transition temperature?
a) size
b) fluidity
c) internal composition
d) internal environment
Explanation: At the transition temperature, the bilayer distinctly changes from liquid crystalline phase to crystalline gel. This occurs when the temperature is lowered from a standard warm temperature of 37⁰C.
8. The ___________ the degree of unsaturation of the fatty acids of the bilayer, the ___________ the temperature before the bilayer gels.
a) greater, lower
b) greater, more
c) lesser, higher
d) lesser, higher
Explanation: When the number of unsaturated fatty acids in the membrane is more, lower the transition temperature at which the membrane gels.
9. Which of the following molecules affects the mobility of fatty acyl chains in the plasma membrane?
a) starch
b) glycogen
c) cholesterol
d) carbohydrates
Explanation: Cholesterol disrupts the packing between fatty acyl chains and interferes with their mobility. It makes the membrane durable while decreasing the permeability of the membrane.
10.Which of the following occurs in the membrane, when the temperature is lowered?
a) denaturation
b) desaturation
c) saccharification
d) glycolysis
Explanation: When the temperature of the surrounding is lowered, the cells respond metabolically. Membrane remodeling takes place to make the cell more cold resistant. This takes place by desaturation of fatty acyl chains to form double bonds.