Q.6
Which
of the
following types of
cytokines is responsible
for the growth
and maturation of
B cells?
A. Interleukin-1
B. Interleukin-2
C. Interleukin-4
D. Interleukin-7
Explanation :
The interleukin 4 (IL4, IL-4) is a cytokine that induces differentiation of naive helper T cells (Th0 cells) to Th2 cells. Upon activation by IL-4, Th2 cells subsequently produce additional IL-4 in a positive feedback loop.
Q.23
The most essential fatty acid is
A. Linoleic acid
B. Linolenic acid
C. Arachidonic acid
D. Palmitic acid
Explanation :
Linoleic acid
- Linoleic acid is the most important essential fatty acid because it serves as a basis for the production of other EFA like arachidonic acid.
Q.26
Which is non essential mineral
A. Sodium
B. Magnese
C. Lead
D. Iron
Explanation :
- Lead is non-essential toxic mineral.
Q.28
Resting membrane potential in nerve fibre -
A. Can be measured by two electrodes on surface of neuron
B. Is equal to the potential of ventricular muscle fibre
C. Increases as extracellular K+ increases
D. Depends upon K+ equilibrium
Explanation :
RMP of nerve- -70mV
- RMP of ventricular muscle--90mV
- Potential difference can be measured if one electrode is on the surface and another one inside the nerve cell.
- If the concentration of K+ in ECF is increased, there is more positivity of the membrane OR Less negativity of the membrane OR Decreased magnitude of RMP.
- Resting membrane potential is reached due to the potential difference between ICF and ECF. This is majorly as result of K+ ion concentration difference in ECF and ICF.
Q.30
Membrane fluidity is increased by
A. Stearic Acid
B. Palmitic acid
C. Linoleic acid
D. Cholesterol
Explanation :
The temperature at which the crystalline or gel like state of membrane structures turns into fluid like state is known as Transition temperature. Higher the transition temperature, lower the fluidity of the membrane. The transition temperature is increased maximum by the more saturated fatty acids which interact with each other through their long chains strongly and results in lesser fluidity.
The question is about what increases the fluidity. That means, what decreases the transition temperature. Unsaturated fatty acids like Linoleic and Linolenic acids decrease the transition temperature and increase the fluidity of the cell membrane. Though cholesterol also increases the fluidity at temperatures below the transition temperature, it decreases fluidity above transition temperatures.
Q.32
Tzank cell is –
A. Keratinocyte
B. Fibroblasts
C. Neutrophils
D. Lymphocytes
Explanation :
- Tzank cells are acantholytic cells i.e. large rounded keratinocytes with relatively large nucleus with condensed or hazy cytoplasm.
Q.34
Myosin filament has a fixed length of
A. 0.16nm
B. 1.6 microns
C. 16nm
D. 1.6 mm
Explanation :
- The total length of each myosin filament is uniform, almost exactly 1.6 micrometers.
