Question: 10
Lung is a derivative of ________ germ layer.
A. Surface ectodermal
B. Neuroectodermal
C. Mesodermal
D. Endodermal
E. Both A and C
Correct Answer: D. Endodermal
Explanation:
During embryo development, the germ layers ectoderm, endoderm and mesoderm are differentiated
from blastula in a process called gastrulation. Later organogenesis takes place from those germ
layers. Lung is one of the foregut derivatives of endoderm.
Question: 11
The passage of materials between the nucleus and the cytosol takes place through
A. Vesicle
B. Nuclear pore
C. Nucleosome
D. Cajal body
E. Nuclear speckle
Correct Answer: B. Nuclear pore
Explanation:
Nuclear pores are small perforations on the nuclear envelope that allow ransportation of substances
across the nucleus and cytoplasm. Cajal body and nuclear speckle are small subnuclear organelles.
Nucleosome is a chromosomal structure containing histones in DNA. Vesicles present in cytoplasm
transport substances from one part of a cell to another part.
Question: 12
The state of a neuron which inhibits the generation of action potential is said to be
A. Depolarized
B. Repolarized
C. Hyperpolarized
D. Resting potential
E. A, B and D
Correct Answer: C. Hyperpolarized.
Explanation:
Resting potential is the state of a neuron which is not under any stimulus. The normal resting potential
of human nerves is -70 mV. When a neuron receives stimulus, the ce
ll’s interior will be depolarized
with influx of Na+ ions which will result in action potential. Immediately after the generation of action
potential the cell is hyperpolarized; that makes the cell more negative and keeps the neuron in a
refractory period so that the next action potential cannot generate. Next is the repolarization i.e.
neuron will come to its original resting state.