The certain drug acts at synapses and affects the action of neurotransmitter substances. The effects of four different drugs are given below:
Drug-I: Inhibits the enzyme cholinesterase.
Drug-II: Prevents the release of acetylcholine.
Drug-III: Competes with acetylcholine at receptor sites.
Drug-IV: Inhibits the enzyme which destroys nor-adrenaline.
Which two drugs would prevent a skeletal muscle from responding to an electrical stimulus of the presynaptic neuron?
Important Questions on Locomotion and Movement
-line
-line
-zone
-band
Assertion (A): Skeletal muscles have very limited power of regeneration.
Reason (R): Satellite cells are present in them.
The correct option among the following is
How does muscle cells change their shape?
During muscular contraction which of the following events occur?
(a) 'H' zone disappears
(b) 'A' band widens
(c) 'I' band reduces in width
(d) Myosin hydrolyzes ATP, releasing the ADP and Pi
(e) Z-lines attached to actins are pulled inwards.
Choose the correct answer from the options given below.
Reason (R): The above said molecules have a role in masking and unmasking the active sites on actin.
(i) Muscles show three essential properties such as excitability, conductivity and contractility.
(ii) Muscular tissue is endodermal in origin except muscle of iris and ciliary body.
(iii) The cytoplasm of muscle fibre has several myofibrils.
(iv) Skeletal muscles exhibit slow and prolonged contractions.
(v) The regular arrangement of myosin and actin filaments is responsible for alternate dark and light bands of striated muscle.
Statement II: Actin is a motor protein that is able to convert chemical energy into mechanical energy
