Select the total number of true statements from the following?
1. Each myosin (thick) filament is also a polymerized protein.
2. Many monomeric proteins called meromyosins constitute one thick filament.
3. Each meromyosin has two important parts, a globular head with a short arm and a tail, the former being called the heavy meromyosin (HMM) and the latter being called the light meromyosin (LMM).
4. The HMM component, i.e., the head and short arm projects outwards at regular distance and angle from each other from the surface of a polymerized myosin filament and it is known as cross arm.
5. The globular head is an active ATPase enzyme and has binding sites for ATP and active sites for actin.
Important Questions on Locomotion and Movement
(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.
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.
-line
-line
-zone
-band
a. Absence of sarcomere
b. Presence of nucleus
c. Syncytial appearance
d. Presence of gap junctions
Choose the option that reflects features of muscle fibres located in inner walls of reproductive tract.
