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WorksheetsMechanism of Muscle Contraction
Total questions: 20
Worksheet time: 21mins
A characteristic feature of the muscle fibre is the presence of a large number of parallelly arranged filaments in the sarcoplasm called
myofibrils
sarcomeres
muscle bundles
skeletal muscles
The plasma membrane of of a muscle fibre is called as
Sarcoplasm
Sarcoplasmic reticulum
Sarcomere
Sarcolemma
I- band is made up of
Myosin filaments
Actin filaments
Troponin
Tropomyosin
Dark band that contains myosin filaments is called I- band.
True
False
The thin filaments are firmly attached to
M- line
A-line
Z- line
I-line
Which of the following best defines a sarcomere unit?
The portion of the myofibril between two successive ‘Z’ lines is considered as the functional unit of contraction and is called a sarcomere
The portion of the myofibril between two successive ‘M’ lines is considered as the functional unit of contraction and is called a sarcomere
The portion of the myofibril between two successive I- bands is considered as the functional unit of contraction and is called a sarcomere
The portion of the myofibril between two successive A-bands is considered as the functional unit of contraction and is called a sarcomere
Which of the following is the correct sequence of organization of skeletal muscle?
Skeletal muscle - muscle fibre- muscle bundle - myofibril - sarcomere
Skeletal muscle - muscle bundle- muscle fibre- myofibril - sarcomere
Muscle bundle- muscle fibre- skeletal muscle- myofibril - sarcomere
Skeletal muscle - muscle bundle- myofibril- muscle fibre- sarcomere
The contractile protein represented here is
Myosin
Actin
The contractile protein represented here is
Actin
Myosin
In the resting state of a sarcomere, a subunit of ___________ masks the active binding sites for myosin on the actin filaments
Tropomyosin
F actin
G actin
Troponin
Myosin is a polymeric protein made up of monomeric units called as "Meromyosin"
True
False
The globular head of meromyosin is an active ATPase enzyme which means that
It combines ADP and Pi to form ATP
It breaks ATP into ADP and Pi
It allows ATP to bind to myosin
It removes ATP that is bound to Myosin
The site which meromyosin possesses to bind to actin is
ATP binding site
Myosin binding site
Actin binding site
Electron binding site
The ions that help in initiating muscle contraction are
Magnesium ions
Sodium ions
Potassium ions
Calcium ions
During muscle contraction, Z- lines of the sarcomere unit are
pulled outwards thereby increasing the length of sarcomere
compressed perpendicularly thereby decreasing height of sarcomere
elongate perpendicularly thereby increasing height of sarcomere
pulled inwards thereby causing shortening of sarcomere
The correct sequence of cross- bridge formation is represented by
A, B, C, & D
D, A, B & C
C, A, B & D
D, C, B & A
A sarcomere in relaxed state is represented by
A sarcomere in contracting state is represented by
A sarcomere in maximally contracted state is represented by
Z- lines move apart during muscle relaxation because
Calcium ions are added to troponin in actin filaments
Calcium ions are added to tropomyosin in actin filaments
Calcium ions are removed from troponin in actin filaments
Calcium ions are removed from tropomyosin in actin filaments
