Tag: structure of muscle

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Multiple choice zoology locomotion and movement contractile protein structure of muscle muscles and their structure

Consider the following four statements (i) - (iv) and select the correct option.
(i) Actin is present in thin filament.
(ii) H-zone of striated muscle fibre represents both thick and thin filaments.
(iii) There are 11 pairs of ribs in man.
(iv) Sternum Is present on ventral side of the body. 

  1. (i) F (ii) F (iii) T (iv) F

  2. (i) F (ii) F (iii) F (iv) T

  3. (i) T (ii) F (iii) F (iv) F

  4. (i) T (ii) F (iii) T (iv) F
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

(i) Actin is present in thin filament - True

(ii) H-zone of striated muscle fibre represents both thick and thin filaments - False
(iii) There are 11 pairs of ribs in man - False
(iv) The sternum is present on the ventral side of the body - False
So, the correct answer is (c).

Multiple choice zoology locomotion and movement contractile protein structure of muscle muscles and their structure

Each actin filament is made of

  1. 2 'G' Actin molecules

  2. 2 F Actin molecules

  3. 1 F Actin molecules

  4. 1 G Actin molecules
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Actin is the protein which helps in the muscle contraction. It present in two forms G actin (globular actin) and F actin (filament actin). In muscles, actin filament is formed by the two long strand of bead-like twisted actin molecule. 

So, the correct answer is '2 F Actin molecules'.

Multiple choice zoology locomotion and movement contractile protein structure of muscle muscles and their structure

Contractile unit of muscle fibres is

  1. Muscle fibre

  2. Sacromere

  3. Myofibril

  4. Sacrosome
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The entire cross section of the muscle fibre is taken up by long, cylindrical strands of contractile proteins called myofibrils. One myofibril is divided into segments called sarcomeres. These are the contractile units of a muscle. A dark stripe called a Z disc marks the ends of one sarcomere and the beginning of the next.

Multiple choice zoology locomotion and movement contractile protein structure of muscle muscles and their structure

Contractile proteins include:

  1. Troponin

  2. Tropomyosin

  3. Actin and myosin

  4. All the three
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The main components of protein in muscle is actin and myosine that form thin and thick fibers respectively.


The troponin and tropmyosine come under the category of regulatory proteins that regulate the process of muscle contraction.

for example troponin binds with tropomysosine to inhibit actin and myosine interaction during relaxation stage.

Hence the correct answer is (C). 

Multiple choice zoology locomotion and movement contractile protein structure of muscle muscles and their structure

The important muscle proteins that help in movement are

  1. Actin and myosin

  2. Tropomyosin

  3. Troponin

  4. All of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Actin and myosin are the structural filaments that play the main role in muscle contraction by sliding filament theory.

Troponin and tropomyosin are the regulatory proteins that regulate the rate of attachment of myosin heads to actin. Hence they also play an important role in muscle contraction and its movement.
Troponin regulate availability of active sites of actin by attaching with Ca++
So the correct option is D.

Multiple choice zoology locomotion and movement contractile protein structure of muscle muscles and their structure

The monomeric actin is called as

  1. F- actin

  2. M- actin

  3. G- actin

  4. N- actin
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Actin is the thin filament of the muscles. It is a polymer made of many monomers. The monomers of actin are globular in shape and hence called Globular-actin or G-actin. Monomers together form straight chains of polymer action. The polymer action is called F-actin.

So the correct option is C.

Multiple choice zoology locomotion and movement contractile protein structure of muscle muscles and their structure

In a muscle fibre

  1. Sacrolemma is connective tissue holding the myofibrils together

  2. T system contains calcium storage sacs

  3. Both filaments have cross-bridges

  4. All of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Terminal cisternae are enlarged areas of the sarcoplasmic reticulum surrounding the transverse tubule because terminal cisternae ensure rapid calcium delivery, they are well developed in muscles that contract quickly such as fast-twitch skeletal muscle.
So, the T system contains calcium storage sacs.