Myosin Molecule

Q. Which of the following statements are true about myosin?
I. Myosin is made of meromyosin.
II. Each meromyosin has two parts - HMM and LMM
III. The tail is the light meromyosin i.e. LMM
IV. The head with short arm is heavy meromyosin i.e. HMM

1. III
2. I and II
3. IV
4. I, II, III and IV

Q.

ATPase enzyme needed for muscle contraction is located in:

1. Actin

2. Actinin

3. Myosin

4. Troponin

Q. Read the following statements and find out the incorrect statements.

a. Each actin (thin) filament is made of two ‘G‘ (Globular) actins helically wound to each other.
b. Each ‘G‘ actin is a polymer of monomeric ‘F’ (Filamentous) actins.
c. Two filaments of another protein, troponin also run close to the ‘F' actin throughout its length.
d. In the resting state, tropomyosin masks the active binding sites for myosin on the actin filaments.
e. Each meromyosin has two parts, a globular head with a short arm (HMM) and a tail (LMM).

1. a, b and c
2. b, c and d
3. a, b and e
4. c, d and e

Q. The thick filament is made up of monomeric proteins called ______i_______ which has 2 parts, a globular head with short arm and a tail, the former is referred to as ______ii________ while the latter is referred to as ______iii________.

1. i- meromysosin, ii- heavy meromyosisn, iii- light meromyosisn
2. i- tropomyosin, ii- light meromyosisn, iii- heavy meromyosisn
3. i- tropomysosin, ii- heavy meromyosisn, iii- light meromyosisn
4. i- meromysosin, ii- light meromyosisn, iii- heavy meromyosisn

Q.

The contractile unit of muscle fibers is:

1. Muscle fiber

2. Sarcomere

3. Myofibril

4. Sarcosome

Q. Cell-A has osmotic potential of –18 bars and pressure potential of 8 bars, whereas, cell-B has osmotic potential of –14 bars and pressure potential 2 bars. The direction of flow of water will be

1. from cell-B to cell-A
2. from cell-A to cell-B
3. no flow of water
4. in both the directions

Q. Which of the following is a component of the contractile protein called myosin?

1. Troponin
2. Meromyosin
3. Tropomyosin
4. Both a and c

Q. Which molecule has the ATP binding site needed for muscle contraction?

1. Tropomyosin
2. Myosin
3. Actin
4. Troponin

Q. The globular head of HMM is an active ATPase enzyme and has
a. ATP binding sites
b. Actin binding sites
c. Myosin binding sites
d. Troponin binding sites
e. Calcium binding sites

1. $a,c$ and $d$
2. $a,c$ and $e$
3. $a$ and $b$
4. $a$ and $c$

Q. If the membrane potential becomes more negative than the RMP, the membrane is called

1. depolarized
2. repolarized
3. polarized
4. hyperpolarized

Q. The segment of a myofibril that is called a sarcomere runs from

1. one A band to the next A band
2. one end of a skeletal muscle to the opposite end
3. one Z line to the next Z line
4. one H zone to the next H zone

Q. Which of the following is a diagrammatic representation of standard electrocardiogram (ECG)?

1. 
2. 
3. 
4. 

Q. Minerals absorbed by the roots travel up the xylem. How do they reach the parts where they are needed most? Do all the parts of the plant get the same amount of the minerals?

Q. Which of the following is a component of the contractile protein called myosin?

1. Troponin
2. Meromyosin
3. Tropomyosin
4. Both a and c

Q.

A meromyosin molecule doesn’t contain :

1. head

2. arm

3. trunk

4. tail

Q.

ATPase of the muscle is located in

(a) actinin (b) troponin (c) myosin (d) actin

Q.

What Proteins Contribute Towards The Striated Appearance Of Myofibrils?

Q. Match the following:
$\begin{array}{cc}\text{i. Heavy Meromyosin}& \text{1. Globular head with short arm}\\ \text{ii. Light Meromyosin}& \text{2. Filamentous actin}\\ \text{iii. F actin}& \text{3. Globular actin}\\ \text{iv. G actin}& \text{4. Tail}\end{array}$

1. i-2, ii-3, iii-4, iv-1
2. i-4, ii-1, iii-3, iv-2
3. i-1, ii-4, iii-2, iv-3
4. i-2, ii-1, iii-4, iv-3

Q. Resting membrane potential ranges from

1. -40mV to -90mV
2. -70mV to -130mV
3. -10mV to +30mV
4. 40mV to 90mV

Q.

Cell A has an osmotic potential of −18 bars and a pressure potential of 8 bars, whereas cell B has an osmotic potential of −14 bars and a pressure potential of 2 bars. The direction of flow of water will be

1. No flow of water

2. From cell B to cell A

3. In both the directions

4. From cell A to cell B

Q. Which of the following is an ATP-dependent motor protein

1. Actin
2. Myosin
3. Troponin
4. Tropomyosin

Q.

Label the correct parts of Myosin Monomer:

1. A. Cross arm

   B. Actin binding site

   C. Head

   D. ATP binding site

2. A. Head

   B. Cross arm

   C. Acting binding site

   D. ATP binding site

3. A. Acting binding site

   B. Head

   C. ATP binding site

   D. Cross arm

4. A. ATP binding

   B. Actin binding site

   C. Head

   D. Cross arm

Q. Which molecule has the ATP binding site needed for muscle contraction?

1. Myosin
2. Actin
3. Troponin
4. Tropomyosin

Q. A myosin molecule has two ATP binding sites.

1. False
2. True

Q. Which of the following statements are true about myosin?
I. Myosin is made of meromyosin.
II. Each meromyosin has two parts - HMM and LMM
III. The tail is the light meromyosin i.e. LMM
IV. The head with short arm is heavy meromyosin i.e. HMM

1. III
2. I and II
3. I, II, III and IV
4. IV

Q. The contractile protein of skeletal muscle involving ATPase activity is

1. Troponin
2. Myosin
3. Tropomyosin
4. Alpha - actinin

Q.

A myosin molecule has________ ATP binding sites and ________actin binding sites

1. 1 and 2

2. 2 and 1

3. 2 and 2

4. 1 and 1

Q. Major protein in thick filaments of skeletal muscle fibre is?

1. Myosin
2. Actin
3. Tropomyosin
4. Troponin

Q. Short/ Long answer type questions.
Name three important functions of ATP in skeletal muscle contraction.

Q. Name the ion responsible for unmasking of active sites for myosin for cross-bridge activity during muscle contraction

1. Sodium
2. Potassium
3. Calcium
4. Magnesium