Stimulation of a muscle fiber by a motor neuron occurs at:

1. the neuromuscular junction

2. the transverse tubules

3. the myofibril

4. the sarcoplasmic reticulum

What is true about the white muscle fibers?

1. Myoglobin content is high

2. They have a large number of mitochondria

3. They depend on anaerobic process for energy

4. They are adapted for slow sustained activities

Which of the following property cannot be attributed to white fibers?

1. Fewer mitochondria

2. Anaerobic process for energy

3. Sarcoplasmic reticulum is high

4. More quantity of myoglobin

If production of pyruvic acid by anaerobic metabolism in a muscle is faster than it can be utilized, the surplus is converted to:
1. lactic acid
2. adenosine diphosphate
3. carboxylic acid
4. creatine phosphokinase

Arrange the following events involved in muscular contraction

(i) Action potential enters muscle fibre through T-tubules

(ii) Ca²⁺ binds with troponin-C

(iii) Actomyosin cross bridge formation

(iv) Sliding of thin myofilament along the thick myofilament

(v) Exposure of active sites on actin filaments

(vi) Release of Ca²⁺ from sarcoplasmic reticulum

1. $\left(\mathrm{i}\right)\to \left(\mathrm{ii}\right)\to \left(\mathrm{iii}\right)\to \left(\mathrm{iv}\right)\to \left(\mathrm{v}\right)\to \left(\mathrm{vi}\right)$

2. $\mathrm{(vi)\to (v)\to (iv)\to (iii)\to (ii)\to (i)}$

3. $\left(\mathrm{i}\right)\to \left(\mathrm{ii}\right)\to \left(\mathrm{vi}\right)\to \left(\mathrm{v}\right)\to \left(\mathrm{iii}\right)\to \left(\mathrm{iv}\right)$

4. $\left(\mathrm{i}\right)\to \left(\mathrm{vi}\right)\to \left(\mathrm{ii}\right)\to \left(\mathrm{v}\right)\to \left(\mathrm{iii}\right)\to \left(\mathrm{iv}\right)$

In a healthy person, the red muscle fibres appear red due to stored

1. Carboxyhemoglobin

2. Carbaminohemoglobin

3. Myoglobin

4. Erythropoietin

Red muscle fibres differs from white muscle fibres in having

1. More sarcoplasmic reticulum

2. Less myoglobin content

3. More number of mitochondria

4. High lactic acid due to anaerobic oxidation

Lack of relaxation between successive stimuli in sustained muscle contraction is known as 

1. fatigue   

2. tetanus   

3. tonus   

4. spasm

Identify the incorrectly matched pair: