question_answer 11)

Match the following columns.

Column I	Column II
a. Fast muscle fibres	1. Myoglobin
b. Slow muscle fibres	2. Lactic acid
c. Actin filament	3. Contractile unit
d. Sarcomere	4. I-bond

Codes       A   B  C   D                         A    B   C    D (a) 1   2   4   3                       (b) 2    1    3    4 (c) 2    1   4   3                      (d) 3    2    4    1

Answer:

                1.(c)  Fast muscle fibres contract spontaneously and reach anaerobic conditions in shorter time, so as to accumulate lactic acid faster in the muscles. 2. Slow muscle fibres have better ability to endure, as they are resistant to fatigue and contract slowly, it is because, of accumulation, of large amount, of myoglobin in them. 3. Actin filament form the isometric band in the muscle fibre because it is the only this actin protein which is present in that region. Sarcomere is the contractile unit of skeletal muscle.