Question
Biology Question on Structural Organisation of Animals and plants
Characteristics of smooth muscle fibres are
A
spindle-shaped, unbranched, nonstriated, uninucleate and involuntary
B
spindle-shaped, unbranched, unstriped, multinucleate and involuntary
C
cylindrical, unbranched, unstriped, multinucleate and involuntary
D
cylindrical, unbranched, striated, multinucleate and voluntary.
Answer
spindle-shaped, unbranched, nonstriated, uninucleate and involuntary
Explanation
Solution
The smooth muscle consists of long, narrow unbranched spindle-shaped fibres. Each fibre contains a single oval nucleus in its thick middle part. The cross- striations are absent so that the fibres look smooth, hence the name nonstriated. Its contraction is not under the control of the animal, therefore, also called involuntary muscle.