Question

Study the following and identify the incorrect statements.
(I) Muscles of the iris and ciliary body are the smooth muscles of mesodermal origin
(II) Slow and sustained involuntary contractions of smooth muscles are called spasms.
(III) Quiescent mononucleate myogenic cells of skeletal muscles are called pericytes.
(IV) The skeletal muscle fibre is multi nucleate and is a syncitium.

• A. I, IV
• B. II, IV
• C. III, IV
• D. I, II

Answer 1

The correct option is D I, II

There are three germ layers namely, ectoderm, endoderm and mesoderm. The eye is derived from both ectodermal and mesodermal sources. The retina, iris, ciliary body and optic nerves are formed by neuroectoderm.

Spasm is sudden involuntary contractions of smooth muscles which are not sustained for a long time. Spasms generally are short-lived.

Pericytes are an important component for the formation of skeletal muscles. The pericytes are quiescent mononucleated myogenic cells.

The condition when a large number of nuclei are found due to the absence of cytoplasmic division is called as syncytium. It occurs in skeletal muscle fibres.

Thus, the correct answer is option D.