Question

The slow twitch muscle fibres which are rich in myoglobins and have abundant mitochondria are-
A. White skeletal muscle
B. Cardiac muscles
C. Red skeletal muscle
D. Involuntary muscles

Answer 1

Muscle is a specialized tissue of mesodermal origin. Muscles contribute about 40-50 percent of the body weight of a human adult. They have special properties like excitable, contractibility, extensibility and elasticity. These muscles are broadly classified into three categories – skeletal, visceral and cardiac.

Complete answer:
Now, we are considering all the options that we are provided with.
White skeletal muscles appear pale or whitish in colour due to less quantity of myoglobin and are called white fibres. They possess fewer mitochondria in them, but the amount of sarcoplasmic reticulum is high. They depend on anaerobic processes for energy and are called anaerobic muscles.
Cardiac muscles are found only in the heart wall and are involuntary in nature as the nervous system does not control their activities directly. They show characters of both unstriped and striped muscle fibres with branching patterns to form a network in the heart wall.
Muscle contains a red coloured oxygen storing pigment called myoglobin. The myoglobin content is high in some of the muscles which gives a reddish appearance. Such muscles are called the red fibres. These muscles also contain plenty of mitochondria, which can utilize the large amount of oxygen stored in them for ATP production. These muscles can also be called aerobic muscles.
Involuntary muscles are those types of muscles which are not under the control of our will. Examples- cardiac muscles, smooth muscles, etc.

Therefore the correct answer is option A

Note:
Skeletal muscles are closely associated with the skeletal components of the body. These muscles are under the control of the conscious mind and can be moved at will, hence are called voluntary muscles. Under the light microscope, the skeletal muscles exhibit transverse stripes, and hence are called striated muscles.