Question

Cardiac muscle cells differ from the striated muscle cells in having_______________________.
A. a centrally located nucleus
B. different myofibrils
C. fewer mitochondria
D. no sarcoplasmic reticulum.

Answer 1

Hint:
Muscles are soft tissues that are present in most animals and function to produce force and motion. They are associated with maintaining posture, locomotion and movement of certain internal organs in different biological functions.

Complete answer:
In living animals, the body contains specific types of soft tissues which are associated with movement and locomotion. These tissues are known as muscles. They contain protein filaments of actin and myosin which move past or slide over one another and produce contraction. The contraction produced changes the length and shapes of the cell. The main function of the muscle fibres is to produce motion and force.
Muscle can be divided into three types which are smooth muscle, cardiac muscles and striated muscles. Cardiac muscles are the muscles that form the muscles of the heart and are not under the control, hence, are involuntary in nature. The cardiac muscle cells are known as cardiomyocytes. The cardiac muscle cells contain a single nucleus. They are known to contain several to large numbers of mitochondria which functions to provide energy to the muscle cells. The cardiac muscle cells are joined together with the help of intercalated discs to form long fibres.
Striated muscles are also known as skeletal muscles and they are under conscious control and are known as voluntary muscles. The striated muscles are cylindrical and are multinucleated. They bear more than one nucleus and contain multiple mitochondria which helps in the energy generation. The striated muscles are attached to the bones with the help of tendons.
The myofibrils or the muscle fibres are composed of actin and myosin filaments. These are repeated muscle units which are known as sarcomeres. The sarcomere is responsible for the striated appearance of the striated muscles. These striated muscle fibres are the most important component that is required for the muscle contraction.

Hence, the correct answer is option (A).

Note: The muscle fibres are the soft tissues present in the living animals and they are of three types. The different types of muscle fibres are cardiac, smooth and striated muscles. The cardiac muscles are present in the muscles of the heart and contain only a single nucleus with a large number of mitochondria. The striated muscles are multinucleated and contain fewer mitochondria.