Question

Since each myofibril is attached at either end of the muscle fiber, when sarcomeres shorten, the muscle fiber

A) lengthens.

B) shortens.

C) strengthens.

D) weakens.

E) pulls from the middle.

Answer 1

Answer: When sarcomeres shorten, the muscle fiber SHORTENS.

Step-by-step explanation:

A muscle fiber is made up of many myofibrils that are attached at either end, which are composed of repeating subunits called sarcomeres that are responsible for muscle contraction. There are two types of filaments that makes up myofibrils they include;

- thick filaments and

- thin filaments

These filaments form the overlapping layers of sarcomeres. The contraction of muscle occurs through sliding- filaments model in the sarcomeres. The sarcomere and the muscle fibre shortens in length during muscle contraction ,due to the thick and thin filaments sliding over each other. I hope this helps, thanks.

Answer 2

B. Shortens

Step-by-step explanation:

Myofibrils are components of the animal skeletal muscles that are made up of sacromeres. They perform the muscular contraction and relaxation via the sliding filament model.

To produce motion, A cross-bridge forms between actin and the myosin heads triggering shortening of the sacromere. This shortening of the sacromere results in the contraction of the muscle fibers, which the net effect can be seen to be a shortening of the fibers