Question

at the end of the contractile period, energy from the breakdown of atp is used to
produce lactic acid.
unlink the troponin-tropomyosin complexes.
repair any muscle damaged during contraction.
transport calcium back into the sarcoplasmic reticulum.
digest energy sources to generate new atp for the next round of contractions.
7 multiple choice 1 point
all of the following occur during the latent period of muscle contraction except which one?
troponin-tropomyosin complex shifts, exposing myosin heads.
muscle cell membrane initiates an electrical impulse, which travels into the muscle cell.
myofibrils shorten.
myosin heads bind to actin filaments.
calcium is released from the sarcoplasmic reticulum.

Explanation:

For the first question: After muscle contraction, ATP energy is used to pump calcium ions back into the sarcoplasmic reticulum to reset the muscle for relaxation. Lactic acid is a byproduct of anaerobic respiration, unlinking troponin-tropomyosin does not use ATP for this purpose at this stage, repair is a separate process, and digesting energy sources is for ATP synthesis, not the immediate end of contraction.

For the second question: The latent period is the time between stimulation and the start of muscle shortening. During this period, electrical impulses travel, calcium is released, troponin-tropomyosin shifts, and myosin binds to actin—but myofibrils do not shorten yet, as shortening occurs in the contraction period.

Answer:

First question: transport calcium back into the sarcoplasmic reticulum.
Second question: Myofibrils shorten.