Question

you are hired to work in a laboratory to measure the rate of human muscle contraction. which of the following might decrease in quantity in muscle cells undergoing contractions?
a sodium
b water
c lactic acid
d carbon dioxide
e atp

Explanation:

Muscle contraction is an energy - requiring process. ATP (adenosine triphosphate) is the energy currency of the cell. When muscles contract, ATP is hydrolyzed to ADP (adenosine diphosphate) and inorganic phosphate (\(P_i\)) to release energy for the contraction process. Sodium (\(Na^+\)) ions are involved in the generation of action potentials for muscle contraction but their quantity does not decrease in a way that is directly related to the energy - consuming contraction process. Water is a medium for various cellular reactions but its quantity is not the key factor decreasing during contraction. Lactic acid is produced during anaerobic respiration in muscles (when oxygen is limited) but it is a by - product, not a substance that is consumed in the contraction process itself. Carbon dioxide is a product of cellular respiration (both aerobic and anaerobic in some cases) but not a substrate that is decreased during muscle contraction.

Answer:

E. ATP