A Radioactive Source Decays from 20 MCi to 2

question 15

Multiple Choice

A radioactive source decays from 20 mCi to 2.5 mCi in 18 hours.What is the physical half-life?

• A)8 hours
• B)7 hours
• C)6 hours
• D)5 hours

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Definitions:

Troponin

A protein complex involved in the regulation of skeletal and cardiac muscle contraction, which binds to calcium ions causing a change that allows muscle contraction.

ATPase Activity

The enzymatic activity involved in hydrolyzing ATP (adenosine triphosphate) to release energy.

Thin Myofilament

A component of the muscle fiber responsible for muscle contraction, composed primarily of the protein actin.

Globular (G) Actin

A monomeric form of actin protein that can polymerize to form filamentous (F) actin, part of the cytoskeleton in cells.