Which Statement Concerning Cross Bridges Is INCORRECT

question 161

Multiple Choice

Which statement concerning cross bridges is INCORRECT?

• A) Cross bridges are the globular heads of myosin molecules.
• B) Cross bridges have actin binding sites that are normally covered by troponin and tropomyosin except during excitation-contraction coupling.
• C) Cross bridges bind with actin and then bend to pull the thin filaments inward during contraction according to the sliding filament mechanism.
• D) Mg2+ is necessary to bind ATP to the cross bridge.

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Definitions:

Variable Costs

Costs that change in proportion to the level of production or sales. They increase as production increases and decrease as production decreases.

Fixed Costs

Costs that remain constant regardless of the amount of production or business operations.

Contribution Margin

The difference between sales revenue and variable costs of a product or service, indicating the amount contributed towards covering fixed costs and generating profit.

Financial Break-even Point

The level of revenue necessary for a firm to cover all its operating expenses and financial costs, achieving a net income of zero.