Proton Pumps Are Used in Various Ways by Members of Every

question 24

Multiple Choice

Proton pumps are used in various ways by members of every domain of organisms: Bacteria,Archaea,and Eukarya.What does this most probably mean?

• A)Proton pumps must have evolved before any living organisms were present on Earth.
• B)Proton pumps are an essential feature of all cell membranes.
• C)Proton gradients across a membrane were used by cells that were the common ancestor of all three domains of life.
• D)Cells of each domain evolved proton pumps independently when oceans became more acidic.

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Definitions:

MC

Marginal Cost, the increase or decrease in the total cost of a production run for making one additional unit of an item.

AFC

Average Fixed Cost represents the fixed expenses of a firm divided by the quantity of output produced.

Variable Inputs

Inputs or resources whose usage level can be changed in the short term to match the level of production output.

Property Resources

Physical and intangible entities that generate economic value owned by individuals or companies.