Please Use the Following Information to Answer the Question(s) Below

question 10

Multiple Choice

Please use the following information to answer the question(s) below.
Nitrogenase, the enzyme that catalyzes nitrogen fixation, is inhibited whenever free O₂ reaches a critical concentration. Consequently, nitrogen fixation cannot occur in cells wherein photosynthesis produces free O₂. Consider the colonial aquatic cyanobacterium Anabaena, whose heterocytes are described as having "a thickened cell wall that restricts entry of O₂ produced by neighboring cells. Intracellular connections allow heterocysts to transport fixed nitrogen to neighboring cells in exchange for carbohydrates."
-Given that the enzymes that catalyze nitrogen fixation are inhibited by oxygen, what are two "strategies" that nitrogen-fixing prokaryotes might use to protect these enzymes from oxygen?
1) package them in membranes that are impermeable to all gases
2) be obligate anaerobes
3) be facultative aerobes
4) package these enzymes in specialized cells or compartments that inhibit oxygen entry

• A) 1 and 4
• B) 2 and 4
• C) 2 and 3
• D) 3 and 4

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Definitions:

Weighted-Average Method

An inventory valuation technique that calculates the cost of inventory by taking the average cost of all similar items present in the inventory.

First-In, First-Out Method

An inventory valuation method whereby the oldest inventory items are recorded as sold first, thus the cost of items purchased first is charged against revenue earlier.

Equivalent Units

A concept used in cost accounting to convert units of production into a common measure.

First-In, First-Out Method

An inventory valuation method where the oldest inventory items are recorded as sold first, leaving the newest inventory in stock.