Meaning: 'Result' refers to an outcome or consequence of an action, in this case, the chemical changes in physiology.

Wrong options:

• restoration: Restoration implies returning something to a previous state, which does not fit the context of physiological processes resulting from chemical changes.
• pleading: Pleading is a verb or noun related to requesting or begging, which is irrelevant in this scientific context.
• idea: Idea refers to a thought or concept, which does not convey the outcome of chemical changes in physiology.

Correct answer: signal

Explanation: The word 'signal' is a noun that appropriately describes the transmission of information from one end of the neuron to the other, fitting grammatically and contextually in the phrase 'causing a __ to pass.'

Meaning: 'Signal' refers to a message or indication, particularly in the context of communication within the nervous system.

Wrong options:

• change: Change is a noun that indicates a transformation but does not specifically refer to the communication aspect in this context.
• waste: Waste refers to unwanted or unusable materials, which does not fit the context of neuronal communication.
• pressure: Pressure is a physical force and does not relate to the transmission of information in the nervous system.

Correct answer: storage

Explanation: The word 'storage' fits grammatically as a noun that indicates the act of keeping something for future use, aligning well with the context of oxygen being held in the blood.

Meaning: 'Storage' refers to the act of keeping or holding something, in this case, oxygen in the blood by a protein.

Wrong options:

• extention: Extention is a misspelling of 'extension' and does not fit the context of holding oxygen; it implies lengthening or expanding.
• base: Base refers to a fundamental principle or foundation, which does not relate to the act of holding oxygen in the blood.
• strength: Strength refers to the quality of being strong, which is unrelated to the concept of holding or storing oxygen.

Correct answer: passes

Explanation: The word 'passes' is a verb that correctly describes the action of the protein moving through the lungs, fitting grammatically in the phrase 'as it __ through the lungs.'

Meaning: 'Passes' means to move or go through a place, in this case, referring to the movement of the protein through the lungs.

Wrong options:

• grosses: Grosses is a verb that does not fit in this context; it refers to earning or obtaining, which is irrelevant here.
• stamps: Stamps is a verb that means to mark or impress, which does not apply to the movement of a protein in the lungs.
• brings: Brings is a verb that implies carrying something to a place, which does not accurately describe the action of the protein in this context.

Correct answer: usage

Explanation: The word 'usage' fits grammatically as a noun that indicates the act of using something, aligning well with the context of oxygen being utilized throughout the body.

Meaning: 'Usage' refers to the manner in which something is used, in this case, oxygen in the body.

Wrong options:

• usage: Usage is the correct answer.
• rough: Rough is an adjective that describes texture and does not fit the context of how oxygen is utilized.
• lying: Lying is a verb that means to recline or to be in a horizontal position, which is irrelevant in this context.
• staying: Staying is a verb that means remaining in a place, which does not relate to the act of using oxygen.