Before the Advent of Online Stores, Book Sales in the United

question 22

True/False

Before the advent of online stores, book sales in the United States were dominated by two large chains.

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Definitions:

Parietal Cells

Stomach cells that secrete hydrochloric acid, which is necessary to convert pepsinogen to pepsin. Parietal cells also secrete intrinsic factor, which is necessary for vitamin B12 absorption.

Intrinsic Factor

A substance secreted by parietal cells in the lining of the stomach. It is necessary for vitamin B12 absorption.

Sucrase

An enzyme that digests sugars.

Maltase

An enzyme that breaks down maltose into glucose during digestion.