天然高分子（如纖維素、幾丁質）：练习题

Which of the following best describes the primary biological function of cellulose in plants?

Which of the following elements is found in the repeating unit of chitin but is absent in the repeating unit of cellulose?

A sample of a purified natural polymer is found to contain approximately \( 6.9\% \) nitrogen by mass. Given the molecular weights of carbon, hydrogen, oxygen, and nitrogen are 12.0, 1.0, 16.0, and 14.0 respectively, which polymer is most likely represented by this data?

What is the specific type of glycosidic linkage that connects the repeating units in both the cellulose and chitin polymer chains?

By comparing the molecular formulas of the repeating units in cellulose (\( C_6H_{10}O_5 \)) and chitin (\( C_8H_{13}O_5N \)), what is the net gain in atoms per unit when cellulose is conceptually converted to chitin?

The linear chains of cellulose aggregate to form microfibrils. Describe the specific intermolecular force responsible for this aggregation and explain how this structural arrangement contributes to the tensile strength of plant cell walls.

Cellulose and chitin are natural polymers that provide structural support in plants and animals respectively.
(a) State the name of the monomer unit of chitin.
(b) Explain why both cellulose and chitin are highly insoluble in water, despite having many polar hydroxyl and/or acetamido groups.
(c) In the shells of many crustaceans, chitin is embedded in a matrix of calcium carbonate.
(i) Identify the type of material formed by this combination.
(ii) Describe one advantage of this combined material over chitin alone in terms of mechanical properties.