Which one of the following is NOT a carbohydrate?
The answer to this question is choice A, glucagon is NOT a carbohydrate.
Let’s look at the different choices:
Glucagon: this is a hormone involved in the process of maintaining blood glucose concentration as an aspect of homeostasis. Since it is a hormone, it is a protein and NOT a carbohydrate, making this the correct choice.
Amylose: this is a carbohydrate since amylose is a linear polymer of glucose units in an α(1 → 4) chain.
Ribose: this is once again a carbohydrate since it is a pentose sugar which has 5 carbons.
Amylopectin: this is a carbohydrate that is related to amylose. In contrast, amylose is a linear structure of D-glucose linked units. On the other hand, amylopectin is similar to amylose where there are α(1 → 4) chains BUT amylopectin is branched with α(1 → 6) chains at the branching points.
Maltose: this is a carbohydrate that is composed of only two D-glucose units that is connected via an α(1 → 4) glycosidic bond.
Thus, the only correct choice is A, since it is not a carbohydrate.