MCAT Biology : Types of Carbohydrates

Study concepts, example questions & explanations for MCAT Biology

varsity tutors app store varsity tutors android store

Example Questions

Example Question #1 :Carbohydrates

Drain cleaners a common household staple, used to open clogged drains in bathtubs and sinks. Human hair is a common culprit that clogs pipes, and hair is made predominately of protein. Drain cleaners are effective at breaking down proteins that have accumulated in plumbing. Drain cleaners can be either acidic or basic, and are also effective at breaking down fats that have accumulated with proteins.

A typical reaction—reaction 1—which would be expected for a drain cleaner on contact with human hair, would be as follows in an aqueous solution:

Pic_1

Another reaction that may occur, reaction 2, would take place as follows in an aqueous solution:

Pic_2

In contrast to the proteins in Reactions 1 and 2, the body uses carbohydrates__________.

Possible Answers:

to function as a secondary energy source after fatty acids have been oxidized

to store energy for immediate use

to create strucutral elements of cells

to dissolve nonpolar solutes in blood

to store energy for use over many days

Correct answer:

to store energy for immediate use

解释:

Carboydrates are the main energy currency of cells. They are typically burned first, before fats and proteins, to generate energy. Proteins, in contrast, are usually the functional biomolecules, serving structural and enzymatic roles.

Example Question #1 :Carbohydrates

Which of the following accurately describes glucose?

Possible Answers:

Aldopentose

Aldohexose

Ketopentose

Ketohexose

Correct answer:

Aldohexose

解释:

Glucose is composed of six carbons. When not in ring form, there is an aldehyde at the end of the molecule. As a result, glucose is an example of an aldohexose.

Example Question #2 :Carbohydrates

Which of the following carbohydrates is created in animals, but not in plants?

Possible Answers:

Starch

Amylose

Cellulose

Glycogen

Correct answer:

Glycogen

解释:

Glucose is stored in animals cells in the form of glycogen. Plants store glucose as either starch or cellulose. Amylose is a specialized component of starch, and plays a key role in plant energy storage.

Plants do not form glycogen, similar to the way that humans cannot form (or break down) cellulose.

Example Question #111 :Macromolecules

Which of the following statements is true concerning glucose?

Possible Answers:

-glucopyranose has the anomeric carbon's alcohol group pointing in the opposite direction of the 6th carbon's alcohol group

D-glucose has the highest chiral carbon's hydroxyl group pointing to the left

Maltose and cellulose differ by the type of linkage between the glucose monomers

The 6th carbon attacks the carbonyl carbon in order to create the cyclic structure of glucose

Correct answer:

Maltose and cellulose differ by the type of linkage between the glucose monomers

解释:

Maltose and cellulose are both composed of glucose monomers that are combined in a 1,4 glycosidic linkage, however they differ by the type of 1,4 linkage used. Cellulose uses a beta 1,4 linkage, while maltose uses an alpha 1,4 linkage.

学习工具的大学教师