Question 1

Which of the following correctly describes the difference between the sugar component of RNA and DNA nucleotides?

Accepted Answer

RNA contains ribose, which has a hydroxyl group at the 2' carbon, while DNA contains deoxyribose, which has a hydrogen at the 2' carbon.

Question 2

Which type of bond links nucleotides together in a nucleic acid strand?

Accepted Answer

Phosphodiester bond

Question 3

In the structure of DNA, what type of interaction stabilizes the double helix between complementary base pairs?

Accepted Answer

Hydrogen bonds

Question 4

Which of the following is a monomer of proteins?

Accepted Answer

Amino acid

Question 5

What is the chemical reaction responsible for joining amino acids to form a polypeptide chain?

Accepted Answer

Dehydration synthesis (condensation)

Question 6

Which of the following best describes the structure of a zwitterion at physiological pH?

Accepted Answer

The amino group is protonated ($$\mathrm{NH_3$^+}) $$and the carboxyl group is deprotonated ($$\mathrm{COO^-}).$$

Question 7

Which of the following statements about cellulose and starch is correct?

Accepted Answer

Cellulose is composed of $$\beta-1$$,4 glycosidic linkages, while starch is composed of $$\alpha-1$$,4 glycosidic linkages.

Question 8

Which property of phospholipids is essential for the formation of biological membranes?

Accepted Answer

They are amphipathic, containing both hydrophobic and hydrophilic regions.

Question 9

Which of the following is NOT a function of proteins in living organisms?

Accepted Answer

Storing genetic information

Question 10

Which of the following statements about the peptide bond is TRUE?

Accepted Answer

The peptide bond has partial double-bond character, restricting rotation.

Question 11

Which of the following best explains why most animals cannot digest cellulose?

Accepted Answer

Animals lack the enzyme cellulase required to break $$\beta-1$$,4 glycosidic bonds.

Question 12

Which of the following is a major function of cholesterol in animal cells?

Accepted Answer

It is a precursor for steroid hormones and an important constituent of cell membranes.

Question 13

Which of the following statements about the structure of DNA is correct?

Accepted Answer

The backbone of DNA is held together by covalent phosphodiester bonds, while the two strands are held together by hydrogen bonds between bases.

Question 14

Which of the following is a correct description of the amphipathic nature of phospholipids?

Accepted Answer

Phospholipids have both a hydrophilic head and hydrophobic tails.

Question 15

Which of the following is the correct equation for the formation of a peptide bond between two amino acids?

Accepted Answer

$$\mathrm{R_1${-}COOH} + \mathrm{R_2${-}NH_2$} \rightarrow \mathrm{R_1${-}CO{-}NH{-}R_2$} + \mathrm{H_2O}$$

Question 16

Which of the following is a correct statement about the role of noncovalent interactions in protein folding?

Accepted Answer

Noncovalent interactions are weak, allowing proteins to fold and unfold dynamically.

Midterm

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