Question 1

Which of the following best describes the structural difference between an aldose and a ketose monosaccharide?

Accepted Answer

An aldose contains a carbonyl group at the end of the carbon chain, while a ketose contains a carbonyl group within the carbon chain.

Question 2

Which of the following statements about the D- and L- forms of monosaccharides is correct?

Accepted Answer

The D-form has the –OH group on the chiral carbon farthest from the carbonyl group pointing to the right in a Fischer projection.

Question 3

Which type of glycosidic linkage is found in cellulose, and why can't mammals digest it?

Accepted Answer

Cellulose contains $$\beta-1$$,4-glycosidic linkages, and mammals lack the enzyme $$\beta-$$glucosidase to hydrolyze these bonds.

Question 4

Which of the following best explains why oils are liquid at room temperature while fats are solid?

Accepted Answer

Oils contain a higher proportion of unsaturated fatty acids, which have cis double bonds that prevent tight packing.

Question 5

A patient is diagnosed with Beriberi, a disease caused by a deficiency in which vitamin, and what is the biochemical role of this vitamin?

Accepted Answer

Thiamin (Vitamin B1), which is part of the coenzyme thiamin pyrophosphate (TPP) involved in carbohydrate metabolism.

Question 6

Which of the following statements about phospholipids in biological membranes is correct?

Accepted Answer

Phospholipids form a bilayer with hydrophobic tails facing inward and hydrophilic heads facing outward.

Question 7

Which of the following best describes the primary structure of a protein?

Accepted Answer

The sequence of amino acids linked by peptide bonds.

Question 8

Which of the following is a correct description of the isoelectric point ($$pI) of an $$amino acid?

Accepted Answer

The $$pH at $$which the amino acid has no net electric charge.

Question 9

Which of the following is NOT a function of enzymes in biological systems?

Accepted Answer

Enzymes increase the activation energy required for a reaction.

Question 10

Which of the following statements about competitive enzyme inhibition is correct?

Accepted Answer

A competitive inhibitor resembles the substrate and competes for binding at the active site.

Question 11

Which of the following best explains why mammals can digest starch but not cellulose?

Accepted Answer

Mammals have $$\alpha-$$glucosidase to hydrolyze $$\alpha-1$$,4-glycosidic bonds in starch, but lack $$\beta-$$glucosidase for $$\beta-1$$,4-glycosidic bonds in cellulose.

Question 12

Which of the following is a purine base found in nucleic acids?

Accepted Answer

Adenine

Question 13

Which of the following best describes the difference between DNA and RNA?

Accepted Answer

DNA contains deoxyribose and thymine, while RNA contains ribose and uracil.

Question 14

Which of the following is a function of ribosomal RNA (rRNA)?

Accepted Answer

It is the site of protein synthesis, found in the ribosome.

Question 15

Which of the following best describes the role of phospholipids in cell membranes?

Accepted Answer

They form a bilayer that acts as a barrier to most polar molecules.

Question 16

Which of the following is a correct statement about the effect of temperature on enzyme activity?

Accepted Answer

Enzyme activity increases with temperature up to an optimum, then decreases due to denaturation.

Question 17

Which of the following is a fat-soluble vitamin?

Accepted Answer

Vitamin D

Question 18

Which of the following best describes the function of a coenzyme?

Accepted Answer

A coenzyme prepares the active site for catalytic activity.

Question 19

Which of the following is a correct description of allosteric regulation of enzymes?

Accepted Answer

A molecule binds to a site other than the active site, affecting enzyme activity.

Core Concepts in Biochemistry: Carbohydrates, Lipids, Nucleic Acids, and Proteins

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