Question 1

Lactose intolerance is a common condition in which individuals lack sufficient lactase. Which of the following best explains the relationship between lactose and lactase?

Accepted Answer

Lactase is an enzyme that catalyzes the hydrolysis of lactose into glucose and galactose.

Question 2

Carbon is a central element in organic molecules. Which property of carbon allows it to form large, complex molecules?

Accepted Answer

It can form up to four covalent bonds, allowing for diverse molecular structures.

Question 3

Some drugs exist as two isomers, but only one is biologically active. What is the best explanation for this phenomenon?

Accepted Answer

The three-dimensional arrangement of atoms in isomers affects their interaction with enzymes and receptors.

Question 4

Testosterone and estradiol are both steroid hormones with similar structures. Why do they have such different effects in the body?

Accepted Answer

Small differences in their functional groups lead to different interactions with cellular receptors.

Question 5

Which of the following best describes a dehydration reaction?

Accepted Answer

A reaction that removes water to join monomers into a polymer.

Question 6

Suppose you eat cheese, which contains proteins. Which sequence of reactions must occur for your body to use the amino acids to build its own proteins?

Accepted Answer

Hydrolysis of proteins into amino acids, followed by dehydration reactions to assemble new proteins.

Question 7

Which of the following is the correct molecular formula for a monosaccharide with three carbons?

Accepted Answer

$$\mathrm{C_3H_6O_3}$$

Question 8

Which of the following best describes the difference between starch and cellulose?

Accepted Answer

Both are polymers of glucose, but starch has alpha linkages and cellulose has beta linkages.

Question 9

Trans fats are considered unhealthy. How are trans fats formed?

Accepted Answer

By the partial hydrogenation of unsaturated fats, converting some cis double bonds to trans double bonds.

Question 10

Which of the following statements about phospholipids is correct?

Accepted Answer

They have two fatty acid tails and a phosphate group, making them amphipathic.

Question 11

What is the primary structure of a protein?

Accepted Answer

The sequence of amino acids in a polypeptide chain.

Question 12

A genetic mutation changes a single amino acid in the primary structure of a protein. Which of the following best explains how this might affect the protein's function?

Accepted Answer

It may alter the protein's folding and active site, potentially destroying its function.

Question 13

Which of the following best describes complementary base pairing in DNA?

Accepted Answer

Adenine pairs with thymine, and guanine pairs with cytosine.

Question 14

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

Accepted Answer

It helps maintain membrane fluidity and serves as a precursor for steroid hormones.

Question 15

Which of the following best describes the flow of genetic information in building a protein?

Accepted Answer

DNA $$\rightarrow$$ RNA $$\rightarrow$$ Protein

Question 16

Which of the following is true about the structure of a nucleotide?

Accepted Answer

It consists of a phosphate group, a pentose sugar, and a nitrogenous base.

Question 17

Which of the following best explains why fats are hydrophobic?

Accepted Answer

They contain long hydrocarbon chains that are nonpolar and do not interact with water.

Question 18

Which of the following is a correct description of a peptide bond?

Accepted Answer

A covalent bond formed between the amino group of one amino acid and the carboxyl group of another.

Question 19

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

Accepted Answer

DNA is usually double-stranded, while RNA is usually single-stranded.

Biology Study Guide: Organic Molecules, Macromolecules, and Biomolecules

Study Guide - Practice Questions

Study Guide - Flashcards