Question 1

Which subatomic particle is responsible for the identity of an element, and how is this number represented in the periodic table?

Accepted Answer

Proton; represented as the atomic number

Question 2

A hospital uses a radioactive isotope for PET scans to detect cancer. Which property of isotopes makes them useful for this application?

Accepted Answer

They have a different number of neutrons, making them unstable and able to emit radiation.

Question 3

Which of the following best describes the difference between an ion and an isotope?

Accepted Answer

An ion has a different number of electrons; an isotope has a different number of neutrons.

Question 4

Which type of chemical bond is primarily responsible for holding together the atoms in a molecule of sodium chloride (NaCl)?

Accepted Answer

Ionic bond

Question 5

A water molecule ($$\mathrm{H_2O}) is $$held together by which type of bond, and what property does this bond impart to water?

Accepted Answer

Polar covalent bond; gives water its partial charges and high surface tension

Question 6

Which of the following best explains why metals are good conductors of electricity?

Accepted Answer

They have metallic bonds with a 'sea of electrons' that move freely.

Question 7

Which of the following is a correct example of a secondary bond and its biological significance?

Accepted Answer

Hydrogen bond; stabilizes the double helix structure of DNA

Question 8

A scientist is designing a drug to fit precisely into a protein's active site. Which type of bond interaction is most critical for the specificity of this fit?

Accepted Answer

Hydrogen bonds and van der Waals forces

Question 9

Which of the following statements about carbohydrates is correct?

Accepted Answer

They have a 1:2:1 ratio of carbon, hydrogen, and oxygen and serve as immediate energy sources.

Question 10

Which of the following is the primary building block of proteins, and what type of bond links them together?

Accepted Answer

Amino acids; peptide bond

Question 11

A patient is advised to reduce saturated fat intake. Which structural feature distinguishes saturated from unsaturated fatty acids?

Accepted Answer

Saturated fatty acids have no double bonds between carbon atoms, while unsaturated fatty acids have one or more double bonds.

Question 12

Which of the following best describes the structure and function of phospholipids in biological membranes?

Accepted Answer

They are composed of glycerol, two fatty acids, and a phosphate group; they form a bilayer that is the main component of cell membranes.

Question 13

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

Accepted Answer

Storing genetic information

Question 14

Which of the following statements about nucleic acids is correct?

Accepted Answer

DNA is double-stranded and contains thymine; RNA is single-stranded and contains uracil.

Question 15

A mutation changes a cytosine base in DNA to a thymine. Which type of chemical bond is directly affected in the base pairing of the DNA double helix?

Accepted Answer

Hydrogen bond

Question 16

Which of the following best explains why cholesterol is important in animal cells?

Accepted Answer

It is a sterol that is part of cell membranes and a precursor for hormones.

Question 17

Which of the following best describes the process of dehydration synthesis in the formation of macromolecules?

Accepted Answer

It joins monomers to form polymers by removing a molecule of water.

Question 18

A researcher is studying the energy yield of different macromolecules. Which macromolecule provides the most energy per gram, and why?

Accepted Answer

Lipids, because they have more carbon-hydrogen bonds that release energy when broken

Question 19

Which of the following correctly matches a macromolecule with its monomer and a key function?

Accepted Answer

Carbohydrate – monosaccharide – provides immediate energy

Chemistry of Living Things: Foundations for Microbiology

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