Question 1

Which four elements make up approximately 96% of the human body's weight?

Accepted Answer

Carbon, Oxygen, Nitrogen, Hydrogen

Question 2

A patient develops a goiter due to a deficiency of which essential trace element, and what is the biological consequence?

Accepted Answer

Iodine; impaired thyroid hormone production

Question 3

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons

Question 4

What is the atomic number and mass number of Carbon-14?

Accepted Answer

Atomic number: 6, Mass number: 14

Question 5

Which type of chemical bond is the strongest?

Accepted Answer

Covalent bond

Question 6

When sodium (Na) reacts with chlorine (Cl) to form table salt (NaCl), what type of bond is formed and what happens to the electrons?

Accepted Answer

Ionic bond; sodium donates an electron to chlorine

Question 7

Which property of water allows aquatic organisms to survive in cold climates?

Accepted Answer

Ice floats because water expands upon freezing

Question 8

What is the main reason water is considered a universal solvent in biological systems?

Accepted Answer

Water is a polar molecule and can dissolve ionic and polar substances

Question 9

Which equation correctly represents the chemical reaction for the formation of water from hydrogen and oxygen?

Accepted Answer

$2H_2 + O_2 \rightarrow 2H_2O$

Question 10

A solution has a $[H^+]$ concentration of $1 	imes 10^{-3}$ M. What is its pH, and is it acidic or basic?

Accepted Answer

pH = 3; acidic

Question 11

Which property of water is responsible for the phenomenon of surface tension?

Accepted Answer

Cohesion between water molecules due to hydrogen bonding

Question 12

What is the effect of a 2% drop in body water on cognitive function?

Accepted Answer

It can trigger fuzzy short-term memory and trouble focusing

Question 13

Which of the following is a real-world consequence of uncontrolled exposure to radioactive isotopes?

Accepted Answer

DNA damage leading to increased cancer risk

Question 14

Which of the following best explains why water helps regulate body temperature?

Accepted Answer

Water absorbs large amounts of heat with only modest temperature increase

Question 15

If a solution has $[OH^-] > [H^+]$, what is its pH nature?

Accepted Answer

Basic

Question 16

Which of the following is an example of a compound?

Accepted Answer

NaCl

Question 17

Which type of bond is primarily responsible for the structure of DNA and protein folding?

Accepted Answer

Hydrogen bonds

Question 18

What is the main difference between hydrophilic and hydrophobic substances?

Accepted Answer

Hydrophilic substances are polar and dissolve in water; hydrophobic substances are nonpolar and do not dissolve in water

Question 19

Which of the following best describes the role of potential energy in chemical bonds?

Accepted Answer

Potential energy is stored in the bonds that hold atoms together

Question 20

Acid rain is primarily caused by which chemical process?

Accepted Answer

Sulfur oxides ($SO_x$) and nitrogen oxides ($NO_x$) dissolve in water to form sulfuric and nitric acids

Essential Chemistry for Biology: Chapter 2 Study Notes

Study Guide - Practice Questions