Question 1

Which of the following best describes an element?

Accepted Answer

A pure substance consisting of only one type of atom, distinguished by its atomic number.

Question 2

Which four elements make up approximately 96% of the human body’s mass?

Accepted Answer

Carbon, hydrogen, oxygen, and nitrogen

Question 3

A neutral atom of sodium has an atomic number of 11 and a mass number of 23. How many protons, neutrons, and electrons does it have?

Accepted Answer

11 protons, 12 neutrons, 11 electrons

Question 4

Which statement about radioactive isotopes is correct?

Accepted Answer

They have unstable nuclei that decay, releasing radiation, and can be used in medical imaging.

Question 5

What is the maximum number of electrons that can be held in the first, second, and third electron shells of an atom, respectively?

Accepted Answer

$$2$$, $$8$$, $$8$$

Question 6

Which of the following best explains why water is a good solvent?

Accepted Answer

Water molecules are polar, allowing them to surround and separate ions and polar molecules.

Question 7

Which of the following equations correctly represents the balanced chemical reaction for the formation of water from hydrogen and oxygen gases?

Accepted Answer

$$2H_2 + O_2$ \rightarrow 2H_2O$$

Question 8

A solution with a pH of 4 has how many times more hydrogen ions ($$H^+) $$than a solution with a pH of 7?

Accepted Answer

$$1,000$$ times more

Question 9

Which of the following best describes a buffer and its importance in human blood?

Accepted Answer

A buffer is a substance that resists changes in pH by accepting or donating $$H^+$$ ions, helping maintain homeostasis.

Question 10

Which of the following statements about covalent bonds is correct?

Accepted Answer

Covalent bonds involve the sharing of electron pairs between atoms.

Question 11

Which of the following best describes the difference between saturated and 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 is a correct statement about phospholipids in cell membranes?

Accepted Answer

Phospholipids have two hydrophobic tails and a hydrophilic head, forming a bilayer in water.

Question 13

Which of the following best describes the relationship between monomers and polymers?

Accepted Answer

Monomers are small molecules that join together to form polymers through dehydration reactions.

Question 14

Which of the following is a correct example of a dehydration reaction?

Accepted Answer

Joining two amino acids to form a dipeptide and releasing a molecule of water.

Question 15

Which of the following best describes the structure of a nucleotide?

Accepted Answer

A nucleotide consists of a phosphate group, a five-carbon sugar, and a nitrogenous base.

Question 16

Which of the following is NOT a correct difference between DNA and RNA?

Accepted Answer

DNA contains the base uracil, while RNA contains the base thymine.

Question 17

Which of the following best explains the role of cholesterol in animal cell membranes?

Accepted Answer

Cholesterol increases membrane fluidity at high temperatures and decreases it at low temperatures.

Question 18

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

Accepted Answer

The sequence of amino acids in a polypeptide chain.

Question 19

Which of the following is an example of a chemical bond formed by the transfer of electrons from one atom to another?

Accepted Answer

Ionic bond

Question 20

Which of the following best explains why ice floats on liquid water and how this benefits life?

Accepted Answer

Ice is less dense than liquid water due to hydrogen bonding, allowing it to float and insulate aquatic environments.

General Biology: Foundations of Chemistry and Macromolecules Study Guide

Study Guide - Practice Questions