Question 1

Which of the following statements best explains why oxygen is essential for human life?

Accepted Answer

Oxygen is a component of water and other compounds; its gaseous form is essential for cellular respiration.

Question 2

A neutral atom of magnesium (Mg) has an atomic number of 12 and an atomic mass of 24. How many neutrons does it have?

Accepted Answer

$$24 - 12 = 12$$ neutrons

Question 3

Which of the following best describes an ionic bond?

Accepted Answer

A bond formed by the transfer of electrons from one atom to another, resulting in oppositely charged ions that attract each other.

Question 4

Which element is most abundant in the human body by weight and what is its primary significance?

Accepted Answer

Oxygen; a component of water and essential for respiration.

Question 5

A molecule of water ($$H_2O) is $$held together by which type of bond, and what type of bond forms between two water molecules?

Accepted Answer

Covalent bonds within the molecule; hydrogen bonds between molecules.

Question 6

Which of the following best describes a polar covalent bond?

Accepted Answer

A bond where electrons are shared unequally, resulting in partial charges on the atoms.

Question 7

If a sodium atom (Na) loses one electron, what is the resulting charge and what is this ion called?

Accepted Answer

Positive; cation

Question 8

Which of the following is an example of a decomposition reaction in the body?

Accepted Answer

AB \rightarrow A + B

Question 9

A patient is given a medication that acts as an enzyme inhibitor. What effect will this have on the activation energy ($$E_a) of a $$chemical reaction in the body?

Accepted Answer

It will increase $$E_a$$, making the reaction slower or preventing it from occurring.

Question 10

Which of the following best explains why water is considered an inorganic compound?

Accepted Answer

It does not contain both carbon and hydrogen atoms bonded together.

Question 11

A solution contains $$Na^+$$ and $$Cl^-$$ ions. What type of bond was broken to form these ions in water?

Accepted Answer

Ionic bond

Question 12

Which of the following best describes the difference between a molecule and a compound?

Accepted Answer

A molecule is made of two or more atoms bonded together; a compound is made of two or more different elements bonded together.

Question 13

Which element is essential for oxygen transport in the blood and energy capture in cells?

Accepted Answer

Iron (Fe)

Question 14

A patient has a genetic disorder that affects the number of neutrons in their oxygen atoms, but not the number of protons. What is the result?

Accepted Answer

The patient will have oxygen isotopes in their body.

Question 15

Which of the following best describes a free radical?

Accepted Answer

An atom, ion, or molecule that contains an unpaired electron in its outermost energy level, making it highly reactive.

Question 16

Which of the following is a real-life example of a synthesis (anabolic) reaction in the human body?

Accepted Answer

The formation of proteins from amino acids.

Question 17

Which of the following best explains why calcium (Ca) is important in the human body?

Accepted Answer

It is found in bones and teeth and is important for membrane function, nerve impulses, muscle contraction, and blood clotting.

Question 18

Which of the following best describes the role of enzymes in chemical reactions?

Accepted Answer

Enzymes lower the activation energy required for a reaction, increasing the reaction rate.

Question 19

A reversible reaction is represented as $$A + B \leftrightarrow AB. $$What does this indicate about the reaction?

Accepted Answer

The reaction can proceed in both directions, seeking equilibrium.

Question 20

Which of the following best explains why trace elements such as iodine (I) are important in the human body?

Accepted Answer

They are components of hormones of the thyroid gland and are essential for normal metabolism.

Chemical Level of Organization: Atoms, Elements, and Their Role in Human Physiology

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