Question 1

Which of the following best describes the relationship between matter, mass, and weight?

Accepted Answer

Matter is anything that occupies space and has mass; mass is the amount of matter in an object; weight is mass affected by gravity.

Question 2

Which four elements make up more than 95% of the human body’s mass?

Accepted Answer

Oxygen, carbon, hydrogen, and nitrogen

Question 3

An atom of carbon-14 has 6 protons and 8 neutrons. What is its atomic mass?

Accepted Answer

$$14$$

Question 4

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of the same element have the same number of protons but different numbers of neutrons.

Question 5

Which type of chemical bond involves the sharing of electrons between atoms?

Accepted Answer

Covalent bond

Question 6

What is the key difference between a nonpolar covalent bond and a polar covalent bond?

Accepted Answer

Nonpolar covalent bonds share electrons equally; polar covalent bonds share electrons unequally.

Question 7

Which of the following best explains why water is an excellent solvent for ionic compounds?

Accepted Answer

Water molecules are polar and can surround and separate ions due to their partial charges.

Question 8

Which of the following equations represents a synthesis reaction?

Accepted Answer

$$A + B \rightarrow AB$$

Question 9

A catalyst increases the rate of a chemical reaction by:

Accepted Answer

Lowering the activation energy required for the reaction.

Question 10

Which of the following is a property of water that makes it essential to life?

Accepted Answer

It acts as a lubricant and cushion, absorbs heat without a large temperature increase, and is a universal solvent.

Question 11

Which of the following best describes the role of buffers in the body?

Accepted Answer

Buffers help maintain pH homeostasis by neutralizing small amounts of acids or bases.

Question 12

Which of the following is an example of a pentose monosaccharide?

Accepted Answer

Ribose

Question 13

Which type of lipid is a major component of cell membranes?

Accepted Answer

Phospholipids

Question 14

What is the primary function of carbohydrates in the human body?

Accepted Answer

Energy source

Question 15

Which of the following is a building block of proteins?

Accepted Answer

Amino acids

Question 16

Which macromolecule contains a double helix structure formed by hydrogen bonding between nitrogenous bases?

Accepted Answer

DNA

Question 17

Which of the following is true about ATP?

Accepted Answer

ATP stores significant potential energy in its phosphate bonds.

Question 18

Which of the following best describes an exergonic reaction?

Accepted Answer

A reaction that releases more energy than it absorbs.

Question 19

Which of the following is most likely to be found evenly distributed in water as a homogeneous solution?

Accepted Answer

Sodium ions and chloride ions

Question 20

Which of the following best explains why enzymes are specific to their substrates?

Accepted Answer

The active site of an enzyme binds only substrates of compatible shape and charge, a property known as specificity.

The Chemical Level of Organization: Elements, Atoms, and Compounds in Anatomy & Physiology

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