Question 1

Which of the following statements best explains why ice floats on liquid water?

Accepted Answer

Hydrogen bonds cause water molecules in ice to spread out, making ice less dense than liquid water.

Question 2

Which property of water allows it to move up the stem of a plant against gravity?

Accepted Answer

Cohesion and adhesion working together in capillary action

Question 3

A radioactive isotope of carbon, $$^{14}C$$, is used in medical imaging. What makes $$^{14}C$$ radioactive?

Accepted Answer

$$^{14}C$$ has an unstable nucleus that decays, releasing energy.

Question 4

Which of the following best describes the difference between ionic and covalent bonds?

Accepted Answer

Ionic bonds involve transferring electrons, while covalent bonds involve sharing electrons.

Question 5

Which of the following is a trace element essential for human health, and how do we commonly obtain it?

Accepted Answer

Iodine; obtained from iodized salt and seafood

Question 6

What is the main function of enzymes in biological systems?

Accepted Answer

Enzymes lower the activation energy required for chemical reactions.

Question 7

Which of the following best explains why water is considered a 'universal solvent'?

Accepted Answer

Water is polar, allowing it to dissolve many ions and polar molecules.

Question 8

A person who is lactose intolerant lacks which of the following?

Accepted Answer

The enzyme lactase needed to break down lactose

Question 9

Which macromolecule is primarily responsible for storing and transmitting genetic information?

Accepted Answer

Nucleic acids

Question 10

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

Accepted Answer

A chain of amino acids linked by peptide bonds

Question 11

Which property of water helps moderate Earth's climate and allows aquatic life to survive temperature changes?

Accepted Answer

High specific heat

Question 12

Which of the following is true about saturated and unsaturated fatty acids?

Accepted Answer

Unsaturated fatty acids have double bonds and are liquid at room temperature.

Question 13

Which of the following equations correctly represents the formation of water from hydrogen and oxygen?

Accepted Answer

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

Question 14

Which of the following best describes the 'lock and key' model of enzyme function?

Accepted Answer

Enzymes have a specific shape that only fits certain substrates.

Question 15

Which of the following is a polymer of carbohydrates used for energy storage in animals?

Accepted Answer

Glycogen

Question 16

What is the main difference between a molecule and a compound?

Accepted Answer

A molecule can be made of the same or different elements, while a compound must be made of different elements.

Question 17

Which of the following best explains why humans cannot digest cellulose?

Accepted Answer

Humans lack the enzyme needed to break the bonds in cellulose.

Question 18

Which of the following best describes the role of valence electrons in chemical bonding?

Accepted Answer

Valence electrons are in the outermost shell and determine how atoms interact with each other.

Question 19

Which of the following is an example of a dehydration synthesis reaction?

Accepted Answer

Linking two monosaccharides to form a disaccharide and releasing water

Question 20

Which of the following best explains why enzymes are reusable in chemical reactions?

Accepted Answer

Enzymes are not changed or consumed during the reaction.

General Biology: Chemistry of Life, Water, and Macromolecules

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