Question 1

Which of the following statements best explains why water is considered a 'universal solvent' in biological systems?

Accepted Answer

Water's polarity allows it to form hydrogen bonds with many different solutes, especially those with ionic or polar covalent bonds.

Question 2

A radioactive isotope of carbon, $$^{14}C$$, is used in radiocarbon dating. What makes $$^{14}C$$ different from the most common carbon isotope, $$^{12}C$$?

Accepted Answer

$$^{14}C$$ has more neutrons than $$^{12}C.$$

Question 3

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

Accepted Answer

Ionic bonds involve the transfer of electrons from one atom to another, while covalent bonds involve the sharing of electrons between atoms.

Question 4

A sodium atom ($$Na) $$has an atomic number of 11. After losing one electron to become $$Na^+$$, how many electrons does it have?

Accepted Answer

10

Question 5

Which property of water is most directly responsible for the ability of plants to transport water from their roots to their leaves?

Accepted Answer

Water's cohesive and adhesive properties due to hydrogen bonding

Question 6

Which of the following equations correctly represents the process of aerobic cellular respiration?

Accepted Answer

$$C_6H_{12}O_6$ + 6O_2 \rightarrow 6CO_2 + 6H_2O$$

Question 7

Why is ice less dense than liquid water, and why is this important for aquatic life?

Accepted Answer

Ice is less dense because hydrogen bonds form a crystalline structure that spaces molecules farther apart, allowing ice to float and insulate the water below.

Question 8

A solution has a pH of 3. Which of the following best describes this solution?

Accepted Answer

It has a high concentration of $$H^+$$ ions and is acidic.

Question 9

Which of the following best explains why buffers are important in biological systems?

Accepted Answer

Buffers maintain a stable pH by absorbing or releasing $$H^+$$ ions as needed.

Question 10

Which of the following is a real-world application of radioactive isotopes in medicine?

Accepted Answer

Using $$^{18}F in $$PET scans to track metabolic activity in tissues.

Question 11

Which of the following best describes a polar covalent bond?

Accepted Answer

Electrons are shared unequally, resulting in partial charges on the atoms.

Question 12

A scientist finds a sample with a ratio of $$^{14}C to$$ $$^{12}C$$ that is half of what is found in living organisms. If the half-life of $$^{14}C is $$about 5,700 years, how old is the sample?

Accepted Answer

About 5,700 years

Question 13

Which of the following is NOT a property of water that is critical for life?

Accepted Answer

Water is a good solvent for nonpolar substances.

Question 14

Which of the following best explains why salt ($$NaCl) $$dissolves easily in water?

Accepted Answer

The polar water molecules surround and separate the positive $$Na^+$$ and negative $$Cl^-$$ ions.

Question 15

Which of the following best describes the role of hydrogen bonds in the structure of large biological molecules?

Accepted Answer

Hydrogen bonds are weak interactions that help stabilize the three-dimensional structure of proteins and DNA.

Question 16

Which of the following statements about acids and bases is correct?

Accepted Answer

Acids increase the concentration of $$H^+$$ ions in a solution.

Question 17

Which of the following best explains why coastal regions tend to have more stable temperatures than inland regions?

Accepted Answer

Water has a high specific heat, so it absorbs and releases heat slowly, moderating temperature changes.

Question 18

Which of the following is the correct formula for calculating the atomic mass of an atom?

Accepted Answer

$$	ext{Atomic mass} = 	ext{Number of protons} + 	ext{Number of neutrons}$$

Question 19

A molecule of water ($$H_2O) is $$described as polar. What does this mean in terms of its structure?

Accepted Answer

The molecule has a partial positive charge on the hydrogen atoms and a partial negative charge on the oxygen atom.

General Biology: Chemistry Fundamentals for Life

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