Question 1

Which of the following statements best explains why water is considered an excellent solvent for biological systems?

Accepted Answer

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

Question 2

A patient is diagnosed with acidosis, meaning their blood pH is below 7.4. Which buffer system reaction would help restore normal pH?

Accepted Answer

$$ \mathrm{$$HCO_3$$^- + H^+ \rightarrow H_2CO_3} $$

Question 3

Which of the following best describes the difference between a covalent bond and an ionic bond?

Accepted Answer

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

Question 4

A radioactive isotope of carbon, carbon-14, is used in dating ancient biological materials. Why is carbon-14 not suitable for dating dinosaur bones directly?

Accepted Answer

Carbon-14 dating is only effective for remains less than about 100,000 years old, while dinosaur bones are much older.

Question 5

Which of the following best explains why saturated fats are solid at room temperature while unsaturated fats are liquid?

Accepted Answer

Saturated fats have only single bonds between carbon atoms, allowing them to pack closely together.

Question 6

Which of the following is a correct statement about the structure of DNA?

Accepted Answer

DNA is a double-stranded molecule with deoxyribose sugars and the bases adenine, guanine, cytosine, and thymine.

Question 7

A protein is exposed to high heat, causing it to lose its three-dimensional structure. What is this process called, and what is the likely consequence?

Accepted Answer

Denaturation; the protein will lose its biological function.

Question 8

Which of the following best describes the role of enzymes in biological systems?

Accepted Answer

Enzymes lower the activation energy of reactions, speeding up biochemical processes without being consumed.

Question 9

Which of the following statements about phospholipids is correct?

Accepted Answer

Phospholipids are the primary component of cell membranes, with hydrophilic heads and hydrophobic tails.

Question 10

A solution has a hydrogen ion concentration of $$ 1 	imes 10$$^{-4}$$  M. $$What is its pH?

Accepted Answer

pH = 4

Question 11

Which of the following best explains why water helps regulate body temperature in humans?

Accepted Answer

Water can absorb and hold a large amount of heat energy with only a modest increase in temperature.

Question 12

Which of the following is a property of free radicals that makes them potentially harmful in biological systems?

Accepted Answer

They have unpaired electrons, making them highly reactive and capable of damaging DNA and proteins.

Question 13

Which of the following best describes the process of dehydration synthesis?

Accepted Answer

It removes the equivalent of a water molecule to link monomers together, forming polymers.

Question 14

Which of the following is NOT a function of carbohydrates in living organisms?

Accepted Answer

Catalyzing chemical reactions

Question 15

Which of the following best explains why cellulose is indigestible to most animals, including humans?

Accepted Answer

Cellulose contains beta-glycosidic bonds that most animals lack enzymes to break.

Question 16

Which of the following is true regarding the structure of amino acids?

Accepted Answer

Amino acids contain an amino group, a carboxyl group, and a unique R group attached to a central carbon.

Question 17

Which of the following best describes the flow of genetic information in cells?

Accepted Answer

DNA $$ \rightarrow $$ RNA $$ \rightarrow $$ Protein

Question 18

A molecule of ATP releases energy when which of the following occurs?

Accepted Answer

A phosphate group is removed from ATP, forming ADP and $$ P_i .$$

Question 19

Which of the following elements makes up the largest percentage of body weight in humans?

Accepted Answer

Oxygen

Question 20

Which of the following best explains why enzymes are sensitive to changes in pH and temperature?

Accepted Answer

Changes in pH and temperature can alter the enzyme's three-dimensional structure, affecting its function.

The Chemistry of Living Things: Foundations for General Biology

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