Q: A solution has a pH of 4. What is the concentration of hydrogen ions $$[H^+] in $$this solution?

$$[H^+] = 1 \times 10$$^{-4}$$ \ \mathrm{M}$$

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 ionic and polar compounds.

Question 2

A scientist is studying a molecule with the formula $$C_{6}H$$_{12}$$O_{6}$. Which class of macromolecule monomer does this formula most likely represent?

Accepted Answer

A monosaccharide

Question 3

Which property of water is primarily responsible for the phenomenon of surface tension observed in small insects walking on water?

Accepted Answer

Cohesion between water molecules due to hydrogen bonding

Question 4

A patient is diagnosed with a genetic disorder caused by a single amino acid substitution in a protein. Which level of protein structure is directly altered by this mutation?

Accepted Answer

Primary structure

Question 5

Which of the following best describes the difference between saturated and unsaturated fatty acids?

Accepted Answer

Saturated fatty acids contain only single bonds between carbon atoms, while unsaturated fatty acids contain one or more double bonds.

Question 6

Which functional group is present in all amino acids and is responsible for their acidic properties?

Accepted Answer

Carboxyl group ($$-COOH)$$

Question 7

A dehydration reaction is used to synthesize a disaccharide from two monosaccharides. What is the byproduct of this reaction?

Accepted Answer

Water ($$H_2O)$$

Question 8

Which of the following statements about cellulose and starch is correct?

Accepted Answer

Cellulose is composed of $$\beta-$$glucose monomers, making it indigestible to most animals, while starch is composed of $$\alpha-$$glucose monomers and is digestible.

Question 9

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

Accepted Answer

Hydrogen bonds in ice create a lattice that is less dense than liquid water.

Question 10

A solution has a pH of 4. What is the concentration of hydrogen ions $$[H^+] in $$this solution?

Accepted Answer

$$[H^+] = 1 	imes 10$$^{-4}$$ \ \mathrm{M}$$

Question 11

Which of the following is a correct description of a phospholipid's structure and its role in biological membranes?

Accepted Answer

Phospholipids have a hydrophilic head and two hydrophobic tails, forming a bilayer that is the basis of cell membranes.

Question 12

Which type of bond is primarily responsible for maintaining the secondary structure of proteins, such as $$\alpha-$$helices and $$\beta-$$pleated sheets?

Accepted Answer

Hydrogen bonds

Question 13

A DNA molecule contains 30% adenine. According to Chargaff's rules, what percentage of guanine would you expect to find?

Accepted Answer

20%

Question 14

Which of the following best describes the difference between a dehydration reaction and a hydrolysis reaction in biological systems?

Accepted Answer

Dehydration reactions join monomers by removing water, while hydrolysis reactions break polymers into monomers by adding water.

Question 15

Which of the following best explains why carbon is able to form such a diversity of organic molecules?

Accepted Answer

Carbon can form up to four covalent bonds with other atoms, allowing for a variety of stable structures.

Question 16

A protein is exposed to high heat and loses its function. Which of the following best describes what has happened to the protein?

Accepted Answer

The protein has been denatured, losing its three-dimensional structure.

Question 17

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

Accepted Answer

Storing genetic information

Question 18

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

Accepted Answer

Buffers maintain pH stability by accepting or donating $$H^+$$ ions when acids or bases are added.

Question 19

Which of the following best explains why animals cannot digest cellulose, even though it is made of glucose monomers?

Accepted Answer

Animals lack the enzymes to break the $$\beta-1$$,4-glycosidic bonds found in cellulose.

Chapters 2-5: The Chemistry of Life – General Biology Study Notes

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