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 best explains why water is an excellent solvent for ionic compounds?

Accepted Answer

Water is a polar molecule, allowing it to surround and stabilize both positive and negative ions through hydrogen bonding and electrostatic interactions.

Question 2

A scientist is studying a protein that loses its function when exposed to high temperatures. Which process is most likely occurring, and why is it detrimental to protein function?

Accepted Answer

Denaturation; it disrupts the protein's secondary and tertiary structures, altering its shape and function.

Question 3

Which of the following best describes the relationship between the structure and function of phospholipids in biological membranes?

Accepted Answer

Phospholipids have both hydrophilic heads and hydrophobic tails, enabling them to form bilayers that create selective barriers in membranes.

Question 4

Which of the following functional groups is most likely to make an amino acid side chain hydrophilic?

Accepted Answer

A carboxyl group $$(-COOH)$$

Question 5

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 6

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

Accepted Answer

Hydrogen bonds in ice create an open lattice structure, making ice less dense than liquid water.

Question 7

Which property of water is most important for the transport of water from roots to leaves in plants?

Accepted Answer

Cohesion due to hydrogen bonding

Question 8

A carbohydrate polymer is formed by which type of reaction, and what is a byproduct of this process?

Accepted Answer

Dehydration synthesis; water is released

Question 9

Which of the following statements about the secondary structure of proteins is correct?

Accepted Answer

It involves hydrogen bonding between backbone atoms, forming alpha helices and beta sheets.

Question 10

Which of the following best describes the role of cholesterol in animal cell membranes?

Accepted Answer

Cholesterol stabilizes membrane fluidity by preventing tight packing of phospholipids at low temperatures and restricting movement at high temperatures.

Question 11

A DNA double helix is held together primarily by which type of interaction?

Accepted Answer

Hydrogen bonds between complementary bases

Question 12

Which of the following best explains why phospholipids spontaneously form bilayers in aqueous environments?

Accepted Answer

Their hydrophobic tails avoid water while hydrophilic heads interact with water, leading to bilayer formation.

Question 13

Which of the following is a correct comparison between DNA and RNA?

Accepted Answer

DNA is usually double-stranded, while RNA is usually single-stranded.

Question 14

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

Accepted Answer

Enzymes act as catalysts, lowering the activation energy and increasing the rate of chemical reactions.

Question 15

A cell is placed in a solution and begins to swell. Which type of solution is the cell in, and what is the direction of water movement?

Accepted Answer

Hypotonic; water moves into the cell

Question 16

Which of the following best explains why saturated fatty acids tend to make membranes less fluid than unsaturated fatty acids?

Accepted Answer

Saturated fatty acids lack double bonds, allowing them to pack closely together and decrease membrane fluidity.

Question 17

Which of the following is a correct statement about the tertiary structure of a protein?

Accepted Answer

It results from interactions between R-groups of amino acids, including hydrogen bonds, ionic bonds, disulfide bridges, and hydrophobic interactions.

Question 18

Which of the following best describes the process of facilitated diffusion across a cell membrane?

Accepted Answer

Movement of molecules from high to low concentration through a protein channel, without energy input.

Question 19

Which of the following best explains why cellulose is a good structural molecule in plant cell walls?

Accepted Answer

Cellulose forms long, unbranched chains with hydrogen bonds between them, providing rigidity and strength.

Question 20

Which of the following is a function of carbohydrates in cells?

Accepted Answer

Providing energy and serving as structural components

General Biology Study Guide: Chemistry of Life, Macromolecules, and Cell Structure

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