Question 1

Which of the following monomer building blocks is necessary to assemble selectively permeable boundaries around and inside cells?

Accepted Answer

Fatty acids are necessary to assemble selectively permeable boundaries around and inside cells. They can form phospholipid bilayers, a major component of cell membranes, which are selectively permeable and control the passage of molecules in and out of the cell. Sugars are important for energy storage and structural support, amino acids form proteins, and nucleotides are the building blocks of DNA and RNA.

Question 2

DNA and RNA are different types of nucleic acid polymer.Which of the following is true of DNA but NOT true of RNA?

Accepted Answer

The answer of DNA and RNA are different types of...

Question 3

Figure 2-34
-Oligosaccharides are short sugar polymers that can become covalently linked to proteins and lipids through condensation reactions.These modified proteins and lipids are called glycoproteins and glycolipids, respectively.Within a protein, which of the amino acids (shown in Figure 2-34) is the most probable target for this type of modification?

Accepted Answer

Serine contains a hydroxyl group (-OH) on its side chain, which can form a covalent bond with an oligosaccharide through a condensation reaction, resulting in the creation of a glycosidic bond. Therefore, serine is the most probable target for this type of modification.

Question 4

Choose the answer that best fits the following statement: Cholesterol is an essential component of biological membranes.Although it is much smaller than the typical phospholipids and glycolipids in the membrane, it is a/an __________ molecule, having both hydrophilic and hydrophobic regions.

Accepted Answer

Cholesterol is an amphipathic molecule, which means it has both hydrophilic and hydrophobic regions. This allows it to integrate into the hydrophobic region of the membrane while also interacting with the hydrophilic heads of the phospholipids.

Question 5

Which combination of answers best completes the following statement: When atoms are held together by __________ __________, they are typically referred to as __________.

Accepted Answer

Ionic interactions are the electrostatic forces that hold ions together in a crystal lattice or in solution. When atoms are held together by ionic interactions, they are typically referred to as salts, not molecules.

Question 6

There is incredible chemical diversity even in the simplest of cells.A typical bacterial cell contains more than 6000 different types of molecules.From the list below, select the class of molecules with the largest number of different types.

Accepted Answer

The answer of There is incredible chemical diversity even in...

Question 7

Most types of molecules in the cell have asymmetric (chiral) carbons.Consequently there is the potential to have two different molecules that look much the same but are mirror images of each other and therefore not equivalent.These special types of isomers are called stereoisomers.Which of the four carbons circled in Figure 2-37 is the asymmetric carbon that determines whether the amino acid (threonine in this case) is a ᴅ or an ʟ stereoisomer?  Figure 2-37

Accepted Answer

The answer of Most types of molecules in the cell...

Question 8

Carbon atoms can form double bonds with other carbon atoms, nitrogen atoms, and oxygen atoms.Double bonds can have important consequences for biological molecules because they are __________ compared to single covalent bonds.

Accepted Answer

Double bonds are rigid with respect to rotation. This means that they lock the atoms in a specific orientation relative to each other, which can have important consequences for the structure and function of biological molecules.

Question 9

Cells contain buffers that help maintain a neutral pH.Which of the following statements is not relevant to how buffers work?

Accepted Answer

The statement "Buffers catalyze oxidation-reduction reactions" is not relevant to how buffers work. Buffers work by accepting or donating protons, thus helping to maintain a constant pH in a solution. Oxidation-reduction reactions are not directly related to pH and do not play a role in how buffers function.

Question 10

Although covalent bonds are 10-100 times stronger than noncovalent interactions, many biological processes depend upon the number and type of noncovalent interactions between molecules.Which of the noncovalent interactions below will contribute most to the strong and specific binding of two molecules, such as a pair of proteins?

Accepted Answer

Electrostatic attractions, also known as ionic bonds or salt bridges, are generally stronger than other noncovalent interactions and contribute significantly to the specificity and strength of molecular binding.

Question 11

Which of the following are examples of isomers?

Accepted Answer

Glucose and galactose are examples of isomers because they have the same molecular formula (C6H12O6) but different structures or arrangements of atoms.

Question 12

The amino acids glutamine and glutamic acid are shown in Figure 2-38.They differ only in the structure of part of their side chains (circled).At pH₇, what type of interactions are possible for glutamic acid but not for glutamine? Figure 2-38

Accepted Answer

Glutamic acid has a carboxyl group (-COOH) in its side chain, which can become negatively charged at the physiological pH of 7.4. This allows for the possibility of forming ionic bonds with positively charged groups on other molecules or proteins. Glutamine, on the other hand, has an amide group (-CONH2) in its side chain, which cannot ionize under physiological conditions and therefore cannot form ionic bonds.

Question 13

The pH of an aqueous solution is an indication of the concentration of available protons.However, you should not expect to find lone protons in solution; rather, the proton is added to a water molecule to form a/an __________ ion.

Accepted Answer

Protons in aqueous solution react with water molecules to form hydronium ions (H3O+). Therefore, the correct answer is D, hydronium ion.

Question 14

Figure 2-26
-Larger molecules have hydrogen-bonding networks that contribute to specific, high-affinity binding.Smaller molecules such as urea can also form these networks.How many hydrogen bonds can urea (Figure 2-26) form if dissolved in water?

Accepted Answer

Urea can form a total of 6 hydrogen bonds when dissolved in water: two from each of the NH2 groups (acting as hydrogen bond donors) and two from the carbonyl oxygen (acting as a hydrogen bond acceptor).

Question 15

Many types of cells have stores of lipids in their cytoplasm, usually seen as fat droplets.What is the lipid most commonly found in these droplets?

Accepted Answer

Triacylglycerol is the most commonly found lipid in fat droplets within cells. This is because it is an efficient storage form of energy, providing twice as much energy per gram as carbohydrates or proteins. Cholesterol is not a storage lipid and is primarily found in cell membranes. Palmitic acid is a type of fatty acid commonly found in triacylglycerols, but it is not the lipid stored in droplets. Isoprene is a type of unsaturated hydrocarbon that is not typically found in lipid droplets in cells.

Question 16

Cells require one particular monosaccharide as a starting material to synthesize nucleotide building blocks.Which of the monosaccharides below fills this important role?

Accepted Answer

Nucleotide building blocks contain a pentose sugar, and the specific pentose sugar required for nucleotide synthesis is ribose. Glucose, fructose, and ribulose are not pentose sugars and therefore do not play a role in nucleotide synthesis.

Question 17

__________ play an important role in organizing lipid molecules with long hydrocarbon tails into biological membranes.

Accepted Answer

Hydrophobic forces play a crucial role in organizing lipid molecules into biological membranes as they cause the hydrophobic tails to aggregate together in order to avoid contact with the polar environment. This results in the formation of a lipid bilayer, where the hydrophobic tails face each other and the polar head groups face the aqueous environment. Hydrogen bonds and ionic bonds are not involved in this process, while van der Waals attractions may contribute to the stability of the membrane but are not the primary force driving its formation.

Question 18

Aromatic carbon compounds such as benzene are planar and very stable.Double-bond character extends around the entire ring, which is why it is often drawn as a hexagon with a circle inside.This characteristic is caused by electron

Accepted Answer

The planarity and stability of aromatic carbon compounds are due to the phenomenon of electron resonance, where the electrons in the double bonds delocalize around the entire ring. This gives rise to a unique stability and characteristic properties of these compounds.

Question 19

Which of the following expressions accurately describes the calculation of pH?

Accepted Answer

The correct formula for calculating pH is pH = -log[H+]. Choice A accurately represents this formula, where [HS+] represents the concentration of hydrogen ions in solution.

Question 20

Substances that release protons when they dissolve in water are acids.Which of the following household substance is acidic?

Accepted Answer

Coffee contains acidic compounds such as chlorogenic acid, citric acid, and acetic acid, which release protons when they dissolve in water, making it acidic. Bleach, hand soap, and water are not acidic.

Quiz 2: Chemical Components of Cells

Which of the following monomer building blocks is necessary to assemble selectively permeable boundaries around and inside cells?

DNA and RNA are different types of nucleic acid polymer.Which of the following is true of DNA but NOT true of RNA?

Choose the answer that best fits the following statement: Cholesterol is an essential component of biological membranes.Although it is much smaller than the typical phospholipids and glycolipids in the membrane, it is a/an __________ molecule, having both hydrophilic and hydrophobic regions.

Which combination of answers best completes the following statement: When atoms are held together by , they are typically referred to as __.

There is incredible chemical diversity even in the simplest of cells.A typical bacterial cell contains more than 6000 different types of molecules.From the list below, select the class of molecules with the largest number of different types.

Carbon atoms can form double bonds with other carbon atoms, nitrogen atoms, and oxygen atoms.Double bonds can have important consequences for biological molecules because they are __________ compared to single covalent bonds.

Cells contain buffers that help maintain a neutral pH.Which of the following statements is not relevant to how buffers work?

Which of the following are examples of isomers?

The amino acids glutamine and glutamic acid are shown in Figure 2-38.They differ only in the structure of part of their side chains (circled) .At pH₇, what type of interactions are possible for glutamic acid but not for glutamine? Figure 2-38

The pH of an aqueous solution is an indication of the concentration of available protons.However, you should not expect to find lone protons in solution; rather, the proton is added to a water molecule to form a/an __________ ion.

Figure 2-26 -Larger molecules have hydrogen-bonding networks that contribute to specific, high-affinity binding.Smaller molecules such as urea can also form these networks.How many hydrogen bonds can urea (Figure 2-26) form if dissolved in water?

Many types of cells have stores of lipids in their cytoplasm, usually seen as fat droplets.What is the lipid most commonly found in these droplets?

Cells require one particular monosaccharide as a starting material to synthesize nucleotide building blocks.Which of the monosaccharides below fills this important role?

__________ play an important role in organizing lipid molecules with long hydrocarbon tails into biological membranes.

Aromatic carbon compounds such as benzene are planar and very stable.Double-bond character extends around the entire ring, which is why it is often drawn as a hexagon with a circle inside.This characteristic is caused by electron

Which of the following expressions accurately describes the calculation of pH?

Substances that release protons when they dissolve in water are acids.Which of the following household substance is acidic?

Quiz 2: Chemical Components of Cells

Which of the following monomer building blocks is necessary to assemble selectively permeable boundaries around and inside cells?

DNA and RNA are different types of nucleic acid polymer.Which of the following is true of DNA but NOT true of RNA?

Choose the answer that best fits the following statement: Cholesterol is an essential component of biological membranes.Although it is much smaller than the typical phospholipids and glycolipids in the membrane, it is a/an __________ molecule, having both hydrophilic and hydrophobic regions.

Which combination of answers best completes the following statement: When atoms are held together by __________ __________, they are typically referred to as __________.

There is incredible chemical diversity even in the simplest of cells.A typical bacterial cell contains more than 6000 different types of molecules.From the list below, select the class of molecules with the largest number of different types.

Carbon atoms can form double bonds with other carbon atoms, nitrogen atoms, and oxygen atoms.Double bonds can have important consequences for biological molecules because they are __________ compared to single covalent bonds.

Cells contain buffers that help maintain a neutral pH.Which of the following statements is not relevant to how buffers work?

Which of the following are examples of isomers?

The amino acids glutamine and glutamic acid are shown in Figure 2-38.They differ only in the structure of part of their side chains (circled) .At pH7, what type of interactions are possible for glutamic acid but not for glutamine? Figure 2-38

The pH of an aqueous solution is an indication of the concentration of available protons.However, you should not expect to find lone protons in solution; rather, the proton is added to a water molecule to form a/an __________ ion.

Figure 2-26 -Larger molecules have hydrogen-bonding networks that contribute to specific, high-affinity binding.Smaller molecules such as urea can also form these networks.How many hydrogen bonds can urea (Figure 2-26) form if dissolved in water?

Many types of cells have stores of lipids in their cytoplasm, usually seen as fat droplets.What is the lipid most commonly found in these droplets?

Cells require one particular monosaccharide as a starting material to synthesize nucleotide building blocks.Which of the monosaccharides below fills this important role?

__________ play an important role in organizing lipid molecules with long hydrocarbon tails into biological membranes.

Aromatic carbon compounds such as benzene are planar and very stable.Double-bond character extends around the entire ring, which is why it is often drawn as a hexagon with a circle inside.This characteristic is caused by electron

Which of the following expressions accurately describes the calculation of pH?

Substances that release protons when they dissolve in water are acids.Which of the following household substance is acidic?

Which combination of answers best completes the following statement: When atoms are held together by , they are typically referred to as __.

The amino acids glutamine and glutamic acid are shown in Figure 2-38.They differ only in the structure of part of their side chains (circled) .At pH₇, what type of interactions are possible for glutamic acid but not for glutamine? Figure 2-38