Chapter 5 Test - AP Biology

The molecule shown above does not contain a sulfhydryl functional group. A sulfhydryl group is characterized by a sulfur atom bonded to a hydrogen atom, and it is commonly found in compounds such as thiols. However, in the given molecule, there is no sulfur-hydrogen bond present, indicating the absence of a sulfhydryl group.

Molecule B contains a sulfhydryl functional group. Sulfhydryl groups are characterized by the presence of a sulfur atom bonded to a hydrogen atom. In molecule B, there is a sulfur atom bonded to a hydrogen atom, indicating the presence of a sulfhydryl functional group.

Uracil is not found in DNA, but it is found in RNA. DNA contains the nitrogenous bases adenine, thymine, guanine, and cytosine. Thymine pairs with adenine, while guanine pairs with cytosine in DNA. Uracil replaces thymine in RNA and pairs with adenine. Therefore, uracil is the correct answer as it is not found in DNA.

The 20 different amino acids found in polypeptides exhibit different chemical and physical properties because of different side chains (R groups). The side chains, also known as R groups, vary in size, shape, charge, and chemical composition. These variations in the side chains determine the unique properties of each amino acid, such as its hydrophobicity, polarity, and ability to form hydrogen bonds or participate in chemical reactions. Therefore, the side chains play a crucial role in determining the overall structure and function of proteins.

A is a hydroxyl functional group because it contains an -OH group attached to a carbon atom. The -OH group is characteristic of hydroxyl functional groups, which are commonly found in alcohols and organic compounds.

Nucleotides are the building blocks of nucleic acids, such as DNA and RNA. They consist of three components: a nitrogenous base, a phosphate group, and a pentose sugar. The nitrogenous base can be adenine, guanine, cytosine, thymine (in DNA), or uracil (in RNA). The phosphate group provides a negative charge and links nucleotides together through phosphodiester bonds. The pentose sugar, either ribose or deoxyribose, forms the backbone of the nucleotide. Therefore, the description that best fits nucleotides is "a nitrogenous base, a phosphate group, and a pentose sugar."

Glucose is not one of the four major groups of macromolecules found in living organisms. The four major groups of macromolecules are carbohydrates, lipids, proteins, and nucleic acids. Glucose is a type of carbohydrate and therefore belongs to one of the major groups.

Triacylglycerol is a lipid made with three fatty acids and glycerol. This is because triacylglycerol, also known as triglyceride, is composed of a glycerol molecule bonded to three fatty acid molecules through ester linkages. This structure allows for the storage of energy in the form of fat, as well as insulation and protection of organs.

The correct answer is that humans have enzymes that can hydrolyze the alpha (α) glycosidic linkages of starch but not the beta (β) glycosidic linkages of cellulose. This is because humans produce an enzyme called amylase, which can break down the alpha (α) glycosidic linkages in starch molecules, converting them into glucose for digestion. However, humans do not produce the enzyme cellulase, which is necessary to break down the beta (β) glycosidic linkages in cellulose molecules. Therefore, humans are unable to digest cellulose.

A molecule with the chemical formula C16H32O16 is likely a carbohydrate because the ratio of carbon to hydrogen to oxygen atoms is consistent with the general formula for carbohydrates. Carbohydrates are organic compounds composed of carbon, hydrogen, and oxygen in a ratio of 1:2:1. The given formula matches this ratio, suggesting that the molecule is a carbohydrate.

The α helix and the β pleated sheet are both common polypeptide forms found in the secondary level of protein structure. The secondary structure refers to the local folding patterns of the polypeptide chain, specifically the hydrogen bonding between the amino acids. The α helix is a coiled structure held together by hydrogen bonds, while the β pleated sheet consists of strands that are connected by hydrogen bonds. The primary structure refers to the linear sequence of amino acids, while the tertiary structure refers to the overall 3D folding of the polypeptide chain. The quaternary structure refers to the arrangement of multiple polypeptide chains in a protein complex.

Denaturation is the correct answer because it refers to the change in a protein's three-dimensional shape or conformation due to disruption of hydrogen bonds, disulfide bridges, or ionic bonds. This disruption can be caused by factors such as heat, pH changes, or exposure to certain chemicals. Denaturation often leads to loss of protein function and can be irreversible in some cases.

Polymers of polysaccharides, fats, and proteins are synthesized from monomers through the process of dehydration reactions. In this process, water molecules are removed, allowing the monomers to join together and form larger molecules. This occurs through the formation of covalent bonds between the monomers. Dehydration reactions are essential for the formation of complex macromolecules such as carbohydrates, lipids, and proteins, as they enable the monomers to link together and create the long chains characteristic of these polymers.

The two molecules shown above are best described as structural isomers because they have the same molecular formula but differ in the arrangement of their atoms. This can be observed by comparing the connectivity of the atoms in each molecule. Optical isomers refer to molecules that are mirror images of each other and have different spatial arrangements, while radioactive and nonradioactive isotopes refer to atoms with different numbers of neutrons in their nuclei. Geometric isomers refer to molecules with the same connectivity but differ in their spatial arrangement around a double bond or a ring.

Dehydration reactions involve the removal of water molecules to form bonds between monomers, resulting in the assembly of polymers. On the other hand, hydrolysis is a process that breaks down polymers into monomers by adding water molecules. Therefore, the correct answer is that dehydration reactions assemble polymers, and hydrolysis breaks down polymers.

The given information states that the new organism has the fewest amino acid differences with frogs compared to humans, gibbons, and rats. This suggests that the new organism is more closely related to frogs than to humans.

In eukaryotic cells, the flow of information starts with DNA, which contains the genetic instructions. These instructions are then transcribed into RNA molecules through a process called transcription. The RNA molecules are then translated into proteins through a process called translation. Therefore, the correct answer is DNA → RNA → proteins.

Changing any of the levels of structural organization (primary, secondary, tertiary, quaternary) can alter the function of a protein. The primary structure refers to the sequence of amino acids in the protein, and any change in this sequence can result in a different protein with different functions. The secondary structure refers to the folding of the protein into alpha helices or beta sheets, and altering this folding pattern can affect the protein's function. The tertiary structure refers to the overall 3D shape of the protein, and changing this shape can impact its function. The quaternary structure refers to the arrangement of multiple protein subunits, and modifying this arrangement can also change the protein's function. Therefore, altering any of these levels of structural organization can influence the function of a protein.

Organic chemistry is a branch of chemistry that focuses on the study of carbon compounds. Carbon is unique in its ability to form a wide variety of molecules due to its ability to form strong covalent bonds with other carbon atoms and other elements. Organic chemistry is concerned with the structure, properties, composition, reactions, and synthesis of carbon-based compounds, including hydrocarbons and their derivatives. This branch of chemistry is essential in understanding and developing materials, pharmaceuticals, and many other important substances in our daily lives.

Dehydration reactions are used in forming triacylglycerides, polysaccharides, and proteins. In these reactions, water molecules are removed to form bonds between the monomers, resulting in the formation of larger compounds. Triacylglycerides are formed by removing water molecules between fatty acids and glycerol, polysaccharides are formed by removing water molecules between sugar monomers, and proteins are formed by removing water molecules between amino acids. Therefore, all three compounds can be formed through dehydration reactions.

The functional group shown above is called carboxyl. This functional group consists of a carbonyl group (C=O) and a hydroxyl group (OH) attached to the same carbon atom. It is commonly found in carboxylic acids and their derivatives.

The tertiary structure of a protein refers to the unique three-dimensional shape that a fully folded polypeptide adopts. This structure is determined by the interactions between the amino acid residues in the polypeptide chain, such as hydrogen bonding, disulfide bridges, hydrophobic interactions, and electrostatic interactions. These interactions stabilize the protein's three-dimensional shape and are crucial for its proper function. The bonding together of several polypeptide chains by weak bonds refers to the quaternary structure of a protein, which is not the same as the tertiary structure.

Molecule A is water-soluble because it has a hydroxyl functional group. The hydroxyl group (-OH) is polar and can form hydrogen bonds with water molecules, allowing it to dissolve in water. This property makes molecule A soluble in water.

The correct answer is that humans have enzymes that can hydrolyze the alpha (α) glycosidic linkages of starch but not the beta (β) glycosidic linkages of cellulose. This is because humans produce an enzyme called amylase, which can break down the alpha glycosidic linkages in starch, converting it into glucose. However, humans do not produce an enzyme that can break down the beta glycosidic linkages in cellulose, making it indigestible for us.

In the double helix structure of nucleic acids, cytosine hydrogen bonds to guanine. This is a key feature of DNA and RNA molecules, where complementary base pairing occurs. Cytosine and guanine form three hydrogen bonds with each other, creating a stable and specific pairing. This base pairing is essential for the accurate replication and transmission of genetic information.

Polysaccharides, lipids, and proteins are similar in that they are synthesized from monomers by dehydration reactions. Dehydration reactions involve the removal of a water molecule to form a covalent bond between monomers, resulting in the synthesis of larger molecules. This process is commonly observed in the formation of macromolecules such as polysaccharides (formed from monosaccharides), lipids (formed from fatty acids and glycerol), and proteins (formed from amino acids). Therefore, the correct answer is that these biomolecules are synthesized from monomers by dehydration reactions.

The complementary strand of DNA is formed by pairing the nucleotides in a specific way. Adenine (A) always pairs with thymine (T), and guanine (G) always pairs with cytosine (C). Therefore, the complementary strand for the given sequence 5'ATTGCA3' would be 3'TAACGT5'. Each base in the original sequence is paired with its complementary base in the complementary strand.

Cellulose is a major structural component of plant cell walls. Cellulose is a polysaccharide made up of glucose monomers, not sucrose monomers. It is not a storage polysaccharide for energy in either plant or animal cells. While it is true that lipids are a major component of animal cell plasma membranes, cellulose is not.

Glycogen, starch, and chitin are all examples of polysaccharides. Polysaccharides are complex carbohydrates made up of multiple sugar molecules bonded together. Glycogen is the storage form of glucose in animals, starch is the storage form of glucose in plants, and chitin is a structural polysaccharide found in the exoskeleton of arthropods and cell walls of fungi. Therefore, the correct answer is A, B, and C.

Lactose is classified as a disaccharide because it is composed of two monosaccharide units, glucose and galactose, joined together by a glycosidic linkage. A pentose refers to a monosaccharide with five carbon atoms, while a hexose refers to a monosaccharide with six carbon atoms. Lactose is not a monosaccharide because it is composed of two sugar units, and it is not a polysaccharide because it is not made up of many sugar units. Therefore, the correct classification for lactose is as a disaccharide.

When two amino acid molecules bond together to form a larger molecule, a process called dehydration synthesis or condensation reaction occurs. In this reaction, a water molecule is removed from the amino acids, resulting in the formation of a peptide bond between them. This process requires the removal of a water molecule, making the answer "removal of a water molecule" correct.

The correct answer is "arrangement of carbon, hydrogen, and oxygen atoms." This is because glucose and fructose have the same number of carbon, hydrogen, and oxygen atoms, but they differ in the way these atoms are arranged within the molecules. The arrangement of atoms determines the structure and properties of a molecule, so this is the most accurate explanation for the difference between glucose and fructose.

Hydrogen bonds maintain the secondary structure of a protein. Secondary structure refers to the local folding patterns within a protein, including alpha helices and beta sheets. These structures are stabilized by hydrogen bonds formed between the backbone atoms of the protein. Hydrogen bonds occur when a hydrogen atom is bonded to an electronegative atom, such as oxygen or nitrogen, and is attracted to another electronegative atom nearby. These bonds provide stability and contribute to the overall shape and function of the protein.

The term "structural isomers" refers to molecules that have the same molecular formula but different structural arrangements. In this case, the two sugar molecules shown have the same molecular formula but differ in the arrangement of their atoms. Therefore, the correct term to describe their relationship is "structural isomers."

The DNA double helix molecule is composed of two strands that are held together by hydrogen bonds. These bonds form between complementary nitrogenous bases on each strand, specifically adenine (A) with thymine (T), and cytosine (C) with guanine (G). The hydrogen bonds provide stability and strength to the DNA molecule, allowing it to maintain its structure. Without these bonds, the strands would easily separate, making DNA replication and transcription impossible.

The number of peptide bonds in a protein is equal to the number of amino acids minus one. Since the protein in question contains 556 amino acids, there would be 555 peptide bonds present.

Changing one amino acid in a protein can have multiple consequences. Firstly, it can alter the primary structure of the protein, as the sequence of amino acids would be different. Additionally, this change can also affect the tertiary structure of the protein, as the altered amino acid may disrupt the folding pattern. Lastly, the biological activity or function of the protein may be altered, as even a single amino acid change can affect the protein's ability to interact with other molecules or carry out its specific function. Therefore, all options A, B, and C are correct.

A polypeptide is a chain of amino acids linked together by peptide bonds. It is a polymer because it is made up of repeating units (amino acids) bonded together. Therefore, the correct answer is "polymer of amino acids."

Starch and cellulose are both polymers of glucose. This means that they are composed of repeating units of glucose molecules linked together. Starch is a storage polysaccharide found in plants, while cellulose is a structural polysaccharide that forms the cell wall of plants. Both starch and cellulose are made up of glucose monomers, but the arrangement of the glucose molecules differs between the two, resulting in different properties and functions.

Peptide bonds are created during the formation of the primary structure of a protein. These bonds form between the amino acids in a protein chain, linking them together to create a linear sequence. Hydrogen bonds, disulfide bonds, and phosphodiester bonds are not involved in the formation of the primary structure of a protein.

Saturated fatty acids have a higher ratio of hydrogen to carbon than unsaturated fatty acids because they do not have any double bonds between carbon atoms. This means that each carbon atom in a saturated fatty acid is bonded to the maximum number of hydrogen atoms possible. In contrast, unsaturated fatty acids have one or more double bonds between carbon atoms, which reduces the number of hydrogen atoms that can be bonded to each carbon atom. This difference in hydrogen to carbon ratio is what distinguishes saturated fatty acids from unsaturated fatty acids.

The correct answer is that DNA nucleotides contain a different sugar than RNA nucleotides. DNA and RNA are both nucleic acids, not proteins. While DNA is double-stranded and RNA is typically single-stranded, this is not a statement that summarizes the structural differences between DNA and RNA. The main structural difference between DNA and RNA lies in the sugar component of their nucleotides, with DNA containing deoxyribose sugar and RNA containing ribose sugar.

Hydrogen bonds stabilize the alpha helix and beta pleated sheet structures of proteins. These bonds occur between the hydrogen atom of one amino acid and the electronegative atom (usually oxygen or nitrogen) of another amino acid in the protein chain. The hydrogen bond forms a weak attraction between these atoms, helping to maintain the secondary structure of the protein. The alpha helix is stabilized by hydrogen bonds between the carbonyl oxygen of one amino acid and the amide hydrogen of another amino acid, while the beta pleated sheet is stabilized by hydrogen bonds between adjacent strands.

Guanine and adenine are nitrogenous bases of the purine type. Purines are one of the two types of nitrogenous bases found in DNA and RNA, the other being pyrimidines. Guanine and adenine have a double-ring structure, which is characteristic of purines. Cytosine, thymine, and uracil are pyrimidines, which have a single-ring structure. Therefore, guanine and adenine are the correct answer as they are the nitrogenous bases of the purine type.

Based on the electronegativity of oxygen, it is known that oxygen has a high electronegativity, meaning it has a strong attraction for electrons. In molecule B, there is an oxygen atom bonded to a hydrogen atom, which forms a polar covalent bond. This polar bond allows the oxygen atom to pull the shared electrons closer to itself, creating a partial positive charge on the hydrogen atom. This makes the hydrogen atom more likely to dissociate as a proton, making molecule B the stronger acid compared to molecule A.

The correct answer is 120 thymine and 120 adenine molecules. This is because purines (adenine and guanine) always pair with pyrimidines (thymine and cytosine) in DNA. Adenine pairs with thymine through two hydrogen bonds, while guanine pairs with cytosine through three hydrogen bonds. Therefore, if there are 120 purines (adenine and guanine) in the DNA molecule, there must also be 120 pyrimidines (thymine and cytosine). Since the question specifies that there are a total of 120 purines and 120 pyrimidines, the only possible combination is 120 thymine and 120 adenine molecules.

In a globular protein in aqueous solution, the amino acid alanine, with its nonpolar side chain (-CH3), would be found in the interior of the protein. This is because the nonpolar side chain would prefer to be shielded from the surrounding water molecules. On the other hand, serine, with its polar side chain (-CH2-OH), would be found on the exterior of the protein. The polar side chain can form hydrogen bonds with water molecules, making it more favorable to be exposed to the aqueous environment.

The globular protein transthyretin is composed of four polypeptide subunits, each of which has an α helix region. The primary structure refers to the sequence of amino acids in a protein, which is necessary for the formation of the polypeptide chains. The secondary structure refers to the local folding patterns of the polypeptide chain, such as α helices. The tertiary structure refers to the overall three-dimensional shape of the protein, which is crucial for its function. The quaternary structure refers to the arrangement of multiple polypeptide subunits in a protein complex. Therefore, transthyretin must have primary, secondary, tertiary, and quaternary structures to form its functional globular shape with four subunits.

RNA functions in the synthesis of proteins. RNA molecules are responsible for carrying the genetic information from DNA to the ribosomes, where proteins are synthesized. This process is known as protein synthesis or translation. RNA molecules act as templates for the assembly of amino acids into proteins, following the instructions encoded in the DNA. Therefore, the major purpose of RNA is to function in the synthesis of proteins.

The hydrogenation of vegetable oil involves adding hydrogen atoms to the oil molecules, which results in a decrease in the number of carbon-carbon double bonds in the molecules. This process also increases the number of hydrogen atoms in the molecules. Additionally, hydrogenation can cause the oil to solidify at room temperature, turning it into a solid fat. Therefore, all options A, B, and C are correct.