A) Energy storage

Explanation: Fats are primarily important for energy storage, providing a significant amount of energy per gram compared to carbohydrates like glycogen or starch.

C) Large, complex organic molecules

Explanation: Macromolecules refer to large and complex organic molecules, which play essential roles in biological functions and structures.

D) Primary

Explanation: The primary structure of a protein refers to the linear sequence of amino acids that make up the protein chain, which is the fundamental level of protein structure.

B) By hydrolysis

Explanation: Triglycerides are broken apart by hydrolysis, a reaction that adds water to cleave the bonds between glycerol and fatty acids.

D) Amino acids

Explanation: Amino acids are the monomers that make up proteins, linking together to form polypeptide chains that fold into functional proteins.

B) The amino acid sequence

Explanation: The primary structure of a protein is defined by the linear sequence of amino acids, which is crucial for determining the protein's overall structure and function.

B) Four interconnected rings of C atoms

Explanation: Steroids are characterized by their structure, which consists of four interconnected rings of carbon atoms, distinguishing them from other types of organic molecules.

C) Nucleotide

Explanation: The monomer of nucleic acids is a nucleotide, which is the basic building block that forms DNA and RNA.

B) Polypeptides

Explanation: Peptide bonds link amino acids together to form polypeptides, which are the building blocks of proteins.

B) They are the building blocks of cells

Explanation: Macromolecules are crucial in biology as they serve as the building blocks of cells, providing structure and facilitating various biological functions.

B) The chemical basis of life and organic molecules

Explanation: Chapter 3 emphasizes the chemical basis of life, specifically focusing on organic molecules and their significance in biological systems.

B) Structural support, cushioning, and insulation

Explanation: Fats also serve structural roles in the body, providing cushioning and insulation, which are essential for protecting organs and maintaining body temperature.

B) Disaccharide

Explanation: Maltose is classified as a disaccharide because it is composed of two monosaccharides (glucose) linked together.

C) By genes

Explanation: The primary structure of a protein, including the sequence of amino acids, is determined by the genetic information encoded in genes.

B) By bonding glycerol to 3 fatty acids

Explanation: Triglycerides are formed by bonding glycerol to three fatty acids through a dehydration (condensation) reaction, which is essential for their structure.

B) Waterproofing

Explanation: Waxes serve as a waterproofing agent, helping to protect plant leaves and insect cuticles from moisture loss and environmental factors.

B) Solids

Explanation: Saturated fatty acids tend to be solid at room temperature, as exemplified by substances like butter.

B) They contain one or more double bonds

Explanation: Unsaturated fatty acids are characterized by the presence of one or more double bonds between carbon atoms, distinguishing them from saturated fatty acids.

C) They cause nonpolar amino acids to avoid water contact

Explanation: The hydrophobic effects lead nonpolar amino acids to cluster in the center of the protein, away from water, which is essential for proper protein folding.

C) Carbon

Explanation: Organic molecules are defined by the presence of carbon (C), which is a fundamental element in the chemistry of life and is highly abundant in living organisms.

B) Hydrolysis

Explanation: Hydrolysis is the process that breaks down maltose into its constituent glucose molecules by adding a water molecule, effectively reversing the dehydration reaction.

B) Dehydration (condensation)

Explanation: The formation of triglycerides involves a dehydration (condensation) reaction, where water is removed to bond glycerol with fatty acids.

D) All of the above

Explanation: The tertiary structure of a protein is stabilized by various interactions, including ionic bonds, hydrogen bonds, hydrophobic interactions, and sometimes disulfide bridges, contributing to the overall 3D shape of the protein.

B) Beehives

Explanation: Waxes function as structural elements in colonies, such as in beehives, where they provide stability and protection.

C) Tertiary structure

Explanation: The tertiary structure can sometimes be the final level of protein structure, especially when it consists of a single polypeptide that folds into its functional form.

B) Tertiary structure

Explanation: The folding of secondary structures and random coiled regions into a three-dimensional shape results in the tertiary structure of a protein.

B) Hydrogen bonds

Explanation: The two strands of DNA are held together by hydrogen bonds between the complementary nitrogenous bases, which is essential for the stability of the double helix structure.

B) One or more

Explanation: Proteins can consist of one or more polypeptides, which can fold and combine to create the functional structures of proteins.

A) C, H, O, N, and S

Explanation: Proteins are primarily composed of carbon (C), hydrogen (H), oxygen (O), nitrogen (N), and small amounts of sulfur (S), which are essential for their structure and function.

B) Its complex 3-D shape

Explanation: The tertiary structure of a protein is defined by its folding into a complex three-dimensional shape, which is essential for its function.

E) Water

Explanation: Water is not classified as an organic molecule; the four major classes of organic molecules include carbohydrates, lipids, proteins, and nucleic acids.

B) Phosphate group, 5C sugar, and a base

Explanation: A nucleotide is composed of a phosphate group, a 5-carbon sugar (either ribose or deoxyribose), and a nitrogenous base, which can be a single or double ring structure.

B) A hydrogen atom and a hydroxyl (OH-) group

Explanation: In carbohydrates, most carbon atoms are linked to a hydrogen atom and a hydroxyl (OH-) group, which is crucial for their chemical properties and reactivity.

B) To distinguish forms and functions of carbohydrates

Explanation: One of the key objectives in studying carbohydrates is to distinguish their various forms and functions, which is essential for understanding their role in biological systems.

C) Nucleic Acids

Explanation: Nucleic acids, such as DNA and RNA, are responsible for storing and transmitting genetic information in living organisms.

C) Triglycerides

Explanation: Fats are primarily composed of triglycerides, which are also known as triacylglycerols, indicating their structure and classification as a type of lipid.

B) Long-chain fatty acids and long-chain alcohols

Explanation: Waxes are formed from the bonding of long-chain fatty acids with long-chain alcohols, which gives them their unique properties.

B) Nonpolar

Explanation: Waxes are very nonpolar, which contributes to their waterproof properties and their effectiveness in protecting surfaces like plant leaves and insect cuticles.

B) Hydrogen and Carbon

Explanation: Lipids are organic molecules primarily composed of hydrogen (H) and carbon (C) atoms, which contribute to their unique properties and functions in living organisms.

B) The arrangement of multiple polypeptide chains

Explanation: The quaternary structure of a protein refers to the assembly and arrangement of two or more polypeptide chains into a functional protein complex, which may include interactions between different subunits.

B) Cholesterol

Explanation: Cholesterol is a well-known type of steroid that plays a critical role in cell membrane structure and function, as well as serving as a precursor for other steroids.

D) They are involved in signaling pathways and enzymatic reactions

Explanation: Protein-protein interactions are essential for many cellular processes, including signaling pathways and enzymatic reactions, highlighting their importance in maintaining cellular functions.

C) Monounsaturated

Explanation: Monounsaturated fatty acids contain one double bond, while polyunsaturated fatty acids contain two or more double bonds.

C) Sucrose

Explanation: Sucrose, which is composed of glucose and fructose, is a well-known example of a disaccharide and is commonly used to sweeten food.

C) Twice as much

Explanation: 1 g of fat stores twice as much energy as 1 g of glycogen or starch, highlighting the efficiency of fats as an energy source.

B) 2

Explanation: Maltose consists of two glucose units, which are linked together through a glycosidic bond formed during the dehydration process.

A) Very specific binding at the surface

Explanation: The binding interactions between proteins are characterized by their high specificity, occurring at the surface of the proteins, which is crucial for the correct functioning of cellular processes.

B) Hydrogen bonds

Explanation: Hydrogen bonds form between atoms in the polypeptide backbone and between atoms in different side chains, playing a crucial role in promoting protein folding and stability.

B) They provide structural support and energy

Explanation: Carbohydrates serve as a primary source of energy and also play a crucial role in providing structural support in various organisms.

C) Both ring and linear forms

Explanation: Glucose can be represented in both ring and linear structures, showcasing its versatility as a monosaccharide.

B) Sugar-phosphate backbone

Explanation: The sugar-phosphate backbone is formed by alternating sugar and phosphate groups, providing structural integrity to the nucleic acid chain.

D) Disulfide bridge

Explanation: Disulfide bridges are covalent bonds that link two cysteine (Cys) amino acids containing sulfhydryl groups, providing significant stability to protein structure.

C) Storage, expression, and transmission of genetic information

Explanation: Nucleic acids are primarily responsible for the storage, expression, and transmission of genetic information, which is essential for heredity and cellular function.

B) Dehydration

Explanation: Maltose is formed from two glucose molecules through a dehydration reaction, where a water molecule is removed to create a glycosidic bond between the two monosaccharides.

B) Secondary

Explanation: The secondary structure of a protein is characterized by the formation of alpha helices and beta sheets due to hydrogen bonding between the backbone atoms in the polypeptide chain.

C) Ribose

Explanation: Ribose is a pentose sugar, which means it has five carbon atoms and is a crucial component of RNA molecules.

C) They are nonpolar and insoluble in water

Explanation: The defining feature of lipids is their nonpolar nature, which makes them very insoluble in water, distinguishing them from other organic molecules.

B) Two monosaccharides

Explanation: Disaccharides are defined as carbohydrates (CHO) that are composed of two monosaccharides joined together, which is a key characteristic of this class of sugars.

C) Their structure, which differs only slightly

Explanation: Estrogen and testosterone are both steroids that differ only slightly in their chemical structure, which leads to different biological functions and effects in the body.

C) They are made up of two or more polypeptides

Explanation: Quaternary structure refers to proteins that are composed of two or more polypeptide chains (subunits) that come together to form a functional group.

B) Chemical and physical interactions

Explanation: The folding of proteins into secondary structures, such as α helices and β pleated sheets, is primarily driven by chemical and physical interactions among the amino acids.

B) Helix

Explanation: The double-stranded structure of DNA forms a helical shape known as a double helix, which is crucial for its function and stability.

B) Dehydration (condensation) reaction

Explanation: Amino acids are joined together by a dehydration (condensation) reaction, which results in the formation of peptide bonds, essential for building polypeptides.

C) Hydrolysis

Explanation: Hydrolysis is the process that breaks peptide bonds apart, effectively separating polypeptides back into individual amino acids.

B) They involve two or more different proteins

Explanation: Protein-protein interactions are crucial in many cellular processes, specifically involving interactions between two or more different proteins, which are essential for various biological functions.

C) 20

Explanation: There are 20 standard amino acids that serve as the building blocks for proteins, each with a common structure but differing in their variable R-groups.

B) Monomers

Explanation: Polymers are composed of smaller units called monomers. For example, proteins are polymers made up of amino acids (monomers), and nucleic acids are polymers made up of nucleotides.

D) Lipids

Explanation: Lipids are the main components of cell membranes, providing structural integrity and serving as barriers that separate the interior of the cell from its external environment.

D) Van der Waals forces

Explanation: Van der Waals forces are weak attractive forces that occur between atoms, contributing to the overall stability and folding of proteins.

B) Transport of sugar

Explanation: Sucrose is the form in which sugar is transported in plants, making it crucial for the distribution of energy throughout the plant.

B) It consists of a linear sequence of amino acids

Explanation: The primary structure of ribonuclease, like all proteins, is characterized by its linear sequence of amino acids, which is fundamental to its function.

C) They are always macromolecules

Explanation: While organic molecules contain carbon and are found in living organisms, they can vary in size and complexity; not all organic molecules are macromolecules.

B) Simplest sugars

Explanation: Monosaccharides are defined as the simplest form of sugars, serving as the building blocks for more complex carbohydrates.

C) Single covalent bonds

Explanation: Saturated fatty acids are characterized by having all carbon atoms linked by single covalent bonds, which contributes to their solid state at room temperature.

B) C6H12O6

Explanation: Glucose is a hexose monosaccharide with the chemical formula C6H12O6, making it a six-carbon sugar that is water-soluble.

C) Due to the presence of double bonds

Explanation: The state of fats at room temperature is influenced by the presence of double bonds in their fatty acid chains; fats with more double bonds (unsaturated fats) tend to be liquid, while those with fewer or no double bonds (saturated fats) are solid.

B) By dehydration/condensation reaction

Explanation: Disaccharides are formed through a dehydration or condensation reaction, where two monosaccharides are joined together, releasing water in the process.

B) Hydrolysis

Explanation: Disaccharides are broken apart by hydrolysis, a chemical process that involves the addition of water to split the sugar into its constituent monosaccharides.

D) Thymine (T)

Explanation: Thymine (T) is a base found in DNA, whereas RNA contains uracil (U) instead of thymine.

B) Glycerol, 2 fatty acids, and a phosphate group

Explanation: Phospholipids are composed of glycerol, two fatty acids, and a phosphate group, which are essential for their function in cell membranes.

D) Ribose sugar

Explanation: DNA contains deoxyribose sugar, not ribose sugar, which is found in RNA. This distinction is important in differentiating between DNA and RNA.

D) Chitin

Explanation: Chitin is a structural polysaccharide that forms the exoskeletons of insects and the cell walls of fungi.

A) Energy storage

Explanation: Glycogen is a polysaccharide that serves as the primary energy storage molecule in animals, allowing for quick energy release when needed.

B) Immediate energy source

Explanation: Carbohydrates serve as an immediate energy source for living organisms, providing the necessary fuel for biological processes.

C) Temperature of the environment

Explanation: While temperature can influence protein stability and activity, it is not one of the primary factors specifically listed regarding protein-protein interactions, which focus on binding specificity, the number of proteins involved, surface characteristics, and affinity.

B) The R-group of the amino acids

Explanation: The side-chain or R-group of each amino acid determines the protein's structure and function, influencing how the protein folds and interacts with other molecules.

E) Phosphorus

Explanation: While proteins are composed of carbon, hydrogen, oxygen, and nitrogen, phosphorus is not a common element in their structure, as it is more associated with nucleic acids.

E) All of the above

Explanation: All the options listed are correct; carbohydrates can be polymers made of glucose, lipids can consist of fatty acids, proteins are made of amino acids, and nucleic acids are made of nucleotides.

B) It provides stability and protection for genetic information

Explanation: The double-stranded structure of DNA offers stability and protects the genetic information stored within, making it crucial for the integrity of genetic material.

C) Not very water soluble

Explanation: Steroids are usually not very water soluble, which is a key characteristic that affects their biological functions and interactions in the body.

E) Vitamins

Explanation: The four major classes of organic molecules found in living organisms are carbohydrates, lipids, proteins, and nucleic acids. Vitamins are not classified as one of these major classes.

B) Bonds between oppositely charged side chains

Explanation: Ionic bonds occur between oppositely charged side chains, contributing to the folding and stability of proteins through ionic and polar interactions.

C) Ribose or deoxyribose

Explanation: Nucleotides contain a 5-carbon sugar that can either be ribose (found in RNA) or deoxyribose (found in DNA), which is essential for the structure of nucleic acids.

C) Catalyzing biochemical reactions

Explanation: Proteins primarily function as enzymes that catalyze biochemical reactions, facilitating various processes essential for life.

C) Catalyzing biochemical reactions

Explanation: While lipids serve many functions such as energy storage, structural roles in cell membranes, insulation, and signaling, they do not typically catalyze biochemical reactions; that role is primarily fulfilled by proteins (enzymes).

C) Phosphate region

Explanation: The phosphate region of a phospholipid is polar and hydrophilic, making it attracted to water, in contrast to the nonpolar, hydrophobic fatty acid chains.

B) C, H, and O

Explanation: Carbohydrates are composed primarily of carbon (C), hydrogen (H), and oxygen (O) atoms, which are essential for their structure and function.

A) Cn(H2O)n

Explanation: The general formula for carbohydrates is represented as Cn(H2O)n, indicating that for every carbon atom, there is a corresponding water molecule.

B) Deoxyribonucleic acid

Explanation: DNA stands for deoxyribonucleic acid, which is the molecule that carries genetic information in living organisms.

B) Ribose

Explanation: RNA contains ribose as its sugar component, while DNA contains deoxyribose.

C) Double-stranded

Explanation: DNA is primarily characterized by its double-stranded structure, which consists of two strands that coil around each other, forming a double helix.

C) Milk sugar

Explanation: Lactose is known as milk sugar, composed of glucose and galactose, and is the sugar found in milk products.

C) Adenosine triphosphate (ATP)

Explanation: ATP is not a class of nucleic acid; it is a nucleotide that serves as an energy carrier in cells. The two classes of nucleic acids are DNA and RNA.

B) Pentose

Explanation: Deoxyribose is a pentose sugar with five carbon atoms, and it is a key component of DNA molecules.

C) They are organic molecules

Explanation: Lipids are classified as organic molecules, which are essential components of living organisms and play various roles in biological processes.

B) Their nonpolar nature

Explanation: The primary reason for the insolubility of lipids in water is their nonpolar nature, which prevents them from forming hydrogen bonds with water molecules.

B) Carbon and nitrogen atoms

Explanation: The base of a nucleotide consists of a ring structure made up of carbon (C) and nitrogen (N) atoms, which are critical for the genetic coding in DNA and RNA.

B) Single strand

Explanation: RNA is typically found as a single strand, distinguishing it from the double-stranded structure of DNA.

C) Starch

Explanation: Starch is a polysaccharide that serves as an energy storage molecule in plants, composed of glucose molecules.

C) They are polymers made up of amino acids

Explanation: Proteins are indeed polymers that can contain hundreds of amino acids, which are their monomeric building blocks.

C) Plant oils

Explanation: Unsaturated fatty acids, such as those found in plant oils, tend to be liquid at room temperature, contrasting with saturated fats that are typically solid.

B) Double strand

Explanation: DNA is structured as a double helix, consisting of two strands that are complementary to each other.

B) They have a hydrophilic phosphate region and hydrophobic fatty acid chains

Explanation: Phospholipids are amphipathic because they possess a polar, hydrophilic phosphate region and nonpolar, hydrophobic fatty acid chains, allowing them to form bilayers in aqueous environments.

C) To decode genetic information into instructions for linking amino acids

Explanation: RNA plays a crucial role in decoding genetic information and translating it into instructions for linking together specific sequences of amino acids to form polypeptide chains.

C) Separate polypeptide chains that bind together

Explanation: In quaternary structure, protein subunits refer to the separate polypeptide chains that can bind to each other to form a functional protein complex.

B) α helices and β pleated sheets

Explanation: The two main types of secondary structures in proteins are α helices and β pleated sheets, which are key determinants of a protein's characteristics.

B) It is essential for its function

Explanation: The specific shape of a protein's secondary structure is crucial because it directly impacts the protein's function and interactions with other molecules.

C) Nucleic acids provide instructions for forming polypeptide chains

Explanation: Nucleic acids, particularly RNA, are involved in decoding genetic information and provide the instructions necessary for linking amino acids to form polypeptide chains.

D) Cellulose

Explanation: Cellulose is the main structural polysaccharide in plants, providing support and rigidity to plant cell walls.

B) Irregular structures with no specific shape

Explanation: 'Random coiled regions' refer to parts of a protein that do not adopt the regular structures of α helices or β pleated sheets, indicating a lack of specific folding.

C) 1 form for DNA, several for RNA

Explanation: DNA generally exists in one form (double helix), while RNA can exist in several forms, including mRNA, tRNA, and rRNA.

B) It stores genetic information coded in the sequence of its monomer building blocks

Explanation: DNA is responsible for storing genetic information, which is encoded in the sequence of its nucleotide building blocks.

B) They cause regions to fold into spirals or sheets

Explanation: Certain sequences of amino acids form hydrogen bonds that facilitate the folding of the protein into secondary structures like spirals (α helices) or sheets (β pleated sheets).

B) They are nonpolar and hydrophobic

Explanation: The fatty acid chains of phospholipids are nonpolar and hydrophobic, which means they do not interact favorably with water, contributing to the formation of cell membranes.

C) Many monosaccharides linked together

Explanation: Polysaccharides are defined as long polymers formed by the linkage of many monosaccharides, which are the simplest form of carbohydrates.