STEM Biology Ch3 Online Test

In a triple bond, three pairs of electrons are shared between two atoms. Each pair of electrons consists of two electrons, so the total number of electrons shared in a triple bond is six.

Sucrose is a carbohydrate because it is a type of sugar composed of glucose and fructose molecules. Carbohydrates are organic compounds that provide energy to the body and are made up of carbon, hydrogen, and oxygen atoms. DNA, insulin, and wax are not carbohydrates. DNA is a nucleic acid, insulin is a protein, and wax is a lipid.

Polysaccharides are a type of complex carbohydrate. They are made up of long chains of monosaccharides (simple sugars) linked together. Examples of polysaccharides include starch, glycogen, and cellulose. These molecules serve as a source of energy and provide structural support in organisms. Lipids, proteins, and unsaturated fats are different types of biomolecules that have distinct structures and functions, but they are not classified as polysaccharides.

Steroids are not examples of carbohydrates because they have a different chemical structure. Carbohydrates are organic compounds made up of carbon, hydrogen, and oxygen, while steroids have a structure composed of four interconnected carbon rings. Carbohydrates, on the other hand, include sugars, cellulose, and glycogen, which are all composed of simple sugar molecules or chains of sugar molecules. Steroids, such as cholesterol and hormones like testosterone and estrogen, have different functions and are not classified as carbohydrates.

Amino acids are the building blocks or monomers of proteins. Proteins are large, complex molecules that perform various functions in the body, such as acting as enzymes, hormones, antibodies, and structural components. Amino acids are linked together through peptide bonds to form polypeptide chains, which then fold into specific three-dimensional structures to create proteins. Therefore, the correct answer is proteins.

The correct answer is C because carbon (C) is the element that is present in all organic compounds. Organic compounds are compounds that contain carbon atoms bonded to other elements such as hydrogen, oxygen, nitrogen, and others. Carbon is unique in its ability to form stable covalent bonds with a variety of other elements, allowing for the vast diversity of organic compounds found in nature.

Nucleic acids are composed of nucleotides, which consist of a sugar molecule, a phosphate group, and a nitrogenous base. Amino acids are the building blocks of proteins, not nucleic acids. CH2 chains are not directly related to nucleic acids. Sugars, while they are a component of nucleotides, do not encompass the entire structure of nucleic acids. Therefore, nucleotides are the organic molecules most closely related to nucleic acids.

Nucleic acids are macromolecules that are responsible for storing and transmitting genetic information. They are composed of nucleotides, which consist of a sugar molecule, a phosphate group, and a nitrogenous base. DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) are the two types of nucleic acids found in living organisms. DNA carries the genetic instructions for the development, functioning, and reproduction of all known organisms, while RNA plays a crucial role in protein synthesis. Therefore, the correct answer is DNA and RNA.

Carbon atoms have four valence electrons in their outermost energy level. In order to achieve a stable electron configuration, carbon atoms can share these electrons with other atoms, forming up to four covalent bonds. Therefore, the correct answer is four or 4.

In a condensation reaction, two molecules combine to form a larger molecule and release a smaller molecule as a byproduct. In this case, the two molecules combine to form a larger molecule and release a molecule of water (H2O) as a byproduct.

The breakdown of polymers into monomers is called hydrolysis. In this reaction, water molecules are used to break the chemical bonds holding the polymer together, resulting in the formation of individual monomer units. This process is commonly observed in various biological and chemical processes, such as the digestion of food in the human body or the degradation of plastic materials. Hydrolysis is an essential mechanism for recycling and reusing polymers, as it allows for the recovery of valuable monomer units.

The active site is the specific region of an enzyme where the substrate binds and undergoes a chemical reaction. It is like a lock and key mechanism, where the substrate is the key and the active site is the lock. The active site has a unique shape and chemical properties that allow it to selectively bind to the substrate and facilitate the conversion of the substrate into a product. This interaction between the substrate and the active site is crucial for enzyme function and catalysis of biochemical reactions.

Sugar is classified as a carbohydrate because it is a type of simple carbohydrate called a monosaccharide. Carbohydrates are organic molecules that consist of carbon, hydrogen, and oxygen atoms, and they serve as a major source of energy for living organisms. Sugars, such as glucose and fructose, are examples of monosaccharides that are easily broken down by the body to provide energy. Therefore, sugar is the correct answer as it falls under the classification of carbohydrates.

Animals store glucose in the form of glycogen. Glycogen is a polysaccharide that serves as the main storage form of glucose in animals. It is primarily stored in the liver and muscles. When blood glucose levels are low, glycogen can be broken down into glucose molecules to provide energy for the body. Unlike cellulose, which is a structural polysaccharide found in plant cell walls, glycogen is a readily available energy source for animals. Wax and lipids are not forms in which glucose is stored in animals.

Amino acids are the building blocks of proteins. Proteins are made up of long chains of amino acids that are linked together by peptide bonds. Therefore, amino acids are the organic molecules that are most closely related to proteins.

Proteins are composed of long chains of amino acids. Amino acids are the building blocks of proteins and are linked together through peptide bonds to form these long chains. Therefore, proteins are the only option among the given choices that contain long chains of amino acids.

Molecules like molecule 2 are found in lipids because lipids are made up of fatty acids and glycerol, which can combine to form various types of lipids such as triglycerides, phospholipids, and cholesterol. Molecule 2 in the illustration resembles a fatty acid structure, which is a key component of lipids. Therefore, lipids are the most appropriate category for molecules like molecule 2.

Lipids are organic molecules that are composed of carbon, hydrogen, and oxygen atoms. They are characterized by the presence of long chains of carbon atoms, often with hydrogen atoms attached. The answer "CH2 chains" is the most closely related to lipids because lipids are primarily made up of these chains. Amino acids are the building blocks of proteins, nucleotides are the building blocks of nucleic acids, and sugars are carbohydrates. None of these options are as directly related to lipids as CH2 chains.

Carbon is different from many other elements because it has four electrons in its outermost energy level, which allows it to readily bond with other carbon atoms. Additionally, carbon can form single, double, or triple bonds with other atoms. Therefore, the correct answer is "all of the above."

A phospholipid molecule consists of a glycerol molecule, two fatty acid chains, and a phosphate group. The phosphate group is attached to the glycerol molecule, forming the hydrophilic (water-loving) "head" of the molecule, while the two fatty acid chains make up the hydrophobic (water-repellent) "tails". This unique structure allows phospholipids to form the basis of cell membranes, with the hydrophilic heads facing outward towards the watery environment and the hydrophobic tails pointing inward, creating a barrier. Therefore, the correct answer is three fatty acids, as phospholipids typically have two fatty acid chains.

Lipids are classified as nonpolar molecules because they consist mainly of hydrocarbon chains, which are composed of carbon and hydrogen atoms. These hydrocarbon chains have a relatively equal distribution of electrons, resulting in a nonpolar covalent bond. As a result, lipids are insoluble in water, as water is a polar molecule. Instead, lipids are soluble in nonpolar solvents like oil or alcohol. This nonpolar nature of lipids allows them to serve as a major component of cell membranes, providing a hydrophobic barrier that controls the movement of substances in and out of cells.

Starch is not considered a lipid because it is a complex carbohydrate, not a fat or oil. Lipids are organic compounds that are insoluble in water and include fats, oils, cholesterol, and waxes. Starch, on the other hand, is a polysaccharide made up of glucose molecules and is used by plants as a storage form of energy.

Saturated fatty acids contain carbon atoms that are each bonded to four other atoms. This means that each carbon atom in a saturated fatty acid is bonded to two hydrogen atoms and two other carbon atoms. This arrangement of bonds results in a straight, rigid structure with no double bonds. Saturated fatty acids have a higher melting point and are typically solid at room temperature. They are commonly found in animal fats and some plant oils.

Lipids are a class of molecules that are insoluble in water due to their nonpolar nature. They are, however, soluble in oil, as both lipids and oil are nonpolar substances. Therefore, the correct answer is oil.