AP - Intro To Chapter 3

Hydrocarbons are hydrophobic because the covalent bonds between hydrogen and carbon are nonpolar. In a hydrocarbon molecule, the carbon and hydrogen atoms share electrons equally, resulting in a nonpolar covalent bond. This means that there is no separation of charge within the molecule, and as a result, hydrocarbons do not have a significant attraction to water molecules, which are polar. Therefore, hydrocarbons tend to be insoluble in water and are considered hydrophobic.

Carbohydrate molecules are a source of energy. When consumed, carbohydrates are broken down into glucose, which is then used by the body as fuel for various metabolic processes. This energy is essential for the proper functioning of cells, tissues, and organs. Carbohydrates are the body's primary source of energy, providing quick and readily available fuel for activities and bodily functions.

Glucose dissolves in water because it has polar hydroxyl groups that interact with polar water molecules. The hydroxyl groups in glucose are highly electronegative, creating a partial negative charge on the oxygen atom and a partial positive charge on the hydrogen atom. This polarity allows glucose molecules to form hydrogen bonds with water molecules, leading to their dissolution in water. The interaction between the polar hydroxyl groups of glucose and the polar water molecules enables the formation of a stable solute-solvent interaction, resulting in the dissolution of glucose in water.

Sucrose is a disaccharide composed of glucose and fructose. It is formed through a condensation reaction between a glucose molecule and a fructose molecule, resulting in the formation of a glycosidic bond. This bond connects the two monosaccharides, glucose and fructose, together to form the sucrose molecule.

Unsaturated fats are generally liquids at room temperature because they have double bonds in the carbon chains of their fatty acids. These double bonds create kinks in the fatty acid chains, preventing them from packing tightly together. As a result, unsaturated fats have a lower melting point and remain in a liquid state at room temperature. In contrast, saturated fats have no double bonds and their fatty acid chains can pack tightly together, leading to a solid state at room temperature.

Glycogen is the correct answer because it is a carbohydrate energy storage molecule specifically found in animal liver and muscle cells. Starch, cellulose, and chitin are also carbohydrates, but they are not found in animal liver and muscle cells. Protein is not a carbohydrate energy storage molecule.

Carbohydrate is the most inclusive term among the given options. It encompasses all the other terms mentioned in the question. Monosaccharide, disaccharide, and polysaccharide are all types of carbohydrates. Starch is a complex carbohydrate made up of multiple glucose units. Therefore, carbohydrate is the broadest term that includes all the other options.

Cellulose is the most structurally complex carbohydrate among the given options. It is a polysaccharide made up of repeating glucose units linked together by β-1,4-glycosidic bonds. The glucose units in cellulose are arranged in a linear and rigid structure, forming long chains that are interconnected by hydrogen bonds. This complex arrangement gives cellulose its strength and rigidity, making it an important component of plant cell walls. In contrast, sucrose, fructose, glucose, and disaccharides are simpler carbohydrates with fewer structural complexities.

Lipids are organic compounds that are insoluble in water and have many important functions in the body. They store energy, serve as structural components of cellular membranes, and function as hormones. However, lipids do not have many oxygen-containing functional groups. Instead, lipids are primarily composed of carbon, hydrogen, and oxygen atoms, with a higher ratio of carbon and hydrogen atoms compared to oxygen atoms.

Condensation is the correct answer because it refers to a chemical reaction in which polymers are synthesized from their building blocks. In condensation reactions, two or more molecules combine, releasing a small molecule such as water as a byproduct. This process allows the monomers (building blocks) to join together and form a polymer chain. Hydrolysis, oxidation, reduction, and dissociation do not specifically involve the synthesis of polymers from building blocks.