IB Biology Practice Questions Test! Quiz

Carbohydrates play a crucial role in animal cells as a source of energy storage. They are broken down during cellular respiration to release ATP, which is used as a fuel for various cellular processes. Carbohydrates are stored in the form of glycogen in animals, which can be quickly converted back into glucose when energy is needed. This allows animals to maintain a steady supply of energy for their metabolic activities. Therefore, the role of carbohydrates in animal cells is primarily to serve as an energy reserve.

High temperature can cause denaturation of an enzyme because it disrupts the weak bonds, such as hydrogen bonds and van der Waals forces, that maintain the enzyme's three-dimensional structure. This disruption leads to a loss of the enzyme's active site shape and functionality, rendering it unable to catalyze reactions effectively.

When a dipeptide is formed from amino acids, the reaction that occurs is condensation. Condensation is a chemical reaction in which two molecules combine to form a larger molecule, with the release of a small molecule such as water. In the case of dipeptide formation, two amino acids join together through a condensation reaction, where the carboxyl group of one amino acid reacts with the amino group of another amino acid, resulting in the formation of a peptide bond between them.

Ribose is a monosaccharide because it is a simple sugar consisting of a single sugar unit. Monosaccharides are the building blocks of carbohydrates and are the simplest form of sugar. Glycogen and amylase are polysaccharides, which are made up of multiple sugar units, while glycerol is a type of alcohol and not a sugar molecule. Therefore, Ribose is the correct answer as it fits the definition of a monosaccharide.

Phosphorus is an essential element in the structure of nucleotides. Nucleotides are the building blocks of nucleic acids such as DNA and RNA. Phosphorus forms the backbone of these nucleotides, linking them together to form the long chains that make up the structure of DNA and RNA molecules. This role of phosphorus is crucial for the proper functioning of genetic material and the transmission of genetic information.

Membrane proteins are proteins that are embedded in the cell membrane and perform various functions. One of the functions of a membrane protein could be enzymatic activity. Enzymes are proteins that catalyze biochemical reactions in the cell, and many enzymes are found in the cell membrane. These membrane proteins can act as enzymes to facilitate specific chemical reactions, such as breaking down or building up molecules. Therefore, enzymatic activity is a plausible function for a membrane protein.

Protein molecules have various functions in the body, including acting as enzymes, hormones, transporters, and providing structural support. However, energy storage is not a primary function of protein molecules. Carbohydrates and lipids are the main macronutrients responsible for energy storage in the body, while proteins primarily play a role in building and repairing tissues, regulating bodily processes, and transporting molecules.

Increasing the substrate concentration can reduce the effect of a competitive inhibitor of an enzyme because a competitive inhibitor competes with the substrate for the active site of the enzyme. By increasing the substrate concentration, there will be a higher chance for the substrate to bind to the enzyme's active site instead of the inhibitor. This effectively reduces the inhibitory effect of the competitive inhibitor, allowing the enzyme to function more efficiently.

The large intestine is responsible for re-absorbing the majority of water in the digestive system. As food passes through the small intestine, most of the nutrients and water are absorbed into the bloodstream. By the time the remaining waste material reaches the large intestine, the majority of water has already been absorbed, leaving behind a more solid waste product. The large intestine's main function is to further absorb water and electrolytes, helping to form solid feces before elimination.

Hydrogen bonding is involved in the cohesion of water, which refers to the attraction between water molecules that allows them to stick together. This bonding also results in the thermal properties of water, such as its high specific heat and heat of vaporization. However, hydrogen bonding is not a bond within the water molecule itself, as water molecules are held together by covalent bonds. Therefore, the correct features for hydrogen bonding are I and II only.