Biology Chapter 2 Practice Quiz: Life's Chemical Basis

A covalent bond is formed when atoms share electrons. Ionic bonds involve the transfer of electrons, hydrogen bonds are weak intermolecular attractions, and metallic bonds occur between metal ions.

Water is a polar molecule with partial positive and negative charges that interact with dissolved substances. This polarity enables water to dissolve ionic and other polar compounds effectively.

Lipids store a large amount of energy in a compact form and are hydrophobic, making them ideal for long-term energy reserves. In contrast, carbohydrates are used primarily for immediate energy needs, proteins serve various functions, and nucleic acids store genetic information.

Proteins play many roles including acting as enzymes, providing structure, and transporting molecules. However, storing genetic information is the responsibility of nucleic acids.

The Lock and Key Model explains enzyme specificity by suggesting that the enzyme's active site is precisely shaped to match its substrate. Although modern perspectives include induced fit, the classic model is the Lock and Key.

Hydrogen bonds between water molecules generate strong cohesive forces that produce high surface tension. Other intermolecular forces are present but do not play as significant a role in this property.

A neutral solution has a pH of 7, indicating equal concentrations of hydrogen ions and hydroxide ions. Values below 7 are acidic and above 7 are basic.

Dehydration synthesis, also known as a condensation reaction, involves joining monomers by removing water. This process is key to forming macromolecules such as proteins and polysaccharides.

Hydrolysis involves the addition of water to break the covalent bonds in a polymer, separating it into smaller subunits. It is the reverse of dehydration synthesis.

Carbon is central to organic chemistry because it can form four covalent bonds, enabling the creation of complex and diverse molecules. This versatility makes carbon the backbone of biomolecules.

Hydrogen bonds between the backbone amide and carbonyl groups stabilize the secondary structures like alpha-helices and beta-sheets in proteins. Disulfide and ionic bonds contribute to other aspects of protein structure.

RNA contains ribose as its sugar component, contrasting with the deoxyribose found in DNA. This difference contributes to variations in structure and reactivity between RNA and DNA.

Nucleic acids, such as DNA and RNA, carry the genetic information necessary for life processes. They are uniquely structured to store, replicate, and transmit genetic data.

Sucrose is a disaccharide consisting of glucose and fructose molecules bonded together. Glucose is a monosaccharide, whereas starch and cellulose are examples of polysaccharides.

Enzymes function by lowering the activation energy required for a reaction, thereby speeding up the process. They achieve this without altering the overall equilibrium of the reaction.

The polar nature of water, with its partial positive and negative regions, enables it to surround and dissolve a variety of polar and ionic substances. This makes water an ideal solvent for many biochemical reactions.

Enzymes are specific because their active sites are uniquely shaped to bind only particular substrates. This specificity ensures that biochemical reactions proceed efficiently and accurately.

During dehydration synthesis, monomers are linked together by covalent bonds while a water molecule is eliminated for each bond formed. This reaction is essential for creating complex polymers such as proteins and carbohydrates.

The precise conformation of an enzyme's active site is critical because it stabilizes the transition state of the reaction, lowering the activation energy. This facilitates a faster reaction rate and improved catalytic efficiency.

Buffer systems work by reversibly binding hydrogen ions, which helps to prevent drastic changes in pH. This reversible binding is essential for maintaining the stable internal environment necessary for biological processes.