General Biology I- Exam 2

Sunlight is the main source of energy for life on Earth because it is responsible for photosynthesis, the process by which plants convert sunlight into chemical energy. This energy is then passed on to other organisms in the food chain. Additionally, sunlight provides warmth and light, which are essential for the survival and growth of living organisms.

A double helix refers to the twisted ladder structure of DNA. This structure consists of two strands that are twisted around each other, forming a helix shape. The strands are held together by hydrogen bonds between complementary base pairs (adenine with thymine, and guanine with cytosine). The double helix structure of DNA is essential for its stability and for the accurate transmission of genetic information during DNA replication and protein synthesis.

Glucose is considered the most important sugar because it serves as the primary source of energy for the body's cells. It is a simple sugar that is easily broken down and used by cells to produce ATP, the molecule that fuels cellular processes. Glucose is also essential for brain function and is the preferred energy source for the brain. Additionally, glucose plays a crucial role in maintaining blood sugar levels and is involved in various metabolic processes in the body.

Enzymes are proteins because they are made up of amino acids, which are the building blocks of proteins. They also exhibit the characteristic properties of proteins, such as being able to catalyze specific chemical reactions in the body. Enzymes play a crucial role in various biological processes, including digestion, metabolism, and cellular signaling. Therefore, it is correct to say that enzymes are proteins.

The correct answer is "Fats, oils, etc..." because lipids are a group of molecules that include fats, oils, and other similar compounds. They are hydrophobic and insoluble in water, and they play important roles in energy storage, insulation, and cell membrane structure.

Proteins can be denatured through various methods, including intense heat, pH change, and altering salt concentration. Heat disrupts the weak bonds that hold the protein structure together, causing it to unfold and lose its function. pH change can alter the charges on the protein, affecting its shape and stability. Changing salt concentration can disrupt the ionic interactions between amino acids, leading to protein denaturation. Therefore, all of the above methods can denature a protein.

DNA is double stranded because it consists of two strands that are twisted together in a double helix structure. Each strand is made up of a sequence of nucleotides, which are the building blocks of DNA. The two strands are held together by hydrogen bonds between complementary nucleotides. This double stranded structure is important for DNA replication and for the storage and transmission of genetic information.

Sucrose is indeed known as table sugar. It is a type of sugar that is commonly used in households for sweetening food and beverages. Sucrose is derived from sugar cane or sugar beet and is composed of glucose and fructose molecules. It is a crystalline solid that is white in color and has a sweet taste. Sucrose is highly soluble in water and is widely used in cooking and baking. Therefore, the given answer "True" is correct.

ATP is the abbreviation for Adenosine Triphosphate. Adenosine Triphosphate is a molecule that stores and releases energy in cells. It is often referred to as the "energy currency" of the cell because it provides the energy needed for various cellular processes. The three phosphate groups in ATP are responsible for storing and releasing energy as they are broken and formed. Therefore, ATP is the correct abbreviation for Adenosine Triphosphate.

Carbohydrates are organic compounds that are made up of sugars, starches, and fibers. They are an essential source of energy for the body and are found in various foods such as fruits, vegetables, grains, and dairy products. Carbohydrates play a crucial role in providing fuel for the brain, muscles, and other organs, as well as aiding in digestion and maintaining overall health.

Chitin is the correct answer because it is a substance commonly found in the exoskeletons of spiders, insects, and other arthropods. It is a tough and flexible material that provides structural support and protection for their bodies. Chitin is also found in the cell walls of fungi and the beaks of cephalopods, making it a versatile and important component in various biological structures.

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Synthesis refers to the process of combining separate elements or components to create something new. Building up implies that the synthesis is adding or constructing something. Therefore, the statement "Synthesis is building up" is true as it accurately describes the process of synthesis.

The nitrogenous bases of DNA are Adenine, Thymine, Guanine, and Cytosine. These bases are the building blocks of DNA and are responsible for carrying genetic information. Adenine pairs with Thymine, and Guanine pairs with Cytosine, forming the base pairs that make up the DNA double helix structure. Uracil is a nitrogenous base found in RNA, not DNA.

Dehydration is the correct answer because it refers to a chemical reaction in which two molecules combine to form a larger molecule by losing a water molecule. This process involves the formation of a covalent bond between the two molecules, resulting in the removal of a hydroxyl group (-OH) from one molecule and a hydrogen atom (-H) from the other. This reaction is commonly observed in the synthesis of complex organic compounds, such as proteins and carbohydrates. On the other hand, hydrolysis is the opposite process, where a molecule is broken down into smaller units by the addition of water.

There are 20 amino acids. Amino acids are the building blocks of proteins and are essential for various biological processes. They are composed of an amino group, a carboxyl group, and a unique side chain. These side chains determine the properties and functions of each amino acid. There are 20 different side chains, resulting in 20 different amino acids that can be combined in different sequences to form proteins.

Organic chemistry is the branch of chemistry that focuses on the study of carbon compounds. Carbon is unique in its ability to form a wide variety of compounds due to its bonding properties. Organic chemistry explores the structure, properties, composition, reactions, and synthesis of carbon-based compounds, including hydrocarbons and their derivatives. This field plays a crucial role in understanding and developing materials, medicines, polymers, dyes, and many other important substances.

Cellulose is a complex carbohydrate found in the cell walls of plants, and it cannot be digested by humans due to the lack of necessary enzymes. Therefore, it cannot be used for energy in humans.

Proteins are made up of different types of amino acids. There are 20 different types of amino acids that make up proteins. Each amino acid has a unique structure and properties, which allows proteins to have diverse functions in the body. These amino acids are linked together in a specific order to form a protein chain, and the sequence of amino acids determines the protein's structure and function.

DNA, or deoxyribonucleic acid, is a double-stranded molecule that consists of two strands twisted around each other in a helical structure called a double helix. Each strand is made up of a long chain of nucleotides, which are the building blocks of DNA. The two strands are held together by hydrogen bonds between complementary nucleotide bases. Therefore, the correct answer is 2, as DNA has two strands.

Carbohydrates are composed of monosaccharides, which are the monomers or building blocks of carbs. Monosaccharides are simple sugars, such as glucose and fructose, that can be joined together through dehydration synthesis to form larger carbohydrate molecules. Nucleotides are the monomers of nucleic acids, amino acids are the monomers of proteins, and glycerol is a component of lipids. Therefore, the correct answer is monosaccharide.

Lipids are generally hydrophobic because they consist of nonpolar molecules, such as fats and oils, which do not dissolve in water. This is due to their long hydrocarbon chains that repel water molecules. Lipids play important roles in the body, such as storing energy, insulating organs, and forming cell membranes.

A carbohydrate is a macromolecule composed of carbon, hydrogen, and oxygen atoms. It is made up of monomers called monosaccharides. When two monosaccharides join together through a glycosidic bond, they form a disaccharide. Therefore, a disaccharide is the polymer of a carbohydrate. Phospholipid, DNA, and secondary structure are not polymers of carbohydrates.

Saturated fats are known for being solid at room temperature. This is because they have a higher melting point compared to unsaturated fats. Saturated fats have a straight molecular structure with single bonds, which allows them to pack tightly together and form a solid state. In contrast, unsaturated fats have double bonds, causing kinks in their structure, and resulting in a liquid state at room temperature.

A monomer refers to a single unit of macromolecules. Macromolecules are large molecules made up of smaller subunits called monomers. These monomers can link together to form polymers through chemical reactions such as polymerization. Therefore, the correct answer is "A single unit of macromolecules."

The carbon skeletons in organic compounds can vary in length, branching, presence of double bonds, and formation of rings. This means that the carbon atoms can be arranged in different ways, resulting in different structures and properties of the compounds. Therefore, all of the given options (length, branching, double bonds, and rings) are correct as they represent the possible variations in carbon skeletons.

Enzymes actually speed up chemical reactions by lowering the activation energy required for the reaction to occur. They do this by binding to the reactant molecules and bringing them closer together, allowing the reaction to happen more quickly. Therefore, the given statement is incorrect.

The correct answer is A + T, G + C. In DNA, the nucleotide bases always pair up in a specific way: adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C). This is known as complementary base pairing. Therefore, A always pairs with T, and G always pairs with C.

Cellulose cannot be used for energy in humans because humans lack the necessary enzyme, cellulase, to break down cellulose into glucose for energy. While cellulose is a complex carbohydrate found in plant cell walls, humans primarily rely on the digestion of starch and glycogen, which are easily broken down into glucose. Therefore, cellulose passes through the human digestive system undigested and does not provide any energy.

A polymer is a substance made up of multiple units of macromolecules. Macromolecules are large molecules made up of smaller units called monomers. When these monomers join together in a repeating pattern, they form a polymer. Polymers can be found in various forms, such as plastics, rubber, and fibers. They have a wide range of applications in industries like packaging, textiles, and construction.

Unsaturated fats are characterized by their liquid state at room temperature. Unlike saturated fats, which have no double bonds in their carbon chains and are solid at room temperature, unsaturated fats have one or more double bonds in their carbon chains, causing them to be liquid at room temperature. This property makes them more beneficial for health as they are less likely to contribute to the buildup of plaque in arteries and can help lower bad cholesterol levels.

Proteins are made up of amino acids, which are linked together by peptide bonds. Each amino acid has an amino group (-NH2) on one end and a carboxyl group (-COOH) on the other end. The amino group of one amino acid forms a peptide bond with the carboxyl group of another amino acid, resulting in the formation of a polypeptide chain. Therefore, every protein has a free amino group on one end and a free carboxyl group on the other end.

CHO is a commonly used abbreviation for carbohydrates in the field of nutrition and biochemistry. Carbohydrates are one of the three main macronutrients, along with proteins and fats, and they are an essential source of energy for the body. Therefore, it is accurate to say that CHO stands for carbohydrates.

Organic compounds are compounds that contain carbon. This is because organic chemistry is the branch of chemistry that deals with the study of carbon-based compounds. Carbon is unique in its ability to form a wide variety of complex molecules due to its ability to form strong covalent bonds with other elements. Therefore, any compound that contains carbon is considered organic. Carbonic, regular, and isomers do not specifically refer to compounds that contain carbon, so they are not the correct answers.

ATP (adenosine triphosphate) is the correct answer because it is an organic phosphate that contains three phosphates. ATP is the primary source of energy for cellular processes and the high-energy bonds between its phosphates store energy that can be used by cells. DNA, RNA, and mRNA are not organic phosphates and do not have three phosphates present.

Organisms are made up of chemicals that are based mostly on the element carbon. Carbon is a fundamental element for life as it has the unique ability to form stable covalent bonds with other carbon atoms and with other elements. This allows carbon to form the complex and diverse organic molecules that are essential for the structure and function of living organisms. Carbon is the backbone of biological macromolecules such as proteins, nucleic acids, carbohydrates, and lipids, which are vital for life processes such as growth, reproduction, and metabolism.

Antiparallel refers to the orientation of the two strands in a DNA molecule. In an antiparallel arrangement, one strand runs in the 5' to 3' direction, while the other strand runs in the opposite direction, from 3' to 5'. This arrangement is important because it allows for the complementary base pairing between the two strands, where adenine (A) pairs with thymine (T) and guanine (G) pairs with cytosine (C). This complementary base pairing is crucial for DNA replication and the synthesis of RNA during transcription.

Carbohydrates are organic compounds that consist of carbon, hydrogen, and oxygen atoms. They are classified based on the number of sugar molecules they contain. Monosaccharides are the simplest form of carbohydrates and cannot be further broken down into smaller sugar molecules. They are the building blocks of more complex carbohydrates like disaccharides and polysaccharides. Therefore, monosaccharides are the correct answer as they are the basic units of carbohydrates.

Hydrophilic chemical groups are those that have an affinity for water, meaning they attract and interact with water molecules. They can form hydrogen bonds with water and easily dissolve in it. This is why they "love" water. Conversely, hydrophobic chemical groups repel water and do not interact with it. They tend to be nonpolar or have nonpolar regions, making them insoluble in water. Therefore, they do not "love" water.

The structure of DNA is composed of two strands that are twisted around each other to form a double helix. This twisted ladder-like shape allows the DNA molecule to be stable and compact while still maintaining the ability to store and transmit genetic information. The double helix structure is formed by the pairing of complementary nucleotide bases (adenine with thymine, and guanine with cytosine) between the two strands, creating a strong and efficient way to store and replicate genetic information.

To form a polymer from a monomer, the process of dehydration synthesis is used. This involves removing a water molecule from between two monomer units, which results in the formation of a covalent bond between them. By removing water, the monomers are able to join together and form a larger, more complex molecule known as a polymer. This process can be repeated multiple times, allowing for the formation of longer polymer chains.

Monosaccharides are the simplest form of carbohydrates, consisting of a single sugar molecule. They cannot be broken down further into smaller carbohydrates. Examples of monosaccharides include glucose, fructose, and galactose. Disaccharides, on the other hand, are composed of two monosaccharide units linked together, while polysaccharides are complex carbohydrates made up of many monosaccharide units. Therefore, monosaccharides are the correct answer as they are the most basic and fundamental units of carbohydrates.

Glucose and fructose combine to form sucrose. Sucrose is a disaccharide made up of one glucose molecule and one fructose molecule. This combination occurs through a condensation reaction, where a molecule of water is eliminated, resulting in the formation of a new bond between the two monosaccharides. Sucrose is commonly found in table sugar and is widely used as a sweetener.

Chitin is a substance that is primarily found in the cell walls of fungi and the exoskeletons of arthropods. It provides structural support and protection to these organisms. Chitin is a tough and flexible material, making it ideal for forming the rigid exoskeletons of insects, crustaceans, and other arthropods. It also plays a role in the cell walls of fungi, providing strength and stability to their structures. Therefore, chitin is mainly used in the construction of fungi and arthropod exoskeletons.

Sucrose is the most common disaccharide. Disaccharides are carbohydrates composed of two sugar units joined together. Sucrose, also known as table sugar, is made up of one glucose molecule and one fructose molecule. It is commonly found in many foods and beverages and is the main type of sugar used in cooking and baking. Monosaccharides, on the other hand, are simple sugars made up of a single sugar unit. Therefore, sucrose cannot be classified as a monosaccharide.

Enzymes are highly specific biological catalysts that facilitate chemical reactions in living organisms. Each enzyme is designed to bind to a specific substrate and catalyze a specific reaction. This specificity is due to the unique shape and active site of each enzyme, which allows it to interact with only certain molecules. Therefore, it is true that each enzyme catalyzes only one type of reaction.

Enzymes are not monomers. Monomers are the building blocks of polymers, and enzymes are actually proteins, which are a type of polymer. Enzymes are made up of long chains of amino acids that are folded into complex structures, allowing them to catalyze chemical reactions in the body. Therefore, enzymes cannot be considered monomers.