Biology 130 Test

Nucleotides are indeed the monomeric units that make up DNA and RNA. They also serve as second messengers in cell signaling, transmitting signals within cells. Additionally, nucleotides play a crucial role in energy-transferring reactions during metabolism. Therefore, the statement is true.

Amino acids can form two common secondary structures: alpha-helix and beta pleated sheets. In an alpha-helix, the polypeptide chain coils into a spiral shape, stabilized by hydrogen bonds between the amino acids. In a beta pleated sheet, the polypeptide chain folds back and forth, forming a sheet-like structure, also stabilized by hydrogen bonds. These secondary structures play a crucial role in determining the overall shape and function of proteins.

Glycogen is a polysaccharide that serves as a storage form of glucose in animals. It is composed of many glucose molecules linked together in a branched structure. Cholesterol and Seine are not related to glycogen. Therefore, the correct answer is glucose, as glycogen is made up of glucose molecules.

Proteins consist of one or more polypeptide chains and have tertiary structures. Polypeptide chains are formed by the bonding of amino acids, and proteins can have multiple polypeptide chains. The tertiary structure refers to the overall three-dimensional shape of a protein, which is crucial for its function. Therefore, the correct answer is A and C, as proteins consist of polypeptide chains and have tertiary structures.

The correct answer is A, B and D. Ribonucleic acid (RNA) is usually single stranded, meaning it consists of a single chain of nucleotides. It contains the nitrogenous bases adenine, guanine, cytosine, and uracil. Unlike deoxyribonucleic acid (DNA), RNA does not contain thymine but instead contains uracil. Additionally, the sugar in RNA is always ribose. Therefore, options A, B, and D are all correct statements about RNA.

Adenosine monophosphate is an example of a nucleotide because it is composed of a nitrogenous base (adenine), a five-carbon sugar (ribose), and a phosphate group. Nucleotides are the building blocks of nucleic acids such as DNA and RNA, and they play a crucial role in various cellular processes including energy transfer, enzyme reactions, and genetic coding. Adenosine monophosphate specifically consists of a single phosphate group attached to the 5' carbon of the ribose sugar, making it a monophosphate.

The tertiary structure of a protein refers to the three-dimensional arrangement of its secondary structural elements, such as alpha helices and beta sheets. It is determined by the interactions between amino acid side chains, including hydrogen bonding, hydrophobic interactions, and disulfide bonds. Therefore, the correct answer is "The way the secondary structure is oriented," as the tertiary structure is directly influenced by the arrangement and orientation of the secondary structural elements.

A purine consists of a 2 ring structure and an example of a purine is adenine. Purines are one of the two types of nitrogenous bases found in DNA and RNA, the other being pyrimidines. Adenine is one of the four bases found in DNA, along with cytosine, guanine, and thymine. It forms a base pair with thymine in DNA and with uracil in RNA. Adenine is involved in the coding and decoding of genetic information, playing a crucial role in the structure and function of DNA and RNA molecules.

Deoxyribose is a pentose sugar with 5 carbon atoms, just like ribose. Therefore, the statement that pentose can be found as ribose but not as deoxyribose is incorrect. Both ribose and deoxyribose are examples of pentose sugars.

Eukaryotes have a nucleus, which is an organelle that contains the DNA. Prokaryotes, on the other hand, do not have a nucleus and their DNA lies free in the cell. Therefore, both statements A and C are correct, as they highlight the presence of a nucleus in eukaryotes and its absence in prokaryotes.

Viruses are an exception to the cell theory because they cannot be independently produced. Unlike cells, viruses require a host cell to replicate and carry out their life cycle. They lack the necessary cellular machinery to reproduce on their own. Therefore, viruses are not considered living organisms according to the cell theory, which states that all living organisms are composed of cells and arise from pre-existing cells.

DNA is stabilized by hydrophobic bonds because the hydrophobic bases in the DNA molecule tend to cluster together in the interior of the double helix, away from the surrounding water molecules. This clustering reduces the contact between the hydrophobic bases and water, which is energetically favorable. The hydrophobic interactions between the bases contribute to the stability of the DNA molecule by helping to hold the two strands of the double helix together. Additionally, the hydrophobic interactions also play a role in the binding of DNA to proteins, such as enzymes and transcription factors, which is essential for many cellular processes.

The primary structure of a protein is determined by the sequence of amino acids in a polypeptide. This refers to the specific order in which the amino acids are linked together to form the protein. The primary structure is the most basic level of protein structure and plays a crucial role in determining the protein's overall shape and function. The sequence of nucleic acids in a polypeptide (option A) is incorrect as nucleic acids are involved in DNA and RNA, not proteins. The secondary structure (option B) refers to the local folding patterns of the protein, which are influenced by the primary structure. Therefore, the correct answer is A and C, as both options A and C are referring to the sequence of amino acids in a polypeptide.

The correct answer is "All of the Above" because "R" groups can indeed be classified into all of the mentioned categories. Some "R" groups can be polar charged, meaning they have a charge and are attracted to water molecules. Some "R" groups can be polar uncharged, meaning they do not have a charge but are still attracted to water molecules. Some "R" groups can be nonpolar, meaning they do not have a charge and are not attracted to water molecules. Additionally, there may be "R" groups with unique properties that do not fall into any of the other categories.

The secondary structure of a protein results from hydrogen bonding. Hydrogen bonds form between the oxygen atom of one amino acid and the hydrogen atom of another amino acid in the protein chain. These bonds stabilize the structure and determine the folding pattern of the protein. Covalent bonding refers to the bonds formed between atoms within the amino acids themselves, not between different amino acids. Hydrophobic bonds refer to the interactions between nonpolar amino acids in the protein. The sequence of amino acids is responsible for the primary structure of the protein, not the secondary structure.

Amino acids are the building blocks of proteins, which are essential for the structure and function of cells. Proteins are made up of long chains of amino acids, connected by peptide bonds. Each amino acid has a unique side chain, which gives it specific properties and allows it to interact with other molecules. Therefore, option C, "are the structural units of proteins," is the correct answer as it accurately describes the role of amino acids in the formation of proteins.

The correct answer is "Prokaryotes and Eukaryotes." This is because prokaryotes and eukaryotes are two different types of cells, with prokaryotes being smaller and simpler in structure compared to eukaryotes. The cytoskeleton is a network of protein filaments that provide structural support and enable cell movement. In both prokaryotes and eukaryotes, the cytoskeleton is present, but it is more complex and diverse in eukaryotes. Therefore, the cytoskeleton in prokaryotes is smaller and simpler than in eukaryotes, making "Prokaryotes and Eukaryotes" the correct answer.

The correct answer is "a and b". Free radicals are responsible for both the process of one atom losing electrons and another gaining electrons (resulting in charged atoms or ions), as well as the formation between two metals.

Phosphoglycerides are a type of lipid that serves as a source of energy in the diet. They can be broken down and utilized by the body for energy production. Additionally, phosphoglycerides are an essential component of biological membranes, providing structural support and regulating the movement of molecules in and out of cells. Therefore, the correct answer is A and C.

Starch is the principal food reserve in plants and it is available in two forms: amylose and amylopectin. Amylose is a linear chain of glucose molecules, while amylopectin is a branched chain of glucose molecules. These two forms of starch provide energy storage for plants and are important components of their structure.

Coenzymes are nonprotein substances that are required for enzyme action. They are usually adenosine nucleotides combined with vitamins of the B complex. This means that coenzymes can be both nonprotein substances and adenosine nucleotides combined with B complex vitamins. Therefore, the correct answer is "all of the above".

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The exception to the cell theory is that not all cells are enclosed by a physical barrier cell membrane. For example, red blood cells in mammals do not have a nucleus or membrane-bound organelles. They are an exception to the general characteristics of cells, as they lack a cell membrane.

Macromolecules are large, complex molecules that are critical to the structure and function of living organisms. The four main types of macromolecules are:

Carbohydrates: Serve as energy sources and structural components.

Proteins: Perform a wide variety of functions including catalyzing metabolic reactions (enzymes), providing structural support, and regulating processes.

Lipids: Function as energy storage molecules, make up cell membranes, and serve as signaling molecules.

Nucleic acids: DNA and RNA, which store and transmit genetic information.

These macromolecules are essential for life and play crucial roles in biological processes.

The given answer includes the three types of cytoskeletal filaments found in eukaryotic cells: microfilaments, intermediate filaments, and microtubules. These structures are part of the cytoskeleton, which provides structural support, helps with cell movement, and is involved in various cellular processes. Therefore, these three choices are correct as they represent eukaryotic structures.

A lipid is a type of biomolecule that serves various biological roles, such as being a major component of cell membranes, providing insulation and protection to organs, and serving as a source of energy. Therefore, it is incorrect to say that there is no biological role for lipids.

Certain atoms attract other atoms more than others, which can result in a polar molecule. This is because if the bond between the atoms is shaped in a certain way, it can cause an unequal sharing of electrons. Free radicals, on the other hand, are atoms or molecules that have orbitals containing a single unpaired electron and are capable of independent existence. Therefore, the correct answer is a and b, as both statements are true.

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Polar molecules are characterized by having an uneven distribution of charge, with one end being slightly positive and the other end being slightly negative. Cell walls, plastids, and large vacuoles all exhibit this characteristic, making them true of polar molecules. Therefore, the correct answer is "all of the above".

The cell membrane is composed of a phospholipid bilayer, which is stabilized by hydrogen bonds between the polar heads of the phospholipids. These hydrogen bonds help to maintain the structural integrity of the membrane and ensure its proper function. Cell signaling and aging can both be influenced by the stability of the cell membrane, as it plays a crucial role in the communication between cells and in the aging process. Metabolism, on the other hand, is not directly related to the stabilization of the cell membrane.

Plant cells have all of the above (organelles, a network of internal membrane, and a cytoskeleton), while animal cells do not have these features. Organelles are specialized structures within a cell that perform specific functions. Plant cells have various organelles such as chloroplasts, which are responsible for photosynthesis. The network of internal membrane refers to the endoplasmic reticulum and Golgi apparatus, which are involved in protein synthesis and transportation. The cytoskeleton provides structural support and helps with cell movement. Animal cells lack these features, making "All of the above" the correct answer.

A covalent bond is the correct answer because ionization refers to the process of forming ions by gaining or losing electrons. In a covalent bond, electrons are shared between atoms rather than being transferred completely. This means that covalent compounds do not easily ionize, as the shared electrons are not easily gained or lost. Ionic bonds, on the other hand, involve the complete transfer of electrons from one atom to another, resulting in the formation of ions. Hydrogen bonds and London dispersion forces are types of intermolecular forces, not types of bonds.

Eukaryotic cells are true for the following statements: They acquire and utilize energy, carry out a variety of chemical reactions, and engage in numerous mechanical activities. Eukaryotic cells have organelles such as mitochondria that produce energy through cellular respiration. They also have various enzymes and metabolic pathways that allow them to carry out a wide range of chemical reactions. Additionally, eukaryotic cells have a cytoskeleton that enables them to perform mechanical activities such as cell division, movement, and shape changes.

Carbohydrates are essential macromolecules that serve as a primary source of energy for living organisms. They are broken down into glucose, which is used by cells to produce ATP, the energy currency of the cell. While other functions like storing genetic information (nucleic acids), catalyzing biochemical reactions (proteins), and providing insulation and protection (lipids) are important, they are not the primary functions of carbohydrates.