Bio 2 Mid-term Exam (Spring 2014)

Water is known as the universal solvent because it has the ability to dissolve a wide range of substances. This is due to its unique molecular structure, which allows it to form hydrogen bonds with other molecules. Water's polarity and high dielectric constant make it an excellent solvent for ionic compounds and polar molecules. It can dissolve many salts, sugars, acids, and bases, making it essential for various biological, chemical, and industrial processes.

The part labeled B in the diagram is ribose. Ribose is a type of sugar molecule that is a component of RNA (ribonucleic acid) and plays a crucial role in the synthesis of ATP (adenosine triphosphate), the primary energy currency of cells.

The part labeled B in this question is the Ribose Sugar. Ribose is a type of sugar that is a component of nucleotides, the building blocks of DNA and RNA. It is a five-carbon sugar molecule that forms the backbone of the nucleotide structure. The other options listed in the question are also components of nucleotides, but B specifically refers to the Ribose Sugar.

Uracil is not a nucleotide found in DNA. DNA is composed of four nucleotides: adenine, cytosine, guanine, and thymine. Uracil, on the other hand, is a nucleotide found in RNA. RNA uses uracil instead of thymine. Therefore, uracil is not present in DNA.

Chlorophyll is the correct answer because it is the main light-absorbing pigment found in plant leaves. It is responsible for capturing sunlight during photosynthesis and converting it into chemical energy. Chloroplasts are the organelles where photosynthesis takes place, thylakoids are the membrane structures within chloroplasts where chlorophyll is located, and grana are stacks of thylakoids. However, the question specifically asks for the main light-absorbing molecules, which are chlorophyll.

S phase is the phase of the cell cycle where DNA replication occurs. During this phase, the cell prepares for division by duplicating its DNA. This is an essential step in cell division as it ensures that each daughter cell receives a complete set of genetic material. The other options, such as cell growth and normal function, cell growth and preparation for mitosis, and nuclear membrane reforms, are not specific to S phase and can occur in other phases of the cell cycle as well.

The stage of mitosis illustrated on the right is metaphase. This is indicated by the alignment of chromosomes along the equatorial plate of the cell. In metaphase, the nuclear envelope has dissolved, and the spindle fibers attach to the centromeres of the chromosomes, causing them to line up in the middle of the cell. This alignment is crucial for the equal distribution of genetic material during cell division.

Ribosomes can be found on the surface of the endoplasmic reticulum. This is because the endoplasmic reticulum is involved in protein synthesis, and ribosomes are the cellular structures responsible for protein synthesis. They attach to the surface of the endoplasmic reticulum and help in the production of proteins that are either secreted from the cell or used within the cell itself.

Organic compounds are defined as compounds that contain carbon atoms bonded to hydrogen atoms. Carbon is the element that is essential for the formation of organic compounds.

Lipids are organic molecules that are insoluble in water and play important roles in energy storage, insulation, and cell membrane structure. The monomers that make up a lipid are glycerol and fatty acids. Glycerol is a three-carbon alcohol with hydroxyl groups, while fatty acids are long hydrocarbon chains with a carboxyl group at one end. They combine through dehydration synthesis, forming ester bonds between the hydroxyl group of glycerol and the carboxyl group of fatty acids. This combination results in the formation of triglycerides, the most common type of lipid.

The stage of mitosis illustrated on the right is anaphase. Anaphase is characterized by the separation of sister chromatids, which were previously attached at the centromere. In this stage, the spindle fibers contract and pull the sister chromatids apart, moving them towards opposite poles of the cell. This process ensures that each daughter cell will receive a complete set of chromosomes.

During prophase, the nuclear membrane breaks down. This is a characteristic of prophase because it allows the chromosomes to be released from the nucleus and become more accessible for the subsequent stages of cell division. The breakdown of the nuclear membrane also signifies the start of mitosis or meiosis, as it allows the chromosomes to condense and prepare for their movement to opposite poles of the cell. This breakdown is essential for the proper segregation and distribution of genetic material during cell division.

G2 phase is the third phase of the cell cycle, following the S phase where DNA is replicated. During G2 phase, the cell continues to grow and prepares itself for mitosis, the process of cell division. This includes synthesizing proteins and organelles needed for cell division, as well as checking for any errors in DNA replication. The nuclear membrane reforms during the next phase, which is the M phase. Therefore, the characteristic of G2 phase is cell growth and preparation for mitosis.

A prokaryotic cell does not have a nucleus. Unlike eukaryotic cells, which have a well-defined nucleus enclosed by a nuclear membrane, prokaryotic cells have their DNA floating freely in the cytoplasm. The absence of a nucleus allows for a simpler structure in prokaryotic cells, as they lack many of the membrane-bound organelles found in eukaryotic cells. Instead, prokaryotic cells have a nucleoid region where the DNA is located. This difference in cellular organization is one of the key distinctions between prokaryotic and eukaryotic cells.

The correct answer is the citric acid cycle. The citric acid cycle, also known as the Krebs cycle, is a series of chemical reactions that occur in the mitochondrial matrix. It is an essential part of cellular respiration and involves the oxidation of acetyl-CoA to produce energy-rich molecules such as ATP, NADH, and FADH2. This cycle plays a crucial role in extracting energy from carbohydrates, fats, and proteins to fuel cellular processes.

The correct answer is folded inner membrane. In the diagram, structure A appears as a folded membrane within the mitochondria. This folded inner membrane is known as the cristae and it plays a crucial role in the process of cellular respiration, where ATP (energy) is produced. The folds increase the surface area of the inner membrane, allowing for more space for the enzymes and proteins involved in ATP production. Therefore, folded inner membrane is the most appropriate description for structure A in the given diagram.

Glycolysis is the process by which glucose is broken down into pyruvate. NADH and ATP are also produced during glycolysis. Therefore, the correct answer is pyruvate, NADH, and ATP.

The term "mitosis" refers to the process of cell division, specifically the division of the nucleus. During mitosis, the genetic material within the nucleus is evenly distributed into two separate daughter cells. This process is crucial for growth, development, and the replacement of damaged or old cells in multicellular organisms. Mitosis does not involve the division of the entire cell or the cytoplasm, but rather focuses on the division of the nucleus and its genetic material.

Glycolysis is the process of breaking down glucose to produce energy in the form of ATP. It takes place in the cytoplasm of the cell. This is where glucose molecules are converted into pyruvate through a series of enzymatic reactions. The cytoplasm is the fluid-filled region of the cell outside the organelles, making it the correct location for glycolysis to occur.

The process by which a DNA molecule is copied is replication. During replication, the DNA molecule unwinds and separates into two strands, and each strand serves as a template for the synthesis of a new complementary strand. This results in two identical DNA molecules, each containing one original strand and one newly synthesized strand. Replication is a crucial step in cell division and ensures that each daughter cell receives an exact copy of the genetic information. Transcription is the process of synthesizing RNA from a DNA template, while translation is the process of synthesizing proteins using the information encoded in mRNA. Mutation refers to a change in the DNA sequence.

Glycolysis is the process in which glucose is broken down into smaller molecules. One of the end products of glycolysis is pyruvate, a three-carbon molecule. Therefore, the correct answer is pyruvate.

There are 20 amino acids found in humans. These are the building blocks of proteins and are essential for various biological processes in the body. Each amino acid has a specific role and function, and they play a crucial role in maintaining the structure and function of cells, tissues, and organs.

Photosynthesis is the correct answer because it is the process by which plants use sunlight to convert carbon dioxide and water into glucose and oxygen. During photosynthesis, plants capture energy from sunlight and use it to produce glucose, which serves as their source of energy. This process takes place in the chloroplasts of plant cells, specifically in the chlorophyll pigment. Cellular respiration, on the other hand, is the process by which cells break down glucose to release energy. The cell cycle and mitosis are not related to the process of plants using sunlight to make glucose.

The main function of the Golgi apparatus is to process and deliver proteins. It receives proteins from the endoplasmic reticulum, modifies them by adding sugars and other molecules, and packages them into vesicles for transport to their final destinations within the cell or for secretion outside the cell. This process ensures that proteins are properly folded, modified, and targeted to their intended locations, allowing them to carry out their specific functions in the cell.

The nucleus is the storehouse for most of a cell's genetic information. It contains the cell's DNA, which carries the instructions for the cell's growth, development, and reproduction. The nucleus is surrounded by a nuclear membrane, which helps protect the DNA and regulate the movement of molecules in and out of the nucleus. Within the nucleus, the DNA is organized into structures called chromosomes, which contain the genes that determine an organism's traits. Overall, the nucleus plays a crucial role in storing and regulating the cell's genetic information.

A membrane-bound sac that contains digestive enzymes is called a lysosome. Lysosomes are organelles found in animal cells that contain various hydrolytic enzymes, which help break down waste materials, cellular debris, and foreign substances. These enzymes are enclosed within a membrane to prevent them from damaging the cell. Lysosomes play a crucial role in cellular digestion and recycling, as they fuse with other vesicles or engulf materials through endocytosis, allowing the enzymes to break down the contents and release nutrients for the cell to utilize.

Cellular respiration is the process by which cells convert carbon-based molecules from food and oxygen into ATP (adenosine triphosphate), the energy currency of the cell. This process occurs in the mitochondria and involves a series of biochemical reactions that release energy stored in the bonds of glucose and other organic molecules. ATP is then used by the cell to carry out various cellular activities. The other options in the question either do not accurately describe the process of cellular respiration or involve incorrect relationships between the molecules involved.

Glycolysis is the process of breaking down glucose to produce energy in the form of ATP. It is the first step in cellular respiration and occurs in the cytoplasm of the cell. This is because the enzymes and molecules necessary for glycolysis are present in the cytoplasm, making it the ideal location for this metabolic pathway. The other options, such as the mitochondrial matrix and inner membrane, are involved in later stages of cellular respiration but not in the initial glycolysis process. Chloroplasts are found in plant cells and are responsible for photosynthesis, not glycolysis.

The ATP molecule is responsible for storing and transferring energy in cells. It acts as a high-energy molecule that can be easily broken down to release energy when needed. This energy is used for various cellular processes such as muscle contraction, active transport, and synthesis of molecules. Additionally, ATP can also transfer its stored energy to other molecules, enabling them to perform their respective functions. Therefore, "stores and transfers energy" is the best phrase to describe the function of the ATP molecule.

The correct answer is the breakdown of carbon-based molecules into smaller molecules. ATP is produced through cellular respiration, where carbon-based molecules such as glucose are broken down into smaller molecules like carbon dioxide and water. During this process, energy is released, which is used to generate ATP. Therefore, the chemical energy required to produce ATP comes from the breakdown of carbon-based molecules.

ATP synthase is located at the end of the electron transport chain. This enzyme is responsible for the synthesis of ATP, the main energy currency of the cell. It uses the proton gradient generated during electron transport to drive the conversion of ADP and inorganic phosphate into ATP. ATP synthase is embedded in the inner mitochondrial membrane in eukaryotes and the plasma membrane in prokaryotes. It consists of two main components: a proton channel (Fo) and a catalytic domain (F1), which work together to produce ATP.

Proteins are polymers of amino acids, meaning they are composed of long chains of amino acids linked together. Amino acids are the building blocks of proteins, and when they join together through peptide bonds, they form a polymer structure. Carbohydrates, lipids, and nucleic acids are not polymers of amino acids and do not have the same structure as proteins.

The electron transport chain in photosynthesis is a series of proteins located in the thylakoid membrane. This chain is responsible for transferring electrons from photosystem II to photosystem I, generating ATP and NADPH in the process. The thylakoid membrane is where the photosystems and other components of the electron transport chain are embedded, allowing for efficient electron transfer and energy production.

Chloroplasts are the organelles in plant cells where photosynthesis takes place. They contain chlorophyll, a pigment that absorbs sunlight. During photosynthesis, chloroplasts capture the energy from sunlight and convert it into chemical energy in the form of glucose (simple sugars). This chemical energy is stored in the plant cells and can be used for various metabolic processes. Therefore, the statement "Chloroplasts absorb sunlight and store chemical energy" best describes the process of photosynthesis.

A catalyst is a substance that speeds up a chemical reaction by decreasing the activation energy required for the reaction to occur. Activation energy is the energy needed to break the bonds of the reactant molecules and initiate the reaction. By lowering the activation energy, a catalyst allows the reaction to proceed at a faster rate. Therefore, the phrase "decreases the activation energy" best describes the effect of a catalyst on a chemical reaction.

The correct answer is mitochondrial matrix. The diagram mentioned in the question is not visible, but based on the options provided, structure B is identified as the mitochondrial matrix. The mitochondrial matrix is the fluid-filled space inside the inner membrane of the mitochondria. It contains enzymes that are involved in various metabolic reactions, including the citric acid cycle and fatty acid oxidation.

not-available-via-ai

Cellulose is a structural form of carbohydrate because it is a major component of plant cell walls. It provides structural support to plants and is composed of long chains of glucose molecules linked together. Starch, on the other hand, is a storage form of carbohydrate found in plants, while enzyme and RNA are not carbohydrates at all.

The correct answer is cytoplasm. Cytoplasm is the jelly-like substance that is contained inside the cell membrane. It is responsible for providing support to the organelles within the cell and facilitating various cellular processes. The cytoplasm also contains nutrients, ions, and other molecules necessary for the cell's functioning.

Glycolysis is the correct answer because it is the initial step in cellular respiration where glucose is broken down into two molecules of pyruvate. This process occurs in the cytoplasm and does not require oxygen. Photosynthesis, on the other hand, is the process by which plants convert sunlight into energy, while aerobic respiration and electron transport are later stages in cellular respiration that require oxygen and occur in the mitochondria.

A molecule of ATP, or adenosine triphosphate, consists of adenosine, ribose (a sugar molecule), and three phosphate groups. ATP is the primary energy currency of cells and is involved in various cellular processes. The adenosine provides the core structure, the ribose is the sugar molecule that forms the backbone of ATP, and the three phosphate groups are responsible for storing and releasing energy when the high-energy bonds between them are broken.

The molecule pictured in the diagram is ATP (adenosine triphosphate). ATP is a nucleotide that plays a crucial role in cellular energy transfer. It consists of an adenine base, a ribose sugar, and three phosphate groups. The high-energy phosphate bonds in ATP can be hydrolyzed to release energy, which is used for various cellular processes such as muscle contraction, active transport, and synthesis of macromolecules.

The main function of the Krebs cycle is to produce molecules that carry high-energy electrons to the electron transport chain. The Krebs cycle, also known as the citric acid cycle, is a series of chemical reactions that occur in the mitochondria of cells. During the cycle, acetyl-CoA molecules are oxidized, resulting in the production of NADH and FADH2. These molecules then carry high-energy electrons to the electron transport chain, where they are used to generate ATP through oxidative phosphorylation. Therefore, the correct answer is "producing molecules that carry high-energy electrons to the electron transport chain."

In the light-dependent reactions of photosynthesis, energy is captured from sunlight by the pigment chlorophyll in the chloroplasts of plant cells. This energy is then used to convert water into oxygen and produce energy-rich molecules such as ATP and NADPH, which are essential for the next stage of photosynthesis. The captured energy is stored in these molecules and will be used in the light-independent reactions to produce sugars. Therefore, the correct answer is "Energy is captured."

Chemosynthesis is a process by which organisms use chemical compounds as a source of energy to produce food. Unlike photosynthesis, which uses sunlight as the energy source, chemosynthesis occurs in environments where sunlight is not available, such as deep-sea hydrothermal vents or underground caves. These organisms are able to extract energy from chemical compounds, such as hydrogen sulfide or methane, and convert it into usable energy. Therefore, chemical compounds are the correct source of energy used in chemosynthesis.

Nucleic acids are polymers of nucleotides. They are composed of long chains of nucleotide monomers, which consist of a sugar molecule, a phosphate group, and a nitrogenous base. Nucleic acids, such as DNA and RNA, play crucial roles in storing and transmitting genetic information in living organisms. Proteins, carbohydrates, and lipids are also important biomolecules, but they are not polymers of nucleotides.

not-available-via-ai

Carbon is unique in that it can make four chemical bonds. This allows carbon atoms to form stable covalent bonds with other carbon atoms and with other elements, resulting in a vast number of possible combinations. This ability of carbon to form multiple bonds and create complex molecular structures is the basis for the immense diversity of organic molecules found in nature.

Water cannot diffuse through lipids easily because it is a polar molecule and lipids are nonpolar. Polar molecules like water are repelled by nonpolar substances like lipids. This is why water forms droplets on a waxed car or beads up on a freshly waxed surface. Therefore, the statement that water can diffuse through lipids easily is not true.

The diagram of the monomer suggests that it is a nucleotide, which is the building block of nucleic acids. Nucleic acids, such as DNA and RNA, are composed of long chains of nucleotides. Therefore, the correct answer is Nucleic Acids.