Biology Quiz - 2019 Batch

The final electron acceptor of the electron transport chain in aerobic respiration is oxygen. Oxygen acts as the final electron acceptor in the process of oxidative phosphorylation, where it combines with electrons and protons to form water. This reaction allows for the production of ATP, the energy currency of the cell. Without oxygen, the electron transport chain cannot function properly, leading to a decrease in ATP production and ultimately, cell death.

Large numbers of ribosomes are present in cells that specialize in producing proteins. Ribosomes are responsible for protein synthesis, and cells that require a high production of proteins, such as muscle cells or cells in the pancreas that produce digestive enzymes, will have a large number of ribosomes. Lipids, glycogen, cellulose, and nucleic acids are not directly synthesized by ribosomes, so they would not require a high number of ribosomes in specialized cells.

The correct answer is C) nuclear lamina. The nuclear lamina is a group of proteins that provides structural support and helps maintain the shape of the nucleus. It forms a mesh-like network on the inner surface of the nuclear envelope and interacts with chromatin and other nuclear components. The nuclear lamina also plays a role in regulating gene expression and DNA replication. Polymers and polypeptides are general terms for large molecules composed of repeating subunits, while pores are openings that allow for the movement of molecules in and out of the nucleus.

In a polymer made of 55 monomers, each monomer is connected to the adjacent one through a condensation reaction, which releases one water molecule. Since there are 55 monomers, there will be a total of 54 condensation reactions, and thus 54 water molecules will be removed in this reaction.

Prokaryotes, which include bacteria and archaea, are classified into two different domains: Bacteria and Archaea. This classification is based on their distinct genetic and structural characteristics. Bacteria are single-celled organisms that lack a nucleus and membrane-bound organelles, while archaea are also single-celled organisms but have unique molecular features that differentiate them from bacteria. The domains Bacteria and Archaea represent the two main branches of prokaryotic life, highlighting their evolutionary divergence and biological diversity.

Phospholipids and proteins are the major structural components of the cell membrane. Phospholipids form a bilayer that makes up the basic structure of the membrane, with their hydrophilic heads facing outward and their hydrophobic tails facing inward. This arrangement provides a barrier that separates the inside and outside of the cell. Proteins are embedded within the phospholipid bilayer and have various functions, such as transporting molecules across the membrane and acting as receptors for cell signaling. Together, phospholipids and proteins give the cell membrane its structure and functionality.

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Nucleic acids are composed of monomers called nucleotides. A nucleotide consists of a sugar molecule (ribose or deoxyribose), a phosphate group, and a nitrogenous base (adenine, guanine, cytosine, thymine, or uracil). Nucleotides form the building blocks of DNA and RNA, which are essential for genetic information storage and protein synthesis. Nucleosides, on the other hand, lack the phosphate group and are not considered monomers of nucleic acids. Amino acids are the building blocks of proteins, and the nucleus is an organelle within a cell.

The primary factor that determines whether a specific cellular component ends up in the supernatant or the pellet during the fractionation of homogenized cells using centrifugation is the size and weight of the component. This is because centrifugation separates components based on their sedimentation rate, which is influenced by their size and weight. Larger and heavier components will sediment faster and end up in the pellet, while smaller and lighter components will remain in the supernatant. Solubility, percentage of carbohydrates, presence or absence of nucleic acids, and presence or absence of lipids do not directly determine the distribution of cellular components in the supernatant or pellet during centrifugation.

Sister chromatids are attached to each other by cohesion. Cohesion is a protein complex that holds the two identical DNA strands of sister chromatids together during cell division. This attachment ensures that the genetic material is properly distributed to the daughter cells. Chemical bonds and microtubules are not involved in the attachment of sister chromatids.

The proteins cohesion and separase are related to sister chromatids. Cohesion is responsible for holding sister chromatids together during cell division, ensuring that they are properly segregated to daughter cells. Separase, on the other hand, is an enzyme that cleaves the cohesion protein, allowing the separation of sister chromatids. Therefore, cohesion and separase play crucial roles in the proper distribution of genetic material during cell division.

Chitin is a structural polysaccharide that is found in the cell walls of fungi. It provides strength and rigidity to the cell wall, helping to protect the fungal cells and maintain their shape. Chitin is not found in plant cells, and it is not related to phospholipids or steroids. Therefore, the correct answer is that chitin is used to build the cell wall of fungi.

The G1 phase is the most important checkpoint in the cell cycle. During this phase, the cell undergoes growth and prepares for DNA replication. At the G1 checkpoint, the cell checks for any DNA damage or errors in the replicated DNA. If any issues are found, the cell can either repair the damage or undergo programmed cell death (apoptosis) to prevent the propagation of damaged DNA. This checkpoint ensures that the cell is ready to proceed to the next phase of the cell cycle and helps maintain genomic stability.

During glycolysis, which is the first step of cellular respiration, one molecule of glucose is converted into two molecules of pyruvate. In this process, a net of two molecules of ATP are produced per molecule of glucose. Since there are 5 moles of glucose being oxidized, the net amount of moles of ATP released from glycolysis would be 5 moles of glucose multiplied by 2 moles of ATP per glucose, which equals 10 moles of ATP.

The radius of a nuclear pore is 50 nm.

Fever is not a misfolding disease. Cystic fibrosis, Alzheimer's, and mad cow disease are all examples of misfolding diseases, where proteins in the body fold incorrectly and cause various health issues. Fever, on the other hand, is a symptom that occurs as a result of the body's immune response to an infection or illness. It is not caused by misfolded proteins.

Cholesterol is a lipid molecule that is present in the plasma membranes of some animals. It plays a crucial role in maintaining the fluidity of the membrane. When the temperature drops, the phospholipids in the membrane tend to pack together, making the membrane less fluid. However, the presence of cholesterol prevents this packing by inserting itself between the phospholipids, preventing them from becoming too closely packed. This helps to maintain the fluidity of the membrane even at lower temperatures, ensuring that the membrane functions properly and allowing the cells to continue their normal activities.

When red blood cells are transferred to seawater, which has a higher concentration of NaCl than mammalian blood, osmosis will occur. Osmosis is the movement of water from an area of lower solute concentration to an area of higher solute concentration through a semipermeable membrane. In this case, water will leave the red blood cells in an attempt to equalize the concentration of NaCl inside and outside the cells. As a result, the cells will lose water, shrink, and eventually shrivel and collapse.

The term "amphipathic" refers to a molecule or compound that has both polar and non-polar regions. This means that one part of the molecule is attracted to water (hydrophilic) while another part repels water (hydrophobic). This characteristic is commonly found in phospholipids, which make up the cell membrane. The polar region of an amphipathic molecule interacts with water, while the non-polar region avoids water. Therefore, the correct answer is B) Polar-non polar.

During prometaphase, the nuclear envelope suddenly fragments. This is because the nuclear envelope disassembles to allow the microtubules of the mitotic spindle to interact with the chromosomes. The breakdown of the nuclear envelope is a crucial step in preparing the chromosomes for their separation during anaphase. Therefore, prometaphase is the stage where the nuclear envelope undergoes fragmentation.

In prokaryotes, the respiratory chain is located in the plasma membrane. This is because prokaryotes lack mitochondria, so their plasma membrane serves as the site for cellular respiration. On the other hand, in eukaryotes, the respiratory chain is located in the mitochondrial inner membrane. This is because eukaryotic cells have mitochondria, which are specialized organelles responsible for cellular respiration. The inner membrane of the mitochondria provides a highly folded surface area for the respiratory chain enzymes to carry out the electron transport chain and generate ATP.

The function of proteins in chromosomes is to maintain the structure of chromosomes and help control the activity of the genes. Proteins play a crucial role in organizing and condensing the DNA within chromosomes, ensuring that it is tightly packed and protected. Additionally, proteins called histones help regulate gene expression by controlling the accessibility of genes to the transcription machinery. Therefore, both maintaining chromosome structure and controlling gene activity are important functions of proteins in chromosomes.

Binary fission is the correct answer because it is the primary method of reproduction in bacteria. During binary fission, a single bacterial cell divides into two identical daughter cells. This process allows bacteria to rapidly reproduce and increase their population. Meiosis and mitosis are not related to bacterial reproduction as they are specific to eukaryotic cells.

Anaphase is the correct answer because it is the shortest stage of the M phase. During anaphase, the sister chromatids are separated and pulled towards opposite ends of the cell. This process is facilitated by the spindle fibers. Once the sister chromatids are separated, the cell proceeds to telophase, where the nuclear envelope reforms around each set of chromosomes. Cytokinesis, on the other hand, is the final stage of the cell cycle where the cytoplasm divides to form two daughter cells. Therefore, anaphase is the correct answer as it is the shortest stage of the M phase.

Glycolysis and the citric acid cycle together account for almost 10% of the ATP generated by cellular respiration. Glycolysis is the initial step in glucose metabolism, where glucose is broken down into pyruvate, generating a small amount of ATP. The citric acid cycle, also known as the Krebs cycle, further breaks down pyruvate into carbon dioxide, producing more ATP in the process. Together, these two processes contribute to the majority of ATP production in cellular respiration.

The regulatory molecules in the cell cycle are mainly made of cyclins and CDKs. Cyclins are proteins that regulate the progression of the cell cycle by binding to and activating cyclin-dependent kinases (CDKs). CDKs are enzymes that control the cell cycle by phosphorylating target proteins, thus regulating their activity. These two types of molecules work together to ensure the proper progression and regulation of the cell cycle.

The correct answer is 6 NADH, 2 FADH2, 4 CO2. This is because during the citric acid cycle, one mole of glucose is completely oxidized and produces 6 molecules of NADH, 2 molecules of FADH2, and 4 molecules of CO2. NADH and FADH2 are electron carriers that play a crucial role in oxidative phosphorylation, which generates ATP. CO2 is a waste product of cellular respiration.

CO2 would likely move through the lipid bilayer of a plasma membrane most rapidly because it is a small, nonpolar molecule. The lipid bilayer is composed of hydrophobic tails that repel polar molecules, making it difficult for them to pass through. CO2, being nonpolar, can easily dissolve in the lipid bilayer and diffuse across it. On the other hand, amino acids, glucose, K+, and starch are larger and/or polar molecules that would have a harder time crossing the lipid bilayer.

Cellulose is the correct answer because it is a complex carbohydrate found in the cell walls of plants. It is composed of long chains of glucose molecules that are arranged in a linear and parallel manner, forming microfibrils. These microfibrils provide strength and rigidity to plant cells, making cellulose a key structural component in the plant kingdom. Chitin, starch, and amylose do not exhibit the same microfibril structure as cellulose.

An organism with a cell wall would most likely be unable to take in materials through phagocytosis. Phagocytosis is a process by which cells engulf and ingest solid particles or other cells. However, organisms with a cell wall have a rigid structure surrounding their cells, which prevents them from engulfing and ingesting particles in this way. Diffusion, osmosis, active transport, and facilitated diffusion are all passive processes that do not require the organism to engulf particles, making them more likely to occur in organisms with a cell wall.

The correct answer is Dyneins, Redial spoke. Dyneins are motor proteins that move along microtubules and are involved in the movement of cilia and flagella. Radial spokes, on the other hand, are protein complexes that connect the central microtubules to the outer microtubule doublets in cilia and flagella. Therefore, the letters B and C in the answer choice represent dyneins and radial spokes, respectively.

The correct answer is "Lumen of ER." The letter A represents the lumen of the endoplasmic reticulum (ER). The ER is a network of membranous tubules and sacs within the cell that is involved in the synthesis, folding, and transport of proteins. The lumen of the ER refers to the inner space or cavity within these tubules and sacs.

The given question asks for the incorrect statement relating to microfilaments. The options provided are: Cytoplasmic streaming, They support cell's shape, They are called Actin filaments, and None of the above. The correct answer is "None of the above" because all the statements mentioned are correct. Cytoplasmic streaming is a process where cytoplasm moves within the cell, microfilaments do support cell's shape, and microfilaments are indeed called Actin filaments. Therefore, there is no incorrect statement among the given options.

As electrons travel down the electron transport chain and become closer to the oxygen in aerobic respiration, both free energy and electronegativity increase. Free energy increases because the electrons release energy as they move down the chain, which is used to generate ATP. Electronegativity increases because oxygen has a higher electronegativity than the previous molecules in the chain, causing the electrons to be more strongly attracted to it. Therefore, both options stating that free energy increases and electronegativity increases are correct.

The question is asking which of the given options does not belong to the tertiary level of links. In the tertiary level of links, Van der Waals, Hydrophobic, and Ionic interactions play a significant role in stabilizing the three-dimensional structure of a protein. Hydrophilic interactions, on the other hand, are more commonly associated with the secondary level of protein structure. Therefore, the correct answer is D) Hydrophilic.

Passive transport is the correct answer because it is a broad term that includes all the other processes mentioned. Osmosis is a type of passive transport where water molecules move across a membrane from an area of lower solute concentration to an area of higher solute concentration. Diffusion of a solute across a membrane and facilitated diffusion are also types of passive transport, where solute molecules move from an area of higher concentration to an area of lower concentration without the need for energy. Transport of an ion down its electrochemical gradient is a specific type of passive transport.

Cristae is a term used to describe the folded inner membrane structures found in mitochondria. Thylakoids are the flattened membrane sacs found in chloroplasts, specifically involved in the light-dependent reactions of photosynthesis. Grana refers to the stacks of thylakoids found in chloroplasts. Granum is the singular form of grana. All of these structures are similar in the sense that they are membrane-bound compartments involved in energy-related processes within cells.

The photo in question indicates the presence of intermediate filaments in the cytoskeleton. Intermediate filaments are a type of structural protein that provide mechanical support and stability to the cell. They are composed of various proteins, such as keratins, vimentins, and neurofilaments, and are typically found in the cytoplasm of cells. This photo may show the characteristic appearance of intermediate filaments, such as their rope-like or filamentous structure, which distinguishes them from other components of the cytoskeleton, such as actin filaments and microtubules.

The correct answer is yeasts and dinoflagellates. Yeasts are unicellular fungi that reproduce through a process called budding, which is similar to how cells divide in multicellular eukaryotes. Dinoflagellates are unicellular protists that undergo a process called binary fission, which is also similar to cell division in multicellular eukaryotes. Both yeasts and dinoflagellates exhibit division mechanisms that resemble those of multicellular eukaryotes.

During cellular respiration, acetyl CoA accumulates in the mitochondrial matrix. This is because acetyl CoA is produced in the cytosol during the breakdown of glucose, and it then enters the mitochondria to undergo further reactions in the citric acid cycle. The citric acid cycle takes place in the mitochondrial matrix, where acetyl CoA combines with oxaloacetate to form citrate. Therefore, the accumulation of acetyl CoA occurs in the mitochondrial matrix during cellular respiration.

A characteristic feature of a carrier protein in a plasma membrane is that it exhibits a specificity for a particular type of molecule. This means that carrier proteins are selective in the molecules they transport across the membrane. They have binding sites that only recognize and transport specific molecules, ensuring that only the required substances are transported across the membrane. This specificity allows carrier proteins to regulate the movement of molecules in and out of the cell, maintaining homeostasis and controlling cellular processes.

The correct answer is that there are only weak hydrophobic interactions in the interior of the membrane. This allows lipids and proteins to move laterally because the weak interactions make it easier for them to slide past each other. If there were strong interactions, it would restrict the movement of lipids and proteins in the membrane.

Telophase is the correct answer because it is the final stage of mitosis. During telophase, the duplicated chromosomes reach the opposite poles of the cell and begin to unwind. Nuclear envelopes start to form around each set of chromosomes, and the nucleoli reappear. Cytokinesis, which is the division of the cytoplasm, typically occurs simultaneously or shortly after telophase. Therefore, telophase marks the end of mitosis and the beginning of two new daughter cells.

Proton-motive force refers to the force exerted on a proton by a transmembrane proton concentration gradient. This force is generated during cellular respiration when protons are pumped across the inner mitochondrial membrane, creating a concentration gradient. The protons then flow back into the mitochondrion through ATP synthase, driving the synthesis of ATP. The proton-motive force is essential for the production of ATP, the energy currency of the cell.

The letter X represents "Stroma." Stroma is a term used in biology to refer to the fluid-filled space inside the chloroplasts of plant cells. It is where the light-independent reactions of photosynthesis take place. The stroma contains enzymes and other molecules necessary for the synthesis of glucose from carbon dioxide and water. It also surrounds the thylakoid membrane, which is responsible for the light-dependent reactions of photosynthesis. Therefore, the letter X represents the stroma, which is an essential component of the chloroplasts and plays a crucial role in photosynthesis.

NAD+ is used as an electron carrier during glycolysis. It accepts electrons and hydrogen ions from glucose and transfers them to other molecules in the process. NAD+ is reduced to NADH during this process, and it plays a crucial role in the production of ATP during glycolysis. FAD and FADH2 are involved in other metabolic pathways, but they are not directly used as electron carriers in glycolysis.

The correct answer is Transcription. Transcription is the process where DNA is converted into mRNA. During transcription, an enzyme called RNA polymerase binds to the DNA molecule and synthesizes a complementary mRNA molecule. This mRNA molecule carries the genetic information from the DNA to the ribosomes, where it is used as a template for protein synthesis in the process known as translation. Cloning and cleavage are not directly related to the process that occurs between DNA and mRNA in protein synthesis.

The movement of chromosomes along microtubules can be explained by both the Pac Man theory and the centrosomes pull microtubule easily theory. The Pac Man theory suggests that the microtubules act like "Pac Man" and directly attach to the chromosomes, pulling them along. On the other hand, the centrosomes pull microtubule easily theory suggests that the centrosomes, which are located at the opposite ends of the cell, exert force on the microtubules, causing them to move and pull the chromosomes along with them. Both of these explanations contribute to the understanding of how chromosomes move along microtubules.

Cotransport proteins are able to use the electrochemical gradients of ions across the plasma membrane to transport other molecules or ions against their concentration gradient. This is achieved by coupling the movement of the desired molecule or ion with the movement of the ions that are already moving down their electrochemical gradient. Therefore, cotransport proteins can utilize the existing ion gradients to transport molecules or ions into or out of the cell.

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