Biology Quizzes Exam 2
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What defines the element to which a particular atom belongs?
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The number of neutrons in the nucleus.
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The number of protons in the nucleus.
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The number of electrons orbiting around the nucleus.
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The number of protons plus the number of neutrons in the nucleus
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The number of protons plus the number of electrons plus the number of electrons.
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Biology Quizzes Exam 2 assesses understanding of fundamental biological concepts including atomic structure, chemical reactions such as respiration, properties of water, and thermodynamics. It is designed to test knowledge crucial for learners in biology.
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- 2.
What causes a hydrogen bond?
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Equal sharing of electrons between oxygen and hydrogen atoms
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Attraction between ions
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Unequal sharing of electrons between covalently oxygen and hydrogen atoms
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A covalent bond that shares more than two electrons
Correct Answer
A. Unequal sharing of electrons between covalently oxygen and hydrogen atomsExplanation
A hydrogen bond is caused by unequal sharing of electrons between covalently bonded oxygen and hydrogen atoms. In a covalent bond, electrons are shared between atoms, but in a hydrogen bond, the electron pair is more attracted to the oxygen atom, resulting in an uneven distribution of electrons. This unequal sharing creates a partial positive charge on the hydrogen atom and a partial negative charge on the oxygen atom, leading to an electrostatic attraction between neighboring molecules.Rate this question:
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- 3.
Distinguish between a hydrophilic and a hydrophobic substance.
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Hydrophobic substances do not mix well with water; hydrophilic substances mix well with water.
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Hydrophobic substances mix well with water; hydrophilic substances do not mix well with water.
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Hydrophobic substances form by synthesis; hydrophilic substances form by hydrolysis.
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Hydrophobic substances form by hydrolysis; hydrophilic substances form by synthesis.
Correct Answer
A. Hydrophobic substances do not mix well with water; hydrophilic substances mix well with water.Explanation
Hydrophobic substances are those that do not mix well with water, meaning they repel or are not soluble in water. On the other hand, hydrophilic substances are those that mix well with water, meaning they are soluble in water or attract water molecules. Therefore, the correct answer is that hydrophobic substances do not mix well with water, while hydrophilic substances do mix well with water.Rate this question:
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- 4.
Which general type of chemical reaction is respiration?
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Oxidation
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Reduction
Correct Answer
A. OxidationExplanation
Respiration is a chemical reaction that occurs in living organisms to produce energy. During respiration, glucose is oxidized, or broken down, to release energy in the form of ATP. This process involves the transfer of electrons from glucose to oxygen, resulting in the oxidation of glucose and the reduction of oxygen. Therefore, respiration is classified as an oxidation reaction.Rate this question:
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- 5.
Whic of the following generally describes the process of synthesis (=dehydration synthesis)
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Removal of -H and -OH from monomers to join the monomers into a polymer, and forming water.
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Using water movlcules to break polymers into monomers.
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The attraction of two water molecules to each other due to partial chages on each molecule.
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The gain of an electron as a hydrogen atom.
Correct Answer
A. Removal of -H and -OH from monomers to join the monomers into a polymer, and forming water.Explanation
The process of synthesis, also known as dehydration synthesis, involves the removal of -H and -OH groups from monomers to join them together into a polymer. This process forms a covalent bond between the monomers, resulting in the formation of a larger molecule. The removal of -H and -OH groups releases water molecules as a byproduct. Therefore, the correct answer is the removal of -H and -OH from monomers to join them into a polymer and forming water.Rate this question:
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- 6.
What does the second law of thermodynamics state?
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The amount of energy in the universe is constant.
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Energy can neither be created or destroyed.
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The amount of matter in the universe is constant
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Ome useful energy is lost to a system whenever an energy trnasfer occurs.
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Both 1 and 2 above are part of the second law of thermodymanics
Correct Answer
A. Ome useful energy is lost to a system whenever an energy trnasfer occurs.Explanation
The second law of thermodynamics states that some useful energy is lost to a system whenever an energy transfer occurs. This means that energy cannot be completely converted from one form to another without some loss of usable energy. It also implies that the entropy of a closed system will always increase over time, leading to a decrease in the amount of available energy for useful work. This principle is fundamental to understanding the limitations and inefficiencies in energy conversion processes.Rate this question:
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- 7.
What is the relationship between monosaccharides and polysaccharides?
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Polysaccharides are composed of monosaccharide units
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Monosarccharides are composed of polysaccharide units
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Monosachcarides only bond chemically to polysaccharides as side groups on the polysaccharide chain
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they are both sugars, but there is no other chemical relationship between them
Correct Answer
A. Polysaccharides are composed of monosaccharide unitsExplanation
Polysaccharides are complex carbohydrates made up of multiple monosaccharide units bonded together. This means that monosaccharides are the building blocks or subunits of polysaccharides. Therefore, the relationship between monosaccharides and polysaccharides is that polysaccharides are composed of monosaccharide units.Rate this question:
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- 8.
What are the basic units that comprise an unsaturated fat molecule?
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Glycerol and 3 fatty acids, at leasat one of which is unsaturated
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1 fatty acid and 3 glycerol molecules, one of which is unsaturated
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a chain of carbons with some double bonds between them
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A bonding of amnio acids and monosaccharides
Correct Answer
A. Glycerol and 3 fatty acids, at leasat one of which is unsaturatedExplanation
An unsaturated fat molecule is composed of glycerol and three fatty acids, at least one of which is unsaturated. Glycerol is a three-carbon molecule that serves as the backbone for the fatty acids. Fatty acids are long chains of carbon atoms with a carboxyl group at one end. In unsaturated fats, there is at least one double bond between carbon atoms in the fatty acid chain. This double bond causes a kink in the chain, preventing the fatty acids from packing tightly together and resulting in a liquid or soft consistency at room temperature.Rate this question:
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- 9.
What is a secondary structure of a protein?
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The order of amino acids
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Folding and turning back on itself into a globular three-dimentional structure.
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Interaction of two or more separtely-formed peptide subunits to form a functioning protein unit.
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The twisting of the string of amino acids into an alpha-helix or pleated sheet.
Correct Answer
A. The twisting of the string of amino acids into an alpha-helix or pleated sheet.Explanation
The secondary structure of a protein refers to the twisting of the string of amino acids into an alpha-helix or pleated sheet. This structure is formed by hydrogen bonding between the amino acids in the protein chain, resulting in a stable and recurring pattern. The alpha-helix is a right-handed coil, while the pleated sheet consists of strands connected by hydrogen bonds. These secondary structures play a crucial role in determining the overall shape and stability of the protein, and are essential for its proper functioning.Rate this question:
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- 10.
Which of the following best describes an enzyme?
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Organic catalyst
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A lipid carrier molecule
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an inorganic catalyst
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A substance that is changed by a chemical reaction
Correct Answer
A. Organic catalystExplanation
An enzyme is best described as an organic catalyst because it is a protein molecule that speeds up chemical reactions in living organisms without being consumed in the process. Enzymes are highly specific and can catalyze a wide range of reactions, playing a crucial role in various biological processes such as metabolism, digestion, and DNA replication. They are composed of amino acids and have a complex three-dimensional structure that allows them to bind to specific substrates and facilitate the conversion of reactants into products.Rate this question:
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- 11.
What is the enzyme-substrate complex?
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The sum of the reactants and products of a chemical reaction
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The binding the substrate to the enzyme during catalysis
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The complex of various substrates upon which an enzyme acts
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a fixation on substrates by enzymes that requires deep Freudian psychotherapy
Correct Answer
A. The binding the substrate to the enzyme during catalysisExplanation
The enzyme-substrate complex refers to the binding of the substrate to the enzyme during catalysis. This complex is formed when the enzyme and substrate interact with each other, allowing the enzyme to catalyze the chemical reaction. The enzyme-substrate complex is a temporary structure that facilitates the conversion of the substrate into the product.Rate this question:
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- 12.
What is the active site of an enzyme?
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The end of the protein chain that contains "enzyme" information
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The place on the enzyme where energy-containing molecules bind to power the enzyme
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the place that binds an enzyme to the cell membrane
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The place on the enzyme where catalysis occurs
Correct Answer
A. The place on the enzyme where catalysis occursExplanation
The active site of an enzyme is the specific region on the enzyme where catalysis occurs. This is where the enzyme binds to its substrate, the molecule that it acts upon, and facilitates the chemical reaction by lowering the activation energy required for the reaction to proceed. The active site has a specific shape and chemical properties that allow it to interact and bind with the substrate, forming an enzyme-substrate complex. This interaction is crucial for the enzyme to catalyze the conversion of the substrate into the desired product.Rate this question:
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- 13.
Why are enzymes very specific in their action?
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The substrate fits into the enzyme in a very specific manner
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The enzyme "learns" to recognize a specific substrate as it is formed and develops, but could "learn" to recognize any substrate
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The substrate "molds" itself to the enzyme so that any enzyme can catalyse any specific reaction
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The enzyme contains a copy of the substrate molecule that it uses as a "model" for the type of molecule with which it will react
Correct Answer
A. The substrate fits into the enzyme in a very specific mannerExplanation
Enzymes are very specific in their action because the substrate fits into the enzyme in a very specific manner. This means that the shape and structure of the substrate molecule perfectly match with the active site of the enzyme, allowing for a precise and efficient reaction to occur. The active site of the enzyme acts as a lock, and the substrate molecule acts as the key that fits perfectly into that lock. This specificity ensures that only the correct substrate will bind to the enzyme and undergo the desired reaction, while preventing any unwanted reactions with other molecules.Rate this question:
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- 14.
What is the mechanism by which enzymes work
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Enzymes supply energy to the substrate for the reaction to proceed
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Enzymes transfer energy between substrate molecules for the reation to occur
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Enzymes lower the activation energy needed to begin the rection
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Enzymes act as a "workbench" for other molecules to carry out the reaction but have no other role
Correct Answer
A. Enzymes lower the activation energy needed to begin the rectionExplanation
Enzymes lower the activation energy needed to begin the reaction. Activation energy is the energy required to start a chemical reaction. Enzymes act as catalysts, which means they speed up the reaction by lowering the activation energy. They do this by binding to the substrate and creating an environment that allows the reaction to occur more easily. This lowers the energy barrier, making it easier for the reaction to proceed.Rate this question:
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- 15.
How does competitive inhibition work?
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A substance similar in shape to the substrate becomes permanently attached to the active site
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Two enzymes try to attach to the substrate and neither can
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Energy supplied to the enzyme does not allow it to catalyse a reaction
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Other substances compete with the enzyme to attach to the substrate
Correct Answer
A. A substance similar in shape to the substrate becomes permanently attached to the active siteExplanation
Competitive inhibition occurs when a substance, which has a similar shape to the substrate, binds to the active site of the enzyme. This binding is usually reversible, but in this case, it becomes permanently attached to the active site. As a result, the substrate is unable to bind to the enzyme and the catalytic reaction is hindered or prevented. This inhibition can be overcome by increasing the concentration of the substrate, allowing it to outcompete the inhibitory substance and bind to the active site.Rate this question:
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- 16.
What happpens when an enzyme is denatured?
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it becomes ineffective and cannot catalyze a reaction
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If the enzyme is a protein, the tertiary structure is changed
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the shape of the active site is altered
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All of the above
Correct Answer
A. All of the aboveExplanation
When an enzyme is denatured, it undergoes structural changes that affect its effectiveness. If the enzyme is a protein, its tertiary structure is altered, leading to a change in the shape of the active site. As a result, the enzyme becomes ineffective and cannot catalyze a reaction. Therefore, all of the given statements are true, explaining why the correct answer is "All of the above."Rate this question:
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- 17.
Which of these is a coenzyme?
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Vitamin C
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Iron
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Cholesterol
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DNA
Correct Answer
A. Vitamin CExplanation
Vitamin C is a coenzyme because it plays a crucial role in many enzymatic reactions in the body. Coenzymes are organic molecules that work together with enzymes to facilitate various biochemical reactions. Vitamin C acts as a cofactor for enzymes involved in collagen synthesis, neurotransmitter production, and the synthesis of carnitine, which is essential for fatty acid metabolism. Without vitamin C, these enzymatic reactions would not occur efficiently. Therefore, vitamin C qualifies as a coenzyme.Rate this question:
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- 18.
How does a noncompetitive inhibitor affect an enzyme?
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It constantly attaches to and detaches from the active site, blocking the substrate from the enzyme part of the time
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It attaches to the substrate, preventing it from interacting with the enzyme
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It attaches to an allosteric site, changing the shape of the active site.
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It causes the enzyme to become bound to a membrane
Correct Answer
A. It attaches to an allosteric site, changing the shape of the active site.Explanation
A noncompetitive inhibitor affects an enzyme by attaching to an allosteric site, which is a different site on the enzyme than the active site. This binding causes a conformational change in the enzyme, altering the shape of the active site. As a result, the substrate is unable to bind to the active site and the enzyme is unable to catalyze the reaction effectively.Rate this question:
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- 19.
A biochemical pathway is a series of reactions within an organism that result in particular products being formed. The role of enztymes in biochemical pathways is:
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To identify intermediates in the pathway and independently carry them to their next destination
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To become intermediate products in the reaction, providing raw materials fo the next step of the reaction
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To provide an interconnected "bucket brigade" that passes the intermediates from point to point in the pathway
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Mediate each step of the reaction
Correct Answer
A. Mediate each step of the reactionExplanation
Enzymes play a crucial role in biochemical pathways by mediating each step of the reaction. They act as catalysts, facilitating the conversion of substrates into products by lowering the activation energy required for the reaction to occur. Enzymes bind to specific substrates and undergo conformational changes, allowing the reaction to proceed at a faster rate. They are not consumed or altered during the reaction and can be used repeatedly. Therefore, enzymes act as molecular facilitators, ensuring that each step of the biochemical pathway occurs efficiently and effectively.Rate this question:
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- 20.
What does the Cell Theory state?
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Organisms begin as a mass of nonliving organic materials that organize into cells spontaneously
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Some organisms are cellular in nature, some are not
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All organisms are composed of units called cells.
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Living things are composed fo fibrous strings called cells that weave together like cloth to form an organism.
Correct Answer
A. All organisms are composed of units called cells.Explanation
The Cell Theory states that all organisms are composed of units called cells. This means that every living organism, from the simplest bacteria to complex multicellular organisms like humans, is made up of cells. Cells are the basic structural and functional units of life, and they are responsible for carrying out all the processes necessary for an organism to survive and function. The Cell Theory was proposed by Matthias Schleiden and Theodor Schwann in the 19th century and is a fundamental principle in biology.Rate this question:
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- 21.
Waht were the contributions of Rudolf Virchow in the history of cell theory?
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He coined the term "cell".
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He restated and reinforce Oken's ideas that cells come from existing cells by cell division.
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All organisms are cellular in nature.
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He was one of the first to observe and describe microorganisms as "animicules
Correct Answer
A. He restated and reinforce Oken's ideas that cells come from existing cells by cell division.Explanation
Rudolf Virchow made significant contributions to the history of cell theory by restating and reinforcing Oken's ideas that cells come from existing cells through cell division. This concept, known as biogenesis, challenged the prevailing belief of spontaneous generation and laid the foundation for the understanding that all organisms are made up of cells. Virchow's work played a crucial role in shaping modern cell theory and our understanding of the fundamental unit of life.Rate this question:
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- 22.
Which of the following best describes the structure of cellular membranes according to the fluid-mozaic model?
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Proteins embedded in a bilayer of phospholipid
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Phospholipid embedded in a bilayer of proteins
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A bilayer of phospholipid sandwiched between an outer and an inner layer of protein
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A bilayer of protein sandwiched between an outer and an inner layer of phospholipid
Correct Answer
A. Proteins embedded in a bilayer of phospholipidExplanation
According to the fluid-mosaic model, cellular membranes are composed of a bilayer of phospholipids with proteins embedded within it. This model suggests that the phospholipid bilayer acts as a fluid matrix, with proteins floating within it like a mosaic. The proteins play various roles in the membrane, such as transport, signaling, and structural support. Therefore, the correct answer is "proteins embedded in a bilayer of phospholipid."Rate this question:
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- 23.
In general, the molecules that act to carry substances across the cell membrane are
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Lipids
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Proteins
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Nucleic acids
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Carbohydrates
Correct Answer
A. ProteinsExplanation
Proteins are the molecules that act to carry substances across the cell membrane. They serve as transporters, channels, and carriers, allowing the movement of various substances such as ions, nutrients, and waste products in and out of the cell. Proteins have specific structures that enable them to interact with different molecules and facilitate their transport across the hydrophobic lipid bilayer of the cell membrane. Lipids also play a role in cell membrane structure, but they do not have the same level of specificity and functionality as proteins when it comes to substance transport. Nucleic acids and carbohydrates are not primarily involved in carrying substances across the cell membrane.Rate this question:
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- 24.
What is osmosis?
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The movement of a substance across a semipermeable membrane.
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Diffusion of a substance through water.
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Diffusion of water across a semipermeable membrane.
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Diffusion of water within a solution.
Correct Answer
A. Diffusion of water across a semipermeable membrane.Explanation
Osmosis is the process of water molecules moving from an area of lower solute concentration to an area of higher solute concentration across a semipermeable membrane. This movement occurs in order to equalize the concentration of solute on both sides of the membrane. Therefore, the correct answer is "Diffusion of water across a semipermeable membrane."Rate this question:
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- 25.
What is the function of the nucleus?
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Information storage for cell metabolism and heredity
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Processing energy from food
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Packaging and transport of materials for export from the cel
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Intracellular digestion of foodstuffs
Correct Answer
A. Information storage for cell metabolism and heredityExplanation
The nucleus is responsible for storing genetic information and controlling cell metabolism. It contains DNA, which serves as the blueprint for the cell's structure and function. The nucleus regulates gene expression and protein synthesis, ensuring that the cell functions properly and passes on its genetic material to future generations. Additionally, the nucleus plays a crucial role in cell division, ensuring the accurate distribution of genetic material to daughter cells.Rate this question:
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- 26.
What is the function of smooth ER (endoplasmic reticulum)?
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information processing
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Protein synthesis
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Lipid (steroid) synthesis and detoxification
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Cell movement
Correct Answer
A. Lipid (steroid) synthesis and detoxificationExplanation
Smooth ER is responsible for lipid (steroid) synthesis and detoxification. It plays a crucial role in the production of lipids, including steroids, which are important for various cellular functions. Additionally, smooth ER is involved in detoxification processes, helping to remove harmful substances from the cell. This organelle does not have a direct role in information processing, protein synthesis, or cell movement.Rate this question:
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- 27.
What is the cause of Pompe's Disease?
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An imbalance of enzymes in the nucleus
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Lack of an enzyme in the lysosomes
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Improper fusion of vesicles to the Golgi apparatus
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The ribosomes do not stick properly to the rough ER
Correct Answer
A. An imbalance of enzymes in the nucleusExplanation
Pompe's Disease is caused by an imbalance of enzymes in the nucleus. This means that there is an abnormality in the levels or activity of certain enzymes within the nucleus of cells. This imbalance can disrupt various cellular processes and lead to the characteristic symptoms of Pompe's Disease.Rate this question:
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- 28.
Which of the following cellular structures is associated only with animal cells and not with plant cells?
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Cell wall
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Nucleus
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Mitochondrion
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Lysosome
Correct Answer
A. LysosomeExplanation
Lysosomes are cellular structures that are only found in animal cells and not in plant cells. Lysosomes are responsible for the digestion and recycling of cellular waste and materials. They contain enzymes that break down molecules such as proteins, lipids, and carbohydrates. Plant cells, on the other hand, have a rigid cell wall that provides support and protection. The presence of lysosomes in animal cells and their absence in plant cells is one of the key differences between these two types of cells.Rate this question:
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