Ansc 221: Cells, Metabolism, And Genetics
Questions and Answers
- 1.
Plasma membranes are a feature of ______.
- A.
Prokaryotic cells
- B.
Eukaryotic cells
- C.
All cells
- D.
Plant cells only
- E.
Animal cells only
Correct Answer
C. All cellsExplanation
Plasma membranes are a feature of all cells because they are essential for maintaining the integrity and functionality of the cell. The plasma membrane acts as a selective barrier, regulating the movement of substances in and out of the cell. It also plays a crucial role in cell signaling and communication with the external environment. Therefore, plasma membranes are present in both prokaryotic and eukaryotic cells, as well as in plant and animal cells.Rate this question:
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- 2.
Which of the following is NOT a component of plasma membranes?
- A.
Glycosylated proteins
- B.
Glycosylated nucleic acids
- C.
Phospholipids
- D.
Glycolipids
- E.
Cholesterol
Correct Answer
B. Glycosylated nucleic acids -
- 3.
Which of the following are true of the plasma membrane?
- A.
It is composed of an extracellular and intracellular layer of phospholipids
- B.
The membrane contains peripheral proteins
- C.
Integral proteins span through the membrane
- D.
The membrane contains glycolipids and glycoproteins
- E.
B, C, and D
Correct Answer
E. B, C, and DExplanation
The plasma membrane is composed of an extracellular and intracellular layer of phospholipids, which is true. The membrane contains peripheral proteins, which are proteins that are not embedded in the lipid bilayer but are attached to either the inner or outer surface of the membrane. Integral proteins, on the other hand, span through the membrane, meaning they are embedded within the lipid bilayer. The membrane also contains glycolipids and glycoproteins, which are molecules that have carbohydrates attached to them. Therefore, options B, C, and D are all true statements about the plasma membrane.Rate this question:
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- 4.
The pathway from the ER to the Golgi to the plasma membrane is called the ______.
- A.
Protein synthesis pathway
- B.
Protein sorting pathway
- C.
Trans-Golgi pathway
- D.
Secretory pathway
- E.
Route 66
Correct Answer
D. Secretory pathwayExplanation
The pathway from the ER to the Golgi to the plasma membrane is called the secretory pathway. This pathway is responsible for the transport and secretion of proteins and other molecules from the ER to their final destination at the plasma membrane. It involves the sorting and packaging of proteins in the Golgi apparatus before they are transported to the cell surface. The secretory pathway is essential for various cellular processes, including the secretion of hormones, enzymes, and other signaling molecules.Rate this question:
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- 5.
The process of covalently attaching a carbohydrate to a protein or lipid is ______.
- A.
Glycosylation
- B.
Acetylation
- C.
Protein synthesis
- D.
Esterification
- E.
Facilitated diffusion
Correct Answer
A. GlycosylationExplanation
Glycosylation is the process of covalently attaching a carbohydrate to a protein or lipid. This process plays a crucial role in various biological functions, such as protein folding, stability, and recognition. It helps in determining the structure and function of the glycoprotein or glycolipid. Glycosylation can occur in the endoplasmic reticulum and Golgi apparatus, where specific enzymes catalyze the attachment of carbohydrates to proteins or lipids. This process is essential for cellular communication, immune response, and many other biological processes. Therefore, glycosylation is the correct answer for the given question.Rate this question:
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- 6.
Which of the following are 2 major functions of the SRP protein/RNA complex?
- A.
Attaches to the nucleolus where ribosome subunits are assembled AND serves as a docking station for charged tRNAs
- B.
Recognizes the ER signal sequence and pauses translation AND SRP binds to receptor in ER membrane, which docks the ribosome over a channel protein
- C.
Provides a channel for electrolytes to enter and leave the endoplasmic reticulum AND recognizes the ER signal sequence and pauses translation
Correct Answer
B. Recognizes the ER signal sequence and pauses translation AND SRP binds to receptor in ER membrane, which docks the ribosome over a channel proteinExplanation
The SRP protein/RNA complex has two major functions. Firstly, it recognizes the ER signal sequence and pauses translation. This helps in directing the ribosome to the endoplasmic reticulum (ER) for protein synthesis. Secondly, the SRP binds to a receptor in the ER membrane, which then docks the ribosome over a channel protein. This allows for the efficient translocation of the growing polypeptide chain into the ER lumen.Rate this question:
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- 7.
Facilitated diffusion but not passive diffusion requires energy.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
Facilitated diffusion is a type of passive transport that does not require energy. It involves the movement of molecules across a membrane with the help of specific carrier proteins. These proteins facilitate the movement of molecules down their concentration gradient, without the need for energy input. Therefore, the correct answer is False.Rate this question:
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- 8.
The following solutes have very low permeability through the plasma membrane.
- A.
Very small uncharged polar molecules
- B.
Water and urea
- C.
Charged polar molecules and macromolecules
- D.
Polar organic molecules
- E.
All of the above
Correct Answer
C. Charged polar molecules and macromoleculesExplanation
Charged polar molecules and macromolecules have very low permeability through the plasma membrane because they are larger in size and have charge, which makes it difficult for them to pass through the hydrophobic lipid bilayer of the membrane. The hydrophobic interior of the membrane repels charged molecules, while the large size of macromolecules prevents them from passing through the small pores of the membrane. Therefore, these solutes have limited ability to diffuse across the plasma membrane.Rate this question:
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- 9.
Water can freely diffuse through animal cell membranes.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
Water can freely diffuse through animal cell membranes. False. Animal cell membranes are selectively permeable, meaning they allow certain substances to pass through while restricting others. While small water molecules can pass through the lipid bilayer of the cell membrane, the process is not completely free or unregulated. The movement of water across the membrane is facilitated by specialized channels called aquaporins, which control the flow of water in and out of the cell.Rate this question:
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- 10.
Which of the following organelles would become more active when a cell is induced to produce more protein secretions?
- A.
Nucleus, SER, vacuoles, plasma membrane
- B.
Nucleus, RER, Golgi, mitochondria
- C.
RER, Golgi, peroxisomes
- D.
Mitochondria, Golgi, lysosomes
- E.
All components of the endomembrane system
Correct Answer
B. Nucleus, RER, Golgi, mitochondriaExplanation
When a cell is induced to produce more protein secretions, the nucleus becomes more active because it contains the DNA that encodes the instructions for protein synthesis. The rough endoplasmic reticulum (RER) becomes more active as it is responsible for protein synthesis and modification. The Golgi apparatus also becomes more active as it processes and packages proteins for secretion. Additionally, the mitochondria become more active as they provide the energy needed for protein synthesis. Therefore, the correct answer is nucleus, RER, Golgi, mitochondria.Rate this question:
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- 11.
Approximately 75% of all genes encode transmembrane proteins.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
Approximately 25% of all genes encode transmembrane proteins.Rate this question:
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- 12.
Which of the following is the major lipid found in membranes?
- A.
Steroids
- B.
Phospholipids
- C.
Cholesterol
- D.
Triglycerides
- E.
Saturated fatty acids
Correct Answer
B. PhospholipidsExplanation
Phospholipids are the major lipid found in membranes. They are composed of a hydrophilic head and hydrophobic tails, which allows them to form a bilayer structure in cell membranes. This arrangement provides a barrier that separates the internal environment of the cell from the external environment. Phospholipids also play a role in cell signaling and transport of molecules across the membrane. Steroids, cholesterol, triglycerides, and saturated fatty acids are also lipids, but they do not make up the majority of lipids in membranes.Rate this question:
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- 13.
Which of the following is NOT true of the plasma membrane?
- A.
It is composed of an extracellular and intracellular layer of phospholipids
- B.
The membrane contains peripheral proteins
- C.
The membrane contains glycolipids and glycoproteins
- D.
Integral proteins span through the membrane
- E.
The extracellular and intracellular layer of leaflets are highly symmetrical
Correct Answer
E. The extracellular and intracellular layer of leaflets are highly symmetricalExplanation
The extracellular and intracellular layer of leaflets in the plasma membrane are not highly symmetrical. The plasma membrane is composed of an extracellular and intracellular layer of phospholipids, and it contains peripheral proteins, glycolipids, and glycoproteins. Integral proteins span through the membrane, but the symmetry of the leaflets is not a characteristic of the plasma membrane.Rate this question:
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- 14.
Scientists unearth a Wooly Mammoth from the Siberian Ice Sheath and discover that a eukaryotic "amoeba"-like cell is still alive. Which component of the cell membrane might contribute to maintaining the fluidity of plasma membranes under freezing conditions?
- A.
Peripheral proteins
- B.
High levels of long fatty acyl tails within the lipid bilayer
- C.
High levels of unsaturated fatty acyl tails within the lipid bilayer
- D.
Absence of cholesterol
- E.
High levels of saturated fatty acyl tails within the lipid bilayer
Correct Answer
C. High levels of unsaturated fatty acyl tails within the lipid bilayerExplanation
High levels of unsaturated fatty acyl tails within the lipid bilayer might contribute to maintaining the fluidity of plasma membranes under freezing conditions. Unsaturated fatty acids have double bonds in their carbon chains, which create kinks in the structure. These kinks prevent the fatty acid chains from packing closely together, making the membrane more fluid and flexible. In freezing conditions, maintaining fluidity is important to prevent the membrane from becoming rigid and losing its function. Therefore, high levels of unsaturated fatty acyl tails would help the cell membrane remain fluid even in freezing temperatures.Rate this question:
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- 15.
The movement of water across a semipermeable membrane to balance solute concentrations is called osmosis and requires energy output.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
Osmosis is the movement of water across a semipermeable membrane to balance solute concentrations, but it does not require energy output. In osmosis, water molecules move from an area of lower solute concentration to an area of higher solute concentration, in order to equalize the concentration on both sides of the membrane. This process occurs passively, without the need for energy input. Therefore, the correct answer is False.Rate this question:
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- 16.
Carbohydrates of the plasma membrane ____.
- A.
Are associated with a protein or lipid
- B.
Are located on the outer surface of the plasma membrane
- C.
Can function as cell markers for recognition by other cells
- D.
A and B
- E.
All of the above
Correct Answer
E. All of the aboveExplanation
Carbohydrates of the plasma membrane are associated with a protein or lipid, meaning they are attached to either a protein or a lipid molecule. They are also located on the outer surface of the plasma membrane, making them accessible for interactions with other cells. Additionally, these carbohydrates can function as cell markers for recognition by other cells, allowing for cell-cell communication and signaling. Therefore, the correct answer is "all of the above" as all the statements are true.Rate this question:
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- 17.
A transmembrane protein in the plasma membrane is glycosylated at two sites in the polypeptide sequence. One site is Asn-Val-Ser and the other is Asn-Gly-Thn. Where in the protein would you expect these two sites to be found?
- A.
In hydrophilic regions that project into the extracellular environment
- B.
In hydrophilic regions the project into the cytosol
- C.
In transmembrane segments
- D.
Could be anywhere
- E.
A and B
Correct Answer
E. A and BExplanation
The correct answer is A and B. The glycosylation sites are found in hydrophilic regions that project into both the extracellular environment and the cytosol. This means that the protein has regions that are exposed to both the inside and outside of the cell, allowing for interactions with molecules in both compartments.Rate this question:
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- 18.
What structural features of a membrane are major contributors to selective permeability?
- A.
Glycolipids on the outer surface of the membrane
- B.
Peripheral membrane proteins on the inside of the membrane
- C.
Phospholipid bilayer
- D.
Lipid exchage proteins
- E.
C and D
Correct Answer
E. C and DExplanation
The structural features of a membrane that are major contributors to selective permeability are the phospholipid bilayer and lipid exchange proteins. The phospholipid bilayer forms the basic structure of the membrane and consists of a hydrophilic head and hydrophobic tails, creating a barrier that only allows certain molecules to pass through. Lipid exchange proteins help transport specific lipids across the membrane, further contributing to the selective permeability of the membrane. Therefore, options C and D are correct as they include both of these important structural features.Rate this question:
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- 19.
Both ______ and _______ are performed by transmembrane proteins, but the latter requires the input of some types of energy.
- A.
Diffusion, facilitated diffusion
- B.
Facilitated diffusion, active transport
- C.
Diffusion, active transport
- D.
Active transport, osmosis
- E.
Osmosis, diffusion
Correct Answer
B. Facilitated diffusion, active transportExplanation
Facilitated diffusion is a type of passive transport where transmembrane proteins help in the movement of molecules across the cell membrane, but it does not require any input of energy. On the other hand, active transport is a process that also involves transmembrane proteins but requires the input of energy to move molecules against their concentration gradient. Therefore, the correct answer is facilitated diffusion, active transport.Rate this question:
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- 20.
What term is used to describe the process in which water is moved across a membrane to try and equilibrate solute concentration on either side of the membrane?
- A.
Osmosis
- B.
Diffusion
- C.
Facilitated diffusion
- D.
Passive diffusion
- E.
Active transport
Correct Answer
A. OsmosisExplanation
Osmosis is the term used to describe the process in which water is moved across a membrane to try and equilibrate solute concentration on either side of the membrane. It is a passive process that does not require energy and occurs when there is a difference in solute concentration on either side of the membrane. The water molecules move from an area of lower solute concentration to an area of higher solute concentration, in an attempt to balance the concentration on both sides of the membrane.Rate this question:
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- 21.
An electrochemical gradient occurs with solutes that have a net positive or negative charge.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
An electrochemical gradient refers to the difference in electrical charge and concentration of ions across a membrane. It occurs when solutes with a net positive or negative charge are present. This is because charged particles are influenced by both electrical and chemical forces, leading to the establishment of a gradient. Therefore, the statement that an electrochemical gradient occurs with solutes that have a net positive or negative charge is true.Rate this question:
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- 22.
If cells are in a _____ environment, this means that the concentration of a solute is ______ outside the cell than inside.
- A.
Hypertonic, higher
- B.
Hypotonic, lower
- C.
Hypotonic, higher
- D.
Hypertonic, lower
- E.
A and B
Correct Answer
E. A and BExplanation
If cells are in a hypertonic environment, this means that the concentration of a solute is higher outside the cell than inside. Similarly, if cells are in a hypotonic environment, this means that the concentration of a solute is lower outside the cell than inside. Therefore, both options A and B are correct as they describe different scenarios of solute concentration relative to the cell.Rate this question:
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- 23.
Secreted proteins most likely will pass through the _____, particularly if they are ____ prior to being moved out of the cell.
- A.
Rough ER, activated
- B.
Nucleus, phosphorylated
- C.
Golgi apparatus, glycosylated
- D.
Smooth ER, translated
- E.
Lysosome, cleaved
Correct Answer
C. Golgi apparatus, glycosylatedExplanation
Secreted proteins are synthesized in the rough endoplasmic reticulum (ER) and then transported to the Golgi apparatus. The Golgi apparatus is responsible for modifying and packaging proteins before they are transported out of the cell. One common modification that occurs in the Golgi apparatus is glycosylation, where sugar molecules are added to the protein. This modification helps in stabilizing the protein, aiding in proper folding, and targeting it to the correct destination. Therefore, the correct answer is Golgi apparatus, glycosylated.Rate this question:
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- 24.
The process by which large macromolecules are transported outside the cell via vesicle formation at the Golgi apparatus and subsequent fusion with the plasma membrane is called ______.
- A.
Facilitated diffusion
- B.
Active transport
- C.
Endocytosis
- D.
Exocytosis
Correct Answer
D. ExocytosisExplanation
Exocytosis is the correct answer because it describes the process of large macromolecules being transported outside the cell. In exocytosis, vesicles are formed at the Golgi apparatus and then fuse with the plasma membrane, releasing their contents into the extracellular space. This process is essential for the secretion of proteins, hormones, and other molecules from cells. Facilitated diffusion and active transport involve the movement of molecules across the cell membrane but do not specifically refer to the transport of large macromolecules. Endocytosis, on the other hand, is the process by which substances are taken into the cell through the formation of vesicles.Rate this question:
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- 25.
All cells of a multicellular organism may not respond in the same manner to a particular ligand that binds to a cell surface receptor. The difference in response may be due to _____.
- A.
The type of receptor for the ligand that the cell expresses
- B.
The type of signal transduction pathways that the cell expresses
- C.
The affinity of the ligand for the receptor in a given cell type
- D.
The type of target proteins that the cell expresses
- E.
All of the above
Correct Answer
E. All of the aboveExplanation
The correct answer is "all of the above". The difference in response of cells to a particular ligand can be due to multiple factors. The type of receptor that the cell expresses can determine how the ligand binds and activates signaling pathways. The type of signal transduction pathways that the cell expresses can further modulate the cellular response. Additionally, the affinity of the ligand for the receptor in a given cell type and the type of target proteins that the cell expresses can also influence the response. Therefore, all of these factors can contribute to the variation in cellular response to a ligand.Rate this question:
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- 26.
When a cell secretes a signaling molecule that binds to receptors on neighboring cells of the same type as well as the same cell, this is called _____ signaling.
- A.
Autocrine
- B.
Contact-dependent
- C.
Direct intercellular
- D.
Paracrine
- E.
Endocrine
Correct Answer
A. AutocrineExplanation
Autocrine signaling refers to a type of cell signaling where a cell secretes a signaling molecule that binds to receptors on both neighboring cells of the same type and the same cell that secreted it. This means that the signaling molecule acts on the cell that produced it, creating a feedback loop.Rate this question:
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- 27.
A substrate binds an enzyme as a signal molecule binds a ______.
- A.
Second messenger
- B.
Kinase
- C.
Receptor
- D.
Transcription factor
- E.
G-protein
Correct Answer
C. ReceptorExplanation
A substrate binds an enzyme in a similar way that a signal molecule binds a receptor. Just as a substrate interacts with an enzyme to initiate a chemical reaction, a signal molecule interacts with a receptor to initiate a cellular response. Both processes involve specific binding and recognition between molecules, leading to a downstream effect.Rate this question:
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- 28.
The benefit of second messengers in signal transduction pathways is _______.
- A.
Amplification of the signal
- B.
An increase in the speed of a cellular response
- C.
Duplication of the ligands in the system
- D.
A and B
- E.
All of the above
Correct Answer
D. A and BExplanation
Second messengers play a crucial role in signal transduction pathways by amplifying the original signal and increasing the speed of cellular response. They act as intermediaries between the extracellular ligands and the intracellular targets, allowing for a more efficient and rapid cellular response. Therefore, the correct answer is "A and B" as both amplification of the signal and an increase in the speed of a cellular response are benefits of second messengers in signal transduction pathways.Rate this question:
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- 29.
A hormone binds a receptor and activates the cAMP signal transduction pathway ultimately leading to the cell response. Which of the following is NOT a likely mechanism for reversing (or shutting off) cAMP transduction?
- A.
The GTP on the alpha subunit of the G protein is hydrolyzed to GDP
- B.
Activate phosphodiesterase
- C.
Activate adenylyl cyclase
- D.
The hormone dissociating from the receptor
- E.
Protein phosphates remove phosphates from proteins initially activated by protein kinase A
Correct Answer
C. Activate adenylyl cyclaseExplanation
Adenylyl cyclase is responsible for producing cAMP, which is a key molecule in the cAMP signal transduction pathway. Activating adenylyl cyclase would further increase cAMP levels and enhance the pathway, rather than reversing or shutting it off. Therefore, activating adenylyl cyclase is not a likely mechanism for reversing cAMP transduction.Rate this question:
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- 30.
Various cells in the body respond to the hormone epinephrine in various ways due to ______.
- A.
Differential gene regulation
- B.
Cellular respiration
- C.
Protein kinases
- D.
Metabolism
- E.
Phosphodiesterase
Correct Answer
A. Differential gene regulationExplanation
The various cells in the body respond to the hormone epinephrine in different ways due to differential gene regulation. This means that different genes are turned on or off in different cells, leading to different responses to the hormone. The regulation of gene expression allows cells to have specific functions and responses to external signals like epinephrine. Therefore, the variability in gene regulation among different cells is responsible for the diverse responses to epinephrine throughout the body.Rate this question:
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- 31.
Which of the following does NOT describe a typical cellular response to signaling molecules?
- A.
Activation of enzymes within the cell
- B.
Change in a gene sequence that encodes a particular protein
- C.
Change in the function of structural proteins which determine cell shape
- D.
Altercation levels of certain proteins in the cell by changes in level of gene expression
Correct Answer
B. Change in a gene sequence that encodes a particular proteinExplanation
A typical cellular response to signaling molecules involves the activation of enzymes within the cell, which can lead to various biochemical reactions and processes. It can also involve a change in the function of structural proteins, which determine cell shape and provide support. Additionally, signaling molecules can alter the levels of certain proteins in the cell by changes in gene expression. However, a change in a gene sequence that encodes a particular protein does not describe a typical cellular response to signaling molecules. This is because changes in gene sequences occur during processes like mutation or genetic recombination, rather than in direct response to signaling molecules.Rate this question:
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- 32.
Due to gene regulation, cells _____ into specialized types of cells.
- A.
Divide
- B.
Migrate
- C.
Differentiate
- D.
Translate
- E.
Grow
Correct Answer
C. DifferentiateExplanation
Gene regulation refers to the process by which genes are turned on or off in response to signals or environmental cues. This regulation ultimately determines the fate of a cell and whether it will differentiate into a specialized type of cell or not. Therefore, the correct answer is "differentiate" as it accurately describes the process by which cells develop into specialized types of cells through gene regulation.Rate this question:
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- 33.
The function of the ECM in animals is ______.
- A.
To provide structural support
- B.
To organize cells within tissues
- C.
Cell signaling
- D.
To provide strength
- E.
All of the above
Correct Answer
E. All of the aboveExplanation
The extracellular matrix (ECM) in animals serves multiple functions. It provides structural support to tissues by forming a framework that holds cells together. Additionally, the ECM helps organize cells within tissues by providing a scaffold for cell attachment and migration. Moreover, the ECM plays a crucial role in cell signaling, as it contains various signaling molecules that regulate cell behavior and communication. Lastly, the ECM contributes to the strength and resilience of tissues. Therefore, the correct answer is "all of the above."Rate this question:
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- 34.
The polysaccharide that forms the hard outer covering of many invertebrates is _____.
- A.
Collagen
- B.
Chitin
- C.
Chrondroitin sulfate
- D.
Pectin
- E.
Cellulose
Correct Answer
B. ChitinExplanation
Chitin is a polysaccharide that forms the hard outer covering of many invertebrates. It is a strong and flexible material that provides structural support and protection to these organisms. Collagen is a protein, not a polysaccharide, and is found in connective tissues. Chrondroitin sulfate is a component of cartilage, not the outer covering of invertebrates. Pectin is a polysaccharide found in plant cell walls, not in the outer covering of invertebrates. Cellulose is also a polysaccharide, but it is found in plant cell walls, not in the hard outer covering of invertebrates.Rate this question:
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- 35.
Which of the following is involved in the process of tissue and organ formation in multicellular organisms?
- A.
Cell growth
- B.
Cell division
- C.
Cell connections
- D.
Cell differentiation
- E.
All of the above
Correct Answer
E. All of the aboveExplanation
All of the options listed - cell growth, cell division, cell connections, and cell differentiation - are involved in the process of tissue and organ formation in multicellular organisms. Cell growth refers to the increase in size of cells, while cell division involves the replication of cells. Cell connections are important for cells to communicate and coordinate their activities. Cell differentiation refers to the process by which cells become specialized for specific functions. Together, these processes contribute to the development and organization of tissues and organs in multicellular organisms.Rate this question:
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- 36.
The tissue type common to animals that functions in the conduction of electrical signals is _____.
- A.
Epithelial
- B.
Dermal
- C.
Nervous
- D.
Muscle
- E.
Ground
Correct Answer
C. NervousExplanation
The correct answer is "nervous." Nervous tissue is responsible for conducting electrical signals in animals. This tissue type is found in the brain, spinal cord, and nerves, and it allows for the transmission of information throughout the body. Nervous tissue contains specialized cells called neurons, which are capable of generating and transmitting electrical impulses, allowing for communication and coordination of various bodily functions.Rate this question:
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- 37.
Gap junctions prevent the leakage of materials across animal cell layers.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
Gap junctions actually facilitate the exchange of materials between animal cell layers, rather than preventing leakage. These specialized channels allow for the direct transfer of ions, small molecules, and electrical signals between adjacent cells, enabling communication and coordination within tissues. Therefore, the correct answer is False.Rate this question:
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- 38.
During glycolysis, glucose is broken down into ____.
- A.
Pyruvate
- B.
NADH
- C.
Oxygen
- D.
Acetyl CoA
- E.
ATP
Correct Answer
A. PyruvateExplanation
During glycolysis, glucose is broken down into pyruvate. Glycolysis is the initial step in cellular respiration, where glucose is converted into pyruvate through a series of enzymatic reactions. This process occurs in the cytoplasm of cells and does not require oxygen. The breakdown of glucose into pyruvate generates a small amount of ATP and NADH, which can be further used in the production of more ATP through other metabolic pathways. Therefore, pyruvate is the correct answer as it is the end product of glycolysis.Rate this question:
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- 39.
Where does glycolysis take place?
- A.
Mitochondrial matrix
- B.
Mitochondrial inner membrane
- C.
Mitochondrial membrane
- D.
Cytosol
- E.
Mitochondrial intermembrane space
Correct Answer
D. CytosolExplanation
Glycolysis is the metabolic pathway that converts glucose into pyruvate. It is the first step in cellular respiration and occurs in the cytosol, the fluid portion of the cell outside the organelles. This process does not take place in the mitochondria, as the other options suggest. Instead, glycolysis occurs in the cytosol to break down glucose and produce ATP.Rate this question:
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- 40.
The ATP made during glycolysis is generated by ____.
- A.
Electron transport
- B.
Oxidation of NADH and NAD+
- C.
Chemisosmosis
- D.
Photophosphorylation
- E.
Substrate-level phosphorylation
Correct Answer
E. Substrate-level phosphorylationExplanation
During glycolysis, ATP is generated by substrate-level phosphorylation. This process involves the direct transfer of a phosphate group from a high-energy molecule (such as a substrate) to ADP, forming ATP. In glycolysis, this occurs twice, resulting in a net production of two ATP molecules. Substrate-level phosphorylation is different from oxidative phosphorylation, which occurs in the electron transport chain, and photophosphorylation, which occurs in photosynthesis. Chemosmosis is a process that involves the movement of ions across a membrane to generate ATP, but it is not specifically related to glycolysis.Rate this question:
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- 41.
The enzyme responsible for oxidizing pyruvate once it enters the mitochondrial matrix is _____.
- A.
Pyruvate oxidase
- B.
Pyruvate dehydrogenase
- C.
Hexokinase
- D.
Peptidase
- E.
ATP synthase
Correct Answer
B. Pyruvate dehydrogenaseExplanation
Pyruvate dehydrogenase is the correct answer because it is the enzyme responsible for oxidizing pyruvate once it enters the mitochondrial matrix. This enzyme catalyzes the conversion of pyruvate to acetyl-CoA, which is an important step in the citric acid cycle (also known as the Krebs cycle) that takes place in the mitochondria. This conversion allows for the further breakdown of glucose and the production of energy in the form of ATP.Rate this question:
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- 42.
In which phase of the cell cycle does the cell divide?
- A.
G1 phase
- B.
S phase
- C.
M phase
- D.
G2 phase
- E.
None of the above
Correct Answer
C. M phaseExplanation
The M phase of the cell cycle is the phase in which the cell actually divides. It is also known as mitosis or cell division. During this phase, the cell undergoes a series of complex processes that result in the formation of two daughter cells with identical genetic information. These daughter cells can then go on to perform their specific functions in the body.Rate this question:
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- 43.
Which of the following is a reason for meiotic division?
- A.
Asexual reproduction
- B.
Multicellularity
- C.
Gamete formation in animals
- D.
All of the above
- E.
A and B
Correct Answer
C. Gamete formation in animalsExplanation
Meiotic division is a type of cell division that occurs in sexually reproducing organisms to produce gametes. Gametes are specialized cells that fuse during fertilization to form a new individual. Asexual reproduction does not involve the formation of gametes, while multicellularity refers to the presence of multiple cells in an organism, but does not directly relate to meiotic division. Therefore, the correct answer is "gamete formation in animals" as it accurately describes the purpose of meiotic division.Rate this question:
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- 44.
During which phase of cellular division does Mendel's law of segregation physically occur?
- A.
Mitosis
- B.
Meiosis I
- C.
Meiosis II
- D.
All of the above
- E.
B and C
Correct Answer
B. Meiosis IExplanation
During the phase of cellular division known as meiosis I, Mendel's law of segregation physically occurs. This is because meiosis I is the stage where homologous chromosomes separate, resulting in the segregation of alleles into different gametes. This process is crucial for the formation of haploid cells with unique combinations of genetic material, which is the basis for genetic variation and inheritance as described by Mendel's law of segregation.Rate this question:
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- 45.
An individual that has the same allele of a gene on both chromosomes is said to be _____.
- A.
Dihybrid
- B.
Recessive
- C.
Homozygous
- D.
Heterozygous
- E.
Hemizygous
Correct Answer
C. HomozygousExplanation
An individual that has the same allele of a gene on both chromosomes is said to be homozygous. This means that both copies of the gene are identical, either both dominant or both recessive. Homozygosity can result in the expression of a particular trait or characteristic, as both copies of the gene carry the same information. In contrast, heterozygosity refers to having different alleles of a gene on each chromosome.Rate this question:
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- 46.
If the SsWw individual is mated with another SsWw individual, what is the probability of producing a SSWW offspring?
- A.
1/16
- B.
1/8
- C.
1/4
- D.
1/2
Correct Answer
A. 1/16Explanation
When two SsWw individuals are mated, each parent can produce four types of gametes: SW, Sw, sW, and sw. The probability of producing a SSWW offspring is the probability of getting SW from one parent and SW from the other parent, which is 1/4 * 1/4 = 1/16.Rate this question:
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- 47.
A geneticist finds that a gene that gives werewolves long fangs also makes them extra hairy. This is an example of _____.
- A.
Expressivity
- B.
Pleiotropy
- C.
Penetrance
- D.
Codominance
Correct Answer
B. PleiotropyExplanation
Pleiotropy refers to a single gene having multiple effects on an organism's phenotype. In this case, the gene responsible for long fangs in werewolves also affects their hairiness. This demonstrates pleiotropy because a single gene is influencing multiple traits in the organism.Rate this question:
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- 48.
A situation where alleles at one gene influence the phenotypic expression of alleles of another gene would be called ____.
- A.
Multiple alleles
- B.
Lethal
- C.
Codominance
- D.
Hemizygosity
- E.
Epistasis
Correct Answer
E. EpistasisExplanation
Epistasis refers to a situation where alleles at one gene can mask or modify the phenotypic expression of alleles at another gene. This means that the presence of certain alleles at one gene can override or suppress the effects of alleles at another gene, influencing the overall phenotype. Therefore, epistasis is the appropriate term to describe the given scenario.Rate this question:
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- 49.
A replicated chromosome is composed of ____.
- A.
Two homologous chromosomes held together at the centromere
- B.
Four sister chromatids held together at the centromere
- C.
Two sister chromatids held together at the centromere
- D.
Four homologous chromosomes held together at the centromere
- E.
One chromosome with a centromere
Correct Answer
C. Two sister chromatids held together at the centromereExplanation
A replicated chromosome is composed of two sister chromatids held together at the centromere. This is because during DNA replication, each chromosome is duplicated to form two identical sister chromatids. These sister chromatids remain attached to each other at the centromere until they separate during cell division. This arrangement ensures that each daughter cell receives an exact copy of the genetic material.Rate this question:
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- 50.
Selected genotypes at the BRCA1 locus in humans have been shown to cause breast cancer in woman. However, not all women with predisposing genotypes will get breast cancer. This is an example of ______.
- A.
Expressivity
- B.
Heterogeneity
- C.
Phenocopy
- D.
Penetrance
- E.
Pleiotropy
Correct Answer
D. PenetranceExplanation
Penetrance refers to the proportion of individuals with a specific genotype who exhibit the associated phenotype. In this case, the selected genotypes at the BRCA1 locus have been shown to cause breast cancer in some women, indicating that the genotype has high penetrance. However, not all women with these genotypes will develop breast cancer, suggesting that penetrance is incomplete in this context.Rate this question:
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