Molecular And Cellular Biology Quiz!
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Questions and Answers
- 1.
If the atomic number of a neutral atom is 6, how many protons and electrons does the atom have?
- A.
0 protons, 6 electrons
- B.
3 protons, 3 electrons
- C.
6 protons, 0 electrons
- D.
6 protons, 6 electrons
Correct Answer
D. 6 protons, 6 electronsExplanation
The atomic number of an atom represents the number of protons in its nucleus. Since the atomic number is given as 6, the atom must have 6 protons. In a neutral atom, the number of protons is equal to the number of electrons. Therefore, the atom also has 6 electrons.Rate this question:
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- 2.
The mass of an atom is 23, and its atomic number is 11. How many protons, electrons, and neutrons does this atom have?
- A.
11 protons, 11 electrons, and 12 neutrons
- B.
11 protons, 11 electrons, and 1 neutron
- C.
11 protons, 1 electrons, 11 neutrons
- D.
6 protons, 5 electrons, and 12 neutrons
Correct Answer
A. 11 protons, 11 electrons, and 12 neutronsExplanation
The atomic number of an atom represents the number of protons it has. In this case, the atomic number is 11, so the atom has 11 protons. Since atoms are electrically neutral, the number of electrons is also equal to the number of protons, so it also has 11 electrons. The mass of the atom is given as 23, which is the sum of the protons and neutrons. Therefore, to find the number of neutrons, we subtract the atomic number (11) from the mass number (23), giving us 12 neutrons.Rate this question:
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- 3.
Which of the following terms describes an atom that has donated an electron to become a positively charged particle?
- A.
Anion
- B.
Cation
- C.
Compound
- D.
Molecule
Correct Answer
B. CationExplanation
A cation is an atom that has donated an electron, resulting in a positive charge. When an atom loses an electron, it becomes positively charged because the number of protons in its nucleus is greater than the number of electrons. This creates an imbalance of positive and negative charges, causing the atom to become a cation. Anions, on the other hand, are atoms that have gained an electron and therefore have a negative charge. Compounds and molecules are not specific to the charge of an atom, but rather refer to the combination of two or more atoms.Rate this question:
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- 4.
A carbon atom has four electrons in its valence shell, while a hydrogen atom has on electron in its valence shell. How many atoms of hydrogen can be covalently bonded to carbon?
- A.
Two
- B.
Three
- C.
Four
- D.
Five
Correct Answer
C. FourExplanation
A carbon atom can form four covalent bonds because it has four electrons available in its valence shell. Since a hydrogen atom can form only one covalent bond, four hydrogen atoms can be covalently bonded to a carbon atom, resulting in a total of four hydrogen atoms bonded to carbon.Rate this question:
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- 5.
Which of the following is an organic molecule?
- A.
CO2
- B.
CH4
- C.
NH3
- D.
H2
Correct Answer
B. CH4Explanation
CH4 (methane) is an organic molecule because it consists of carbon (C) bonded to hydrogen (H) atoms. Organic molecules are characterized by the presence of carbon atoms, which can form covalent bonds with other elements such as hydrogen, oxygen, nitrogen, and more. In the case of CH4, the carbon atom is bonded to four hydrogen atoms, making it an organic compound commonly found in natural gas and produced by various biological processes. On the other hand, CO2 (carbon dioxide), NH3 (ammonia), and H2 (hydrogen gas) do not contain carbon atoms and are therefore not organic molecules.Rate this question:
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- 6.
Which of the following properties of water causes water droplets to form beads on surfaces, such as on a leaf?
- A.
Adhesion
- B.
Specific heat
- C.
Surface tension
- D.
Ability to dissolve substances
Correct Answer
C. Surface tensionExplanation
Surface tension is the property of water that causes water droplets to form beads on surfaces, such as on a leaf. Surface tension is the force that acts on the surface of a liquid, causing it to behave like a stretched elastic sheet. This force is responsible for the cohesive nature of water molecules, which allows them to stick together and form droplets rather than spreading out. This cohesive force is stronger than the adhesive force between water and the surface, causing the water droplets to bead up instead of spreading out.Rate this question:
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- 7.
Which of the following bonds gives rise to the properties of water that make it essential for life?
- A.
The ionic bonds between water molecules
- B.
The ionic bonds within a water molecule
- C.
The hydrogen bonds between water molecules
- D.
The hydrogen bonds within a water molecule
Correct Answer
C. The hydrogen bonds between water moleculesExplanation
The properties of water that make it essential for life are due to the hydrogen bonds between water molecules. Hydrogen bonds are formed between the slightly positive hydrogen atom of one water molecule and the slightly negative oxygen atom of another water molecule. These bonds give water its high boiling point, high specific heat capacity, and cohesion, which are crucial for various biological processes such as temperature regulation, transportation of nutrients, and maintaining the structure of cells. Ionic bonds, on the other hand, involve the transfer of electrons between atoms and are not responsible for the unique properties of water.Rate this question:
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- 8.
Proteins are build from which of the following monomers?
- A.
Monosaccharides
- B.
Nucleotides
- C.
Amino acids
- D.
Fatty acids
Correct Answer
C. Amino acidsExplanation
Proteins are built from amino acids. Amino acids are organic compounds that contain an amino group, a carboxyl group, and a side chain. They are the building blocks of proteins and are linked together through peptide bonds to form long chains called polypeptides. These polypeptide chains then fold into specific three-dimensional structures to create functional proteins. Monosaccharides are the monomers of carbohydrates, nucleotides are the monomers of nucleic acids, and fatty acids are the monomers of lipids.Rate this question:
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- 9.
Which of the following scenarios would most likely result in a membrane potential?
- A.
The concentration of potassium ions inside the cell is the same as the concentration of hydrogen ions outside the cell
- B.
The concentration of potassium inside the cell is the same as the concentration of oxygen outside the cell
- C.
The concentration of potassium inside the cell is greater that the concentration of potassium outside the cell
- D.
The concentration of potassium inside the cell is greater than the concentration of potassium outside the cell
Correct Answer
D. The concentration of potassium inside the cell is greater than the concentration of potassium outside the cellExplanation
The membrane potential is the difference in electrical charge across the cell membrane. This potential is generated by the unequal distribution of ions, particularly potassium ions, across the cell membrane. When the concentration of potassium inside the cell is greater than outside, it creates an electrochemical gradient, resulting in a membrane potential. This difference in concentration drives the movement of potassium ions across the membrane, leading to the establishment of a membrane potential.Rate this question:
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- 10.
Which of the following statements about thermodynamics explains why energy is required to move a hydrogen atom against a chemical gradient?
- A.
The first law of thermodynamics states that energy can neither be created nor destroyed
- B.
The second law of thermodynamics states that energy must be conserved
- C.
The first law of thermodynamics states that entropy increases
- D.
The second law of thermodynamics states that entropy increases
Correct Answer
D. The second law of thermodynamics states that entropy increasesExplanation
The second law of thermodynamics states that entropy increases. Entropy is a measure of the disorder or randomness in a system. When a hydrogen atom is moved against a chemical gradient, it goes from a state of lower entropy to a state of higher entropy. This means that the system becomes more ordered, which requires energy input. Therefore, according to the second law of thermodynamics, energy is required to move a hydrogen atom against a chemical gradient.Rate this question:
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- 11.
Which of the following equations is an anabolic reaction?
- A.
6CO2 + 6 H2O -> C6H12O6 + 6O2
- B.
2H2O2 -> 2H2O + O2
- C.
C6H12O6 + 6O2 -> 6CO2 + 6H2O
- D.
2NH3 -> N2 +3H2
Correct Answer
A. 6CO2 + 6 H2O -> C6H12O6 + 6O2Explanation
The equation 6CO2 + 6 H2O -> C6H12O6 + 6O2 is an anabolic reaction because it involves the synthesis of glucose (C6H12O6) from carbon dioxide (CO2) and water (H2O) through the process of photosynthesis. Anabolic reactions are characterized by the building up or synthesis of complex molecules from simpler ones, which is exactly what happens in this equation.Rate this question:
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- 12.
If the iron ion Fe3+ has an oxidation number of +3, which two of the following are true?
- A.
Fe3+ can donate three electrons to form a chemical bond
- B.
Fe3+ can accept an electron to form a chemical bond
- C.
Fe3+ is an oxidizing agent
- D.
Fe3+ is a reducing agent
Correct Answer(s)
B. Fe3+ can accept an electron to form a chemical bond
C. Fe3+ is an oxidizing agentExplanation
Fe3+ can accept an electron to form a chemical bond because it has a positive oxidation number, indicating a tendency to gain electrons. Additionally, Fe3+ is an oxidizing agent because it can accept electrons from other substances, causing them to be oxidized.Rate this question:
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- 13.
Which of the following terms describes a molecule that inhibits the function of an enzyme by altering the shape of the enzyme's active site?
- A.
Coenzyme
- B.
Repressor
- C.
Activator
- D.
Substrate
Correct Answer
B. RepressorExplanation
A molecule that inhibits the function of an enzyme by altering the shape of the enzyme's active site is called a repressor. Repressors bind to the enzyme and cause a conformational change in the active site, preventing the substrate from binding and inhibiting the enzyme's activity. Coenzymes are molecules that assist enzymes in their function but do not inhibit them. Activators are molecules that enhance the activity of enzymes, while substrates are the molecules that bind to the active site of an enzyme and undergo a chemical reaction.Rate this question:
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- 14.
Which of the following types of regulation is described below: Enzyme X catalyzes the metabolism of Amino Acid G. When Amino Acid G is bound to Enzyme X, the affinity for Amino Acid G increases at the other active site on Enzyme X
- A.
Competitive inhibition
- B.
Noncompetitive inhibition
- C.
Positive cooperativity
- D.
Negative cooperativity
Correct Answer
C. Positive cooperativityExplanation
Positive cooperativity is the correct answer because it describes a type of regulation where the binding of a substrate to one active site of an enzyme increases the affinity of the enzyme for the same substrate at other active sites. In this case, when Amino Acid G is bound to Enzyme X, it increases the affinity for Amino Acid G at the other active site on Enzyme X. This positive interaction between the substrate and enzyme enhances the catalytic activity of the enzyme.Rate this question:
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- 15.
Why do some photosynthetic structures like leaves appear green?
- A.
The epidermis of the leaf absorbs red and blue light
- B.
The epidermis of the leaf absorbs green light
- C.
The chlorophyll of the leaf absorbs red and blue light
- D.
The chlorophyll of the leaf absorbs green light
Correct Answer
C. The chlorophyll of the leaf absorbs red and blue lightExplanation
Chlorophyll is the pigment responsible for photosynthesis in plants. It absorbs light energy from the sun, primarily in the red and blue regions of the visible spectrum. The green light is not effectively absorbed by chlorophyll and is instead reflected or transmitted, giving leaves their green color. Therefore, the chlorophyll in the leaf absorbs red and blue light, while green light is not absorbed and is reflected back, making the leaf appear green.Rate this question:
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- 16.
The Calvin Cycle produces one molecule of glucose from which of the following three molecules?
- A.
ATP, HADPH, and O2
- B.
ATP, NADPH and CO2
- C.
CO2, H2O, and ATP
- D.
CO2, H2O, and O2
Correct Answer
B. ATP, NADPH and CO2Explanation
The Calvin Cycle is a series of chemical reactions that occur in the chloroplasts of plants during photosynthesis. It uses ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate) as energy sources, and CO2 (carbon dioxide) as a carbon source. These molecules are used to produce glucose, which is a sugar molecule that serves as a primary source of energy for the plant. Therefore, the correct answer is ATP, NADPH, and CO2.Rate this question:
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- 17.
In the balanced chemical equation for cellular respiration, C6H12O6 + 6O2 -> 6CO2 + 6H2O, which molecule is oxidized and which is reduced?
- A.
C6H12O6 is oxidized and CO2 is reduced
- B.
C6H12O6 is oxidized and O2 is reduced
- C.
O2 is oxidized and H2O is reduced
- D.
O2 is oxidized and C6H12O6 is reduced
Correct Answer
B. C6H12O6 is oxidized and O2 is reducedExplanation
In cellular respiration, glucose (C6H12O6) is oxidized, meaning it loses electrons, while oxygen (O2) is reduced, meaning it gains electrons. This is evident in the balanced chemical equation where glucose is converted into carbon dioxide (CO2) and oxygen is converted into water (H2O). The process of oxidation and reduction is a fundamental part of cellular respiration, where glucose is broken down to release energy for the cell to use.Rate this question:
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- 18.
Which of the following molecules is the final electron acceptor in lactic acid fermentation
- A.
NAD+
- B.
NADH
- C.
Pyruvate
- D.
O2
Correct Answer
C. PyruvateExplanation
Pyruvate is the final electron acceptor in lactic acid fermentation. During this process, glucose is converted into two molecules of pyruvate through glycolysis. In the absence of oxygen, pyruvate accepts electrons from NADH, which is generated during glycolysis. This electron transfer regenerates NAD+ to be used again in glycolysis, allowing for the continued production of ATP. Therefore, pyruvate acts as the final electron acceptor in lactic acid fermentation.Rate this question:
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- 19.
Which of the following is NOT a similarity between photosynthesis and chemosynthesis?
- A.
The electron donor in photosynthesis and chemosynthesis is water
- B.
The final electron acceptor in photosynthesis and chemosynthesis is carbon dioxide
- C.
Carbon dioxide is reduced to sugars in both processes
- D.
An inorganic molecule is a product of both processes
Correct Answer
A. The electron donor in photosynthesis and chemosynthesis is waterExplanation
Both photosynthesis and chemosynthesis involve the reduction of carbon dioxide to sugars and the production of an inorganic molecule as a product. However, the electron donor in photosynthesis is water, while in chemosynthesis, it is typically an inorganic molecule such as hydrogen sulfide or ammonia.Rate this question:
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- 20.
Which of the following structures is NOT bound by a cellular membrane?
- A.
Nucleus
- B.
Chloroplast
- C.
Ribosome
- D.
Lysosome
Correct Answer
C. RibosomeExplanation
Ribosomes are not bound by a cellular membrane. They are small, spherical structures found in both prokaryotic and eukaryotic cells. Ribosomes are responsible for protein synthesis and can be found either free-floating in the cytoplasm or attached to the endoplasmic reticulum. Unlike the other structures listed (nucleus, chloroplast, and lysosome), ribosomes do not have a membrane surrounding them.Rate this question:
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- 21.
Which of the following features distinguishes prokaryotic cells from eukaryotic cells?
- A.
Division by binary fission
- B.
The presence of DNA
- C.
An organized cell membrane
- D.
A rigid cell wall
Correct Answer
A. Division by binary fissionExplanation
Prokaryotic cells are distinguished from eukaryotic cells by their ability to divide by binary fission. Binary fission is a form of asexual reproduction where the cell divides into two identical daughter cells. Eukaryotic cells, on the other hand, undergo a more complex process of cell division called mitosis or meiosis. The presence of DNA, an organized cell membrane, and a rigid cell wall are characteristics shared by both prokaryotic and eukaryotic cells.Rate this question:
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- 22.
Which TWO of the following metabolic reactions occur in plants?
- A.
6CO2 +6H2O -> C6H12O6 + 6O2
- B.
C6H12O6 + 6O2 -> 6CO2 +6H2O
- C.
N2 + 8H+ + 8e- -> 2NH3 + H2
- D.
CO2 + 4H2S + O2 -> CH2O +4S + 3H2O
Correct Answer(s)
A. 6CO2 +6H2O -> C6H12O6 + 6O2
B. C6H12O6 + 6O2 -> 6CO2 +6H2OExplanation
The correct answer is 6CO2 + 6H2O -> C6H12O6 + 6O2 and C6H12O6 + 6O2 -> 6CO2 + 6H2O. These reactions represent photosynthesis, which is a metabolic process that occurs in plants. In photosynthesis, plants use carbon dioxide and water to produce glucose (C6H12O6) and oxygen. This process takes place in the chloroplasts of plant cells and is essential for the plant's survival and the production of oxygen in the atmosphere.Rate this question:
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- 23.
Which of the following is true about the phospholipids that make up the cellular membrane?
- A.
The phosphate heads of the bilayer interact with the extracellular environment and the cytoplasm
- B.
The phosphate heads of the bilayer interact with the cytoplasm only
- C.
The fatty acid tails of the bilayer interact with the extracellular environment and the cytoplasm.
- D.
The fatty acid tails of the bilayer interact with the cytoplasm only
Correct Answer
A. The phosphate heads of the bilayer interact with the extracellular environment and the cytoplasmExplanation
The phospholipids that make up the cellular membrane have phosphate heads that interact with both the extracellular environment and the cytoplasm. This is because the phosphate heads are polar and hydrophilic, meaning they are attracted to water and can interact with the aqueous environment on both sides of the membrane. The fatty acid tails, on the other hand, are nonpolar and hydrophobic, so they are shielded from the aqueous environment and interact with each other in the interior of the bilayer.Rate this question:
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- 24.
Which of the following protein fibers of the cytoskeleton are primarily responsible for the crawling movement of cells such as white blood cells?
- A.
Flagella
- B.
Intermediate filaments
- C.
Microtubules
- D.
Microfilaments
Correct Answer
D. MicrofilamentsExplanation
Microfilaments, also known as actin filaments, are primarily responsible for the crawling movement of cells such as white blood cells. These protein fibers are composed of actin and are involved in various cellular processes, including cell movement, contraction, and shape changes. They form a dynamic network that allows cells to extend protrusions called lamellipodia and filopodia, which help in cell crawling and migration. Microfilaments also interact with other cytoskeletal components and molecular motors to generate the necessary forces for cell movement.Rate this question:
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- 25.
Which of the following statements about the sodium-potassium pump is true?
- A.
Sodium ions are pumped into the cell; potassium ions are pumped out of the cell
- B.
The formation of ATP drives the action of the sodium-potassium pump
- C.
The sodium-potassium pump uses facilitated diffusion to move ions across the membrane
- D.
The sodium-potassium pump is powered by the oxidation of ATP
Correct Answer
D. The sodium-potassium pump is powered by the oxidation of ATPExplanation
The sodium-potassium pump is powered by the oxidation of ATP. This means that the pump uses the energy released from breaking down ATP molecules to move sodium ions out of the cell and potassium ions into the cell. This process is essential for maintaining the proper balance of sodium and potassium ions in cells, which is necessary for proper cell function and nerve impulse transmission.Rate this question:
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- 26.
Which of the following statements about diffusion is true?
- A.
Facilitated diffusion is the movement of molecules from areas of low to high concentration
- B.
Small molecules may move through the membrane by the process of simple diffusion
- C.
ATP drives the facilitated diffusion of molecules across the cell membrane
- D.
The movement of molecules by facilitated diffusion does not require a carrier protein
Correct Answer
B. Small molecules may move through the membrane by the process of simple diffusion -
- 27.
Which TWO of the following statemtns are true of a solution with a high water potential?
- A.
The solution consists of more free water molecules than a solution with a low water potential
- B.
The solution consists of fewer free water molecules than a solution with a low water potential
- C.
The concentration of solutes is high compared to a solution with a low water potential
- D.
The concentration of solutes is low compared to a solution with a low water potential
Correct Answer(s)
A. The solution consists of more free water molecules than a solution with a low water potential
D. The concentration of solutes is low compared to a solution with a low water potentialExplanation
A solution with a high water potential means that there is a high concentration of free water molecules, meaning that there are more water molecules available to move freely. This is in contrast to a solution with a low water potential, where there are fewer free water molecules. Additionally, a solution with a high water potential has a low concentration of solutes compared to a solution with a low water potential, indicating that there are fewer dissolved particles in the solution.Rate this question:
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- 28.
Which of the following will occur when a cell is placed in a hypotonic solution?
- A.
Water will move from outside the cell to inside the cell
- B.
Water will move from inside the cell to outside the cell
- C.
Solute will move from outside the cell to inside the cell
- D.
Solute will move from inside the cell to outside the cell
Correct Answer
A. Water will move from outside the cell to inside the cellExplanation
When a cell is placed in a hypotonic solution, it means that the concentration of solutes outside the cell is lower than inside the cell. In this situation, water will move from outside the cell to inside the cell in an attempt to equalize the concentration of solutes on both sides of the cell membrane. This movement of water is known as osmosis, and it helps maintain the cell's internal environment and prevent it from shrinking or shriveling.Rate this question:
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- 29.
Which of the following facilitates exocytosis in a cell?
- A.
Carrier proteins
- B.
Vesicles
- C.
Pores in the cell membrane
- D.
Cell-surface receptors
Correct Answer
B. VesiclesExplanation
Vesicles facilitate exocytosis in a cell. Exocytosis is the process by which cells release substances from their intracellular compartments into the extracellular space. Vesicles are small membrane-bound sacs that transport molecules within the cell. During exocytosis, these vesicles fuse with the cell membrane, allowing their contents to be released outside the cell. This process is essential for various cellular functions, including the secretion of hormones, neurotransmitters, and digestive enzymes. Carrier proteins, pores in the cell membrane, and cell-surface receptors do not directly facilitate exocytosis but may have other roles in cellular transport and signaling.Rate this question:
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- 30.
During labor, the body releases oxytocin, a hormone that speeds up the time between contractions. As contractions increase, more oxytocin is released, which speeds up the contractions, resulting in the release of more oxytocin. This cycle continues until the baby is born. This phenomenon described is an example of:
- A.
Positive feedback
- B.
Negative feedback
- C.
Homeostasis
- D.
Signal transduction
Correct Answer
A. Positive feedbackExplanation
The phenomenon described in the question is an example of positive feedback. Positive feedback occurs when a response to a stimulus amplifies or increases the original stimulus. In this case, the release of oxytocin during labor stimulates contractions, and as contractions increase, more oxytocin is released, further stimulating contractions. This cycle continues until the baby is born, resulting in a positive feedback loop.Rate this question:
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- 31.
The cell spends most of its life in which of the following phrases?
- A.
G1 phase
- B.
S phase
- C.
G2 phase
- D.
M phase
Correct Answer
A. G1 phaseExplanation
The G1 phase is the first phase of the cell cycle, where the cell grows and carries out its normal functions. It is also known as the gap phase. During this phase, the cell prepares itself for DNA replication and checks for any errors or damage in the DNA. The G1 phase is the longest phase of the cell cycle and the cell spends most of its life in this phase before progressing to the S phase, where DNA replication occurs.Rate this question:
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- 32.
Apoptosis prevents a cell from transition to which of the following phases of cell division?
- A.
G1 phase
- B.
S phase
- C.
G2 phase
- D.
M phase
Correct Answer
D. M phaseExplanation
Apoptosis prevents a cell from transitioning to the M phase of cell division. The M phase, also known as mitosis, is the phase where the cell divides into two daughter cells. Apoptosis is a programmed cell death mechanism that occurs in response to various signals, such as DNA damage or cell stress. It helps to eliminate damaged or unnecessary cells from the body. By preventing the transition to the M phase, apoptosis ensures that only healthy cells continue with cell division, maintaining the integrity and functionality of tissues and organs.Rate this question:
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- 33.
At the end of which of the following phases are chromosomes first clearly visible under a light microscope?
- A.
Interphase
- B.
Prophase
- C.
Metaphase
- D.
Telophase
Correct Answer
B. ProphaseExplanation
During prophase, the first stage of mitosis, the chromosomes condense and become visible under a light microscope. This is because the chromatin fibers, which are normally spread out and diffuse in the nucleus during interphase, start to coil and condense into tightly packed structures. As a result, the chromosomes become distinct and can be observed as condensed, thread-like structures. Therefore, at the end of prophase, the chromosomes are first clearly visible under a light microscope.Rate this question:
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- 34.
In which of the following phases of mitosis does the nucleolus reappear?
- A.
Prophase
- B.
Metaphase
- C.
Anaphase
- D.
Telophase
Correct Answer
D. TelophaseExplanation
During telophase, the final phase of mitosis, the nucleolus reappears. Telophase is characterized by the reformation of the nuclear envelope around the separated daughter chromosomes, and the nucleolus, which is responsible for the production of ribosomes, becomes visible again within the newly formed nuclei.Rate this question:
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- 35.
Which of the following processes occurs during anaphase I of meiosis?
- A.
The spindle pulls homologous chromosomes to either side of the cell
- B.
The spindle pulls sister chromatids to either side of the cell
- C.
Chromosomes align along the metaphase plate
- D.
Two diploid (2n) daughter cells are formed
Correct Answer
A. The spindle pulls homologous chromosomes to either side of the cellExplanation
During anaphase I of meiosis, the spindle pulls homologous chromosomes to either side of the cell. This is a crucial step in meiosis as it ensures that each daughter cell receives one copy of each homologous chromosome, resulting in genetic variation. This separation of homologous chromosomes is different from anaphase II, where the spindle pulls sister chromatids apart. The alignment of chromosomes along the metaphase plate occurs during metaphase I, and the formation of two diploid daughter cells occurs at the end of telophase II.Rate this question:
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- 36.
Which of the following statements about meiosis is true?
- A.
The process of meiosis includes on nuclear division
- B.
Recombination occurs during the first phase of meiosis
- C.
Chromosomes replicate prior to meiosis II
- D.
Meiosis results in four diploid (2n) daughter cells
Correct Answer
B. Recombination occurs during the first phase of meiosisExplanation
During meiosis, recombination occurs during the first phase, known as prophase I. Recombination involves the exchange of genetic material between homologous chromosomes, resulting in genetic variation. This process is essential for the production of genetically diverse gametes. Meiosis consists of two nuclear divisions, meiosis I and meiosis II, and chromosomes replicate prior to meiosis I. Meiosis results in the production of four haploid (n) daughter cells, not diploid cells.Rate this question:
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- 37.
Which of the following nucleotides are two ringed nitrogenous bases?
- A.
Adenosine and thymine
- B.
Cytosine and thymine
- C.
Adenine and guanine
- D.
Guanine and cytosine
Correct Answer
C. Adenine and guanineExplanation
Adenine and guanine are two ringed nitrogenous bases. Nucleotides are composed of three components: a sugar molecule, a phosphate group, and a nitrogenous base. The nitrogenous bases can be categorized into two types: purines and pyrimidines. Adenine and guanine are purines, which means they have a double-ring structure. On the other hand, thymine and cytosine are pyrimidines, which have a single-ring structure. Therefore, the correct answer is adenine and guanine.Rate this question:
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- 38.
Which of the following statements about RNA are true? Select all that apply
- A.
Hydrogen bonds form between A - T and G - C bases
- B.
A sequence of RNA will not contain T bases but will contain U bases
- C.
RNA is single stranded
- D.
RNA is double stranded
Correct Answer(s)
B. A sequence of RNA will not contain T bases but will contain U bases
C. RNA is single strandedExplanation
RNA is single stranded and contains uracil (U) bases instead of thymine (T). Hydrogen bonds form between adenine (A) and uracil (U) bases, as well as between guanine (G) and cytosine (C) bases. Therefore, the correct statements are that a sequence of RNA will not contain T bases but will contain U bases, and RNA is single stranded.Rate this question:
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- 39.
All of the following properties are not shared by chromosomes in an individual somatic cell EXCEPT
- A.
Size
- B.
Shape
- C.
Location of the centromere
- D.
Presence of telomeres
Correct Answer
A. SizeExplanation
Chromosomes in an individual somatic cell share properties such as shape, location of the centromere, and presence of telomeres. However, size is not a property that is shared by all chromosomes in a somatic cell. Each chromosome can vary in size depending on the specific genetic material it carries. Therefore, size is the correct answer as it is the only property that is not shared by all chromosomes in an individual somatic cell.Rate this question:
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- 40.
If a strand of DNA has the base sequence 5' AAGCCCTATAC 3', what would the corresponding base sequence in the complementary strand of DNA?
- A.
3' UUCGGGAUAUG 5'
- B.
3' TTCGGGATATG 5'
- C.
3' GTATAGGGCTT 5'
- D.
3' GUAUAGGGCUU 5'
Correct Answer
B. 3' TTCGGGATATG 5'Explanation
The given question asks for the corresponding base sequence in the complementary strand of DNA. In DNA, adenine (A) pairs with thymine (T) and guanine (G) pairs with cytosine (C). Therefore, the complementary strand of DNA would have the opposite sequence of bases. In this case, the complementary sequence would be 3' TTCGGGATATG 5', which matches the given answer.Rate this question:
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- 41.
DNA is replicated during which of the following cell phases?
- A.
C phase
- B.
M phase
- C.
S phase
- D.
G1 phase
Correct Answer
C. S phaseExplanation
During the S phase of the cell cycle, DNA replication occurs. This is the phase where the cell's DNA is duplicated in preparation for cell division. The S phase follows the G1 phase, during which the cell grows and prepares for DNA replication. After the S phase, the cell enters the G2 phase, where it continues to grow and prepare for cell division. Therefore, the correct answer is S phase.Rate this question:
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- 42.
Which of the following best describes the process of transcription and translation?
- A.
RNA -> protein -> DNA
- B.
DNA -> protein -> RNA
- C.
Protein -> DNA -> RNA
- D.
DNA -> RNA -> protein
Correct Answer
D. DNA -> RNA -> proteinExplanation
The process of transcription and translation involves the conversion of DNA into RNA and then the translation of RNA into protein. Transcription is the process in which DNA is transcribed into RNA, while translation is the process in which RNA is translated into protein. Therefore, the correct sequence is DNA -> RNA -> protein.Rate this question:
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- 43.
If a strand of DNA has the base sequence 5' AAGCCCTATAC 3', what would be the corresponding base sequence on the mRNA transcript?
- A.
3' UUCGGGAUAUG 5'
- B.
3' TTCGGGATATG 5'
- C.
3' GTATAGGGCTT 5'
- D.
3' GUAUAGGGCUU 5'
Correct Answer
A. 3' UUCGGGAUAUG 5'Explanation
The mRNA transcript is synthesized using the complementary base pairing rule, where adenine pairs with uracil, cytosine pairs with guanine, guanine pairs with cytosine, and thymine pairs with adenine. Therefore, the corresponding base sequence on the mRNA transcript would be 3' TTCGGGATATG 5'.Rate this question:
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- 44.
RNA processing in a eukaryotic cell occurs in which of the following locations?
- A.
Ribosomes
- B.
Cell membranes
- C.
Cytoplasm
- D.
Nucleus
Correct Answer
D. NucleusExplanation
RNA processing in a eukaryotic cell occurs in the nucleus. This is because the nucleus is where transcription, the first step of gene expression, takes place. During transcription, the DNA sequence is copied into a pre-mRNA molecule. This pre-mRNA molecule then undergoes various processing steps, such as the removal of introns and addition of a poly-A tail, to form the mature mRNA. Once the mRNA is processed, it can then be transported out of the nucleus and into the cytoplasm, where it can be translated into protein by ribosomes. Therefore, the correct location for RNA processing in a eukaryotic cell is the nucleus.Rate this question:
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- 45.
The process of removing introns from the pre-mRNA molecule in a eukaryotic cell is called:
- A.
Ligation
- B.
Splicing
- C.
Polyadenylation
- D.
Initiation
Correct Answer
B. SplicingExplanation
Splicing is the correct answer because it refers to the process of removing introns, non-coding regions, from the pre-mRNA molecule in a eukaryotic cell. During splicing, the remaining exons, coding regions, are joined together to form the mature mRNA molecule that can be translated into a protein. Ligation refers to the joining of two DNA or RNA fragments, polyadenylation is the addition of a poly(A) tail to the mRNA, and initiation refers to the beginning of transcription or translation.Rate this question:
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- 46.
Which of the following is the site at which the tRNAs are released from the ribosome?
- A.
P site
- B.
E site
- C.
Elongation site
- D.
Termination site
Correct Answer
B. E siteExplanation
The E site is the site at which the tRNAs are released from the ribosome. During translation, the ribosome moves along the mRNA molecule and as each tRNA molecule delivers its amino acid, it moves from the A site to the P site, and finally to the E site where it is released from the ribosome. The E site is responsible for the exit of the tRNA, allowing for the next tRNA to enter the A site and continue the elongation process.Rate this question:
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- 47.
At an ACU codon, the amino acid threonine will be inserted in the growing polypeptide. What is the anticodon of the tRNA molecule that brings threonine to the ribosome?
- A.
ACU
- B.
UCA
- C.
TGA
- D.
UGA
Correct Answer
A. ACUExplanation
The anticodon of the tRNA molecule that brings threonine to the ribosome is UGA. This is because the anticodon is complementary to the codon on the mRNA strand, and UGA is the complementary anticodon to the ACU codon.Rate this question:
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- 48.
Which of the following is true of an enhancer?
- A.
Enhancers are a form of promoter in a bacterial cell
- B.
Enhancers are enzymes that help in the transcription of DNA
- C.
Enhancers are located at a distance to the promoter
- D.
Enhancers are proteins that bind and activate RNA polymersae
Correct Answer
C. Enhancers are located at a distance to the promoterExplanation
Enhancers are DNA sequences that are located at a distance from the promoter. They can increase the transcription of genes by binding to specific transcription factors and enhancing the recruitment of RNA polymerase to the promoter region. This allows for the regulation of gene expression in a spatial and temporal manner. Unlike promoters, enhancers do not have a fixed position or orientation relative to the gene they regulate, and can be located upstream, downstream, or even within introns of the gene.Rate this question:
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- 49.
In both prokaryotes and eukaryotes, the regulation of gene expression most commonly occurs at which point?
- A.
Post-transcription
- B.
Post-translation
- C.
Transcription
- D.
Translation
Correct Answer
C. TranscriptionExplanation
Gene expression refers to the process by which information from a gene is used to create a functional product, such as a protein. Regulation of gene expression involves controlling when and how often a gene is transcribed into RNA. The correct answer is transcription because this is the point at which the genetic information in DNA is copied into RNA. Regulation at this stage allows the cell to control the amount of RNA produced, which ultimately affects the amount of protein that is synthesized. Post-transcription and post-translation refer to processes that occur after transcription, while translation is the process of synthesizing a protein from RNA.Rate this question:
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- 50.
Cell A and Cell B carry the same genes, including Gene 1, Gene 2, Gene 3, and Gene 4. Which of the following scenarios best describes differential gene expression?
- A.
Cell A expresses all four genes; Cell B expresses all four genes
- B.
Cell A expresses only Genes 1 and 2, Cell B expresses only genes 1 and 2
- C.
Cell A expresses only genes 3 and 4, Cell B expresses only genes 3 and 4
- D.
Cell A expresses only genes 1 and 2, Cell B expresses only genes 3 and 4
Correct Answer
D. Cell A expresses only genes 1 and 2, Cell B expresses only genes 3 and 4Explanation
This scenario best describes differential gene expression because it shows that different genes are being expressed in each cell. In Cell A, only genes 1 and 2 are expressed, while in Cell B, only genes 3 and 4 are expressed. This indicates that there is a difference in gene expression between the two cells, as they are expressing different sets of genes.Rate this question:
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