DNA Molecule And DNA Fragments Quiz

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1/50 Questions

The role of pigments is to
- Absorb light energy to excite electrons
- It uses the carbon atoms to add to RuBP
- Combine O2 and H to make water
- Splite disaccharides into monosaccharides

About This Quiz

Can you answer the following DNA questions? Test your knowledge on this science quiz to see how you do and compare your score to others.

DNA Molecule And DNA Fragments Quiz - Quiz

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2.

Experimental evidence shows that the process of glycolysis is present and virtually identical in organisms from all three domains, Archaea,Bacteria, and Eukarya. Which of the following hypotheses could be best supported by this evidence?
- All organisms carry out glycolysis in mitochondria.
- Glycolysis is a universal energy-releasing process and therefore suggests a common ancestor for all forms of life.
- Across the three domains, all organisms depend solely on the process of anaerobic respiration for ATP production.
- The presence of glycolysis as an energyreleasing process in all organisms suggests that convergent evolution occurred.
Correct Answer

A. Glycolysis is a universal energy-releasing process and therefore suggests a common ancestor for all forms of life.

Explanation

The experimental evidence that glycolysis is present and virtually identical in organisms from all three domains suggests that this process is universal and shared by all forms of life. This supports the hypothesis that there is a common ancestor for all organisms, as the presence of glycolysis in such diverse organisms implies that it was present in their common ancestor and has been maintained throughout evolution. This hypothesis is the best supported by the evidence provided.

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3.

In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of
- ATP, CO2, and ethanol (ethyl alcohol).
- ATP, NADH, and pyruvate.
- ATP, pyruvate, and oxygen.
- ATP, pyruvate, and acetyl CoA.
Correct Answer

A. ATP, CO2, and ethanol (ethyl alcohol).

Explanation

In the absence of oxygen, yeast cells undergo fermentation to obtain energy. During fermentation, glucose is broken down into pyruvate, which is then converted into ethanol (ethyl alcohol) and carbon dioxide (CO2). This process also produces a small amount of ATP, which is the energy currency of cells. Therefore, the correct answer is ATP, CO2, and ethanol (ethyl alcohol).

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4.

Which products from the LDR are required for the Calvin Cycle?
- C6H12O6 and O2
- CO2, O2
- ATP and NADPH
- H+ ions, and e-s
Correct Answer

A. ATP and NADPH

Explanation

The Calvin Cycle is a series of chemical reactions that occur in the chloroplasts of plants during photosynthesis. It is responsible for converting carbon dioxide (CO2) into glucose (C6H12O6). ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate) are both necessary for the Calvin Cycle to occur. ATP provides the energy needed for the reactions, while NADPH provides the electrons necessary for the reduction of CO2. Therefore, the correct answer is ATP and NADPH.

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5.

Most energy during cell respiration is harvested during
- The Krebs cycle
- Oxidative phosphoralation
- Glycolysis
- Anaerobic respiration
Correct Answer

A. Oxidative phosphoralation

Explanation

Oxidative phosphorylation is a process that occurs in the inner mitochondrial membrane and is responsible for the majority of energy production during cell respiration. It involves the transfer of electrons from electron carriers produced during the Krebs cycle to the electron transport chain. This transfer of electrons generates a proton gradient, which is then used by ATP synthase to produce ATP. Therefore, oxidative phosphorylation is the main process in which energy is harvested during cell respiration.

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6.

CAM plants keep their stomates closed during the daytime to reduce excess water loss. They can do this because they
- Can fix CO2 into sugars in the mesophyll cells
- Can use the photosystems I and II at night.
- Modify rubisco so it does not bind with oxygen.
- Can incorporate CO2 into organic acids at night.
Correct Answer

A. Can incorporate CO2 into organic acids at night.

Explanation

CAM plants, or Crassulacean Acid Metabolism plants, have a unique adaptation to reduce water loss. They keep their stomates closed during the daytime when it is hot and dry, and open them at night when it is cooler and more humid. This allows them to take in carbon dioxide (CO2) without losing excessive amounts of water through transpiration. During the night, CAM plants incorporate CO2 into organic acids, which are stored in the vacuoles of their cells. Then, during the daytime, these organic acids are broken down, releasing CO2 for photosynthesis. This process helps CAM plants conserve water while still being able to fix CO2 and produce sugars.

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7.

Select all correct answers: Hormones affect cells in many parts of the organism. Hormones...
- Begin signal transduction in cells that have receptor proteins in the membrane.
- Are only found in animals.
- Affect all cells the same way.
- Affect each cell type differently.
Correct Answer(s)

A. Begin signal transduction in cells that have receptor proteins in the membrane.
A. Affect each cell type differently.

Explanation

Hormones begin signal transduction in cells that have receptor proteins in the membrane because hormones bind to these receptors, initiating a cascade of events that ultimately leads to a cellular response. This process allows hormones to communicate with specific target cells and regulate various physiological processes. Additionally, hormones do not affect all cells the same way; instead, they have specific effects on different cell types based on the presence of specific receptors and signaling pathways. Therefore, hormones can affect each cell type differently.

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8.

From the perspective of the cell receiving the message, the three stages of cell signaling are
- Signal reception, signal transduction, and cellular response
- Signal reception, nucleus disintegration, and new cell generation
- The alpha, beta, and gamma stages
- Signal reception, cellular response, and cell division
Correct Answer

A. Signal reception, signal transduction, and cellular response

Explanation

The correct answer is signal reception, signal transduction, and cellular response. In cell signaling, the first stage is signal reception, where a cell detects a signaling molecule from its environment. The second stage is signal transduction, where the signal is transmitted through a series of molecular events within the cell, often involving protein modifications and activation of signaling pathways. Finally, the cellular response occurs, which is the specific action or change in behavior of the cell as a result of the signaling pathway. Therefore, this answer accurately describes the three stages of cell signaling.

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9.

Guard cells do which of the following? (the cells that make the stomata)
- Help balance the photosynthesis-transpiration compromise
- Guard against mineral loss through the stomata
- Contain chloroplasts that import directly into the cells
- Accumulate and close the stomata
Correct Answer

A. Help balance the photosynthesis-transpiration compromise

Explanation

Guard cells help balance the photosynthesis-transpiration compromise. Stomata, which are regulated by guard cells, allow for the exchange of gases such as carbon dioxide and oxygen during photosynthesis. However, the opening of stomata also leads to water loss through transpiration. Guard cells are able to adjust the size of the stomatal opening to regulate the balance between carbon dioxide uptake and water loss, ensuring that the plant can carry out photosynthesis efficiently while minimizing excessive water loss.

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10.

Which of the following experimental procedures would most likely reduce transpiration while allowing the normal growth of a plant?
- Subjecting the leaves of the plant to a partial vacuum
- Increasing the level of carbon dioxide around the plant
- Decreasing the relative humidity around the plant
- Increasing the exposure to direct sunlight
Correct Answer

A. Increasing the level of carbon dioxide around the plant

Explanation

Increasing the level of carbon dioxide around the plant would most likely reduce transpiration while allowing the normal growth of a plant. This is because when the carbon dioxide concentration is higher, the stomata on the plant's leaves can partially close, reducing the loss of water through transpiration. At the same time, the increased carbon dioxide can also enhance photosynthesis and promote plant growth.

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11.

Which of the following describes the events of apoptosis?
- The cell dies, it is lysed, its organelles are phagocytized, its contents are recycled.
- Its DNA and organelles become fragmented, it dies, and it is phagocytized.
- The cell dies and the presence of its fragmented contents stimulates nearby cells to divide.
- Its DNA and organelles are fragmented, the cell shrinks and forms blebs, and the cell self-digests.
Correct Answer

A. Its DNA and organelles are fragmented, the cell shrinks and forms blebs, and the cell self-digests.

Explanation

The correct answer describes the events of apoptosis as follows: the DNA and organelles of the cell become fragmented, the cell shrinks and forms blebs (protrusions on the cell surface), and the cell undergoes self-digestion. This process is a controlled and programmed form of cell death, where the cell breaks down its own components and is eventually eliminated without causing inflammation or damage to surrounding tissues.

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12.

Crossing-over during meiosis permits scientists to determine
- The chance for variation in zygotes
- The rate of mutations
- The distance between genes on a chromosome
- Which traits are dominant or recessive
Correct Answer

A. The distance between genes on a chromosome

Explanation

During meiosis, crossing-over occurs when homologous chromosomes exchange genetic material. This process creates new combinations of alleles, resulting in genetic variation in zygotes. By studying the frequency of crossing-over events, scientists can determine the distance between genes on a chromosome. The closer two genes are to each other, the less likely they are to undergo crossing-over, while genes that are farther apart have a higher chance of crossing-over. Therefore, crossing-over during meiosis allows scientists to estimate the distance between genes on a chromosome.

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13.

What are the 3 parts of a nucleotide?
- Sugar, Phosphate, lipid base
- Phosphate, 6 carbon sugar, Nitrogen Base
- 5 carbon sugar, Phosphate, Lipase
- 5 carbon sugar, Phosphate, and Nitrogenous Base
Correct Answer

A. 5 carbon sugar, Phosphate, and Nitrogenous Base

Explanation

A nucleotide is composed of three parts: a 5 carbon sugar, a phosphate group, and a nitrogenous base. The 5 carbon sugar provides the backbone of the nucleotide, the phosphate group connects the sugars together, and the nitrogenous base is responsible for the genetic coding and determines the specific nucleotide.

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14.

Sections of DNA actually code for how to make...
- Spores
- Nucleic acids
- Protiens
- Anti-codon
Correct Answer

A. Protiens

Explanation

Sections of DNA actually code for how to make proteins. DNA contains genes, which are specific sequences of nucleotides that provide instructions for the synthesis of proteins. Proteins are essential molecules involved in various biological processes, such as cell structure, metabolism, and signaling. The process of protein synthesis begins with the transcription of DNA into RNA, followed by translation of RNA into amino acids, which are then assembled into proteins. Therefore, the correct answer is proteins.

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15.

These small bits of DNA fragments attach because the DNA Template strand must be replicated from the 5’ – 3’ direction.
- Okazaki fragments
- RNA Primers
- DNA SnRPs
- Exons
Correct Answer

A. Okazaki fragments

Explanation

Okazaki fragments are short, discontinuous segments of DNA that are synthesized on the lagging strand during DNA replication. The lagging strand is synthesized in the opposite direction of the leading strand, from 5' to 3' direction. Due to the antiparallel nature of DNA strands, DNA polymerase can only add nucleotides in the 5' to 3' direction. Therefore, to replicate the lagging strand, it is synthesized in short fragments called Okazaki fragments, which are later joined together by DNA ligase. This process ensures that both DNA strands are replicated accurately.

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16.

The ____________________ helps to remove the introns and put the exons together in the nucleus.
- Helicase
- Ligase
- Spliceosome
- Promoter
Correct Answer

A. Spliceosome

Explanation

The spliceosome is a complex of proteins and RNA molecules that is responsible for removing introns (non-coding regions) from pre-mRNA molecules and joining together the exons (coding regions) to form mature mRNA. This process, known as splicing, occurs in the nucleus of eukaryotic cells. Therefore, the spliceosome is the correct answer as it specifically performs the function described in the question.

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17.

The nucleotide sequence of a DNA molecule is 5'-C-A-T-3'. A mRNA molecule molecule with a coplementary codon is transcribed from the DNA in the process of protein synthesis a tRNA pairs with a mRNA codon. What is the nucleotide sequence of the tRNA anti-codon?
- 5'-G-T-A-3'
- 5'-G-U-A-3'
- 5'-C-A-U-3'
- 5'-U-A-C-3'
Correct Answer

A. 5'-C-A-U-3'

Explanation

The mRNA molecule is transcribed from the DNA molecule, so it will have a complementary sequence to the DNA sequence. In DNA, adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G). Therefore, in the mRNA molecule, the nucleotide sequence will be 5'-G-U-A-3'. The tRNA molecule pairs with the mRNA codon, so the tRNA anti-codon will have a complementary sequence to the mRNA codon. Therefore, the nucleotide sequence of the tRNA anti-codon will be 5'-C-A-U-3'.

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18.

The correct sequence between genes and their phenotypic expression is
- RNA-DNA-protein-trait
- DNA-RNA-protein-trait
- Protein-DNA-RNA-trait
- Trait-DNA-RNA-protein
Correct Answer

A. DNA-RNA-protein-trait

Explanation

The correct sequence between genes and their phenotypic expression is DNA-RNA-protein-trait. Genes are segments of DNA that contain the instructions for making proteins. The process of gene expression begins with the transcription of DNA into RNA, which is then translated into proteins. Proteins are the molecules responsible for carrying out various functions in cells, and they ultimately determine the traits or characteristics exhibited by an organism. Therefore, the correct sequence for the expression of genes and phenotypic traits starts with DNA, followed by RNA, protein, and finally, the trait.

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19.

Once transcribed, eukaryotic mRNA typically undergoes substantial alteration thatincludes
- excision of introns.
- fusion into circular forms known as plasmids.
- Fusion with other newly transcribed mRNA
- Linkage to histone molecules.
Correct Answer

A. excision of introns.

Explanation

Eukaryotic mRNA undergoes substantial alteration after transcription, which includes the removal of introns. In contrast to prokaryotic mRNA, eukaryotic mRNA contains non-coding regions called introns that need to be removed before the mRNA can be translated into protein. This process is known as splicing and is essential for the production of functional proteins. The excision of introns ensures that only the coding regions, called exons, are present in the mature mRNA molecule. This process allows for the production of diverse proteins from a single gene through alternative splicing.

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20.

Which of the following are true of RNAi.Choose all that apply.
- It works to stop transcription from occuring
- It evolved to help stop viral infections
- It is found only in prokaryotes
- It was discovered when trying to genetically engineer a flower
Correct Answer(s)

A. It works to stop transcription from occuring
A. It evolved to help stop viral infections
A. It was discovered when trying to genetically engineer a flower

Explanation

RNAi, or RNA interference, is a biological process that regulates gene expression. It works to stop transcription from occurring by degrading mRNA molecules, preventing them from being translated into proteins. RNAi evolved as a defense mechanism against viral infections, helping to silence viral genes and limit their replication. Additionally, RNAi was discovered when scientists were attempting to genetically engineer a flower, specifically the petunia, and observed an unexpected suppression of gene expression.

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21.

Why do eukaryotes express a significantly smaller percentage of their genes than prokaryotes?
- Eukaryotes are less complex than prokaryotes and can not control which genes are randomly expressed.
- Eukaryotic cells are often specialized and need only to express specific regions of the DNA.
- Prokaryotes use and transcribe all of their DNA, while only eukaryotes have "junk DNA" which does not code for anything.
- Only Eukaryotes have ribosomes which transcribes specific sections of DNA.
Correct Answer

A. Eukaryotic cells are often specialized and need only to express specific regions of the DNA.

Explanation

Eukaryotic cells are often specialized and need only to express specific regions of the DNA. This is because different cells in eukaryotes have different functions and therefore require different sets of genes to be expressed. Specialized cells only activate the genes that are necessary for their specific function, while the rest of the genes remain inactive. This allows for efficient gene regulation and conservation of energy and resources. In contrast, prokaryotes do not have specialized cells and therefore need to use and transcribe all of their DNA.

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22.

Which is most affected by the fact that many viruses viral envelope is derived from its host's cell?
- It is more likely to infect other host cells undetected in animals.
- It protects the integrity of the viral genome.
- It reduces genetic variation in the host DNA
- It increases genetic variation of viral RNA
Correct Answer

A. It is more likely to infect other host cells undetected in animals.

Explanation

The fact that many viruses derive their viral envelope from their host's cell makes it more likely for them to infect other host cells undetected in animals. The viral envelope is derived from the host's cell membrane, which allows the virus to camouflage itself and evade detection by the host's immune system. This increases the chances of successful infection and replication within the host, as the virus can go unnoticed and spread to other cells.

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23.

Photosynthesis has been occuring on this planet for approximately 3 billion years. In this time plants have evolved from small single celled bacteria in the ocean and diversified into many ecological niches. Some plants on earth such as giant sequoia manage to transport water 100s of meters into the air without the use of a pump. This is made possible by vascular tissue composed of small tubes that transport the water. They are able to do this because
- Hydrogen bonds among water molecules give it cohesive properties
- Water has adhesive properties
- Water is polar
- All of the above
Correct Answer

A. All of the above

Explanation

Plants are able to transport water 100s of meters into the air without the use of a pump because of the cohesive properties of water molecules due to hydrogen bonds. These hydrogen bonds allow water molecules to stick together, forming a continuous column of water that can be pulled up through the plant's vascular tissue. Additionally, water has adhesive properties, meaning it can stick to other surfaces, which helps it adhere to the walls of the plant's vascular tubes. Lastly, water is polar, meaning it has a positive and negative end, allowing it to interact with other polar molecules and move upward through the plant. Therefore, all of the given options are correct explanations for how plants can transport water without a pump.

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24.

Identical heat lamps are arranged to shine on identical containers of water and methanol (wood alcohol), so that each liquid absorbs the same amount of energy minute by minute. The covalent bonds of methanol molecules are non-polar, so there are no hydrogen bonds among methanol molecules. Which of the following graphs correctly describes what will happen to the temperature of the water and the methanol?
- A
- B
- C
- D
Correct Answer

A. B

Explanation

The correct answer is B because water has hydrogen bonding, which allows it to have a higher specific heat capacity compared to methanol. This means that water can absorb more energy before its temperature increases. As a result, the temperature of water will increase at a slower rate compared to methanol. Therefore, the graph for water shows a gradual increase in temperature over time, while the graph for methanol shows a steeper increase in temperature.

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25.

In general, animal cells differ from plant cells in that animal cells have
- A cell wall made of cellulose
- Lysosomes
- Large vacuoles that store water
- Chloroplasts
Correct Answer

A. Lysosomes

Explanation

Animal cells differ from plant cells in that they have lysosomes. Lysosomes are membrane-bound organelles that contain digestive enzymes. They play a crucial role in breaking down waste materials, cellular debris, and foreign substances. Plant cells, on the other hand, do not have lysosomes. Instead, plant cells have a cell wall made of cellulose, large vacuoles that store water, and chloroplasts for photosynthesis.

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26.

Five dialysis bags, constructed from a semi-permeable membrane that is impermeable to sucrose, were filled with various concentrations of sucrose and then placed in separate beakers containing an initial concentration of 0.6 M sucrose solution. At 10-minute intervals, the bags were massed (weighed) and the percent change in mass of each bag was graphed. Which line represents the bag with the lowest initial concentration of sucrose?
- A
- B
- D
- E
Correct Answer

A. E
27.

Which of the following is an example of a hydrogen bond?
- The peptide bond between amino acids in a protein
- The bonds between two different proteins to create a quaternary structure
- The bond between Na+ and Cl- in salt
- The bond between carbon and hydrogen in methane (CH4)
Correct Answer

A. The bonds between two different proteins to create a quaternary structure
28.

The plasma membrane has many important functions. It is made of a phospholipid bi-layer that has proteins, cholesterol molecules, glycoproteins, and many other molecules embedded in it. Proteins in the plasma membrane serve six major functions: transport, enzymatic activity, signal transduction, cell-cell recogniton, intercellular joining, and attachment to the cytoskeleton. If you were to change the pH of the solution that surrounds the cell, what would be most likely to change as a result.
- The rate of lateral movement of phospholipids
- The ability to move large molecules accross the concentration gradient
- The rate of diffusion of small ions
- All of the above
Correct Answer

A. The ability to move large molecules accross the concentration gradient

Explanation

Changing the pH of the solution surrounding the cell is most likely to affect the ability to move large molecules across the concentration gradient. This is because the plasma membrane plays a crucial role in regulating the movement of molecules in and out of the cell. The concentration gradient refers to the difference in concentration of a substance between two areas. Changing the pH can alter the charge and shape of proteins embedded in the plasma membrane, which are responsible for facilitating the transport of large molecules across the concentration gradient.

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29.

The presence of cholesterol in the plasma membranes of some animals
- Enables the membrane to stay fluid more easily when cell temperature drops.
- Enables the animal to remove hydrogen atoms from saturated phospholipids
- Enables the animal to add hydrogen atoms to unsaturated phospholipids.
- Makes the membrane less flexible, allowing it to sustain greater pressure from within the cell.
Correct Answer

A. Enables the membrane to stay fluid more easily when cell temperature drops.

Explanation

Cholesterol is a lipid molecule that is present in the plasma membrane of animal cells. It has a unique structure that allows it to insert itself between the phospholipids in the membrane. This helps to regulate the fluidity of the membrane. When the temperature drops, the phospholipids tend to pack together more closely, which can make the membrane less fluid and more rigid. However, the presence of cholesterol prevents this from happening by disrupting the packing of the phospholipids. As a result, the membrane remains fluid even at lower temperatures, allowing the cell to function properly.

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30.

In a lab experiment students measured the reaction rates of the enzyme catalase on Hydrogen Peroxide. The yellow line represents the control in the experiment. Which color line would most likely represent an increase in the amount of catalase?
- Red
- Green
- Blue
- Gray
Correct Answer

A. Blue

Explanation

In the lab experiment, the students measured the reaction rates of the enzyme catalase on Hydrogen Peroxide. The yellow line represents the control in the experiment, which means it shows the normal reaction rate of catalase. The question asks which color line would most likely represent an increase in the amount of catalase. Since an increase in the amount of catalase would result in a faster reaction rate, the blue line would most likely represent this increase as it is higher than the yellow line.

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31.

The graph below demonstrates two chemical reactions. One is catalyzed by an enzyme, one is not. Which letter shows the energy of activation for the enzyme?
- A
- B
- C
- D
Correct Answer

A. C

Explanation

In the graph, the energy of activation represents the energy required for a chemical reaction to occur. The enzyme lowers the energy of activation, making the reaction easier and faster. In this case, letter C shows the energy of activation for the enzyme because it is lower compared to the energy of activation for the non-catalyzed reaction (represented by the other letters A, B, and D).

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32.

Which of the following is a major cause of the size limits for certain types of cells?
- The evolution of larger cells after the evolution of smaller cells
- The difference in plasma membranes between prokaryotes and eukaryotes
- The need for a large surface area to volume ratio to allow the cells's function
- The observation that longer cells usually have a greater cell volume
Correct Answer

A. The need for a large surface area to volume ratio to allow the cells's function

Explanation

The need for a large surface area to volume ratio is a major cause of the size limits for certain types of cells. This is because as a cell grows larger, its volume increases faster than its surface area. A large surface area is necessary for the cell to efficiently exchange materials with its environment, such as taking in nutrients and expelling waste products. Therefore, cells must maintain a high surface area to volume ratio to ensure proper functioning.

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33.

Which of the following is likely to lead to an increase in the concentration of ATP in a cell?
- An increase in a cell's anabolic activity
- An increase in a cell's catabolic activity
- An increased amino acid concentration
- An increase in complex carbohydrates
Correct Answer

A. An increase in a cell's catabolic activity

Explanation

An increase in a cell's catabolic activity is likely to lead to an increase in the concentration of ATP in a cell. Catabolic activity involves the breakdown of complex molecules, such as carbohydrates, fats, and proteins, to release energy. ATP is the primary energy currency in cells, and it is produced during cellular respiration, which is a catabolic process. Therefore, an increase in catabolic activity would result in more ATP being produced, leading to an increase in its concentration in the cell.

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34.

Which of the following statements best describes an allosteric binding site?
- It is a binding site that can accept a wide variety of differently shaped molecules.
- It is a binding site, which is separate from the active site, and affects the activity of an enzyme when it is occupied by a ligand.
- It is a description of an active site which has undergone an induced fit.
- It has no affect on the function of the enzymatic activity.
Correct Answer

A. It is a binding site, which is separate from the active site, and affects the activity of an enzyme when it is occupied by a ligand.

Explanation

An allosteric binding site is a separate binding site from the active site of an enzyme. When this site is occupied by a ligand, it can affect the activity of the enzyme. This means that the binding of a molecule to the allosteric site can either enhance or inhibit the enzyme's function. It provides a mechanism for regulation and control of enzyme activity, allowing for fine-tuning of biochemical processes.

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35.

Penicillin is an antibiotic. It helps people get better from a variety of bacterial infections. Penicillin works by attaching itself to the active site on an enzyme that the bacteria uses to create the cell wall. This would be an example of
- Non-competitive inhibition
- Competitive inhibition
- Cofactor inhibition
- Bacterial blocking inhibition
Correct Answer

A. Competitive inhibition

Explanation

Penicillin inhibits the growth of bacteria by attaching itself to the active site on an enzyme that the bacteria uses to create the cell wall. This prevents the enzyme from functioning properly and inhibits the bacterial cell wall synthesis. This mechanism of action is an example of competitive inhibition, where the penicillin competes with the substrate for binding to the active site of the enzyme.

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36.

Identify the type of macromolecule using the hints below:Made of Carbon, Oxygen, and HydrogenUsed for Energy storageHydrophobic
- Carbohydrate
- Lipid
- Protein
- Nucleic Acid
Correct Answer

A. Lipid

Explanation

Lipids are macromolecules made up of carbon, oxygen, and hydrogen. They are known for their hydrophobic nature and are commonly used for energy storage. Therefore, the given hints align perfectly with the characteristics of lipids.

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37.

The direct energy source that drives ATP synthesis during respiratory oxidative phosphorylation is
- Oxidation of glucose to and water.
- The final transfer of electrons to oxygen.
- The difference in H+ ion concentrations on opposite sides of the inner mitochondrial membrane.
- The thermodynamically favorable transfer of phosphate from glycolysis and the citric acid cycle intermediate molecules of ADP.
Correct Answer

A. The difference in H+ ion concentrations on opposite sides of the inner mitochondrial membrane.

Explanation

During respiratory oxidative phosphorylation, the direct energy source that drives ATP synthesis is the difference in H+ ion concentrations on opposite sides of the inner mitochondrial membrane. This process is known as chemiosmosis. As electrons are transferred through the electron transport chain, protons are pumped across the inner mitochondrial membrane, creating a gradient. This gradient drives the flow of protons back across the membrane through ATP synthase, which uses the energy released to synthesize ATP. Therefore, the difference in H+ ion concentrations is the direct energy source for ATP synthesis.

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38.

Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because
- They are species specific.
- They always lead to the same cellular response.
- They amplify the original signal many fold.
- The number of molecules used is small and fixed.
Correct Answer

A. They amplify the original signal many fold.

Explanation

Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because they amplify the original signal many fold. This means that a small initial signal can trigger a series of phosphorylation events, resulting in a large and amplified response within the cell. This allows for efficient and precise signaling, as the original signal can be greatly enhanced and transmitted to the appropriate cellular components.

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39.

What is the role topoisomerase?
- It unwinds the DNA
- It helps to hold open the unwound DNA
- It lays down DNA nucleotides
- It connects okazaki fragments
Correct Answer

A. It helps to hold open the unwound DNA

Explanation

Topoisomerase is an enzyme that plays a crucial role in DNA replication and transcription. It helps to hold open the unwound DNA strands during these processes. By preventing the DNA strands from reannealing, topoisomerase allows other enzymes, such as DNA polymerase, to access the DNA strands and carry out their functions. This ensures that DNA replication and transcription can proceed smoothly and accurately. Therefore, the correct answer is "It helps to hold open the unwound DNA."

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40.

In DNA replication, which of the following does NOT occur?
- Helicase unwinds the double helix
- DNA ligase links the okazaki fragments
- Replication starts at one end of the DNA and finishes at the other
- DNA strands grow in the 5' to 3' direction
Correct Answer

A. Replication starts at one end of the DNA and finishes at the other

Explanation

The given correct answer is "Replication starts at one end of the DNA and finishes at the other." This is not a step that occurs during DNA replication. DNA replication is a bidirectional process where replication starts at multiple points along the DNA molecule, known as origins of replication, and proceeds in both directions until the entire DNA molecule is replicated.

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41.

Which of the following is NOT a function of the Poly-A Tail?
- Signal the end of translation
- Help ribosome attach to the 5’ end of the mRNA
- Help protect the mRNA from degredation
- Facilitate the export of mature mRNA
Correct Answer

A. Signal the end of translation

Explanation

The Poly-A Tail is a sequence of adenine nucleotides added to the 3' end of mRNA during post-transcriptional modification. It serves multiple functions, such as protecting the mRNA from degradation by exonucleases and facilitating the export of mature mRNA from the nucleus to the cytoplasm. Additionally, the Poly-A Tail helps in the initiation of translation by assisting the ribosome in binding to the 5' end of the mRNA. However, it does not directly signal the end of translation, which is typically determined by a stop codon in the mRNA sequence.

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42.

Which would you predict would have the largest affect on the expression of a gene due to a mutation?
- DNA methylation
- Histone acetylation
Correct Answer

A. DNA methylation

Explanation

DNA methylation is the process of adding a methyl group to the DNA molecule, which can result in the silencing of gene expression. This modification can prevent the transcription machinery from accessing the gene, leading to a decrease in gene expression. Therefore, DNA methylation is more likely to have a larger effect on the expression of a gene due to a mutation compared to histone acetylation. Histone acetylation, on the other hand, is the addition of an acetyl group to histone proteins, which generally promotes gene expression by loosening the chromatin structure. However, the impact of histone acetylation on gene expression is generally considered to be less pronounced than DNA methylation.

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43.

In the example of the lac Operon, lactase is created to help metabolize lactose when the amount of glucose is very low. cAMP (the inducer) will bind with the __________________ to tell the operon to begin transcription of the operon
- Repressor
- Activator protein
- Operator
- Co repressor
Correct Answer

A. Activator protein

Explanation

In the example of the lac Operon, lactase is created to help metabolize lactose when the amount of glucose is very low. The inducer cAMP will bind with the activator protein to tell the operon to begin transcription of the operon. This binding of cAMP to the activator protein allows the RNA polymerase to bind to the promoter region and initiate transcription of the lac Operon. The activator protein acts as a positive regulator in this system, enhancing the expression of the operon in the absence of glucose.

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44.

Identify the positive feedback loops
- Thermostat
- Trp Operon
- Microphone and speaker
- Lac operon
- An infant suckling induces lactation, which in turn creates more suckling
Correct Answer(s)

A. Microphone and speaker
A. Lac operon
A. An infant suckling induces lactation, which in turn creates more suckling

Explanation

The positive feedback loops in this list are the microphone and speaker, the Lac operon, and the infant suckling inducing lactation. In a positive feedback loop, the output of a system amplifies or reinforces the input, leading to an increase in the original stimulus. In the case of the microphone and speaker, the sound captured by the microphone is amplified and played back through the speaker, creating a loop of increasing sound. Similarly, the Lac operon in bacteria is activated by lactose, leading to the production of more enzymes that break down lactose, resulting in an increase in lactose metabolism. Lastly, when an infant suckles, it stimulates the production of more milk, which in turn leads to more suckling, creating a positive feedback loop.

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45.

The Cell cycle is a series of events in the life of a dividing eukaryotic cell. It consists of four stages: G₁, S, G₂, and M. The duration of the cell cycle varies from one species to another. The G1 phase varies the most. For example, embryonic cells can pass through the G₁ phase so quickly that it hardly exists, whereas neurons are arrested in the cell cycle and do not divide. Since neurons are destined never to divide again, what conclusion can be made?
- These cells wil go through cell division.
- These cells will be permanently arrested in the G1 phase
- These cells will be permanently arrested in the G2 phase
- These cells will quickly enter the S-phase
Correct Answer

A. These cells will be permanently arrested in the G1 phase

Explanation

Neurons are arrested in the cell cycle and do not divide. Since they are destined never to divide again, it can be concluded that these cells will be permanently arrested in the G1 phase.

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