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The study of microbiology covers the area of science that deals with microscopic organisms, best defined as organisms so small that you typically cannot see them with the naked eye. Can you identify the different kinds of microorganisms out there – bacteria, fungi, protozoa, viruses – and tell us all about them and how they’re studied? Take the following quiz to find out just how much you know about them! Good luck!
Questions and Answers
1.
Who proved that microorganisms cause disease?
A.
Pasteur
B.
Van Leeuwenhoek
C.
Koch
D.
Hooke
Correct Answer
C. Koch
Explanation Koch proved that microorganisms cause disease. He was a German physician and microbiologist who developed the germ theory of disease. Koch's postulates, a set of criteria to establish a causal relationship between a microorganism and a disease, became the standard for identifying the causative agents of infectious diseases. Through his research on anthrax, tuberculosis, and cholera, Koch made significant contributions to the field of medical microbiology and laid the foundation for modern bacteriology.
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2.
Nitrogen bases are building blocks of:
A.
Lipids
B.
Deoxyribose
C.
Nucleotides
D.
Ribosomes
E.
None of these
Correct Answer
C. Nucleotides
Explanation Nitrogen bases are the building blocks of nucleotides. Nucleotides are the basic units that make up DNA and RNA molecules. They consist of a nitrogenous base, a sugar (deoxyribose or ribose), and a phosphate group. The nitrogen bases, including adenine, thymine, guanine, cytosine, and uracil, are responsible for the genetic code and the sequence of nucleotides in DNA and RNA. Therefore, the correct answer is nucleotides.
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3.
Proteins are formed by amino acids connected by:
A.
Alpha 1,4-glycosidic bond
B.
Phosphodiester linkage
C.
Hydrogen bonds
D.
Peptide bonds
Correct Answer
D. Peptide bonds
Explanation Peptide bonds are formed between amino acids to create proteins. These bonds occur through a condensation reaction, where the carboxyl group of one amino acid reacts with the amino group of another amino acid, resulting in the formation of a peptide bond and the release of a water molecule. This process is repeated to form a chain of amino acids, which then folds and interacts with other molecules to create a functional protein. Peptide bonds are essential for the structure and function of proteins, as they determine the sequence and arrangement of amino acids in the protein chain.
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4.
Which of the following is not a kingdom in the five-kingdom system?
A.
Protista
B.
Algae
C.
Plant
D.
Animal
E.
Monera
Correct Answer
B. Algae
Explanation Algae is not a kingdom in the five-kingdom system. The five-kingdom system categorizes living organisms into five kingdoms: Monera, Protista, Fungi, Plantae, and Animalia. Algae is a diverse group of photosynthetic organisms that can be found in various kingdoms, including Protista and Plantae, depending on their characteristics. However, it is not considered a separate kingdom in this classification system.
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5.
The best use of a negative stain is:
A.
To determine cell shape
B.
To see endospore
C.
To determine Gram reaction
D.
To determine motility
Correct Answer
A. To determine cell shape
Explanation A negative stain is a staining technique that stains the background of a specimen, leaving the cells unstained. This allows for a clear visualization of the cell shape and morphology. By using a negative stain, the cells appear as colorless against a stained background, making it easier to observe their size, arrangement, and overall shape. Therefore, the best use of a negative stain is to determine the cell shape.
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6.
We discussed two processes for synthesizing ATP. Which process requires proton gradient across the membrane?
A.
Substrate level phosphorylation
B.
Oxidative level phosphorylation
Correct Answer
B. Oxidative level pHospHorylation
Explanation Oxidative level phosphorylation requires a proton gradient across the membrane. During this process, electrons are transferred through the electron transport chain, which pumps protons from the matrix to the intermembrane space. This creates a proton gradient, and as the protons flow back into the matrix through ATP synthase, ATP is synthesized. Substrate level phosphorylation, on the other hand, involves the direct transfer of a phosphate group from a substrate molecule to ADP to form ATP, and does not require a proton gradient.
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7.
Place the following steps in the correct sequence: 1 - Staining; 2- Making a smear; 3 - Fixing
A.
1-2-3
B.
1-3-2
C.
3-2-1
D.
2-3-1
Correct Answer
D. 2-3-1
Explanation The correct sequence for the given steps is 2-3-1. First, making a smear is done to prepare a thin layer of the sample on a slide. Then, fixing is performed to kill the microorganisms and attach them to the slide. Finally, staining is carried out to enhance the visibility of the microorganisms and differentiate them from the background.
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8.
Which of the following chemicals is found only in the outer membrane of Gram-negative bacteria?
A.
Plasmid
B.
Teichoic acid
C.
Flagella
D.
Lipopolysaccharide
E.
Peptidoglycan
Correct Answer
D. Lipopolysaccharide
Explanation Lipopolysaccharide is a chemical found only in the outer membrane of Gram-negative bacteria. It is a unique component of the outer membrane and plays a crucial role in the structural integrity and protection of the bacteria. Lipopolysaccharide also acts as an endotoxin, triggering an immune response in the host organism. This chemical is not present in Gram-positive bacteria, making it a characteristic feature of Gram-negative bacteria.
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9.
Identify the FALSE statement.
A.
The cell wall of G+ is much thicker than G-
B.
In Gram stain, G- are blue (purple) and G+ are pink (red)
C.
G+ and NOT G- contain teichoic acid in their cell wall
D.
In Gram stain, G+ are blue (purple) and G- are pink (red)
Correct Answer
B. In Gram stain, G- are blue (purple) and G+ are pink (red)
10.
All of the following statements are true of gram-positive cells except which one?
A.
Gram positive cells have more peptidoglycan
B.
Gram positive cells have endotoxin
C.
Gram positive cells are sensitive to penicillin
D.
Gram positive cells are decolorized by alcohol-acetone
Correct Answer
B. Gram positive cells have endotoxin
Explanation Gram positive cells do not have endotoxin. Endotoxin is a component of the outer membrane of gram-negative bacteria, not gram-positive bacteria. Gram-positive cells have a thick layer of peptidoglycan, making them more susceptible to the action of penicillin. Additionally, gram-positive cells retain the crystal violet stain and do not get decolorized by alcohol-acetone during the Gram staining process.
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11.
Which of the following statements are about a gram-negative cell wall is not true?
A.
It has teichoic acids
B.
It contains an endotoxin
C.
It protects the cell from osmotic lysis
D.
It maintains the shape of the cell
Correct Answer
A. It has teichoic acids
Explanation Gram-negative cell walls do not have teichoic acids. Teichoic acids are a characteristic of gram-positive cell walls. Gram-negative cell walls contain lipopolysaccharides, which are responsible for the endotoxin activity. The outer membrane of gram-negative cell walls provides protection against osmotic lysis. The peptidoglycan layer in the cell wall helps maintain the shape of the cell.
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12.
Which of the following is not a kingdom in the five-kingdom system?
A.
Animal
B.
Fungi
C.
Monera
D.
Plant
E.
Virus
Correct Answer
E. Virus
Explanation The five-kingdom system categorizes organisms into five kingdoms based on their characteristics and evolutionary relationships. The kingdoms are Animal, Fungi, Plant, Protista, and Monera. However, viruses are not considered as a kingdom in this system because they are not living organisms. Viruses are acellular and cannot carry out metabolic processes on their own. They require a host cell to reproduce and are considered as infectious agents rather than living organisms.
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13.
Which of the following chemical bonds is the strongest?
A.
Ionic bond
B.
Covalent bond
C.
Hydrogen Bond
D.
They all have the same strength
Correct Answer
B. Covalent bond
Explanation Covalent bonds are the strongest type of chemical bonds. In a covalent bond, two atoms share electrons, creating a strong bond between them. This sharing of electrons results in a stable configuration for both atoms, making the bond difficult to break. Ionic bonds, on the other hand, involve the transfer of electrons from one atom to another, resulting in a weaker bond. Hydrogen bonds are even weaker than both ionic and covalent bonds, as they are formed between a hydrogen atom and an electronegative atom, such as oxygen or nitrogen. Therefore, the correct answer is covalent bond.
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14.
Bacterial cell membrane DOES NOT contain:
A.
Phospholipids
B.
Proteins
C.
Glycoproteins
D.
Lipids
E.
Nucleic acids
Correct Answer
E. Nucleic acids
Explanation The bacterial cell membrane is composed of phospholipids, proteins, and lipids, which are essential components for its structure and function. Glycoproteins are also present in the membrane, serving various roles such as cell recognition and signaling. However, nucleic acids, which include DNA and RNA, are not typically found in the cell membrane. Nucleic acids are primarily located within the bacterial cell's cytoplasm and nucleus, where they play a crucial role in genetic information storage and protein synthesis.
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15.
All of the following can be found in mitochondria except:
A.
Circular DNA
B.
Ribosome
C.
ATP-generating mechanism
D.
Electron transport system
E.
Cell wall
Correct Answer
E. Cell wall
Explanation Mitochondria are membrane-bound organelles found in eukaryotic cells and are responsible for producing energy in the form of ATP. They contain their own circular DNA, which is distinct from the linear DNA found in the cell nucleus. Mitochondria also have ribosomes, which are responsible for protein synthesis. The ATP-generating mechanism and the electron transport system are both crucial components of mitochondrial function. However, mitochondria do not have a cell wall. Cell walls are typically found in prokaryotic cells, such as bacteria, and some eukaryotic cells, such as plant cells.
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16.
This microscope uses an ultraviolet light source.
A.
Dark field microscope
B.
Fluorescence microscope
C.
Electron microscope
D.
Compound light microscope
Correct Answer
B. Fluorescence microscope
Explanation A fluorescence microscope is the correct answer because it uses an ultraviolet light source to excite fluorescent dyes or molecules in the sample. This causes them to emit light of a different wavelength, which can be captured and observed. This technique is commonly used in biological research to study specific molecules or structures within cells.
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17.
These molecules are the primary building blocks of the plasma membrane in cells
A.
Carbohydrates
B.
Nucleic acids
C.
Proteins
D.
Lipids
Correct Answer
D. Lipids
Explanation Lipids are the primary building blocks of the plasma membrane in cells. They form a lipid bilayer, which acts as a barrier to protect the cell and regulate the movement of molecules in and out of the cell. Lipids are hydrophobic, meaning they repel water, making them ideal for creating a barrier. Additionally, lipids are responsible for cell signaling, energy storage, and insulation. Therefore, lipids play a crucial role in maintaining the structure and function of the plasma membrane in cells.
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18.
Which of the following does not contribute to the hydrophobic interaction?
A.
Ionic interaction between hydrophobic molecules
B.
Proximity of hydrophobic molecules
C.
Increase entropy
D.
Exclusion of water
Correct Answer
A. Ionic interaction between hydropHobic molecules
Explanation Ionic interactions between hydrophobic molecules do not contribute to the hydrophobic interaction. The hydrophobic interaction is a phenomenon where nonpolar molecules or groups cluster together in an aqueous environment to minimize their contact with water. This occurs due to the exclusion of water molecules from the hydrophobic region, which leads to an increase in entropy. Proximity of hydrophobic molecules also contributes to the hydrophobic interaction as it allows for the formation of hydrophobic clusters. However, ionic interactions involve charged molecules and are not directly related to the hydrophobic interaction.
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19.
These are the primary molecules making up plasma membrane in cells
A.
Nucleic acids
B.
Carbohydrates
C.
Proteins
D.
Lipids
Correct Answer
D. Lipids
Explanation The primary molecules making up the plasma membrane in cells are lipids. Lipids are a diverse group of molecules that include fats, oils, and phospholipids. They are hydrophobic, meaning they repel water, which makes them ideal for forming the structure of the plasma membrane. The lipid bilayer is formed by two layers of phospholipids, with their hydrophilic heads facing the watery environment inside and outside the cell, and their hydrophobic tails facing each other in the middle. This arrangement provides a barrier that controls the movement of substances in and out of the cell, making lipids essential for maintaining cell integrity and function.
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20.
This is not a major bioelement
A.
Sulfur
B.
Nitrogen
C.
Hydrogen
D.
Magnesium
E.
Phosphate
Correct Answer
D. Magnesium
Explanation Magnesium is not considered a major bioelement because it is not required in large quantities by living organisms. Major bioelements, such as carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur, are essential for life and make up the majority of an organism's composition. While magnesium is still important for various biological processes, it is needed in smaller amounts compared to the major bioelements.
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21.
A protein's function depends upon its unique conformation. Which level of protein folding achieves this conformation?
A.
Primary structure
B.
Beta sheet
C.
Alpha helix
D.
Secondary structure
E.
Tertiary structure
Correct Answer
E. Tertiary structure
Explanation The tertiary structure of a protein is responsible for achieving its unique conformation. This level of protein folding involves the overall three-dimensional arrangement of the protein's secondary structures, such as alpha helices and beta sheets. The tertiary structure is determined by various interactions, including hydrophobic interactions, hydrogen bonding, disulfide bonds, and electrostatic interactions. These interactions help to stabilize the protein's structure and enable it to carry out its specific function. Therefore, the tertiary structure is crucial for determining a protein's overall conformation and functionality.
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22.
Which forces/bonds are involved in quaternary structure of proteins?
A.
Hydrogen bond, S-S bridges, Van der Waals forces, peptide bonds
B.
Hydrogen bond, S-S bridges, Van der Waals forces, peptide bonds, and hydrophobic interactions
C.
Hydrogen bond, S-S bridges, peptide bonds
D.
Hydrogen bond, S-S bridges, Van der Waals forces, hydrophobic interactions
Correct Answer
B. Hydrogen bond, S-S bridges, Van der Waals forces, peptide bonds, and hydropHobic interactions
Explanation The quaternary structure of proteins is determined by the interactions between multiple protein subunits. These interactions include hydrogen bonds, which form between the polar amino acid residues of different subunits, and disulfide (S-S) bridges, which covalently link cysteine residues. Van der Waals forces, which are weak attractions between nonpolar amino acid residues, also contribute to the stability of the quaternary structure. Additionally, peptide bonds, which form between the amino acids within a single polypeptide chain, are essential for the overall structure of the protein. Finally, hydrophobic interactions, which occur between nonpolar amino acids in an aqueous environment, play a crucial role in the folding and assembly of protein subunits.
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23.
This is not an internal structure of a bacteria
A.
Ribosome
B.
Plasmid
C.
Fimbriae
D.
Nucleoid
Correct Answer
C. Fimbriae
Explanation Fimbriae are short, hair-like appendages found on the surface of some bacteria. They are used for attachment to surfaces, including host tissues, and are important for the bacteria to establish infections. In contrast, ribosomes are cellular structures responsible for protein synthesis, plasmids are small, circular DNA molecules that can be found in bacteria and often carry additional genetic information, and nucleoid refers to the region in a bacterial cell where the genetic material is located. Therefore, fimbriae are the only option that does not represent an internal structure of a bacteria.
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24.
You can find nucleotides in
A.
DNA
B.
Amino acids
C.
Fatty acids
D.
Proteins
E.
Carbohydrates
Correct Answer
A. DNA
Explanation Nucleotides are the building blocks of DNA, which is a molecule that contains the genetic instructions for the development and functioning of all living organisms. DNA is made up of a long chain of nucleotides, each consisting of a sugar molecule, a phosphate group, and a nitrogenous base. Nucleotides are not found in amino acids, fatty acids, proteins, or carbohydrates.
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25.
Which are of microbiolgy studies fungi?
A.
Mycology
B.
Parasitology
C.
Biotechnology
D.
Immunology
E.
Bioremediation
Correct Answer
A. Mycology
Explanation Mycology is the branch of microbiology that specifically focuses on the study of fungi. Fungi are a diverse group of organisms that include yeasts, molds, and mushrooms. Mycologists study various aspects of fungi, including their classification, structure, reproduction, genetics, and ecological roles. They also investigate the interactions between fungi and other organisms, as well as the potential uses of fungi in various industries such as medicine, agriculture, and food production. Therefore, Mycology is the correct answer as it is the field that specifically deals with the study of fungi.
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26.
Which of the following compounds has the greatest amount of energy for a cell?
A.
O2
B.
Glucose
C.
CO2
D.
ATP
E.
Pyruvate
Correct Answer
B. Glucose
Explanation Glucose has the greatest amount of energy for a cell compared to the other compounds listed. Glucose is a carbohydrate that is broken down through cellular respiration to produce ATP, the main source of energy for cells. ATP is a high-energy molecule that stores and releases energy as needed by the cell. O2 and CO2 are involved in cellular respiration but do not directly provide energy. Pyruvate is an intermediate product of glucose metabolism and does not contain as much energy as glucose.
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27.
Which of the following is not part of the cell membrane?
A.
Fatty acids
B.
Nucleic acids
C.
Sugars
D.
Amino acids
Correct Answer
B. Nucleic acids
Explanation Nucleic acids are not part of the cell membrane. The cell membrane is primarily composed of lipids, such as fatty acids, which form a lipid bilayer. Sugars are also present in the form of glycolipids and glycoproteins, while amino acids are found in integral membrane proteins. However, nucleic acids, which include DNA and RNA, are not directly involved in the structure or function of the cell membrane. They are primarily responsible for storing and transmitting genetic information within the cell.
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28.
Cell division occurs in prokaryotes by:
A.
Budding
B.
Meiosis
C.
Binary Fission
D.
Mitosis
Correct Answer
C. Binary Fission
Explanation Binary fission is the correct answer because it is the process of cell division in prokaryotes, such as bacteria. In binary fission, the parent cell divides into two identical daughter cells, each containing a copy of the parent's DNA. This process is different from meiosis, which is a type of cell division that occurs in eukaryotes and involves the formation of gametes. Budding is a form of asexual reproduction seen in some organisms, but it is not the primary method of cell division in prokaryotes. Mitosis is a type of cell division that occurs in eukaryotes and is not relevant to prokaryotes.
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29.
Which of the following mechanisms requires energy?
A.
Simple diffusion
B.
Osmosis
C.
Facilitated diffusion
D.
Active transport
Correct Answer
D. Active transport
Explanation Active transport is the only mechanism among the options that requires energy. Active transport is the movement of molecules across a cell membrane against their concentration gradient, from an area of lower concentration to an area of higher concentration. This process requires the use of energy in the form of ATP (adenosine triphosphate) to pump the molecules against the concentration gradient. In contrast, simple diffusion, osmosis, and facilitated diffusion are all passive mechanisms that do not require energy as they involve the movement of molecules along their concentration gradient.
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30.
Cells are made of mostly
A.
Lipids
B.
Proteins
C.
RNA
D.
DNA
E.
Carbohydrates
Correct Answer
B. Proteins
Explanation Cells are made up of various molecules, including lipids, proteins, RNA, DNA, and carbohydrates. However, proteins play a crucial role in the structure and function of cells. They are involved in various cellular processes such as metabolism, signaling, transportation, and cell division. Proteins are responsible for carrying out most of the cell's activities and are essential for the growth, repair, and maintenance of cells. Therefore, the correct answer is proteins.
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31.
What color should a gram-positive organism appear after Gram stain
A.
Pink
B.
Red
C.
Green
D.
Purple
E.
Orange
Correct Answer
D. Purple
Explanation Gram-positive organisms should appear purple after a Gram stain. This is because the Gram stain procedure involves the application of crystal violet dye, which stains the peptidoglycan layer in the cell wall of bacteria. Gram-positive bacteria have a thick peptidoglycan layer that retains the crystal violet dye, causing them to appear purple under a microscope.
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32.
Eukarya
A.
Have a membrane around their DNA
B.
Contain outer membrane and cell membrane
C.
Consist of only multicellular organisms
D.
All of these are correct
E.
None of these are correct
Correct Answer
A. Have a membrane around their DNA
Explanation Eukarya have a membrane around their DNA. This is because eukaryotic cells, which belong to the domain Eukarya, have a well-defined nucleus that contains their DNA. The nucleus is surrounded by a double membrane called the nuclear envelope, which acts as a barrier between the DNA and the rest of the cell. This membrane helps protect and organize the DNA, allowing for more complex cellular functions to occur within the eukaryotic cell. Therefore, the statement "Eukarya have a membrane around their DNA" is correct.
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33.
The type of bond holding Na+ and Cl- ions in NaCl is a(n):
A.
Covalent bond
B.
Double bond
C.
Ionic bond
D.
Hydrogen bond
Correct Answer
C. Ionic bond
Explanation An ionic bond is formed between Na+ and Cl- ions in NaCl. In an ionic bond, one atom transfers electrons to another atom, resulting in the formation of oppositely charged ions. In this case, sodium (Na) loses an electron to become a positively charged ion (Na+), while chlorine (Cl) gains that electron to become a negatively charged ion (Cl-). The strong electrostatic attraction between these oppositely charged ions holds them together in a crystal lattice structure, forming an ionic bond.
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34.
Loss of electrons means:
A.
Phosphorylation
B.
Reduction
C.
Oxidation
Correct Answer
C. Oxidation
Explanation Oxidation refers to the loss of electrons from a substance. In this context, when a substance loses electrons, it is undergoing oxidation. Phosphorylation, on the other hand, refers to the addition of a phosphate group to a molecule, and reduction involves the gain of electrons. Therefore, the correct answer is oxidation as it directly relates to the loss of electrons.
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35.
S-S agar inhibits gram-positive bacteria. On this medium, bacteria that ferment lactose to produce red colonies, and bacteria that do not ferment lactose to produce colorless colonies. This medium is:
A.
Both selective and differential
B.
Differential
C.
Enriched
D.
Selective
Correct Answer
A. Both selective and differential
Explanation S-S agar is both selective and differential. It is selective because it inhibits the growth of gram-positive bacteria, allowing only gram-negative bacteria to grow. It is differential because it allows for the differentiation of bacteria based on their ability to ferment lactose. Bacteria that ferment lactose produce red colonies, while bacteria that do not ferment lactose produce colorless colonies. Therefore, S-S agar serves as a selective medium by inhibiting certain bacteria and a differential medium by allowing for the differentiation of bacteria based on their lactose fermentation abilities.
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36.
Which of the following is not a characteristic of cell membrane
A.
Selective permeability
B.
Composed of Phospholipid bilayer
C.
Contains proteins
D.
Maintain cell shape
E.
Present in all cells
Correct Answer
D. Maintain cell shape
Explanation The cell membrane is responsible for maintaining the shape of the cell by providing structural support and preventing the cell from collapsing or bursting. It is composed of a phospholipid bilayer, which gives it flexibility and allows for selective permeability. The cell membrane also contains proteins that perform various functions such as transport, signaling, and cell adhesion. Therefore, "Maintain cell shape" is not a characteristic of the cell membrane.
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37.
Which of the following mechanisms generate ATP using an electron transport chain?
A.
Fermentation
B.
Glycolysis
C.
Oxidative phosphorylation
D.
Substrate level phosphorylation
E.
Krebs cycle
Correct Answer
C. Oxidative pHospHorylation
Explanation Oxidative phosphorylation is the correct answer because it is the process by which ATP is generated using an electron transport chain. During oxidative phosphorylation, electrons are transferred through a series of protein complexes in the inner mitochondrial membrane, creating a proton gradient. This proton gradient is then used by ATP synthase to produce ATP. Fermentation, glycolysis, substrate level phosphorylation, and the Krebs cycle do not involve an electron transport chain and therefore do not generate ATP through oxidative phosphorylation.
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38.
An example of bioremediation is the use of:
A.
Bacillus thuringiensis to kill crop-eating insects
B.
Cowpox virus to vaccinate against smallpox
C.
Saccharomyces cerevisie to make wine
D.
Pseudomonas to remove uranium from oil at weapons depots
Correct Answer
D. Pseudomonas to remove uranium from oil at weapons depots
Explanation Bioremediation is the use of living organisms to remove or neutralize pollutants from a contaminated environment. Pseudomonas, a type of bacteria, can be used in bioremediation to remove uranium from oil at weapons depots. This bacterium has the ability to break down and metabolize uranium, converting it into a less harmful form. By utilizing Pseudomonas, the uranium contamination can be effectively reduced or eliminated, making the environment safer.
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39.
This microscope achieves the highest magnification and greatest resolution.
A.
Flurorescence microscope
B.
Phase-contrast microscope
C.
Electron microscope
D.
Darkfield microscope
E.
Compound light microscope
Correct Answer
C. Electron microscope
Explanation The electron microscope achieves the highest magnification and greatest resolution compared to the other types of microscopes listed. This is because it uses a beam of electrons instead of light to magnify and image the specimen. The shorter wavelength of electrons allows for higher resolution, enabling scientists to see smaller details and structures within the specimen.
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40.
All of the following organisms are eukaryotes except:
A.
Plants
B.
Archaea
C.
Protozoa
D.
Fungi
E.
All of these are eukaryotes
Correct Answer
B. Archaea
Explanation Archaea are prokaryotes, not eukaryotes. Eukaryotes are organisms that have cells with a nucleus and other membrane-bound organelles, while prokaryotes lack a nucleus and organelles. Plants, protozoa, and fungi are all eukaryotes because they have cells with a nucleus and organelles. However, archaea are prokaryotes, meaning they do not have a nucleus or organelles. Therefore, the correct answer is archaea.
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41.
Which molecule is composed of a chain of amino acids?
A.
Carbohydrates
B.
Proteins
C.
Lipids
D.
Nucleic acids
Correct Answer
B. Proteins
Explanation Proteins are composed of a chain of amino acids. Amino acids are the building blocks of proteins, and they are linked together through peptide bonds to form a long chain. This chain of amino acids then folds and twists into a unique three-dimensional structure, which determines the protein's function. Therefore, proteins are the molecules that are composed of a chain of amino acids.
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42.
The most common solidifying agent added to culture media is:
A.
Starch
B.
Silica gel
C.
Gelatin
D.
Agar
Correct Answer
D. Agar
Explanation Agar is the most common solidifying agent added to culture media. Agar is a gelatinous substance derived from seaweed and has the ability to form a solid gel at a temperature range suitable for microbial growth. It is widely used in microbiology laboratories because it is inert, transparent, and can be easily sterilized. Agar provides a solid surface for the growth of microorganisms, allowing them to form distinct colonies, facilitating their isolation and identification. It also has the advantage of being resistant to degradation by most microorganisms, making it an ideal solidifying agent for culture media.
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43.
The best definition of biotechnology is:
A.
The use of living organisms to make desired products
B.
Curing diseases
C.
The use of microorganisms in sewage treatment
D.
The development of genetic engineering
Correct Answer
A. The use of living organisms to make desired products
Explanation Biotechnology refers to the use of living organisms to create useful products. This can involve various techniques such as genetic engineering, fermentation, and cell culture. By harnessing the capabilities of living organisms, biotechnology allows for the production of a wide range of products including medicines, vaccines, biofuels, and agricultural crops. It also plays a crucial role in improving the efficiency and sustainability of various industrial processes. Therefore, the best definition of biotechnology is the use of living organisms to make desired products.
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44.
Peptidoglycan is made of mostly:
A.
Proteins
B.
Lipids
C.
Nucleic acids
D.
Carbohydrates
Correct Answer
D. Carbohydrates
Explanation Peptidoglycan is a major component of the cell wall in bacteria and is primarily composed of carbohydrates. It consists of long chains of sugar molecules, specifically N-acetylglucosamine and N-acetylmuramic acid, which are cross-linked by short peptide chains. This structure provides strength and rigidity to the bacterial cell wall. Proteins, lipids, and nucleic acids are also present in the cell wall, but they are not the main constituents of peptidoglycan.
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45.
Which of the following is not a product of TCA cycle?
A.
CO2
B.
Acetyle-CoA
C.
NADH
D.
GTP (ATP)
E.
FADH
Correct Answer
B. Acetyle-CoA
Explanation Acetyl-CoA is not a product of the TCA cycle, but rather a reactant that enters the cycle. In the TCA cycle, acetyl-CoA combines with oxaloacetate to form citrate, which then undergoes a series of reactions to produce CO2, NADH, GTP (ATP), and FADH. Acetyl-CoA is generated from the breakdown of glucose or fatty acids and serves as the starting point for the TCA cycle. Therefore, it is not a product but an important molecule that fuels the cycle.
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46.
Which of the following is a scientific name?
A.
Legionnaires' Disease
B.
Legionella Pneumophila
C.
Legionnares' bacterium
D.
Philadelphia fever
Correct Answer
B. Legionella PneumopHila
Explanation Legionella Pneumophila is a scientific name because it follows the proper format for scientific naming, which consists of two parts: the genus name (Legionella) and the species name (Pneumophila). This naming system is used in biology to classify and categorize organisms. In contrast, the other options provided (Legionnaires' Disease, Legionnares' bacterium, Philadelphia fever) are not scientific names as they do not follow the proper naming conventions.
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47.
You have isolated a cell that lacks a membrane enclosed nucleus. You would find all of the following structures except which one?
A.
A ribosome
B.
A chromosome
C.
Peptidoglycan
D.
A lysosome
Correct Answer
D. A lysosome
Explanation The correct answer is "A lysosome". Lysosomes are membrane-bound organelles found in eukaryotic cells, but since the cell in question lacks a membrane-enclosed nucleus, it is most likely a prokaryotic cell. Prokaryotic cells, such as bacteria, do not possess lysosomes. Ribosomes, chromosomes, and peptidoglycan are all commonly found in prokaryotic cells.
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48.
This microscope is used to observe a specimen that emits light when illuminated with an ultra violet light and is an excellent diagnostic tool.
A.
Electron microscope
B.
Compound light microscope
C.
Fluorescence microscope
D.
Darkfield microscope
Correct Answer
C. Fluorescence microscope
Explanation A fluorescence microscope is the correct answer because it is specifically designed to observe specimens that emit light when illuminated with ultraviolet light. This type of microscope is commonly used in diagnostic applications because it allows for the visualization of fluorescently-labeled molecules or structures within the specimen. The emitted light provides valuable information about the presence and location of specific molecules or cellular components, making it an excellent tool for diagnostic purposes.
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49.
Which of the following statements about bacteria is not true?
A.
Bacteria are essential to the presence of life on Earth
B.
Everyone has bacteria in and on his body
C.
Bacteria are used to make some foods
D.
The only good bacterium is a dead bacterium
Correct Answer
D. The only good bacterium is a dead bacterium
Explanation The statement "The only good bacterium is a dead bacterium" is not true. While some bacteria can cause diseases, many bacteria are beneficial and necessary for various ecological processes and human health. For example, bacteria help in digestion, produce vitamins, and play a crucial role in the nitrogen cycle. Therefore, it is incorrect to claim that the only beneficial bacterium is a dead one.
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50.
A denatured protein maintains its:
A.
Structural integrity (3D), but it loses its functions
B.
Tertiary structure
C.
Primary structure
D.
Quarternary structure
E.
Secondary structure
Correct Answer
C. Primary structure
Explanation When a protein is denatured, it loses its secondary, tertiary, and quaternary structures. However, the primary structure of the protein remains intact. The primary structure refers to the linear sequence of amino acids that make up the protein. This sequence is determined by the DNA sequence of the gene encoding the protein. Therefore, even though a denatured protein may no longer be able to perform its specific function, its primary structure remains unchanged.
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