Micro Study Guide 2

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Benedict Ramos
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  • 1/80 Questions

    Cultures of bacterial species were incubated out on the incubator shelf, in an anaerobic jar and in a candle jar. After incubation there was moderate growth of cultures in the candle and anaerobic jars, but heavy growth of the culture on the incubator shelf. This species is a/an

    • Aerobe
    • Anaerobe
    • Facultative anaerobe
    • Microaerophile
    • Capnophile
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About This Quiz

This quiz focuses on key microbiological concepts including bacterial cell wall components, growth conditions, and temperature preferences of different bacteria.

Micro Study Guide 2 - Quiz

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  • 2. 

    Cultures of a bacterial species were incubated on the shelf of a refrigerator, out on a lab bench top, on the shelf of a 37° C incubator and on the shelf of a 50° C incubator. After incubation, there was no growth at 37° C and 50° C, slight growth out on the bench top and abundant growth at refrigeration. What term could be used for this species?

    • Halophile

    • Mesophile

    • Anaerobe

    • Psychrophile

    • Capnophile

    Correct Answer
    A. Psychrophile
    Explanation
    The term "psychrophile" could be used for this species because it is able to thrive and grow in cold temperatures, such as those found in a refrigerator. This is supported by the fact that there was abundant growth at refrigeration and no growth at higher temperatures of 37°C and 50°C.

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  • 3. 

    Microorganisms require small quantities of this nutrient for enzyme function and maintenance of protein structure:

    • Element

    • Macronutrient

    • Water

    • Growth factor

    • Trace element

    Correct Answer
    A. Trace element
    Explanation
    Microorganisms require trace elements in small quantities for enzyme function and maintenance of protein structure. Trace elements are essential for various metabolic processes in microorganisms, as they serve as cofactors for enzymes. These elements, such as iron, copper, zinc, and manganese, play crucial roles in electron transfer reactions, DNA synthesis, and other cellular functions. Although required in small amounts, trace elements are indispensable for the growth and survival of microorganisms.

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  • 4. 

    All of the chemical reactions of the cell are called

    • Catabolism

    • Redox reactions

    • Phosphorylation

    • Metabolism

    • Cellular respiration

    Correct Answer
    A. Metabolism
    Explanation
    Metabolism refers to all the chemical reactions that occur within a cell. It includes both catabolic reactions (breakdown of molecules to release energy) and anabolic reactions (building up of molecules using energy). Redox reactions involve the transfer of electrons between molecules, while phosphorylation is the addition of a phosphate group to a molecule. Cellular respiration is a specific metabolic process that involves the breakdown of glucose to produce energy. Therefore, metabolism is the most appropriate term to encompass all the chemical reactions of the cell.

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  • 5. 

    Bacteria living in a freshwater stream that are moved to salty seawater would

    • Be in a hypotonic solution

    • Gain water

    • Be in a isotonic solution

    • Shrivel

    • None of the choices are correct

    Correct Answer
    A. Shrivel
    Explanation
    When bacteria living in a freshwater stream are moved to salty seawater, they would experience a hypertonic environment. In this situation, the concentration of solutes outside the bacterial cells is higher than inside the cells. As a result, water would move out of the cells through osmosis, causing them to shrink or shrivel. This is because water naturally moves from an area of lower solute concentration (inside the cells) to an area of higher solute concentration (outside the cells) in an attempt to equalize the concentration on both sides.

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  • 6. 

    A microorganism has been described to you as living in hot acidic habitats in the waste piles of coal mines that regularly sustain a pH of 1 and a temperature of nearly 60*C. Which of organism do you immediately assume it is?

    • Gracillucates

    • Firmicutes

    • Actinobacteria

    • Archaea

    • Spirochaetes

    Correct Answer
    A. Archaea
    Explanation
    Archaea is the correct answer because they are known to thrive in extreme environments, such as hot acidic habitats. They have the ability to survive in conditions with low pH and high temperatures, making them well-suited for the described environment in the waste piles of coal mines. Gracillucates, Firmicutes, Actinobacteria, and Spirochaetes are not typically associated with extreme environments like this.

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  • 7. 

    The DNA of microorganisms is made up of subunits called 

    • Histones

    • Amino acids

    • Nucleotides

    • MRNA

    • Polymerases

    Correct Answer
    A. Nucleotides
    Explanation
    The DNA of microorganisms is made up of subunits called nucleotides. Nucleotides are the building blocks of DNA and consist of a sugar molecule, a phosphate group, and a nitrogenous base. They are arranged in a specific sequence to form the genetic code of an organism. This code contains the instructions for the synthesis of proteins and the functioning of the organism. Therefore, nucleotides play a crucial role in the structure and function of DNA in microorganisms.

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  • 8. 

    In anaerobic respiration, all of the following can serve as the final electron acceptor except

    • Nitrate

    • Oxygen

    • Sulfate

    • Nitrite

    • None of the choices are correct

    Correct Answer
    A. Oxygen
    Explanation
    In anaerobic respiration, organisms use alternative electron acceptors when oxygen is not available. Nitrate, sulfate, and nitrite are all common alternative electron acceptors in anaerobic respiration. However, oxygen cannot serve as a final electron acceptor in anaerobic respiration because the process specifically occurs in the absence of oxygen. Therefore, the correct answer is oxygen.

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  • 9. 

    What is the correct sequence of a Gram stain?

    • Gram's iodine, crystal violet, alcohol, safranin

    • Crystal violet, safranin, alcohol, safranin

    • Safranin, crystal violet, Gram's iodine, alcohol

    • Alcohol, crystal violet, safranin, Gram's iodine

    Correct Answer
    A. Safranin, crystal violet, Gram's iodine, alcohol
  • 10. 

    A procaryotic cell wall that has primarily peptidoglycan with small amounts of teichoic acid and lipoteichoic acid is

    • Gram negative

    • Gram positive

    • Archaea

    • Spheroplast

    • Acid fast

    Correct Answer
    A. Gram positive
    Explanation
    A Gram-positive cell wall primarily consists of peptidoglycan, which provides structural support to the cell. It also contains small amounts of teichoic acid and lipoteichoic acid, which help in regulating the movement of ions and molecules across the cell wall. Gram-positive bacteria have a thick peptidoglycan layer that retains the crystal violet stain during the Gram staining process, giving them a purple color. This is in contrast to Gram-negative bacteria, which have a thinner peptidoglycan layer and an outer membrane that does not retain the stain, resulting in a pink color. Therefore, the given characteristics of the cell wall indicate that it belongs to a Gram-positive bacterium.

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  • 11. 

    The term phototroph refers to an organism that

    • Uses CO2 for its carbon source

    • Must obtain organic compounds for its carbon needs

    • Gets energy from sunlight

    • Gets energy by oxidizing chemical compounds

    • Does not need a carbon source

    Correct Answer
    A. Gets energy from sunlight
    Explanation
    The term phototroph refers to an organism that gets energy from sunlight. This means that the organism is able to convert sunlight into usable energy through a process called photosynthesis. It uses this energy to carry out its metabolic activities and sustain its life.

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  • 12. 

    The E. coli that normally live in the human large intestines and produce vitamin K that the body uses would be best termed a ____ relationship

    • Parasitic

    • Saprobic

    • Commensal

    • Mutualistic

    • None of the choices are correct

    Correct Answer
    A. Mutualistic
    Explanation
    The E. coli that normally live in the human large intestines and produce vitamin K that the body uses would be best termed a mutualistic relationship. Mutualism refers to a symbiotic relationship where both organisms involved benefit from each other. In this case, the E. coli bacteria benefit by having a habitat to live in, while the human body benefits from the production of vitamin K. Therefore, both parties in this relationship are mutually dependent and gain advantages from each other's presence.

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  • 13. 

    The term that refers to the presence of flagella all over the cell surface is

    • Amphitrichous

    • Atrichous

    • Lophotrichous

    • Monotrichous

    • Peritrichous

    Correct Answer
    A. Peritrichous
    Explanation
    Peritrichous refers to the presence of flagella all over the cell surface. This means that the flagella are distributed uniformly around the cell, allowing for movement in any direction. This is in contrast to other terms such as monotrichous (single flagellum at one end), lophotrichous (multiple flagella at one end), amphitrichous (multiple flagella at both ends), and atrichous (no flagella).

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  • 14. 

    A microaerophile

    • Grows best in an anaerobic jar

    • Grows with or without oxygen

    • Needs normal atmospheric levels of oxygen

    • Requires a small amount of oxygen but won't grow at normal atmospheric levels

    • None of the choices are correct

    Correct Answer
    A. Requires a small amount of oxygen but won't grow at normal atmospheric levels
    Explanation
    A microaerophile is a type of organism that requires a small amount of oxygen to grow, but cannot tolerate normal atmospheric levels of oxygen. This means that it needs oxygen to survive, but too much oxygen can be harmful to its growth. Therefore, it is best suited to environments where oxygen levels are low, such as in an anaerobic jar.

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  • 15. 

    All of the following are correct about a slime layer except

    • It is a type of glycocalyx

    • It can be easily washed off the cell

    • It protects the cell from loss of water and nutrients

    • It plays a role in cell motility

    • It allows cells to participate in biofilms

    Correct Answer
    A. It plays a role in cell motility
    Explanation
    The statement "it plays a role in cell motility" is incorrect because a slime layer does not contribute to cell motility. A slime layer is a type of glycocalyx that surrounds the cell and protects it from loss of water and nutrients. It also allows cells to participate in biofilms. However, it can be easily washed off the cell, unlike a capsule which is tightly attached to the cell surface.

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  • 16. 

    All bacterial cells have

    • A chromosome

    • Fimbriae

    • Endospores

    • Capsules

    • Flagella

    Correct Answer
    A. A chromosome
    Explanation
    All bacterial cells have a chromosome, which is a single circular DNA molecule that contains the genetic information necessary for the cell's survival and reproduction. The chromosome is located in the nucleoid region of the cell and is responsible for controlling the cell's activities and determining its characteristics. Unlike eukaryotic cells, bacterial cells do not have a nucleus, so the chromosome is not enclosed within a membrane. Instead, it is free-floating within the cytoplasm. The chromosome plays a crucial role in the cell's ability to carry out essential functions such as protein synthesis and cell division.

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  • 17. 

    A halophile would grow best in

    • Acid pools

    • Fresh water ponds

    • Hot geyser springs

    • Arid, desert soil

    • Salt lakes

    Correct Answer
    A. Salt lakes
    Explanation
    A halophile is an organism that thrives in high salt concentrations. Therefore, it would grow best in salt lakes, where the salt concentration is high. Acid pools, fresh water ponds, hot geyser springs, and arid desert soil do not provide the high salt levels that a halophile requires for optimal growth.

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  • 18. 

    If a culture starts out with 1 cell and after 4 hours there are 64 cells, how many generations have occurred?

    • 4

    • 5

    • 6

    • 12

    • Impossible to determine

    Correct Answer
    A. 6
    Explanation
    If a culture starts with 1 cell and after 4 hours there are 64 cells, it means that each cell divides into 2 cells every hour. Therefore, in the first hour, there are 2 cells, in the second hour, there are 4 cells, in the third hour, there are 8 cells, and in the fourth hour, there are 16 cells. So, after 4 hours, there have been 4 generations of cell division. However, since the question asks for the total number of generations that have occurred, we need to include the initial generation, making the total 5 generations.

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  • 19. 

    All of the following pertain to nitrogenous bases except they

    • Form pairs by hydrogen bonding

    • Guanine pairs with uracil

    • Adenine pairs with thymine

    • Cytosine and thymine are pyrimidines

    • Allows variation from one nucleotide to another which creates the encoded information

    Correct Answer
    A. Guanine pairs with uracil
    Explanation
    Guanine does not pair with uracil. Guanine pairs with cytosine through three hydrogen bonds, while adenine pairs with thymine through two hydrogen bonds. The pairing of nitrogenous bases is a fundamental aspect of DNA structure and is crucial for the encoding of genetic information.

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  • 20. 

    Peptidoglycan is a unique macromolecule found in bacterial

    • Cell walls

    • Cell membranes

    • Capsules

    • Slime layers

    • Inclusions

    Correct Answer
    A. Cell walls
    Explanation
    Peptidoglycan is a unique macromolecule found in bacterial cell walls. It provides structural support and protection to the bacterial cell. It forms a mesh-like structure, providing rigidity to the cell wall and preventing the cell from bursting under osmotic pressure. Peptidoglycan is composed of alternating sugar residues, N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM), cross-linked by short peptide chains. This unique composition is specific to bacterial cell walls and is not found in cell membranes, capsules, slime layers, or inclusions.

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  • 21. 

    You inoculate a culture into a test tube containing broth and take it out of the incubator the next day. You see the culture is growing at the bottom of the tube. You conclude the culture must be

    • Aerobic

    • Anaerobic

    • Facultative anaerobe

    • Microaerophilic

    • Aerotolerant

    Correct Answer
    A. Anaerobic
    Explanation
    Based on the information given, the culture is growing at the bottom of the tube. This suggests that the culture is growing in the absence of oxygen, as oxygen tends to accumulate at the top of the tube. Therefore, the culture must be anaerobic, meaning it can survive and grow in the absence of oxygen.

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  • 22. 

    Among the microorganisms, various genomes can include

    • Chromosomes

    • Plasmids

    • Mitochondrial DNA

    • Chloroplast DNA

    • All of the choices are correct

    Correct Answer
    A. All of the choices are correct
    Explanation
    All of the choices are correct because microorganisms, like other organisms, have genomes that consist of chromosomes, plasmids, mitochondrial DNA, and chloroplast DNA. Chromosomes are the main genetic material found in the nucleus of cells, while plasmids are small, circular pieces of DNA that can replicate independently. Microorganisms, such as bacteria and fungi, also have mitochondria and chloroplasts, which have their own DNA. Therefore, all of these components can be found in the genomes of microorganisms.

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  • 23. 

    The site where the old DNA strands separate and new DNA strands will be synthesized is called the

    • Primer

    • Okazaki fragment

    • Template

    • Rolling circle

    • Replication fork

    Correct Answer
    A. Replication fork
    Explanation
    The replication fork is the site where the old DNA strands separate and new DNA strands are synthesized during DNA replication. This is where the DNA helicase enzyme unwinds the double helix and separates the two strands. The newly synthesized DNA strands are then elongated by DNA polymerase using the existing strands as templates. The replication fork moves along the DNA molecule as replication progresses.

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  • 24. 

    Sarcinae refers to

    • Cocci in pairs

    • A cuboidal packet of cells

    • Groups of endospores

    • Coffee-bean shaped rods in pairs

    • Vibrios in threes

    Correct Answer
    A. A cuboidal packet of cells
    Explanation
    Sarcinae refers to a cuboidal packet of cells. This term is used to describe a specific arrangement of bacteria, where the cells divide in three perpendicular planes, forming a cube-like structure. This arrangement is commonly observed in certain bacteria, such as the genus Sarcina. The cells within the packet are typically tightly packed together, creating a distinct appearance under a microscope. This arrangement is different from other options listed, such as cocci in pairs, coffee-bean shaped rods in pairs, or vibrios in threes.

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  • 25. 

    The outcome of the Gram stain is based on differences in the cell's

    • Ribosomes

    • Inclusion

    • Cell wall

    • Cell membrane

    • Flagella

    Correct Answer
    A. Cell wall
    Explanation
    The outcome of the Gram stain is based on differences in the cell wall. Gram-positive bacteria have a thick peptidoglycan layer in their cell wall, which retains the crystal violet stain and appears purple under the microscope. On the other hand, Gram-negative bacteria have a thinner peptidoglycan layer and an outer membrane, which does not retain the stain and appears pink or red after counterstaining with safranin. Therefore, the cell wall composition is crucial in determining the outcome of the Gram stain.

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  • 26. 

    Endospores are

    • Metabolically inactive

    • Resistant to heat and chemical destruction

    • Resistant to destruction by radiation

    • Living structures

    • All of the choices are correct

    Correct Answer
    A. All of the choices are correct
    Explanation
    All of the choices are correct because endospores are metabolically inactive, meaning they are in a dormant state and do not carry out any metabolic processes. They are resistant to heat and chemical destruction, allowing them to survive in extreme conditions. They are also resistant to destruction by radiation, making them highly durable. Despite being inactive, endospores are still living structures, albeit in a dormant state. Therefore, all of the given choices accurately describe the characteristics of endospores.

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  • 27. 

    Microorganisms require large quantities of this nutrient for use in cell structure and metabolism:

    • Element

    • Macronutrient

    • Water

    • Growth factor

    • Trace element

    Correct Answer
    A. Macronutrient
    Explanation
    Macronutrients are essential nutrients that organisms need in large quantities for their cell structure and metabolism. They provide energy and are involved in various biological processes. In the context of microorganisms, macronutrients are crucial for their growth and survival. Therefore, microorganisms require large quantities of macronutrients for their cell structure and metabolism.

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  • 28. 

    The RNA molecules that carry amino acids to the ribosomes during protein synthesis are called

    • Ribosomal RNA

    • Messenger RNA

    • Transfer RNA

    • Primer RNA

    • Ribozymes

    Correct Answer
    A. Transfer RNA
    Explanation
    Transfer RNA (tRNA) molecules are responsible for carrying amino acids to the ribosomes during protein synthesis. Each tRNA molecule has a specific anticodon sequence that matches with the codon sequence on the messenger RNA (mRNA) molecule. This allows the tRNA to recognize and bind to the corresponding codon on the mRNA, bringing the correct amino acid to the growing protein chain. Therefore, tRNA is the correct answer for this question.

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  • 29. 

    The function of bacterial endospores is

    • Convert gaseous nitrogen to a usable form for plants

    • Reproduction and growth

    • Protection of genetic material during harsh conditions

    • Storage of excess cell materials

    • Sites for photosynthesis

    Correct Answer
    A. Protection of genetic material during harsh conditions
    Explanation
    Bacterial endospores serve as a means of protecting the genetic material of the bacteria during harsh conditions. These conditions can include extreme temperatures, lack of nutrients, or exposure to harmful chemicals or radiation. The endospore is a dormant and highly resistant structure that forms inside the bacterial cell, encasing the DNA and other essential components. This protective mechanism allows the bacteria to survive in unfavorable environments until conditions become more favorable for growth and reproduction.

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  • 30. 

    If the DNA sequence is ATTCCGGA, the mRNA transcript would be

    • TAAGGCCT

    • UAAGGCCU

    • ATTCCGGA

    • GUUAATTG

    • CAAGGUTA

    Correct Answer
    A. UAAGGCCU
    Explanation
    The correct answer is UAAGGCCU because in transcription, the DNA sequence is transcribed into mRNA by replacing each DNA base with its complementary RNA base. In this case, A is replaced with U, T is replaced with A, C is replaced with G, and G is replaced with C. Therefore, the mRNA transcript of the given DNA sequence ATTCCGGA would be UAAGGCCU.

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  • 31. 

    A bacterial genus that has waxy mycolic acid in the cell walls is

    • Mycobacterium

    • Mycoplasma

    • Streptococcus

    • Corynebacterium

    • Salmonella

    Correct Answer
    A. Mycobacterium
    Explanation
    Mycobacterium is the correct answer because it is a bacterial genus that is known for having waxy mycolic acid in its cell walls. Mycolic acid helps to protect the bacteria from the host immune system and contributes to their ability to cause chronic infections. Mycobacterium includes several species, including the ones that cause tuberculosis and leprosy. Mycoplasma, Streptococcus, Corynebacterium, and Salmonella do not have waxy mycolic acid in their cell walls, making them incorrect answers.

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  • 32. 

    A bacterial cell exhibiting chemotaxis probably has

    • Fimbriae

    • Capsule

    • Mesosomes

    • Flagella

    • Metachromatic granules

    Correct Answer
    A. Flagella
    Explanation
    A bacterial cell exhibiting chemotaxis probably has flagella. Chemotaxis is the movement of an organism in response to a chemical stimulus, and flagella are the whip-like appendages that bacteria use for movement. Therefore, it is likely that a bacterial cell exhibiting chemotaxis would have flagella to enable it to move towards or away from a particular chemical signal.

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  • 33. 

    In the cell, energy released by electrons is often used to phosphorylate

    • ATP

    • ADP

    • Pyruvic acid

    • Oxygen

    • NAD

    Correct Answer
    A. ADP
    Explanation
    In the cell, energy released by electrons is often used to phosphorylate ADP. This means that ADP (adenosine diphosphate) is converted into ATP (adenosine triphosphate) by adding a phosphate group. ATP is the primary energy currency of the cell and is used to power various cellular processes. Therefore, the energy released by electrons is utilized to generate ATP, which is essential for the cell's energy needs.

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  • 34. 

    Enzymes are

    • Broken down in reactions that require energy input

    • Proteins that function as catalysts

    • Electron carrier molecules

    • Not needed for catabolic reactions

    • All of the choices are correct

    Correct Answer
    A. Proteins that function as catalysts
    Explanation
    Enzymes are proteins that function as catalysts. Catalysts are substances that speed up chemical reactions without being consumed or permanently changed in the process. Enzymes facilitate biochemical reactions by lowering the activation energy required for the reaction to occur. They do so by binding to specific molecules, called substrates, and converting them into products. Enzymes play a crucial role in various biological processes, such as digestion, metabolism, and DNA replication. Therefore, the statement "proteins that function as catalysts" accurately describes the nature and function of enzymes.

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  • 35. 

    If a codon for alanin is GCA, then the anticodon is

    • GCA

    • CGT

    • ACG

    • CGU

    • UGC

    Correct Answer
    A. CGU
    Explanation
    The anticodon is the three nucleotide sequence on a tRNA molecule that is complementary to the codon on mRNA during translation. In this case, the codon for alanine is GCA. To find the anticodon, we need to determine the complementary sequence. The complementary bases for G, C, and A are C, G, and U respectively. Therefore, the anticodon for the codon GCA is CGU.

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  • 36. 

    Bacterial endospores are not produced by

    • Staphylococcus

    • Sporosarcina

    • Bacillus

    • Clostridium

    • All of the choices are correct

    Correct Answer
    A. Staphylococcus
    Explanation
    Bacterial endospores are resistant, dormant structures that certain bacteria produce as a survival mechanism under unfavorable conditions. Staphylococcus is a genus of bacteria that does not produce endospores. Sporosarcina, Bacillus, and Clostridium, on the other hand, are known to produce endospores. Therefore, the correct answer is Staphylococcus.

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  • 37. 

    Lipopolysaccharide is an important cell wall component of

    • Gram negative bacteria

    • Gram positive bacteria

    • Acid fast bacteria

    • Protoplasts

    • Protoplasts

    Correct Answer
    A. Gram negative bacteria
    Explanation
    Lipopolysaccharide is a major component of the outer membrane of gram-negative bacteria. It plays a crucial role in protecting the bacteria from the host immune system and is responsible for many of the pathogenic properties of these bacteria. Gram-positive bacteria do not have an outer membrane and therefore do not contain lipopolysaccharide. Acid-fast bacteria, such as Mycobacterium tuberculosis, have a unique cell wall structure that includes mycolic acids, not lipopolysaccharide. Protoplasts are bacterial cells that have had their cell walls removed, so they also do not contain lipopolysaccharide.

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  • 38. 

    An organism with a temperature growth range of 45*C to 60*C would be called a/an

    • Extremophile

    • Thermophile

    • Psychrophile

    • Facultative psychrophile

    • Thermoduric

    Correct Answer
    A. Thermophile
    Explanation
    An organism with a temperature growth range of 45*C to 60*C would be called a thermophile. Thermophiles are organisms that thrive in high temperatures, typically above 45°C. They have adapted to survive and reproduce in extreme heat, which would be detrimental to most other organisms. Thermophiles are often found in hot springs, hydrothermal vents, and other geothermal environments.

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  • 39. 

    An important indicator of evolutionary relatedness is to determine

    • Size of the periplasmic space

    • Similarities of cell membrane proteins

    • Size of the bacterial chromosome

    • Nitrogen base sequence of rRNA

    • Size of the ribosomes

    Correct Answer
    A. Nitrogen base sequence of rRNA
    Explanation
    The nitrogen base sequence of rRNA is an important indicator of evolutionary relatedness because it is highly conserved among different organisms. Over time, mutations can occur in the DNA sequence of an organism, including the rRNA genes. By comparing the nitrogen base sequences of rRNA from different organisms, scientists can determine how closely related they are. The more similar the sequences, the more closely related the organisms are believed to be. This method is widely used in phylogenetic studies to determine the evolutionary relationships between different species.

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  • 40. 

    The phase of the bacterial growth curve in which newly inoculated cells are adjusting to their new environment, metabolizing but not growing is the

    • Lag phase

    • Log phase

    • Stationary phase

    • Death phase

    • All of the choices are correct

    Correct Answer
    A. Lag phase
    Explanation
    The lag phase of the bacterial growth curve refers to the initial period where newly inoculated cells are adapting to their new environment. During this phase, the cells are metabolizing and preparing for growth, but they are not actively multiplying. This phase is characterized by a slower rate of cell division as the bacteria adjust to the conditions of their new surroundings.

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  • 41. 

    A sequence of bases on a gene that does not code for protein is called a/an

    • Promoter

    • Operator

    • Operon

    • Exon

    • Intron

    Correct Answer
    A. Intron
    Explanation
    An intron is a sequence of bases on a gene that does not code for protein. It is a non-coding region that is transcribed into RNA but is later removed during the process of RNA splicing. In contrast, exons are the coding regions of a gene that are translated into protein. Promoters are DNA sequences that initiate transcription, operators are DNA sequences that control gene expression, and operons are clusters of genes that are transcribed together. Therefore, the correct answer is intron.

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  • 42. 

    Organisms that feed on dead organisms for nutrients are called

    • Saprobes

    • Parasites

    • Autotrophs

    • Lithoautotrophs

    • Phototrophs

    Correct Answer
    A. Saprobes
    Explanation
    Saprobes are organisms that obtain nutrients by feeding on dead organisms. They play a crucial role in decomposition and recycling of organic matter in ecosystems. Unlike parasites, which rely on living hosts, saprobes derive their nutrients from dead organic material. Autotrophs, on the other hand, are organisms that can produce their own food through photosynthesis or chemosynthesis. Lithoautotrophs are a specific type of autotrophs that obtain energy from inorganic compounds. Phototrophs are also autotrophs, but they obtain energy from sunlight through photosynthesis. Therefore, the correct answer for this question is saprobes.

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  • 43. 

    Which is mismatched?

    • Ribosomes - protein synthesis

    • Inclusions - excess cell nutrients and materials

    • Plasmids - genes essential for growth and metabolism

    • Nucleoid - hereditary material

    • Cytoplasm - dense, gelatinous solution

    Correct Answer
    A. Plasmids - genes essential for growth and metabolism
    Explanation
    Plasmids are small, circular pieces of DNA that are separate from the main bacterial chromosome. They often contain non-essential genes, such as those involved in antibiotic resistance or the ability to produce toxins. While plasmids can provide certain advantages to bacterial growth and metabolism, they are not essential for these processes. Therefore, the statement "plasmids - genes essential for growth and metabolism" is mismatched.

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  • 44. 

    The phase of the bacterial growth curve in which the rate of multiplication equals the rate of cell death is the

    • Lag phase

    • Log phase

    • Stationary phase

    • Death phase

    • All of the choices are correct

    Correct Answer
    A. Stationary phase
    Explanation
    The stationary phase of the bacterial growth curve is the phase in which the rate of multiplication equals the rate of cell death. During this phase, the number of new cells being produced is balanced by the number of cells dying, resulting in no net increase in the population size. This phase occurs when the bacteria have depleted essential nutrients or when they have reached the carrying capacity of their environment.

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  • 45. 

    A microorganism that does not have catalase or superoxide dismutase would find it difficult to live in an environment with

    • Carbon dioxide

    • Oxygen

    • High salt

    • Temperatures above 37*C

    • High acidity

    Correct Answer
    A. Oxygen
    Explanation
    Microorganisms that lack catalase or superoxide dismutase would struggle to survive in an environment with oxygen. Catalase and superoxide dismutase are enzymes that help break down harmful reactive oxygen species (ROS) produced during normal cellular metabolism. Without these enzymes, the microorganism would be unable to neutralize ROS, leading to oxidative stress and damage to cellular components. Oxygen is a major source of ROS, so an oxygen-rich environment would be particularly challenging for these microorganisms to survive in.

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  • 46. 

    Which cell structure is an important agent in modern genetic engineering techniques?

    • Ribosomes

    • Capsules

    • Plasmids

    • Inclusions

    • Mesosomes

    Correct Answer
    A. Plasmids
    Explanation
    Plasmids are circular DNA molecules that are separate from the chromosomal DNA in bacteria. They play a crucial role in modern genetic engineering techniques as they can be easily manipulated and transferred between different organisms. Plasmids are often used as vectors to introduce foreign DNA into host cells, allowing scientists to insert, delete, or modify specific genes. This ability to manipulate plasmids has revolutionized genetic engineering, enabling the production of genetically modified organisms and the development of new medical treatments and technologies.

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  • 47. 

    The most immediate result of destruction of a cell's ribosomes would be

    • Material would not be able to cross the cell membrane

    • Protein synthesis would stop

    • Destruction of the cell's DNA

    • Formation of glycogen inclusions

    • Loss of capsule

    Correct Answer
    A. Protein synthesis would stop
    Explanation
    If a cell's ribosomes are destroyed, it would directly result in the stoppage of protein synthesis. Ribosomes are responsible for protein synthesis in cells, and without them, the cell would not be able to produce proteins. Proteins are essential for various cellular functions, including structural support, enzymatic reactions, and cell signaling. Therefore, the destruction of ribosomes would immediately halt the production of proteins, leading to significant disruptions in cellular processes.

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  • 48. 

    The term heterotroph refers to an organism that

    • Uses CO2 for its carbon source

    • Must obtain organic compounds for its carbon needs

    • Gets energy from sunlight

    • Gets energy by oxidizing chemical compounds

    • Does not need a carbon source

    Correct Answer
    A. Must obtain organic compounds for its carbon needs
    Explanation
    A heterotroph is an organism that must obtain organic compounds for its carbon needs. This means that it cannot use CO2 as its carbon source like autotrophs do. Instead, heterotrophs rely on consuming other organisms or organic matter to obtain the necessary carbon compounds for their survival and growth.

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  • 49. 

    The short, numerous appendages used by some bacterial cells for adhering to surfaces are called

    • Flagella

    • Cilia

    • Fimbriae

    • Periplasmic  flagella

    • Option 5

    Correct Answer
    A. Fimbriae
    Explanation
    Fimbriae are short, numerous appendages found on the surface of some bacterial cells. They are used by the bacteria to adhere to surfaces, such as host tissues or other cells. Fimbriae are important for the bacteria to establish infections and colonize specific sites in the body. They can also play a role in biofilm formation, which is a protective matrix that bacteria can form on surfaces. Flagella, on the other hand, are long whip-like structures that bacteria use for movement. Cilia are similar to flagella but are found in eukaryotic cells. Periplasmic flagella are flagella that are located in the periplasmic space of certain bacteria.

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Quiz Review Timeline (Updated): Sep 27, 2023 +

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  • Current Version
  • Sep 27, 2023
    Quiz Edited by
    ProProfs Editorial Team
  • Feb 29, 2020
    Quiz Created by
    Benedict Ramos

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