Micro Study Guide 2
This quiz focuses on key microbiological concepts including bacterial cell wall components, growth conditions, and temperature preferences of different bacteria.
- 1.
A bacterial genus that has waxy mycolic acid in the cell walls is
- A.
Mycobacterium
- B.
Mycoplasma
- C.
Streptococcus
- D.
Corynebacterium
- E.
Salmonella
Correct Answer
A. MycobacteriumExplanation
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.Rate this question:
-
- 2.
Lipopolysaccharide is an important cell wall component of
- A.
Gram negative bacteria
- B.
Gram positive bacteria
- C.
Acid fast bacteria
- D.
Protoplasts
- E.
Protoplasts
Correct Answer
A. Gram negative bacteriaExplanation
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.Rate this question:
-
- 3.
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
- A.
Aerobe
- B.
Anaerobe
- C.
Facultative anaerobe
- D.
Microaerophile
- E.
Capnophile
Correct Answer
C. Facultative anaerobeExplanation
The fact that there was moderate growth of the culture in both the candle jar (anaerobic condition) and the anaerobic jar suggests that the species can tolerate and grow in the absence of oxygen. However, the heavy growth of the culture on the incubator shelf indicates that it can also thrive in the presence of oxygen. Therefore, this species is a facultative anaerobe, which means it can switch between aerobic and anaerobic metabolism depending on the availability of oxygen.Rate this question:
-
- 4.
The decline in growth rate during the death phase is due to all of the following except
- A.
The depletion of nutrients
- B.
The depletion of oxygen
- C.
The excretion of biochemical pollutants
- D.
The excretion of organic acids
- E.
The decrease in temperature of the culture
Correct Answer
E. The decrease in temperature of the cultureExplanation
During the death phase of a culture, the decline in growth rate is primarily caused by the depletion of nutrients, the depletion of oxygen, the excretion of biochemical pollutants, and the excretion of organic acids. These factors contribute to the unfavorable conditions for cell growth and reproduction. However, the decrease in temperature of the culture does not directly affect the growth rate during the death phase.Rate this question:
-
- 5.
An organism with a temperature growth range of 45*C to 60*C would be called a/an
- A.
Extremophile
- B.
Thermophile
- C.
Psychrophile
- D.
Facultative psychrophile
- E.
Thermoduric
Correct Answer
B. ThermophileExplanation
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.Rate this question:
-
- 6.
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?
- A.
Halophile
- B.
Mesophile
- C.
Anaerobe
- D.
Psychrophile
- E.
Capnophile
Correct Answer
D. PsychrophileExplanation
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.Rate this question:
-
- 7.
All of the following pertain to endotoxins except they
- A.
Are specific bacterial cell wall lipids
- B.
Can stimulate fever in the human body
- C.
Can cause shock in the human body
- D.
Are involved in typhoid fever and some meningitis cases
- E.
Are found in acid fast bacterial cell wals
Correct Answer
E. Are found in acid fast bacterial cell walsExplanation
Endotoxins are a type of toxin that are part of the outer membrane of certain bacteria. They are not specific bacterial cell wall lipids, as they are composed of lipopolysaccharides. Endotoxins can stimulate fever and cause shock in the human body. They are involved in typhoid fever and some meningitis cases. However, they are not found in acid-fast bacterial cell walls. Acid-fast bacteria have a unique cell wall structure that includes mycolic acids, but endotoxins are not a component of this cell wall.Rate this question:
-
- 8.
Microorganisms require small quantities of this nutrient for enzyme function and maintenance of protein structure:
- A.
Element
- B.
Macronutrient
- C.
Water
- D.
Growth factor
- E.
Trace element
Correct Answer
E. Trace elementExplanation
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.Rate this question:
-
- 9.
All of the chemical reactions of the cell are called
- A.
Catabolism
- B.
Redox reactions
- C.
Phosphorylation
- D.
Metabolism
- E.
Cellular respiration
Correct Answer
D. MetabolismExplanation
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.Rate this question:
-
- 10.
An important indicator of evolutionary relatedness is to determine
- A.
Size of the periplasmic space
- B.
Similarities of cell membrane proteins
- C.
Size of the bacterial chromosome
- D.
Nitrogen base sequence of rRNA
- E.
Size of the ribosomes
Correct Answer
D. Nitrogen base sequence of rRNAExplanation
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.Rate this question:
-
- 11.
Bacteria living in a freshwater stream that are moved to salty seawater would
- A.
Be in a hypotonic solution
- B.
Gain water
- C.
Be in a isotonic solution
- D.
Shrivel
- E.
None of the choices are correct
Correct Answer
D. ShrivelExplanation
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.Rate this question:
-
- 12.
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?
- A.
Gracillucates
- B.
Firmicutes
- C.
Actinobacteria
- D.
Archaea
- E.
Spirochaetes
Correct Answer
D. ArchaeaExplanation
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.Rate this question:
-
- 13.
The DNA of microorganisms is made up of subunits called
- A.
Histones
- B.
Amino acids
- C.
Nucleotides
- D.
MRNA
- E.
Polymerases
Correct Answer
C. NucleotidesExplanation
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.Rate this question:
-
- 14.
In anaerobic respiration, all of the following can serve as the final electron acceptor except
- A.
Nitrate
- B.
Oxygen
- C.
Sulfate
- D.
Nitrite
- E.
None of the choices are correct
Correct Answer
B. OxygenExplanation
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.Rate this question:
-
- 15.
What is the correct sequence of a Gram stain?
- A.
Gram's iodine, crystal violet, alcohol, safranin
- B.
Crystal violet, safranin, alcohol, safranin
- C.
Safranin, crystal violet, Gram's iodine, alcohol
- D.
Alcohol, crystal violet, safranin, Gram's iodine
Correct Answer
C. Safranin, crystal violet, Gram's iodine, alcohol -
- 16.
A procaryotic cell wall that has primarily peptidoglycan with small amounts of teichoic acid and lipoteichoic acid is
- A.
Gram negative
- B.
Gram positive
- C.
Archaea
- D.
Spheroplast
- E.
Acid fast
Correct Answer
B. Gram positiveExplanation
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.Rate this question:
-
- 17.
The term phototroph refers to an organism that
- A.
Uses CO2 for its carbon source
- B.
Must obtain organic compounds for its carbon needs
- C.
Gets energy from sunlight
- D.
Gets energy by oxidizing chemical compounds
- E.
Does not need a carbon source
Correct Answer
C. Gets energy from sunlightExplanation
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.Rate this question:
-
- 18.
The bacterial chromosome
- A.
Is located in the cell membrane
- B.
Contains all the cell's plasmids
- C.
Is part of the nucleios
- D.
Forms a single linear strand of DNA
- E.
All of the choices are correct
Correct Answer
D. Forms a single linear strand of DNAExplanation
The correct answer is "forms a single linear strand of DNA." This is because the bacterial chromosome is a circular strand of DNA that contains all the genetic information of the bacterium. It is not located in the cell membrane, it does not contain all the cell's plasmids, and it is not part of the nucleios. Therefore, the statement "forms a single linear strand of DNA" is the most accurate explanation for the given answer.Rate this question:
-
- 19.
The phase of the bacterial growth curve in which newly inoculated cells are adjusting to their new environment, metabolizing but not growing is the
- A.
Lag phase
- B.
Log phase
- C.
Stationary phase
- D.
Death phase
- E.
All of the choices are correct
Correct Answer
A. Lag phaseExplanation
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.Rate this question:
-
- 20.
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
- A.
Parasitic
- B.
Saprobic
- C.
Commensal
- D.
Mutualistic
- E.
None of the choices are correct
Correct Answer
D. MutualisticExplanation
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.Rate this question:
-
- 21.
A sequence of bases on a gene that does not code for protein is called a/an
- A.
Promoter
- B.
Operator
- C.
Operon
- D.
Exon
- E.
Intron
Correct Answer
E. IntronExplanation
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.Rate this question:
-
- 22.
Groups of three consecutive bases along the DNA of a gene have the code for one
- A.
Protein
- B.
Nucleotide
- C.
Amino acid
- D.
Purine
- E.
None of the choices are correct
Correct Answer
C. Amino acidExplanation
The groups of three consecutive bases along the DNA of a gene are called codons. Each codon codes for a specific amino acid, which is the building block of proteins. Therefore, the correct answer is amino acid.Rate this question:
-
- 23.
The term that refers to the presence of flagella all over the cell surface is
- A.
Amphitrichous
- B.
Atrichous
- C.
Lophotrichous
- D.
Monotrichous
- E.
Peritrichous
Correct Answer
E. PeritrichousExplanation
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).Rate this question:
-
- 24.
Organisms that feed on dead organisms for nutrients are called
- A.
Saprobes
- B.
Parasites
- C.
Autotrophs
- D.
Lithoautotrophs
- E.
Phototrophs
Correct Answer
A. SaprobesExplanation
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.Rate this question:
-
- 25.
A microaerophile
- A.
Grows best in an anaerobic jar
- B.
Grows with or without oxygen
- C.
Needs normal atmospheric levels of oxygen
- D.
Requires a small amount of oxygen but won't grow at normal atmospheric levels
- E.
None of the choices are correct
Correct Answer
D. Requires a small amount of oxygen but won't grow at normal atmospheric levelsExplanation
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.Rate this question:
-
- 26.
All of the following are correct about a slime layer except
- A.
It is a type of glycocalyx
- B.
It can be easily washed off the cell
- C.
It protects the cell from loss of water and nutrients
- D.
It plays a role in cell motility
- E.
It allows cells to participate in biofilms
Correct Answer
D. It plays a role in cell motilityExplanation
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.Rate this question:
-
- 27.
Which is mismatched?
- A.
Ribosomes - protein synthesis
- B.
Inclusions - excess cell nutrients and materials
- C.
Plasmids - genes essential for growth and metabolism
- D.
Nucleoid - hereditary material
- E.
Cytoplasm - dense, gelatinous solution
Correct Answer
C. Plasmids - genes essential for growth and metabolismExplanation
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.Rate this question:
-
- 28.
The breakdown of peptidoglycan to N-acetylmuramic acid, N-acetylglucosamine and peptides is an example of
- A.
Anabolism
- B.
Catabolism
- C.
Phosphorylation
- D.
Fermentation
- E.
Biosynthesis
Correct Answer
B. CatabolismExplanation
The breakdown of peptidoglycan to N-acetylmuramic acid, N-acetylglucosamine, and peptides is an example of catabolism. Catabolism refers to the metabolic process in which larger molecules are broken down into smaller ones, releasing energy in the process. In this case, the peptidoglycan molecule is being broken down into its constituent parts, resulting in the release of energy. This process is the opposite of anabolism, which involves the synthesis of larger molecules from smaller ones.Rate this question:
-
- 29.
All bacterial cells have
- A.
A chromosome
- B.
Fimbriae
- C.
Endospores
- D.
Capsules
- E.
Flagella
Correct Answer
A. A chromosomeExplanation
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.Rate this question:
-
- 30.
The nontranscribed region of DNA to which RNA polymerase binds to initiate transcriptions is called the
- A.
Promoter
- B.
Operator
- C.
Operon
- D.
Exon
- E.
Intron
Correct Answer
A. PromoterExplanation
The nontranscribed region of DNA to which RNA polymerase binds to initiate transcriptions is called the promoter. The promoter region contains specific sequences of DNA that serve as binding sites for RNA polymerase, allowing it to recognize the start site of a gene and begin transcribing the DNA into RNA. The promoter plays a crucial role in regulating gene expression by determining when and how often a gene is transcribed. It is not the operator, operon, exon, or intron, as these terms refer to other regions or elements within a gene or DNA.Rate this question:
-
- 31.
Bacteria with small bunches of flagella emerging from the same site are said to be
- A.
Lophotrichous
- B.
Peritrichous
- C.
Monotrichous
- D.
Amphitrichous
- E.
Spirilla
Correct Answer
A. LophotrichousExplanation
Bacteria with small bunches of flagella emerging from the same site are called lophotrichous. This means that multiple flagella are present at one end of the bacterium. This arrangement allows the bacteria to move in a corkscrew-like motion.Rate this question:
-
- 32.
The movement of substances from higher to lower concentration across a semipermeable membrane that must have a specific protein carrier but no energy expenditure is called
- A.
Facilitated diffusion
- B.
Diffusion
- C.
Active transport
- D.
Osmosis
- E.
Endocytosis
Correct Answer
A. Facilitated diffusionExplanation
Facilitated diffusion is the correct answer because it involves the movement of substances from higher to lower concentration across a semipermeable membrane with the help of specific protein carriers. Unlike active transport, facilitated diffusion does not require energy expenditure. Diffusion, osmosis, and endocytosis are not the correct answers because they do not involve the use of specific protein carriers.Rate this question:
-
- 33.
The phase of the bacterial growth curve in which the rate of multiplication equals the rate of cell death is the
- A.
Lag phase
- B.
Log phase
- C.
Stationary phase
- D.
Death phase
- E.
All of the choices are correct
Correct Answer
C. Stationary phaseExplanation
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.Rate this question:
-
- 34.
A microorganism that does not have catalase or superoxide dismutase would find it difficult to live in an environment with
- A.
Carbon dioxide
- B.
Oxygen
- C.
High salt
- D.
Temperatures above 37*C
- E.
High acidity
Correct Answer
B. OxygenExplanation
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.Rate this question:
-
- 35.
All of the following structures contribute to the ability of pathogenic bacteria to cause disease except
- A.
Inclusions
- B.
Fimbriae
- C.
Capsule
- D.
Slime layer
- E.
Outer membrane of gram negative cell walls
Correct Answer
A. InclusionsExplanation
Pathogenic bacteria have various structures that contribute to their ability to cause disease. These structures include fimbriae, capsule, slime layer, and the outer membrane of gram-negative cell walls. However, inclusions do not directly contribute to the ability of pathogenic bacteria to cause disease. Inclusions are storage granules found within bacterial cells that store nutrients or other substances. While they play a role in bacterial metabolism and survival, they are not directly involved in the pathogenicity of bacteria.Rate this question:
-
- 36.
In the Gram stain, the mordant is
- A.
Crystal violet
- B.
Safranin
- C.
Alcohol
- D.
Water
- E.
Iodine
Correct Answer
E. IodineExplanation
Iodine is the correct answer because in the Gram stain, iodine acts as the mordant. A mordant is a substance that helps bind the stain to the specimen, making it more visible. In the Gram stain process, iodine is applied after the crystal violet stain. It forms a complex with the crystal violet, creating a larger molecule that is trapped within the cell wall of Gram-positive bacteria. This helps to differentiate Gram-positive bacteria (which retain the stain) from Gram-negative bacteria (which do not).Rate this question:
-
- 37.
A halophile would grow best in
- A.
Acid pools
- B.
Fresh water ponds
- C.
Hot geyser springs
- D.
Arid, desert soil
- E.
Salt lakes
Correct Answer
E. Salt lakesExplanation
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.Rate this question:
-
- 38.
If a culture starts out with 1 cell and after 4 hours there are 64 cells, how many generations have occurred?
- A.
4
- B.
5
- C.
6
- D.
12
- E.
Impossible to determine
Correct Answer
C. 6Explanation
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.Rate this question:
-
- 39.
All of the following pertain to nitrogenous bases except they
- A.
Form pairs by hydrogen bonding
- B.
Guanine pairs with uracil
- C.
Adenine pairs with thymine
- D.
Cytosine and thymine are pyrimidines
- E.
Allows variation from one nucleotide to another which creates the encoded information
Correct Answer
B. Guanine pairs with uracilExplanation
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.Rate this question:
-
- 40.
During aerobic cellular respiration, the final electron acceptor is
- A.
Pyruvic acid
- B.
Oxygen
- C.
Nitrate
- D.
Cytochrome c.
- E.
FAD
Correct Answer
E. FADExplanation
During aerobic cellular respiration, the final electron acceptor is FAD. FAD (flavin adenine dinucleotide) is a coenzyme that plays a crucial role in the electron transport chain. It accepts electrons from other molecules in the chain and passes them along to the next electron carrier, ultimately leading to the production of ATP. Oxygen is not the final electron acceptor in this process, as it acts as the terminal electron acceptor in the electron transport chain but not the final one. Pyruvic acid, nitrate, and cytochrome c are not directly involved in accepting electrons in aerobic cellular respiration.Rate this question:
-
- 41.
Which cell structure is an important agent in modern genetic engineering techniques?
- A.
Ribosomes
- B.
Capsules
- C.
Plasmids
- D.
Inclusions
- E.
Mesosomes
Correct Answer
C. PlasmidsExplanation
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.Rate this question:
-
- 42.
Bacterial cells could have any of the following appendages except
- A.
Flagella
- B.
Cilia
- C.
Fimbriae
- D.
Periplasmic flagella (axial filaments)
- E.
Sex pili
Correct Answer
B. CiliaExplanation
Bacterial cells do not have cilia. Cilia are hair-like structures found on the surface of some eukaryotic cells, such as those in the respiratory tract. Bacterial cells, on the other hand, may have flagella, fimbriae, periplasmic flagella (axial filaments), or sex pili as appendages. Cilia are not present in bacterial cells.Rate this question:
-
- 43.
The most immediate result of destruction of a cell's ribosomes would be
- A.
Material would not be able to cross the cell membrane
- B.
Protein synthesis would stop
- C.
Destruction of the cell's DNA
- D.
Formation of glycogen inclusions
- E.
Loss of capsule
Correct Answer
B. Protein synthesis would stopExplanation
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.Rate this question:
-
- 44.
Peptidoglycan is a unique macromolecule found in bacterial
- A.
Cell walls
- B.
Cell membranes
- C.
Capsules
- D.
Slime layers
- E.
Inclusions
Correct Answer
A. Cell wallsExplanation
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.Rate this question:
-
- 45.
The term heterotroph refers to an organism that
- A.
Uses CO2 for its carbon source
- B.
Must obtain organic compounds for its carbon needs
- C.
Gets energy from sunlight
- D.
Gets energy by oxidizing chemical compounds
- E.
Does not need a carbon source
Correct Answer
B. Must obtain organic compounds for its carbon needsExplanation
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.Rate this question:
-
- 46.
Enzymes that are only produced only when substrate is present are termed
- A.
Exoenzymes
- B.
Endoenzymes
- C.
Constitutive enzymes
- D.
Induced enzymes
- E.
Conjugated enzymes
Correct Answer
D. Induced enzymesExplanation
Induced enzymes are produced only when the substrate is present. This means that the production of these enzymes is regulated by the presence of the substrate, and they are not produced continuously. The induction of these enzymes is a response to the need for their specific function, which is triggered by the presence of the substrate. Therefore, induced enzymes are only produced when their substrate is present, making them the correct answer in this case.Rate this question:
-
- 47.
The use of energy by a cell to enclose a substance in its membrane by forming a vacuole and engulfing it is called
- A.
Facilitated diffusion
- B.
Diffusion
- C.
Active transport
- D.
Osmosis
- E.
Endocytosis
Correct Answer
E. EndocytosisExplanation
Endocytosis is the process in which a cell uses energy to enclose a substance in its membrane by forming a vacuole and engulfing it. This process allows the cell to take in large molecules or particles that cannot pass through the cell membrane by simple diffusion or active transport. It is a form of active transport because it requires energy expenditure by the cell. Facilitated diffusion, diffusion, and osmosis do not involve the formation of a vacuole or engulfing of substances by the cell membrane.Rate this question:
-
- 48.
The short, numerous appendages used by some bacterial cells for adhering to surfaces are called
- A.
Flagella
- B.
Cilia
- C.
Fimbriae
- D.
Periplasmic flagella
- E.
Option 5
Correct Answer
C. FimbriaeExplanation
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.Rate this question:
-
- 49.
The duplication of a cell's DNA is called
- A.
Mitosis
- B.
Replication
- C.
Transcription
- D.
Translation
- E.
Mutation
Correct Answer
B. ReplicationExplanation
Replication is the correct answer because it refers to the process of duplicating a cell's DNA. During replication, the DNA molecule unwinds and separates into two strands, and each strand serves as a template for the synthesis of a new complementary strand. This results in two identical copies of the original DNA molecule. Mitosis is the process of cell division, transcription is the synthesis of RNA from DNA, translation is the synthesis of proteins from RNA, and mutation refers to changes in the DNA sequence.Rate this question:
-
- 50.
Enzymes that catalyze removing electrons from one substrate and adding electrons to another are called
- A.
Phosphotransferases
- B.
Oxidoreductases
- C.
Decarboxylases
- D.
Aminotransferases
- E.
Ligases
Correct Answer
B. OxidoreductasesExplanation
Oxidoreductases are enzymes that catalyze the transfer of electrons from one substrate to another. They remove electrons from one molecule (oxidation) and transfer them to another molecule (reduction). This process is essential for many biological reactions, including energy production and metabolism. Phosphotransferases, decarboxylases, aminotransferases, and ligases are different types of enzymes that catalyze other specific reactions, not specifically involving the transfer of electrons.Rate this question:
-
Quiz Review Timeline +
Our quizzes are rigorously reviewed, monitored and continuously updated by our expert board to maintain accuracy, relevance, and timeliness.
-
Current Version
-
Sep 27, 2023Quiz Edited by
ProProfs Editorial Team -
Feb 29, 2020Quiz Created by
Benedict Ramos