Foundation 3 Questions 1-18

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Question 1

What component of the gram-negative cell membrane can act as an endotoxin during cell lysis?

  1. Peptidoglycan
  2. Mucin
  3. Lipopolysaccharide
  4. Lipoteichoic acid
  5. Teichoic acid

The correct answer is option c. Lipopolysaccharide

Correct Answer Explanation – Correct, when lysed can act as an endotoxin
a. Found in cell wall of gram negative and positive bacteria
b. incorrect as mucin is a glycoprotein involved in the structure of mucous
d. Part of bacterial cell wall in some bacteria
e. Part of bacterial cell wall to maintain its integrity

Question 2

Protein particles which can act as infectious agents are known as?

  1. Virons
  2. Prions
  3. Plasmids
  4. Nucleoid
  5. Proteases

The correct answer is option b. Prions

b is correct, these can be seen in CJD
a. This is a particle of a virus
c. This is the circular ring of DNA in prokaryotes
d. a nucleoid is a nucleus looking shape containing DNA found in prokaryotes
e. Proteases are enzymes that work to break down proteins

Question 3

Endotoxin produced by gram-negative bacteria is present in?

  1. Peptidoglycan
  2. Lipopolysaccharide
  3. Teichoic acid
  4. Outer membrane
  5. Inner membrane

The correct answer is option b. Lipopolysaccharide

b is correct as lipopolysaccharides are polysaccarides and lipids that can form endotoxins
a. peptoglycans form the structure of the outer surface of the plasma membrane
c. techoic acids is a polymer of glycerol phosphate found in the structure of the wall in the plasma membranes
d. Endotoxins are found betweenm the membranes
e. Endotoxins are found inbetween the layers of the membranes

Question 4

Which of the following infectious agents live as parasites on bacteria?

  1. Fungi
  2. Commensals
  3. Bacteriophages
  4. Transposons
  5. Prions

The correct answer is option c. Bacteriophages

c is correct, these are viruses that infect bacterium
a. Fungi typicaly do not grow on the bacteria
b. Commensals are bacteria that are present as usual human physiology
d. Transponsons are DNA segments that can be translated with no complimentary sequences
e. Prions are incorrectly folded proteins that cuase infections, typically neurological infections like CJD

Question 5

All prokaryotes are surrounded by a cell wall except for?

  1. Mycoplasms
  2. Sperochetes
  3. Actinomycetes
  4. Methanogena
  5. Eukaryotes

The correct answer is option a. Mycoplasms

a is correct as mycoplasmids do not have cell walls
b. is incorrect as sperochetes have a cell wall
c. Actinomycetes have a cell wall
d. Methanogena have a cell wall
e. Eukaryotes are not a type of prokaryotes

Question 6

Which antibody is first formed after infection?

  1. IgG
  2. IgM
  3. IgD
  4. IgE
  5. IgA

The correct answer is option b. IgM

IgM is produced first and is a short term antibody
a. IgG is produced by the B plasma cells and remain in circulation for a longer period of time
c. IgD is in immature B-lyphocytes that are co-expressed with IgM antibodies
d. IgE is an immunoglobulin that is found in hypersensitivity reactions produced by B cells
e. IgA is a non-specific antibody found in the bodies mucous membranes such as the eyes

Question 7

Active immunity is induced by?

  1. Infection
  2. Antibodies created by commensial bacteria
  3. Placental transfer of antibodies
  4. Injection of antibodies
  5. Injection of gamma – globulins

The correct answer is option a. Infection

Infection does cause antibodies to be created
b. This is passive immunity
c. This is passive immunity
d. This is passive immunity
e. This is passive immunity

Question 8

The main feature of a prokaryote is the

  1. Absence of locomotion
  2. Absence of nuclear envelope
  3. Absence of nuclear material
  4. Absence of protein synthesis
  5. Absence of plasmid DNA

The correct answer is option b. Absence of nuclear envelope

b is correct as the prokaryotes do not have membrane bound organelles
a. Incorrect as prokaryotic cells are able to move
c. Incorrect as prokaryotes do have nuclear material such as plasmids and free RNA
d. Prokaryotes are able to create their own proteins
e. Most prokaryotes contain plasmids as a DNA store

Question 9

The most important virulence factor is

  1. Adhesions
  2. Invasiveness
  3. Toxigenicity
  4. Enzymes
  5. All of the above

The correct answer is option e. All of the above

All of these are important virulence factors so it is all of the above
a. Adhesion is important so it can stay at the infected surface
b. Invasiveness can increase the evasion of the immune system
c. Toxigenicity can cause symptoms and are important in infections
d. Enzymes are important to digest and breakdown macromolecules

Question 10

Gram positive bacteria have a thick mesh-like cell wall made of peptidoglycan and as a result are stained by gram staining using?

  1. Crystal violet
  2. Haematoxylon
  3. Fast Green
  4. Safranin
  5. EtBr

The correct answer is option A, the thick cell wall of gram +ve bacteria retains the purple colour of crystal violet whereas it is washed out of the thinner cell wall of gram –ve bacteria using ethanol. These cells appear pink due to a counterstain.

a is correct as Crystal violet interacts with the cell wall giving the purple colour
b. Incorrect
c. Incorrect
d. Incorrect, this is the counterstain that makes gram -ve bacteria appear pink
e. Incorrect, this stains DNA

Question 11

Select the Correct statement describing the organelles and cell structure of eukaryotes and prokaryotes

  1. Eukaryotes contain circular DNA arranged within the nucleus as well as diploid chromosomes unlike prokaryotes which contain no circular DNA in their nucleus. Eukaryotes contain 80s ribosomes and do not have a cell wall unlike the 70s ribosomes in prokaryote, with some form of a cell wall
  2. Eukaryotes contain coiled DNA within the nucleus as well as haploid chromosomes similar to prokaryotes which contain haploid chromosomes. Eukaryotes contain 70s ribosomes and do not have a cell wall unlike the 80s ribosomes in prokaryotes, with some form of a cell wall.
  3. Eukaryotes contain coiled DNA within the nucleus as well as diploid chromosomes unlike prokaryotes which have no nucleus, haploid chromosomes and some circular DNA. Eukaryotes contain 80s ribosomes and may occasionally have a cell wall unlike prokaryotes which contain 70s ribosomes and always have some form of cell wall.
  4. Eukaryotes contain coiled DNA within the nucleus as well as diploid chromosomes unlike prokaryotes which have no nucleus and circular DNA. Eukaryotes contain 80s ribosomes and do not have a cell wall whereas prokaryotes contain 70s ribosomes and always have some form of a cell wall.
  5. Prokaryotes contain diploid chromosomes unlike eukaryotes which have no nucleus and circular DNA. Prokaryotes contain 80s ribosomes and do not have a cell wall whereas eukaryotes contain 70s ribosomes and always have some form of a cell wall.

The correct answer is option c. Eukaryotes contain coiled DNA within the nucleus as well as diploid chromosomes unlike prokaryotes which have no nucleus, haploid chromosomes and some circular DNA. Eukaryotes contain 80s ribosomes and may occasionally have a cell wall unlike prokaryotes which contain 70s ribosomes and always have some form of cell wall.

Correct Answer Explanation – Fungi are eukaryotes and they have cell walls!
a. Incorrect as eukaryotes can have cell walls
b. Incorrect as eukaryotes have diploid chromosomes
d. Incorrect as Eukaryotes can have a cell wall
e. Incorrect as prokaryotes have a 70s ribosome, not an 80s

Question 12

Which of the following is untrue regarding infectious agents?

  1. Viruses possess their own machinery for genome replication
  2. Prions can cause normal proteins of the same type to become abnormal
  3. Bacteriophages are viruses that infect bacteria
  4. Biofilms can make bacteria more resistant to antimicrobials and the host immune response
  5. Prions cause simimilar proteins to misform

The correct answer is option a. Viruses possess their own machinery for genome replication

Correct Answer Explanation – Correct, this is untrue as viruses must infect living cells to use their machinery to replicate
b. Incorrect, this statement is true
c. Incorrect, this statement is true
d. Incorrect, this statement is true
e. Incorrect, this statement is true

Question 13

Which of the following is the causative agent of Toxoplasmosis?

  1. Virus
  2. Fungi
  3. Helminth
  4. Protozoa
  5. Bacterium

The correct answer is option d. Protozoa

Correct Answer Explanation – Correct Toxoplasmosis is a disease caused by Toxoplasma gondii which is a protozoan (unicellular) parasite
a. Incorrect, this is an infective agent that only replicates inside living cells
b. Incorrect, do not confuse with Histoplasmosis which is a fungal lung infection
c. Incorrect these are worms that cause diseases such as river blindness and threadworm disease
e. Incorrect these prokaryotes that can cause infections

Question 14

What is the Correct definition of potency? 

  1. The ability of a drug to elicit a pharmacological response at a receptor 
  2. The amount of drug required to produce an effect of given magnitude 
  3. The extent to which a drug binds to receptors at any given concentration 
  4. The ability of a drug to act preferentially at a receptor in presence of another drug 
  5. The time it takes for the drug to be clear of the blood 

The correct answer is option b. The amount of drug required to produce an effect of given magnitude 

b is correct as this is the correct definition of potency
a. Incorrect this describes efficacy
c. Incorrect this describes affinity
d. Incorrect this describes competitive antagonist
d. Incorrect this describes clearance

Question 15

A 43 year old lady presents to her GP complaining that the tablets she takes for her insomnia have stopped working. She has taken zopiclone for the past 12 nights but has noticed in the past couple of days that unlike before, one tablet isn’t enough to send her to sleep.  What pharmacological phenomenon is responsible?

  1. Tolerance
  2. Resistance
  3. Withdrawal
  4. Desensitisation
  5. Hypersensitivity

The correct answer is option a. Tolerance

Correct Answer Explanation – Correct this is the gradual loss of response to the same dose of a drug over days or weeks
b. Incorrect this is the loss of effectiveness normally of an antimicrobial agent or cancer drug
c. Incorrect
d. Incorrect this is the rapid loss of response to a drug (takes seconds) that can occur with the initial dose
d. Incorrect this is an increase in an immune response to the same level of stimulus

Question 16

A patient is admitted under your care with acute appendicitis. He is prescribed IV Morphine. You are later called to see him as he has now become unresponsive. On examination, you note a respiratory rate of 6 cycles per minute and that he has pinpoint pupils. You suspect opiate toxicity. Which of the following is a possible explanation for this?

  1. Downregulation of opiate receptors 
  2. Poor renal function 
  3. Impaired first pass metabolism 
  4. Repeated exposure causing increased tolerance 
  5. Increase in clearance 

The correct answer is option b. Poor renal function 

Correct Answer Explanation – Correct as opiates are renally excreted so poor renal function could lead to drug accumulation (even if you didn’t know this you could get this answer through eliminating the other options – often the case in exams!)
a. Incorrect as this would decrease the chances of the patient experiencing toxicity
c. Incorrect as the drug was given IV so is not affected by first pass metabolism
d. Incorrect as this would decrease the chances of the patient experiencing toxicity
e. Incorrect as this would decrease the chances of the patient experiencing toxicity

Question 17

You are given the task of using an in vitro assay to screen ten thousand drug analogs to find the most potent beta-2 receptor agonist. When analysing your data, which of the following is the best to measure:

  1. Bioavailability
  2. EC50
  3. Half-life
  4. Maximal-effect
  5. TC50

The correct answer is option b. EC(50) – (NOTE: The 50 is supposed to be subscript!)

Correct Answer Explanation – Correct, the dose of the drug that produces 50% of the maximal effect will allude to the potency of each drug (which is the amount of drug needed to produce an effect of a given magnitude)
a. Incorrect, bioavailability is the proportion of an administered dose that reaches the systemic circulation. 
c. Incorrect, this is the time it takes for 50% of a drug to be eliminated or metabolized.
d. Incorrect, a drugs maximal effect is related to its efficacy, but not its potency. For example, a drug can produce a very large maximal effect (have high efficacy), yet have a very low potency and require very high drug concentrations to achieve its effects
c. Incorrect, this is the time it takes for 50% of a population to have a toxic effect from the drug

Question 18

Which of the following enzymes is deficient in up to a quarter of the Asian population which leads to Omeprazole (a proton pump inhibitor) being poorly metabolised?

  1. CYP2D6
  2. CYP2C19
  3. Plasma cholinesterase
  4. N-acetyltransferase
  5. Omeprozolases

The correct answer is option b. CYP2C19

Correct Answer Explanation – Cytochrome P450 enzymes are an important family of isoenzymes within the liver that metabolise many drugs. Genetic variability in these enzymes means different patients may respond to commonly prescribed medications differently. NOTE! In your pharmacokinetics lecture/SDL there is a table diagram that has some examples of polymorphic drug metabolising enzymes!
b is correct as this is the correct CYP enzyme
a. Whilst a good idea is not correct
c. This is less likely as it will be due to ACh metabolisms
d. Again unlikely due to this being in second phase metabolism
e. This is a made up enzyme