Final Exam

Which statement about Natural killer cells is incorrect?

NK cells are immunologically specific.

Under normal conditions which leukocytes are most abundant?

Neutrophils

Choose the incorrect statement regarding sulfa drugs.

do have adverse side effects on humans because they result in folic acid deficiency.

Which antibiotic was most effective against the bacteria being tested?

Both A & D

One similarity between natural penicillins and semisynthetic penicillins is that

Both types contain a β-lactam ring.

Choose the incorrect statement:

Complement system consists of over 45 serum proteins that are produced in the gall bladder

Choose the incorrect pair:

Antimicrobial drugs: chemicals produced by microorganisms that inhibit other microbes.

The ID50 for Bacterium X is 200 cells and Bacterium Z is 350 cells. Which of the following statements is false?

Bacteria X is more virulent.

Choose the incorrect pairs (there are more than one):

Latent disease: Chickenpox

Choose the mismatch pair:

None of the above

Find the incorrect choice: To cause disease, most pathogens must

None of the above

Choose the incorrect statement regarding exotoxins:

are mostly produced by gram-positive bacteria as part of their growth and metabolism and stay inside the cell.

Select all that apply: Antigens

are substances that induce production of antibodies. are either proteins or large polysaccharides. can be bacterial capsules, cell walls, flagella, fimbrae, bacterial toxins, or viral protein coats. can be non-microbial such as egg white, pollen, surface molecules of trnasplanted organs.

Most of the adults received polio vaccine during their childhood resulting in

artificially acquired active immunity

To combat COVID-19, as an emergency use authorization some hospitalized COVID-19 patients receive convalescent plasma from already recovered patients. What type of immunity is conferred by this method?

artificially acquired passive immunity

A human host can prevent a pathogen from getting enough iron by all of the following except

binding iron with siderophores.

Anopheles mosquito bites a healthy human being and transmits Plasmodium that causes malaria. This is an example of

biological transmission by vector

One place in human body where bacteria are not present under normal conditions is

blood

A housefly sitting on feces outside and then sitting on a food item

can transfer microbes from feces to the food by mechanical trnasmission.

_____________ prevent complement activation.

capsule

Which one of the following is NOT a portal of exit:

cerebral fluid

Staphylococcus epidermidis bacteria live on human skin on secretions and sloughed-off cells without causing any benefit or harm to the host. This is an example of

commensalism

A difference between humoral and cellular immunity is that

humoral immunity produces antibodies that attack antigens outsite the cell while cellular immunity attacks antigens that have entered the cells.

A differential white blood cell count measures

identifies the percentages of eosinophils, basophils, nutrophils, monocytes, and lymphocytes.

The capsule resists the host defenses and increases the virulence of bacteria by

impairing phagocytosis.

A decrease in the production of C3 would result in

increased susceptibility to infection.

All of the following are considered first line of defense except

inflammation

The most selective antimicrobial activity would be exhibited by a drug that

inhibits cell wall synthesis.

Tetanus vaccine is a toxoid that means

it is an inactivated exotoxin produced by the tetanus causing bacteria.

The ability of a microorganism to cause disease is called as __________________ while the extent of the ability to cause disease is termed as

pathogenicity; virulence

Following are the steps (not in order) that occur during inflammation. What is the fifth step?

phagocytes stick to the wall of the blood vessel

Following are the steps of phagocytosis (Not in the order that they occur). What is the fourth step?

phagosome fuses with the phagocyte's lysosome creating a phagolysosome.

When the phage chromosome is incorporated into the bacterial chromosome it is called as

prophage

A "T dependent antigen"

requires a T helper cell to activate a B cell.

A drug that inhibits mycolic acid synthesis will be a drug

that will be effective against Mycobacterium.

In Kirby-Bauer test, a larger zone of inhibition would indicate that

the test bacteria is sensitive to the drug.

Choose the mismatch pair:

transmission of microbes in droplet nuclei that travel less than three meters from the reservoir to the host - droplet transmission

It is relatively difficult to target the virus without damaging the host's cellular machinery because

viruses are intracellular parasites.

Choose the incorrect statement:

IgA have 2 antigen binding sites

antigens that are too small to provoke an immune response

All of the above

innate immunity

All of the above

Following are the steps (not written in order that they occur) involved in the process of activation of B cells to produce antibodies in response to a T-dependent antigen. Which answer choice listed below shows the correct sequence of steps?

4, 1, 3, 6, 2, 5, 7

An individual's white blood cell count revealed high white blood cell counts. This indicates that the person may have

All of the above

C3 activation in complement system can result in

All of the above

Dendritic cells

All of the above

Healthcare-associated infections result from the interaction of

All of the above

Normal microbiota play an important role in preventing the overgrowth of pathogens by

All of the above

Phagocytosis

All of the above

Choose the incorrect statement:

Ciliary escalator transports microbes trapped in mucus towards the lungs.

All of the following drugs target bacteria by inhibiting protein synthesis except

Ciprofloxacin

Choose the incorrect response:

Crisis indicates that body temperature is rising.

What is the LD50 for the bacterial toxin tested in the example below:

D

Following are the steps (not in the correct order) of the mechanism by which endotoxins cause fever. What is the correct order of these steps?

E, B, D, A, F, C

On February 28, a 50 year old person experienced dry cough and shortness of breath. On Mar 5, the condition started deteriorating and he was taken to the ER and was hospitalized in ICU with severe difficulty in breathing. Upon investigation, it was found that on Feb 23 he traveled to the big metropolitan city 150 miles away to attend a family wedding and had fun meeting and talking to all 100 guests. Ten more people who attended the wedding were feeling the same symptoms but not severe enough to go to the ER. Upon testing, the doctors found out that the patient had COVID-19 and started the treatment. Fortunately, he was treated successfully and was released from the hospital on Mar 18. Identify the incubation period for this case of COVID-19.

Feb 23 - Feb 27

Sometimes antibiotic treatment of a bacterial disease may result in worsening of symptoms and development of fever. Normally the symptoms are improved quickly. The reason is

If the disease is caused by gram-negative bacteria, treatment results in bacterial cell lysis releasing endotoxins and resulting in worsening of symptoms.

Which antibodies inactivate microbes by blocking their attachment to host cells?

IgG

Which antibodies may trigger activation of the complement system resulting in inflammation and cell lysis?

IgG or IgM

Which antibodies are most effective in agglutinating antigens?

IgM

Choose the incorrect statement:

Immature T cells are eliminated in the thymus gland by clonal deletion.

Choose the incorrect statement:

Second line defense is part of adaptive immune sysytem.

More than half of the antibiotics are produced by

Streptomyces

Following are the steps involved in the process of apoptosis of a virus infected cell by a cytotoxic T lymphocytes. Which one is the third step?

T helper cell binds to the antigen-MHC I complex by TCR and promotes secretion of cytokines.

Choose the mismatch pair:

T helper cells: cooperate with T cells in the production of antibodies.

All of the diseases listed below are communicable diseases except

Tetanus

Which of the following is NOT one of Koch's postulates?

The disease must be transmitted from a diseased animal to a healthy, susceptible animal by direct contact.

As a general rule, microbes tend to use the same portal of entry and exit.

True

One way to prevent or control the infection is to alter the adhesions on the pathogen or receptors on the host cells.

True

Which of the following is not a cytopathic effect of viral infections:

antigenic changes on the viral particle.

The diameter of zone of inhibition by drugs A and B independently is 10 mm and 5 mm respectively. When these two drugs are tested through Kirby-Bauer test, they show a greater zone of inhibition in the middle area. This indicates that

drugs A and B will have a better effect when given simultaneously.

One difference between primary and secondary response is that

during primary response IgM is the first antibody made by B cells followed by IgG while during secondary response IgG are produced rapidly and in greater magnitude as compared to IgM.

Diseases that are new or changing, or show an increase in incidence in the recent past, or show a potential to increase in the near future are termed as

emerging infectious diseases

A drug named maraviroc targets the CCR5 receptors on the human cell where HIV virus binds. Therefore this drug would be classified as

entry and fusion inhibitor

The science that studies when and where diseases occur and how they are transmitted in populations ifs called

epidemiology

A drug that inhibits ergosterol biosynthesis will be effective against

fungi

An enzyme called lysozyme that is naturally present in tears, saliva, sweat, and nasal secretions effectively breaks down the cell walls of

gram-positive bacteria

According to CDC, the best way to prevent getting influenza and COVID-19 is

handwashing with soap and water

Choose the incorrect statement regarding adaptive immunity:

has no memory component.

A monomer antibody

has two antigen binding sites.

The immunity that results when majority of individual in a population being immune to a particular disease is called as

herd immunity

Penicillin is selectively toxic against bacteria because

human cells do not have peptidoglycan cell wall.

Upon maturation, monocytes mature into

macrophages.

Choose the incorrect statement regarding normal microbiota:

may be present for sometime and then disappear.

Choose the incorrect pair:

metronidazole: antiviral

E.coli bacteria that normally lives in large intestine produce bacteriocins that inhibit the growth of Salmonella and Shigella bacteria. This is an example of

microbial antagonism

Easiest and most frequently traveled portal of entry for pathogens is

mucous membranes of respiratory tract

A drug named Isoniazod is effective against Mycobacteria. Hence this drug can be considered as a/an

narrow-spectrum drug

An individual who had chickenpox as a preschooler is immune to chickenpox due to

naturally acquired active immunity

A newborn baby is normally immune to polio for few weeks due to

naturally acquired passive immunity

During a bacterial infection, ________________ dominate during the initial phase of infection whereas ______________ dominate as the infection progresses.

neutrophils; macrophages

A patient was admitted to the hospital to get an appendectomy. During the hospital stay the same patient accquired MRSA. This is an example of

nosocomial infection

E. coli bacteria normally live in human large intestine without causing any harm but if they gain access to urinary bladder can cause urinary tract infections. This is an example of

opportunistic pathogen

If a mosquito bites a healthy human being and transmits Plasmodium, this portal of entry is considered as

parenteral route