Final Exam (Lect. 33-41)

Question 1

In an experiment, test subjects are given a diet without sucrose, while control subjects are given a
diet with sucrose. Which of the following results would NOT be expected?
A. Test subjects would have a more acidic oral pH.
B. Test subjects would have fewer Streptococcus mutans adhering to their teeth.
C. Control subjects would form a multi-species biofilm on their tooth enamel.
D. Test subjects would have a lower incidence of dental caries.
E. There would be a thicker glycocalyx on the teeth of control subjects.

Answer 1

Test subjects would have a lower incidence of dental caries.

Question 2

Which of the following is a major virulence factor in Helicobacter pylori?
A. An antiphagocytic capsule
B. Ability to produce lots of acid
C. An AB toxin
D. The enzyme urease
E. Ability to live within macrophages

Answer 2

The enzyme urease

Question 3

What is the most effective treatment for cholera?
A. Antibiotics as soon as the infection is apparent
B. An oral antitoxin
C. Oral rehydration with isotonic electrolyte
D. Intravenous saline drip
E. Prompt surgery to remove the diseased tissue

Answer 3

Oral rehydration with isotonic electrolyte

Question 4

Which of the following is NOT a part of the Shigella disease cycle?
A. Forms ruffles on M cells in intestine
B. Gets uptaken by macrophages
C. Enters epithelial cells via the basal membrane
D. Spreads between cells via actin polymerization
E. Eventually colonizes the gallbladder, where it can persist for years

Answer 4

Eventually colonizes the gallbladder, where it can persist for years

Question 5

The usual location of a mumps infection is . . .
A. lung epithelial cells
B. glandular epithelial cells
C. intestinal epithelial cells
D. macrophages
E. nerve cells

Answer 5

glandular epithelial cells

Question 6

A 38-year-old intravenous drug user presented at a clinic with a swollen, tender abdomen. The
sclera of his eyes were yellow (icteric), and his skin had a faint yellow coloration. A direct fluorescent
antibody test was positive for a particular infectious agent. What is unusual about this agent?
A. It is transmitted as a foodborne illness, but has non-gastrointestinal symptoms.
B. Antibodies produced against it cause arthritis as a late sequela.
C. It replicates nearly as fast in the body as it does in tissue culture.
D. It is a DNA virus that needs reverse transcriptase to replicate.
E. You can detect the agent with a direct antibody test instead of an indirect test.

Answer 6

It is a DNA virus that needs reverse transcriptase to replicate.

Question 7

Which of the following do the Hepatitis A and B viruses have in common?
A. The portal of entry by which they enter the host
B. The family of virus to which they belong
C. The location of the infection in the host’s body
D. The severity of symptoms
E. They are completely different - they only happen to share a name

Answer 7

The location of the infection in the host’s body

Question 8

The object at the right was isolated from a patient with
diarrhea. What is it?
A. A Giardia trophozoite
B. A flagellated bacterium like Shigella
C. The motile form of Entamoeba histolytica
D. A Cryptococcus oocyte
E. A Histoplasma spore

Answer 8

A Giardia trophozoite

Question 9

A patient presents at a clinic in Mumbai with voluminous “ricewater stool” diarrhea. The best
treatment would consist of what?
A. Intravenous isotonic saline drip
B. Slowly sipping a solution of glucose and salts
C. Vaccination with an AB toxoid vaccine
D. An injection of passive immune globulin
E. Antibiotic therapy against the vibrio causing the disease

Answer 9

Slowly sipping a solution of glucose and salts

Question 10

Chronic diarrhea can be caused by a trophozoite that burrows into and sometimes through the
intestinal lining, causing irritation and abscesses. Which of the following public health steps would
reduce the spread of this disease in a community?
A. Drying up pools of stagnant water
B. Controlling the rat population
C. Killing the snails which the parasite uses for part of its life cycle
D. Moving the hog feedlot farther from the town water source
E. Avoiding the use of human feces from septic tanks as fertilizer

Answer 10

Avoiding the use of human feces from septic tanks as fertilizer

Question 11

Which of the following is NOT a virulence factor associated with Helicobacter pylori?
A. Urease
B. the VacA toxin
C. a cellulolytic toxin
D. an IgG Fc binding protein
E. motility

Answer 11

an IgG Fc binding protein

Question 12

This could be considered the most serious hepatitis infection, since it is chronic, causes liver
cancer and organ failure, and there is no vaccine for it.
A. Hepatitis A
B. Hepatitis B
C. Hepatitis C
D. Hepatitis D
E. Hepatitis E

Answer 12

Hepatitis C

Question 13

Rita Colwell won the Nobel Prize for figuring out that you can stop a Cholera epidemic by filtering
water through ordinary cloth. How does this work?
A. You’re filtering out the Cholera toxin.
B. You’re filtering out a mechanical vector of Vibrio cholerae
C. You’re filtering out the Vibrio cholerae bacteria.
D. You’re increasing the pH of the water.
E. You’re aerating the water, and Vibrio is an anaerobe.

Answer 13

You’re filtering out a mechanical vector of Vibrio cholerae

Question 14

This vaccine-preventable virus is worse in adults than it is in children because it can cause
inflammation of the testes and ovaries.
A. Mumps
B. Norovirus
C. Rotavirus
D. Measles
E. HPV

Answer 14

Mumps

Question 15

This dangerous chronic infection is transmitted mainly by contaminated needles among drug users.
It causes cirrhosis after many years. There is no vaccine. It is . . .
A. E. coli O157:H7
B. Typhoid fever
C. Hepatitis C
D. Campylobacter
E. Hepatitis A

Answer 15

Hepatitis C

Question 16

The organisms shown below were isolated from frothy, foul-smelling diarrhea from a hiker on the
Appalachian Trail, who was successfully treated with metronidazole. They are . . .
A. Vibrio cholerae
B. Flagellated amoebae
C. Schistosomes
D. Cryptosporidium oocysts
E. Giardia trophozoites

Answer 16

Giardia trophozoites

Question 17

All of the following are virulence factors of Helicobacter pylori EXCEPT . . .
A. Survival in phagocytes
B. Flagella
C. An enzyme that buffers the stomach pH
D. A toxin that gets your cells to secrete urea
E. A toxin that kills your cells

Answer 17

Survival in phagocytes

Question 18

This week there was a multi-state recall of sushi from yellow fin tuna that is contaminated with
Salmonella. You didn’t hear about that? You like sushi? Damn! What symptoms can you expect to
experience if you got infected?
A. Intestinal cramps and diarrhea with some blood in the stool
B. Several gallons per day of watery diarrhea
C. Guillain-Barré paralysis
D. Jaundice and abdominal pain
E. High fever, internal organ inflammation and death

Answer 18

Intestinal cramps and diarrhea with some blood in the stool

Question 19

Jordyn is into the party scene at her college. She drinks a lot, occasionally injects drugs at parties
and has sex with three boyfriends. (Jordyn’s situation is not all that uncommon, by the way.) She is
putting herself at increased risk for all of the following EXCEPT . . .
A. Pelvic Inflammatory Disease
B. Hepatitis B
C. Hepatitis C
D. Mumps
E. Lower Respiratory Infections

Answer 19

Mumps

Question 20

Infection with which of the following is more common in the US than in developing countries?
A. Cryptosporidium
B. Giardia
C. Streptococcus mutans
D. Entamoeba histolytica
E. Vibrio cholerae

Answer 20

Streptococcus mutans

Question 21

Helicobacter pylori has all of the following virulence factors EXCEPT . . .
A. secretion of an A-B toxin that increases cAMP production
B. production of an enzyme that buffers stomach acid
C. a toxin that damages and eventually kills stomach endothelial cells
D. a form of motility that allows it to burrow into the gastric mucosa
E. a protein that induces secretion of urea from cells lining the stomach

Answer 21

secretion of an A-B toxin that increases cAMP production

Question 22

A particular variety of _________ is engulfed by GALT macrophages but not killed. Instead
it travels within the macrophages throughout the body, causing high fever and organ failure,
eventually becoming established in the gall bladder.
A. Campylobacter
B. Salmonella
C. E. coli
D. Shigella
E. Vibrio

Answer 22

Salmonella

Question 23

A cause of jaundice and liver inflammation, this infection normally lasts a few weeks, and
then goes away on its own. It can be prevented with a vaccine, or by avoiding food prepared
under unhygienic conditions.
A. Hepatitis A
B. Norovirus
C. Hepatitis E
D. Giardia
E. Hepatitis B

Answer 23

Hepatitis A

Question 24

The cyst of the organism seen below is found in feces. Where would it
normally release trophozoites?
A. In the stomach
B. In the small intestine
C. In fecally-contaminated water
D. In the colon
E. In a snail

Answer 24

In the colon

Question 25

A 20 year-old female was seen at a local university clinic for fever, malaise and a maculopapular
rash on the palms of her hands. Upon further questioning, she revealed that she had noticed a painless
genital ulcer about a month ago, but it had disappeared and she had not worried about it. What is her
illness?
A. Measles
B. Syphilis
C. Gonorrhea
D. Herpes
E. Chlamydia

Answer 25

Syphilis

Question 26

Why are gonorrhea and chlamydia much more serious in women than in men?
A. The symptoms are much more obvious in women.
B. The organisms can cause serious congenital problems in the fetus.
C. The organisms can ascend the Fallopian tubes and cause pelvic inflammatory disease.
D. The organisms can enter the urethra and cause urinary tract infections.
E. An infection can result in genital warts, which can cause cervical carcinoma.

Answer 26

The organisms can ascend the Fallopian tubes and cause pelvic inflammatory disease.

Question 27

Other than signs of meningitis, which of the following is indicative of infection with Neisseria
meningitidis?
A. Respiratory distress
B. A purpuric skin rash and petechial hemorrhages
C. A drip of pus from the urethra
D. Myalgia and muscle cramping
E. Jaundice

Answer 27

A purpuric skin rash and petechial hemorrhages

Question 28

Several campers at a summer camp in the Ozarks developed fever and jaundice, and one
experienced kidney failure. Upon investigation, it was found that the camp had been in the habit of
relaxing the “no dogs on the beach” rule. A likely diagnosis is:
A. Pasteurella multocida
B. Lyme disease
C. Leptospirosis
D. E. coli cystitis
E. Giardia

Answer 28

Leptospirosis

Question 29

A young woman who has recently become sexually active comes to a clinic with a burning sensation
when she urinates. The urine is cloudy. There are no other symptoms. With what is she probably
infected?
A. Neisseria gonorrhoeae
B. Treponema pallidum
C. Chlamydia trachomatis
D. Escherichia coli
E. Herpesvirus type 2

Answer 29

Escherichia coli

Question 30

This from a newspaper: “High School senior Michael Gruber, 17, took a state Regents exam
Wednesday and went to bed with flu-like symptoms that night. By Thursday morning, he couldn’t move
his neck, and he had broken out in a rash. He was so ill he was taken to a local hospital. By Thursday
afternoon, he was dead.” From what did this student most likely die?
A. Leptospirosis
B. Cryptosporidium
C. Bacterial meningitis
D. Brucellosis
E. Mumps

Answer 30

Bacterial meningitis

Question 31

What is the best way to diagnose syphilis in its primary stage?
A. Culture the bacterium on selective agar and look for the distinctive colonies.
B. Look for the unique rash.
C. There will be a very painful ulcer at the site where the virus entered the body.
D. Perform an indirect ELISA with IgM rather than with IgG.
E. Perform a direct fluorescent antibody test.

Answer 31

Perform a direct fluorescent antibody test.

Question 32

A 20-year-old sexually active male shows symptoms of mild urethritis with a clear fluid secretion
from the tip of his penis. A Gram stain of the drip does not show anything that looks like a bacterial
cell. He is embarassed and wants to decline treatment. What is the danger if he is not treated?
A. He could become sterile.
B. The virus that causes this will not go away, and he will experience reinfections.
C. He will likely give it to his girlfriend, who could experience a serious pelvic infection.
D. As his immune system is damaged, he will experience many secondary infections.
E. He could experience disfiguring or fatal autoimmune sequelae after many years.

Answer 32

He will likely give it to his girlfriend, who could experience a serious pelvic infection.

Question 33

A prostitute in Indianapolis develops a macular rash over her entire body, including her palms and
soles, and the inside of her mouth. A direct fluorescent antigen (dFA) test for syphilis is positive. How
long has she had syphilis?
A. She just got it if the dFA test is positive
B. More than a week, but less than a month
C. More than a month, and maybe for a few years
D. At least 5 and maybe as many as 20 years
E. There is no way to determine this from the limited information given

Answer 33

More than a month, and maybe for a few years

Question 34

Mary returns from class to find her roommate, Jill, dazed and disoriented with a high fever, stiff
neck and purple, blotchy rash. What should be done?
A. Jill should be watched for 24 hours to make sure she doesn’t get worse.
B. Jill should go to the student health clinic and get a course of antibiotics.
C. Jill should go to the clinic for antibiotics and should tell her sexual partner to get
checked for STDs.
D. Mary should call 911, and Jill will need surgery to remove infected tissue.
E. This is a major medical situation. Jill needs to be hospitalized immediately, and
everyone in the dorm needs to take antibiotics to avoid getting what she has.

Answer 34

This is a major medical situation. Jill needs to be hospitalized immediately, and
everyone in the dorm needs to take antibiotics to avoid getting what she has.

Question 35

In addition to causing urethritis and vaginitis, which sexually transmitted diseases are well known
for causing pelvic inflammatory disease in women and substantially increasing the likelihood of
sterility or ectopic pregnancies?
A. Trachoma and Chlamydia
B. Candidiasis and Gonorrhea
C. HPV and Herpes
D. Chlamydia and Gonorrhea
E. Syphilis and HPV

Answer 35

Chlamydia and Gonorrhea

Question 36

A woman in her 35th week of pregnancy comes to a clinic with genital blisters, which she says itch
badly and cause a burning sensation. Examination reveals several clusters of small encrusted and
ulcerated blisters. She has had these same symptoms before. What should be done?
A. Prescribe penicillin to treat the infection.
B. Vaccinate her for HPV infection.
C. Suggest that she consider having her baby delivered by C-section.
D. Do an ultrasound to check for potential fetal malformation.
E. Give the baby tetracycline or silver nitrate eye drops when it is delivered.

Answer 36

Suggest that she consider having her baby delivered by C-section.

Question 37

A serious inflammation of the Fallopian tubes that can lead to tubal scarring and sterility or
problems during pregnancy is quite frequently associated with . . .
A. Chlamydia and Gonorrhea
B. Primary and Secondary Syphilis
C. Herpes and Chlamydia
D. Several types of Human Papillomavirus
E. Neisseria gonorrhoeae and Neisseria meningitidis

Answer 37

Chlamydia and Gonorrhea

Question 38

A 20-year-old sexually active male noticed an unusual rash on the palms of his hands. A few
months ago he had developed a hard, painless spot on his tongue, but he didn’t think it was anything
serious and it went away. How should his illness be treated?
A. An immunoglobulin shot should be given to block toxins produced by this organism.
B. He should be started on a long-term course of multiple antibiotics.
C. He should be treated for both syphilis and gonorrhea, which are often found together.
D. He should be given a single shot of penicillin.
E. It is too late to treat his illness at this stage.

Answer 38

He should be given a single shot of penicillin.

Question 39

An infection with HSV-2 is treated with acyclovir. What is the goal of this therapy?
A. To prevent the virus from establishing a latent state
B. To destroy the latent provirus within neurons
C. To reduce the number of virions produced by a replication cycle
D. To prevent the recurrence of symptoms and cure the infection
E. To prevent secondary infections with other viruses of the same family

Answer 39

To reduce the number of virions produced by a replication cycle

Question 40

Chlamydia and Gonorrhea are common causes of urethritis in the United States. They are
considered especially dangerous because they . . .
A. have a latent form that can cause cervical cancer in women
B. can cross the placenta to cause congenital malformations in the fetus
C. can also be transmitted asymptomatically by salivary droplets
D. are very difficult to treat, requiring long-term administration of multiple antibiotics
E. frequently cause permanent inflammatory damage to the female reproductive organs

Answer 40

frequently cause permanent inflammatory damage to the female reproductive organs

Question 41

The earliest sign of an infection with syphilis is . . .
A. a hard, painless ulcer at the site of infection
B. a high fever and unusual rash
C. a series of painful blisters at the site of infection
D. a drip of yellowish pus from the tip of the urethra
E. granuloma formation and associated soft tissue damage

Answer 41

a hard, painless ulcer at the site of infection

Question 42

What is leptospirosis and how do you get it?
A. A parasitic liver infection from fecally-contaminated water
B. A urinary tract infection common in women due to the shorter urethra
C. A latent viral infection you probably got the first time when you were a child
D. An STI acquired by unprotected sex with an infected partner
E. A kidney infection from contact with water contaminated by animal urine

Answer 42

A kidney infection from contact with water contaminated by animal urine

Question 43

Two common STIs can be asymptomatic, but frequently cause painful urination, and in women
cause Fallopian tube damage and pelvic inflammatory disease. Because they are often co-infections,
they are always treated together. They are . . .
A. Syphilis and Gonorrhea
B. Herpes and Syphilis
C. Chlamydia and Gonorrhea
D. Papillomavirus and Chlamydia
E. Herpes and Papillomavirus

Answer 43

Chlamydia and Gonorrhea

Question 44

A patient went to a health clinic with the genital infection seen at the
right. What can you say about the cause of this rash?
A. It is an autoimmune presentation of another infection.
B. It can be transmitted across the placenta and infect the fetus.
C. It began as a hard, painless genital ulcer a while ago.
D. It can only be transmitted in moist environments.
E. It is latent in neurons, and re-infects by anterograde transport to the skin.

Answer 44

It is latent in neurons, and re-infects by anterograde transport to the skin.

Question 45

Which of the following is NOT among the top 5 STIs in the US?
A. Herpes
B. Syphilis
C. Trichomonas
D. Papillomavirus
E. Chlamydia

Answer 45

Syphilis

Question 46

A 20-year-old Purdue student was found by his roommate in a comatose state. He was hard to
wake up, and when he did, he rambled incoherently about a really bad headache and stiff neck. His
arms were covered with small purple hemorrhages. What is most likely wrong with him?
A. He has cystitis
B. He has malaria
C. He has bacterial meningitis
D. He has necrotizing fasciitis
E. He is infected with West Nile Virus

Answer 46

He has bacterial meningitis

Question 47

You work at a public clinic. A patient comes to you with a cluster of painful, fluid-filled blisters on
his penis. He says this is the third time in the past year that he has had this same thing. What would
you tell him?
A. It’s likely syphilis, and it can’t be treated.
B. It’s likely Chlamydia, and it won’t bother him, but he should tell his girlfriend(s).
C. It is Papillomavirus, and he is getting reinfected each time he changes sexual partners.
D. This is the first stage of an HIV infection, and he should start on HAART right away.
E. This is Herpes. It will always be in his cells, and will recur from time to time.

Answer 47

This is Herpes. It will always be in his cells, and will recur from time to time.

Question 48

Leptospirosis is an important disease in dogs. How do dogs get it?
A. By respiratory droplet transmission from other dogs in kennels
B. By eating infected meat
C. By getting too close to infected humans
D. By contact with contaminated urine
E. From being bitten by an infected tick

Answer 48

By contact with contaminated urine

Question 49

Why is gonorrhea considered to be such a serious disease?
A. A toxin can be released that damages the kidneys.
B. Even asymptomatic infections can cause salpingitis and sterility.
C. It is almost untreatable due to antibiotic resistance.
D. It can cause meningitis in addition to reproductive system infections.
E. It almost always causes very painful symptoms.

Answer 49

Even asymptomatic infections can cause salpingitis and sterility.

Question 50

A woman had multiple sexual partners while she was in college.
She is now 23, and five months pregnant with her first child. She
developed a fever with a rash like the one shown at the right. What is
this, and why is it a problem?
A. It is meningitis. She may die from it if it isn’t treated
quickly.
B. It is syphilis. At this stage of the infection, it can’t be
treated.
C. It is syphilis. She can be treated, but her fetus may have been harmed already.
D. It is Chlamydia. If not treated soon, the baby may be born blind.
E. It is Chlamydia. It may cause a pelvic infection that will result in loss of the baby.

Answer 50

It is syphilis. She can be treated, but her fetus may have been harmed already.

Question 51

What do Herpes and Varicella-Zoster Virus have in common?
A. Both have a latent stage in neurons
B. Both can integrate into the host’s DNA as proviruses
C. Both cause warts, but in different locations
D. A vaccine is available for both
E. Both are considered to be STIs

Answer 51

Both have a latent stage in neurons

Question 52

Because of anatomical differences, ______ is far more common in women than in men.
A. Gonorrhea
B. Cystitis
C. Syphilis
D. Leptospirosis
E. Herpes Simplex Virus 2

Answer 52

Cystitis

Question 53

Which set of symptoms seen in a roommate should prompt you to call 9-1-1 for suspected
meningitis?
A. Diarrhea, headache and back pain
B. Cough, muscle soreness and fever
C. Disorientation, stiff neck and purple skin rash
D. Circular skin rash, rapid heartbeat and profuse sweating
E. Headache, nausea and vomiting

Answer 53

Disorientation, stiff neck and purple skin rash

Question 54

A sexually active college male notices a hard but painless sore on his penis. Remembering Bio
221, he knows he needs to see a Doctor. What is the Doctor likely to do?
A. Give him a vaccine and an immune globulin
B. Give him azithromycin pills to take orally
C. Also treat him for Gonorrhea, which is a related virus
D. Give him a shot of penicillin
E. Unfortunately, there is no treatment at this stage of the disease.

Answer 54

Give him a shot of penicillin

Question 55

Why can you never get rid of Herpes?
A. It lives in your skin cells for many years.
B. There is an autoimmune form of the disease even when the virus disappears.
C. It causes viremia and can be distributed everywhere in your body.
D. It is so common that you’re sure to get it again.
E. It exists as a plasmid in the nucleus of your nerve cell bodies.

Answer 55

It exists as a plasmid in the nucleus of your nerve cell bodies.

Question 56

What typically is the eventual cause of death from AIDS?
A. The virus spreads from the blood to other organs and causes organ failure.
B. Hyperactive TC cells eventually damage muscle and brain tissue.
C. The loss of T-cells results in secondary opportunistic infections.
D. B cells are stimulated to produce autoimmune antibodies.
E. Infected T cells proliferate uncontrollably, causing a fatal blood disease.

Answer 56

The loss of T-cells results in secondary opportunistic infections.

Question 57

What is/are the cellular receptor(s) to which the HIV-1 virus binds?
A. CD4 AND CCR5
B. CD4
C. gp120 AND gp41
D. gp120
E. env

Answer 57

CD4 AND CCR5

Question 58

Which of the following is true about the HIV virus?
A. It mainly affects cellular immunity rather than humoral immunity.
B. Very few people experience any symptoms right after infection.
C. There is currently no way to reduce HIV titer in an infected patient.
D. It is a naked virus that can persist for a long time on contaminated surfaces.
E. There is more than a 25% chance of acquiring it from a single sexual encounter

Answer 58

It mainly affects cellular immunity rather than humoral immunity.

Question 59

The HAART treatment for HIV infection involves . . .
A. an inhibitor of viral uncoating
B. a protease inhibitor and two reverse transcriptase inhibitors
C. directly observing the patient swallow the pills
D. a non-nucleoside reverse transcriptase inhibitor and a recombinant vaccine
E. filtering the virus out of the patient’s blood and returning the blood to the heart

Answer 59

a protease inhibitor and two reverse transcriptase inhibitors

Question 60

A different HIV test is used on donated blood than is used to determine if a person is HIV-positive.
It is more sensitive, but has too many false positives. What is the test used for donated blood?
A. Western blot
B. electron microscopy
C. immunoelectrophoresis
D. indirect ELISA
E. direct ELISA

Answer 60

indirect ELISA

Question 61

Which of the following is true about HIV infection?
A. There is more than a 10% chance of acquiring it from a single sexual encounter.
B. HIV viral titer is highest in the first months following the initial infection.
C. It mainly affects humoral immunity; cellular immunity remains intact.
D. The virus can only infect lymphoid cells, and binds to a single receptor, CCR5.
E. Hyperactive NK cells eventually damage muscle and brain tissue, causing death.

Answer 61

HIV viral titer is highest in the first months following the initial infection.

Question 62

Place the following steps in HIV infection in the correct order.
1 - Viral genetic material integrates into the host’s DNA
2 - Viral RNA is reverse transcribed
3 - A viral polyprotein is processed by a protease
4 - The virus is uncoated
5 - A surface glycoprotein binds to a receptor
A. 5 - 4 - 2 - 1 - 3
B. 3 - 4 - 5 - 2 - 1
C. 4 - 5 - 3 - 1 - 2
D. 4 - 5 - 2 - 1 - 3
E. 5 - 1 - 3 - 2 - 4

Answer 62

5 - 4 - 2 - 1 - 3

Question 63

In treating HIV, the goal of HAART is to . . .
A. Cure the patient
B. Increase the number of TC cells
C. Prevent integration of the proviral form of HIV into the patient’s cells
D. Increase the patient’s antibody titer against HIV
E. Prevent viral replication and assembly and reduce viral load

Answer 63

Prevent viral replication and assembly and reduce viral load

Question 64

The env gene of HIV is required for . . .
A. formation of the viral capsid
B. processing the polyprotein
C. integrating the viral DNA into the host genome
D. binding of the virus to CD4 and CCR5 receptors
E. making viral DNA copies from its RNA genome

Answer 64

binding of the virus to CD4 and CCR5 receptors

Question 65

The goal of HIV treatment with Atripla is to . . .
A. reduce TH cells to fewer than 200/l to deprive HIV of a place to replicate
B. prevent HIV from reverse transcribing its RNA
C. enhance antibody production against HIV spike glycoproteins
D. limit viral titer to 10,000 virus per ml of blood serum
E. excise the HIV provirus from the human host’s genome

Answer 65

prevent HIV from reverse transcribing its RNA

Question 66

According to the graph at right . . .
A. an indirect ELISA will detect HIV infection almost
immediately
B. cytokine levels in the HIV patient should only begin to
decline after many years
C. viral titer will increase gradually as TH cell titer decreases
D. HIV begins to infect TC cells once there are no longer
enough TH cells
E. an effective HIV vaccine would have to induce cellular
rather than humoral immunity

Answer 66

an effective HIV vaccine would have to induce cellular
rather than humoral immunity

Question 67

Which of the following best represents the position
of the gp120 protein in the structure of an HIV virus?
A. A
B. B
C. C
D. D
E. E

Answer 67

A

Question 68

Which of the following best describes what is happening in a person (call him Mr. X) two weeks
after infection with HIV?
A. Virions have begun to grow in Mr. X’s blood, but his immune system has not encountered
them yet.
B. Mr. X’s TH cell numbers have begun to decline as the virus starts killing them.
C. The virus is mainly in Mr. X’s macrophages. Antibodies are fighting it, but not T cells yet.
D. Mr. X’s anti-HIV antibody titer has peaked. He will never have this many antibodies again.
E. Mr. X may think he has the flu or mono, with muscle aches and swollen lymph nodes.

Answer 68

Mr. X may think he has the flu or mono, with muscle aches and swollen lymph nodes.

Question 69

What is usually the eventual cause of death for an AIDS patient?
A. HIV titer begins increasing again, and the virus starts killing more and more cells.
B. TH titer becomes too low to sustain an immune response, and other infections occur.
C. HIV begins infecting cells other than T cells, causing a host of secondary symptoms.
D. Anti-HIV antibody titer becomes so high that antibodies begin attacking self cells.
E. Since it is an RNA virus, HIV eventually mutates to a lethal form that kills the patient.

Answer 69

TH titer becomes too low to sustain an immune response, and other infections occur.

Question 70

Why has it proven so difficult to develop a vaccine that is effective against HIV?
A. HIV binds to T cells, but not to B cells, so it is hard to make antibodies against it.
B. The vaccine virus is too small to elicit an immune response.
C. A cellular immune response is needed, but it would take a live vaccine to achieve this.
D. The virus weakens the immune system so much that the vaccine cannot induce immunity.
E. The HIV virus is surrounded by a capsule, and lacks antigenic surface proteins.

Answer 70

A cellular immune response is needed, but it would take a live vaccine to achieve this.

Question 71

Which part of the HIV virus is encoded by the env gene
and is important for attachment to CCR5?
A. A
B. B
C. C
D. D
E. E

Answer 71

A

Question 72

What part of the immune system is mainly responsible for
fighting the initial stage of HIV infection?
A. NK cells
B. TH cells
C. IgM
D. TC cells
E. the Complement Cascade

Answer 72

TC cells

Question 73

What is Toxoplasma gondii?
A. A viral STD that is commonly a co-infection with HIV
B. A bacterium that causes cat-scratch disease
C. A mechanical vector that transmits a virus from cats to humans
D. A protozoan whose cysts can be inhaled or ingested to cause opportunistic infections
E. A fungal neurotoxin that causes a type of cancer called Kaposi Sarcoma

Answer 73

A protozoan whose cysts can be inhaled or ingested to cause opportunistic infections

Question 74

The diagram at the right represents the HIV virus.
Which structures are encoded by the gag gene?
A. Structures A and F
B. Structures C and D
C. Structures B and F
D. Structures A, D and E
E. Structures B and C

Answer 74

Structures C and D

Question 75

What is currently the best treatment for HIV infection?
A. Nucleoside analogs and protease inhibitors that prevent viral replication within T cells.
B. An immune globulin that substantially reduces viral titer in the blood.
C. Immunosuppressive drugs that kill infected TH cells before the virus can replicate in them.
D. Reverse transcriptase inhibitors that prevent the virus from performing proviral insertion.
E. There is currently no treatment for HIV, but we’re hoping
for a vaccine soon.

Answer 75

Nucleoside analogs and protease inhibitors that prevent viral replication within T cells.

Question 76

Which part of the HIV virus shown at the right is labeled
INCORRECTLY.
A. The structures encoded by the gag gene
B. The structure encoded by the env gene
C. The structures encoded by the pol gene
D. The ssRNA genome
E. gp120

Answer 76

The structure encoded by the env gene

Question 77

What is the role of CCR5 in an HIV infection?
A. It is a spike protein on the surface of the virus.
B. It is one of the drugs that is used to treat the infection.
C. It is the main type of cell that the virus infects.
D. It is important for processing the polyproteins during virus assembly.
E. It is one of the cellular receptors to which the virus binds.

Answer 77

It is one of the cellular receptors to which the virus binds.

Question 78

Why is there no HIV vaccine yet, even though many people have tried to make one?
A. The virus has no antigenic surface proteins.
B. The virus has mechanisms to avoid detection by B cells.
C. The virus can undergo antigenic shift as well as drift.
D. The TC cells that fight the infection are only stimulated by a live vaccine.
E. Viral titer remains too high after initial infection for a vaccine to work well.

Answer 78

The TC cells that fight the infection are only stimulated by a live vaccine.

Question 79

Which of the following is NOT required for HIV entry into host cells?
A. gp120
B. CD4
C. integrase
D. the viral envelope
E. CCR5

Answer 79

integrase

Question 80

We said that HIV is a “slow” virus. What is most responsible for keeping the rate of HIV
replication low after the initial acute retroviral syndrome?
A. Interferon ab
B. TC cells
C. TH cells
D. antibodies
E. the complement system

Answer 80

TC cells

Question 81

What is currently the main treatment for HIV infection?
A. drugs that stimulate the immune response to try to keep T cell numbers high
B. allosteric reverse transcriptase inhibitors
C. removal of the provirus from host cells
D. one pill containing three drugs that have at least 2 different modes of action
E. There is currently no treatment for infection with HIV.

Answer 81

one pill containing three drugs that have at least 2 different modes of action

Question 82

An infection of B cells that causes swollen lymph nodes, is transmitted in saliva and can be detected
by the presence of heterophile antibodies:
A. Mononucleosis
B. Yellow Fever
C. Rabies
D. Mumps
E. West Nile Virus

Answer 82

Mononucleosis

Question 83

Which of the following statements about malaria is NOT correct.
A. It is a sporozoal disease transmitted by mosquito bite.
B. The most serious form can recur periodically for many years.
C. An important part of its life cycle must occur in the gut of the mosquito.
D. Acute symptoms (chills, fever, sweat) are caused by lysis of red blood cells.
E. Chronic infections can result in liver damage because a form of the parasite infects
liver cells.

Answer 83

The most serious form can recur periodically for many years.

Question 84

A foodborne pathogen that usually causes meningitis in infants and the elderly.
A. Salmonella
B. Shigella
C. Botulism
D. Bacillus
E. Listeria

Answer 84

Listeria

Question 85

A malaria vaccine would most likely target which form of the pathogen?
A. The trophozoite, since it is frequently extracellular
B. The sporozoite, since it is the form that first enters the patient
C. The gametocyte, since it is the form that gets transmitted to the mosquito
D. The schizont, since there are so many of them
E. The merozoite, since it is the motile form of the parasite

Answer 85

The sporozoite, since it is the form that first enters the patient

Question 86

A patient with suspected mononucleosis goes to a health clinic, where a healthcare worker performs
a mono-spot test, also called a heterophile antibody test. If the test is positive, the patient is making
antibodies against . . .
A. Epstein-Barr virus
B. Heterophile, which is a viral toxin
C. The patient’s own TH cells
D. Listeria monocytogenes
E. Ox red blood cells

Answer 86

Ox red blood cells

Question 87

What form of the malaria parasite is NOT found in
human red blood cells?
A. Merozoites
B. Trophozoites
C. Sporozoites
D. Schizonts
E. Gametocytes

Answer 87

Sporozoites

Question 88

A child was bitten by a dog. The dog was watched for 10 days, and when no symptoms developed
was released. A month later the dog died of rabies. What should be done?
A. Nothing. The child is not at risk for rabies.
B. The child should be given antibiotics to treat potential rabies.
C. The child should receive both passive and active immunization against rabies.
D. The child should have a biopsy done to look for diagnostic Negri bodies.
E. It depends on where the child was bitten (arm, leg, etc.).

Answer 88

Nothing. The child is not at risk for rabies.

Question 89

Jim has been diagnosed with infectious mononucleosis and advised to rest for several weeks.
What is the danger if he ignores this advice?
A. Because mono replicates in T cells, Jim is susceptible to other infections.
B. Because mono is contagious by airborne transmission, Jim could start an epidemic.
C. Because mono triggers antibody production, Jim could develop autoimmune sequelae.
D. Because mono triggers lymphoid cell division, Jim could rupture his enlarged spleen.
E. Because mono is a virus, it could cause systemic viremia and Jim could die

Answer 89

Because mono triggers lymphoid cell division, Jim could rupture his enlarged spleen.

Question 90

Which form of the malaria parasite has enough exposure to human blood serum to make it the
target of a potentially successful vaccine?
A. Trophozoite
B. Gametocyte
C. Sporozoite
D. Merozoite
E. Zygote

Answer 90

Sporozoite

Question 91

. A baby is brought to the emergency room with extreme muscle weakness, unable to even hold her
head up. This has developed over the course of a few days. Her family was in the habit of using honey
rather than sugar as a sweetener. What would a physician expect to find?
A. Listeria toxin in the baby’s bloodstream
B. Clostridial spores in the baby’s lungs
C. High anti-Norovirus antibody titer
D. Clostridial colonization of the baby’s intestine
E. Listeria granulomas in the baby’s brain

Answer 91

Clostridial colonization of the baby’s intestine

Question 92

A vaccine must almost always be given before a patient becomes infected. But the rabies vaccine
is an exception, that is usually administered after infection. Why is it still effective?
A. There is a long incubation period while the virus is traveling to the brain.
B. The vaccine agent replicates faster that the rabies virus does.
C. The infectious agent must be present for the vaccine to induce passive immunity.
D. Antibodies bind to the Negri bodies, and a vaccine is not effective until these are produced.
E. There is some time before B cells turn into plasma cells, where the rabies virus grows.

Answer 92

There is a long incubation period while the virus is traveling to the brain.

Question 93

At right is an abbreviated representation of the malaria life cycle.
The new malaria vaccine RTS,S was developed against which form of
the parasite.
A. The gametocyte, since it is the form that the mosquito ingests
B. The merozoite, since it is the motile form of the parasite
C. The trophozoite, since it is frequently extracellular
D. The schizont, since there are so many of them
E. The sporozoite, since it is the form that first enters the patient

Answer 93

The sporozoite, since it is the form that first enters the patient

Question 94

An important disease in dogs and cattle, transmitted in semen and via
contaminated placental residues, this organism can also cause a human illness characterized by periodic
high fevers.
A. Pasturella
B. Bartonella
C. Toxoplasma
D. Brucella
E. Listeria

Answer 94

Brucella

Question 95

A patient develops a sore throat with swollen lymph nodes. A precipitin test is carried
out using the patient’s serum (at C), proteins from a goat (at A), and proteins from
Streptococcus (at B). The result is shown at the right. How do you explain the result?
A. The patient has Strep throat, and is at risk for autoimmune sequelae.
B. The patient has a thymus deficiency due to an autoimmune disease such as Graves’ disease.
C. The patient’s B cells are infected with a transforming virus like Epstein-Barr virus.
D. The patient probably has a zoonotic infection from eating cheese made from goat milk.
E. The test was done wrong; the patient’s serum should have been placed at A or B.

Answer 95

The patient’s B cells are infected with a transforming virus like Epstein-Barr virus.

Question 96

A person who is bitten by a potentially rabid animal is still given a rabies vaccine, even though she
may have already been exposed to the rabies virus. Why is this done?
A. The “vaccine” is really a passive immunization to neutralize the virus, not a vaccine.
B. It takes a long time for this virus to be transported to cells in which it can replicate.
C. It takes 10 days to find out if the animal was rabid, and that’s enough time to make
antibodies against the virus.
D. The vaccine mainly induces cellular immunity, which develops more quickly than humoral.
E. The vaccine is ineffective, but it is given to reassure the patient that everything possible is
being done for her.

Answer 96

It takes a long time for this virus to be transported to cells in which it can replicate.

Question 97

You’re working in a dog rescue shelter. One of the dogs you brought in last month was pregnant,
and lost her litter of puppies. She has been diagnosed with Brucellosis. What would you tell your
coworkers about this?
A. It’s not a big deal – this is only a serious infection in humans.
B. If you give the infected dog antibiotics now, she won’t be able to spread the infection.
C. Try to wear gloves when handling the dog, since this is transmitted by direct contact.
D. This will be a big problem. You should test all dogs, and neuter and isolate infected ones.
E. The diagnosis must be a mistake – Brucellosis is a cattle disease, not a dog disease.

Answer 97

This will be a big problem. You should test all dogs, and neuter and isolate infected ones.

Question 98

A person who is suffering from infectious mononucleosis (“Mono”) is susceptible to other
infections. Why?
A. The virus that causes mono kills his TH cells.
B. His heart is damaged by antibodies made against the mono bacterium.
C. He is producing heterophile antibodies, which are anti-IgG antibodies.
D. The mono bacterium can spread to his liver, forming granulomas.
E. The mono virus infects his B cells, reducing his ability to produce useful antibodies.

Answer 98

The mono virus infects his B cells, reducing his ability to produce useful antibodies.

Question 99

Which of the forms of the malaria parasite is NOT found in human hosts?
A. Ookinete
B. Sporozoite
C. Schizont
D. Trophozoite
E. Merozoite

Answer 99

Ookinete

Question 100

What actually causes the symptoms associated with malaria?
A. The trophozoites burrow into the intestinal wall, causing diarrhea.
B. The parasite larvae enter the lungs and block alveoli, causing respiratory distress.
C. The parasite multiplies in red blood cells, lysing them and causing cytokine-induced fever.
D. Adult parasites live in blood vessels and eventually block them, causing ischemia.
E. A toxin released by the parasite inhibits neurotransmitters, causing paralysis.

Answer 100

The parasite multiplies in red blood cells, lysing them and causing cytokine-induced fever.

Question 101

A recall warning was put out by a Massachusetts dairy in 2010 about milk potentially contaminated
with a facultative psychrophile that is a concern in dairy products and processed meats. Why is this
such a serious infection?
A. It produces a toxin that affects the kidneys.
B. It causes an epidemic gastrointestinal disease with vomiting and bloody diarrhea.
C. It can integrate into host cells and cause cancer.
D. It can cause stillbirth and meningitis.
E. It can be transmitted by respiratory droplets to a large number of people.

Answer 101

It can cause stillbirth and meningitis.

Question 102

What is the main way by which infants get the disease caused by Clostridium botulinum?
A. C. botulinum spores infect the infant’s umbilical stump
B. By drinking contaminated infant formula
C. By transplacental infection from the infant’s mother
D. As an autoimmune reaction caused by maternal antibodies
E. By exposure to C. botulinum before the infant has acquired a native flora

Answer 102

By exposure to C. botulinum before the infant has acquired a native flora

Question 103

Swollen lymph nodes, orders to avoid exercise, production of diagnostic antibodies and fatigue are
all familiar to someone who has had Mono. All of these are caused by . . .
A. replication of the virus within epithelial cells
B. replication of the virus within B cells
C. proliferation of B cells that have been infected by the virus
D. an immune response to the presence of the virus
E. lysis of erythrocytes by the virus

Answer 103

proliferation of B cells that have been infected by the virus

Question 104

Two viruses that undergo both retrograde and anterograde neuronal transport are . . .
A. Herpes and Epstein Barr Virus
B. Encephalitis and Herpes
C. Epstein Barr Virus and Rabies
D. Brucellosis and Epstein Barr Virus
E. Rabies and Varicella Zoster Virus

Answer 104

Rabies and Varicella Zoster Virus

Question 105

Which of the following is NOT associated with infection by Epstein-Barr Virus?
A. Tumor formation
B. Swollen throat with pus
C. Production of random antibodies
D. Immunocompromised status because of B cell lysis
E. Swollen salivary glands and testes or ovaries

Answer 105

Swollen salivary glands and testes or ovaries

Question 106

West Nile Virus affects what organ(s)?
A. Lungs and Liver
B. Intestinal tract and Liver
C. Brain
D. Skin
E. Lungs

Answer 106

Brain

Question 107

A moderately successful Malaria vaccine was introduced in 2011. It targets the only form of the
Malaria parasite that is found free in the blood. This form is the . . .
A. sporozoite
B. trophozoite
C. ookinete
D. gametocyte
E. merozoite

Answer 107

sporozoite

Question 108

The symptoms of Malaria include headache, fever, chills and sweats. They are caused when . . .
A. the body has an immune reaction to eggs in the liver
B. trophozoites migrate into the liver
C. the parasitic zygote invades red blood cells
D. the merozoites lyse red blood cells
E. the body reacts against the tetracycline used in treatment

Answer 108

the merozoites lyse red blood cells

Question 109

Bacteria growing in the reservoir tank of a home drinking water system would be especially
characterized by
A. microcolony development
B. rapid growth
C. acid production
D. biofilm formation
E. formation of a sticky sheath

Answer 109

biofilm formation

Question 110

The process of making glucose or other cell carbon from CO2 . . .
A. is an oxidation reaction
B. releases energy for the cell to use
C. requires that CO2 first be turned into methane
D. can only be done by phototrophs
E. can be done either aerobically or anaerobically

Answer 110

can be done either aerobically or anaerobically

Question 111

In a hydrothermal vent community, the sulfur and carbon cycles are often mixed. Organisms make
organic compounds and SO4
-2
from CO2 and H2S. During this process . . .
A. energy must be input from the sun
B. SO4
-2
is used as the electron donor
C. electrons from H2S are donated to CO2
D. CO2 provides the energy for the organisms to grow
E. H2S is reduced to SO4
-2

Answer 111

electrons from H2S are donated to CO2

Question 112

Which step in the carbon cycle requires net energy input?
A. Methanogenesis
B. Anaerobic respiration
C. Fermentation
D. Methylotrophy
E. Aerobic electron transport

Answer 112

Methanogenesis

Question 113

Efficient growth in flowing water (river) would be most improved by which of the following
adaptations?
A. Enhanced flagellar motility
B. Sheaths to adhere better to surfaces
C. ABC transporters for more efficient nutrient uptake
D. A broad metabolic capability to degrade many potential carbon sources
E. Ability to produce anti-quoromones to interfere with other bacterial communication

Answer 113

Sheaths to adhere better to surfaces

Question 114

The indicated step in the nitrogen cycle is called . . .
A. Assimilative nitrogen fixation
B. Dissimilative nitrogen fixation
C. Nitrification
D. Denitrification
E. Ammonification

Answer 114

Denitrification

Question 115

The major evolutionary selection pressure in soil
microorganisms favors organisms that have evolved . . .
A. very efficient transporters
B. adhesion pili that form very tight biofilms
C. a rapid specific growth rate ()
D. a highly versatile metabolism
E. anoxygenic photosynthetic mechanisms

Answer 115

a highly versatile metabolism

Question 116

The indicated step in the nitrogen cycle is called . . .
A. Dissimilative nitrogen fixation
B. Assimilative nitrogen fixation
C. Nitrification
D. Denitrification
E. Ammonification

Answer 116

Dissimilative nitrogen fixation

Question 117

Which of the steps in the nitrogen cycle can be carried out by lithotrophic organisms that use
nitrogen compounds as an electron source?
A. Ammonification
B. Nitrification
C. Assimilative Nitrogen Fixation
D. Dissimilative Nitrogen Fixation
E. Denitrification

Answer 117

Nitrification

Question 118

A fungus living within the epidermal cells of a plant root is called . . .
A. a mycorrhizome
B. a lichen
C. a bacteroid
D. Phytophthora blight
E. a Rhizobium nodule

Answer 118

a mycorrhizome

Question 119

Efficient bacterial growth in soil would be most improved by which of the following evolutionary
adaptations?
A. Enhanced flagellar motility
B. Broad metabolic capability to degrade many potential carbon sources
C. Ability to produce anti-quoromones to interfere with other bacterial communication
D. ABC transporters for more efficient nutrient uptake
E. Sheaths to adhere better to surfaces

Answer 119

Broad metabolic capability to degrade many potential carbon sources

Question 120

Which of the following events related to the nitrogen cycle does NOT occur in plant root nodules?
A. Nitrification
B. Assimilative nitrogen fixation
C. Dissimilative nitrogen fixation
D. Amino acid transport
E. Transamination (-NH2 transfer from one amino acid to another)

Answer 120

Nitrification

Question 121

In the association known as an endomycorhizome, what purpose is served by the fungus?
A. It anchors the plant to the rocks.
B. It helps the plant fight off pathogens.
C. It increases the absorptive surface area of the root hairs.
D. It fills up the xylem, preventing viral infections from spreading.
E. It adds nitrogen to the plant.

Answer 121

It increases the absorptive surface area of the root hairs.

Question 122

Methanogenesis, as carried out in the rumen of a cow, is . . .
A. a reduction using electrons from H2
B. a type of heterotrophic growth
C. an oxidation in which electrons are donated to O2
D. the process that the cow uses to obtain nutrients from grass
E. a fermentation reaction that recycles NAD+
from NADH

Answer 122

a reduction using electrons from H2

Question 123

Inhibitors of nitrification are frequently added to agricultural soils. Why?
A. Nitrification turns useful nitrogen into N2, which is lost to the atmosphere.
B. Nitrification reduces the amount of oxygen available in the soil.
C. Nitrification turns NH4+
into NO3-, which is easily leached from the soil by rain.
D. Nitrification is mostly carried out by fungi, whose growth we want to inhibit.
E. Nitrification is a reduction reaction, which competes with photosynthetic oxidation of H2O

Answer 123

Nitrification turns NH4+
into NO3-, which is easily leached from the soil by rain.

Question 124

How do nitrogen fixing Rhizobium bacteria prevent the enzyme Nitrogenase from being damaged
by oxygen?
A. They produce an oxygen-binding protein to keep the free O2 concentration low.
B. They live in anaerobic root nodules, so O2 is not a problem for them.
C. They are surrounded by a tough membrane that excludes O2 from the cells.
D. They attach O2 to an amino acid and transport it into the plant cells to eliminate it.
E. They reduce their respiratory rate, producing less O2 from oxidative phosphorylation.

Answer 124

They produce an oxygen-binding protein to keep the free O2 concentration low.

Question 125

In the association known as a lichen, what purpose is served by the fungus?
A. It fills up xylem, preventing viral infections from spreading.
B. It increases the absorptive surface area of the plant’s root hairs.
C. It helps the lichen fight off pathogens.
D. It anchors the lichen to the rocks.
E. It adds nitrogen to the lichen.

Answer 125

It anchors the lichen to the rocks.

Question 126

Pseudomonas is a common soil organism. Why does Pseudomonas have an evolutionary
advantage in a soil environment?
A. It has many ABC transporters with periplasmic binding proteins.
B. It has one of the highest known intrinsic bacterial growth rate constants, .
C. It can form endospores that allow it to survive environmental nutrient deprivation.
D. It has many sensor kinases and can catabolize a variety of carbon compounds.
E. It can use sunlight as a source of electrons.

Answer 126

It has many sensor kinases and can catabolize a variety of carbon compounds.

Question 127

In a given ecosystem, the producer organisms always have a/an _____ lifestyle and produce _____.
A. lithotrophic ; CO2
B. autotrophic ; reduced carbon compounds
C. organotrophic ; energy
D. phototrophic ; O2
E. heterotrophic ; hydrolases

Answer 127

autotrophic ; reduced carbon compounds

Question 128

Which of the following processes related to the nitrogen cycle MUST occur in plant root nodules?
A. nitrification
B. denitrification
C. dissimilatory nitrogen fixation
D. deamination
E. aspartate-glutamate antiport

Answer 128

aspartate-glutamate antiport

Question 129

Which of the following biogeochemical cycle steps is a chemical reduction?
A. Anammox
B. Nitrification
C. Methylotrophy
D. Methanogenesis
E. Using H2S as a photosynthetic electron donor

Answer 129

Methanogenesis

Question 130

What are mycorrhizae, and what do they do to a plant?
A. They are algae that produce sugar from sunlight in a lichen.
B. They are bacteria that produce leghemoglobin and fix nitrogen in plant roots.
C. They are fungi that increase water and nutrient absorption by plant roots.
D. They are pathogenic fungi that produce plant hormones in the wrong place.
E. They are pathogens without cell walls that are transmitted to plants by insects.

Answer 130

They are fungi that increase water and nutrient absorption by plant roots.

Question 131

Lilly Hall has a water tank on the roof to provide water in emergencies. What would you expect to
find if you sampled the water in this tank?
A. Mostly bacteria with sticky sheaths.
B. Bacteria in microcolonial biofilms rather than in a uniform layer.
C. The water would be very cloudy.
D. Any bacteria that are present should have a high growth rate, m.
E. Most bacteria would be growing on the sides of the tank.

Answer 131

Most bacteria would be growing on the sides of the tank.

Question 132

Which carbon cycle step is an anaerobic reduction of carbon?
A. Methanogenesis
B. Methylotrophy
C. Respiration
D. Hydrolysis
E. Noncyclic photosynthesis

Answer 132

Methanogenesis

Question 133

In this cross section of the Rhizobium root nodule . . .
A. Nitrification takes place in area A
B. Denitrification takes place at C
C. Assimilatory N2 fixation takes place in area B
D. Leghemoglobin is produced in area B
E. Aspartate/glutamate exchange takes place across the bacterial cell membranes in area A.

Answer 133

Aspartate/glutamate exchange takes place across the bacterial cell membranes in area A.

Question 134

Some scientists think life might have evolved deep inside Jupiter’s moon Europa. If so, which of
the following would be one condition for a Europan ecosystem?
A. Producers would have to be sulfate reducing bacteria.
B. Producers would have to be chemoautotrophs.
C. Consumers would have to be lithotrophs.
D. Decomposers would have to be autotrophs.
E. The roles of producers and consumers would be reversed compared to ecosystems on Earth.

Answer 134

Producers would have to be chemoautotrophs.

Question 135

Which of the following would be the most effective way to increase crop yields in phosphatedeficient soil?
A. Add lichens to the soil.
B. Coat crop seeds with ACC deaminase.
C. Add inhibitors of nitrifying bacteria to the soil.
D. Add chemolithotrophic fungi to the soil.
E. Coat crop seeds with spores from arbuscular fungi.

Answer 135

Coat crop seeds with spores from arbuscular fungi.

Question 136

Which of the following is NOT a role for heterotrophs in an ecosystem?
A. They produce CO2.
B. They reduce CO2 using energy from other chemical reactions.
C. They produce complex organic matter.
D. They consume glucose.
E. They decompose complex organic matter.

Answer 136

They reduce CO2 using energy from other chemical reactions.

Question 137

Which of the following can be an anaerobic, carbon-oxidizing step in the carbon biogeochemical
cycle?
A. methanogenesis
B. methylotrophy
C. respiration
D. photosynthesis
E. succession

Answer 137

methylotrophy

Question 138

The numbered steps in the nitrogen cycle shown at the right are . . .
A. 1 = denitrification, 3 = dissimilatory nitrogen fixation
B. 1 = nitrification, 2 = anammox
C. 4 = denitrification, 5 = assimilatory nitrogen fixation
D. 4 = nitrification, 3 = assimilatory nitrogen fixation
E. 3 = nitrification, 5 = anammox

Answer 138

1 = denitrification, 3 = dissimilatory nitrogen fixation

Question 139

The structure shown here both by bright-field microscopy
and by SEM serves what purpose?
A. It helps plants take up phosphorus from the soil.
B. It helps anchor plants to rocks.
C. It fixes nitrogen in plant roots.
D. It is responsible for causing plant tumors.
E. It injects toxins into the plant via its Type III secretory system.

Answer 139

It helps plants take up phosphorus from the soil.

Question 140

Waste treatment facilities need to reduce the amount of BOD in water they emit to the environment.
What is BOD?
A. “bio-organic detritus”
B. a measure of oxygen levels in the water
C. a measure of nutrient levels in the water
D. a toxin that kills cyanobacteria and other pond life

Answer 140

a measure of oxygen levels in the water

Question 141

The secondary stage of sewage treatment . . .
A. is an entirely anaerobic process
B. precipitates PO4
-3
as calcium phosphate
C. produces an effluent with very low fecal coliform levels
D. turns organic polymers into biomass, which is recoverable as flocs
E. must be done in concrete tanks that have no contact with the environment

Answer 141

turns organic polymers into biomass, which is recoverable as flocs

Question 142

Which of the following makes an environmental pollutant difficult to treat by bioremediation?
A. It has been newly introduced into the environment.
B. It is highly water soluble.
C.. It has an aromatic (benzene) ring.
D. It is in the groundwater.
E. It is in the soil.

Answer 142

It has been newly introduced into the environment.

Question 143

One goal of sewage treatment is to reduce BOD of the effluent. Which step in the sewage treatment
process achieves this goal?
A. Primary treatment
B. Secondary treatment
C. Tertiary treatment
D. Floc formation
E. Chlorination

Answer 143

Secondary treatment

Question 144

One of the main goals of wastewater treatment is to reduce the BOD in wastewater. Why is it bad to
have a high BOD in water released to the environment?
A. Bio-organismal diseases can result from drinking water with high BOD.
B. High phosphate and nitrogen levels lead to eutrophication of lakes and rivers.
C. Too much oxygen can alter the population balance in sensitive ecosystems.
D. BOD toxins can accumulate in the food chain and are hard to eliminate.
E. BOD has an offensive odor, and people in nearby communities complain

Answer 144

High phosphate and nitrogen levels lead to eutrophication of lakes and rivers.

Question 145

A sewage treatment plant needs to reduce the amount of BOD in water. BOD is directly related to
A. the bacterial titer in the water sample
B. the level of oxygen in the water
C. microbial growth that can be supported by nutrients in the water
D. levels of toxic chemicals in the water sample
E. bacterial odor determinants (ie. secondary metabolites) in the water

Answer 145

microbial growth that can be supported by nutrients in the water

Question 146

A wastewater technician is examining a confirmatory fecal indicator test from a water sample. What
will she typically look for in a positive test?
A. Bacterial growth in a test tube
B. Colored colonies on differential media
C. A titer greater than 4 bacteria / ml
D. Disease in lab rats given samples of the water to drink
E. Gas production from bacterial fermentation

Answer 146

Colored colonies on differential media

Question 147

Which of the following is typical of chemicals that biomagnify in the environment?
A. They are highly soluble in water
B. They are chlorinated and non-polar
C. They contain fatty acids with many carbon atoms
D. They are reduced compounds that can be easily oxidized
E. They have many hydroxyl groups

Answer 147

They are chlorinated and non-polar

Question 148

It is important for wastewater treatment plants to remove BOD from water to be released to the
environment. How is this usually done?
A. by chlorinating the water before it is released
B. by adding NH4
+ to encourage bacterial growth
C. by aerating the sewage to encourage biofilm formation
D. by anaerobic hydrolysis of complex organic nutrients
E. by selecting for organisms that can use BOD as a carbon source and injecting them back into
the water

Answer 148

by aerating the sewage to encourage biofilm formation

Question 149

Which of the following reactions is NOT likely to occur in the sludge digester at a wastewater
treatment plant?
A. hydrolysis
B. methanogenesis
C. anaerobic respiration
D. methylotrophy
E. fermentation

Answer 149

methylotrophy

Question 150

Biomagnification of a pollutant in the food chain would be most likely for a pollutant with which
of the following combinations of properties?
A. hydrophilic, with many -OH groups
B. hydrophobic, with many -Cl atoms
C. hydrophilic and highly branched
D. hydrophobic and highly methylated
E. hydrophilic with lots of phosphates

Answer 150

hydrophobic, with many -Cl atoms

Question 151

. Bacteria are constantly evolving, and one important way they evolve is by acquiring new genes
from other bacteria. In some environments, the bacteria are very dilute. How are genes exchanged in
such environments?
A. by conjugation through sex pili
B. a virus transduces DNA from one bacterium to another
C. a plasmid is released from one bacterium and swims toward another bacterium
D. bacteria have to grow until they are more concentrated; then they can exchange genes
E. the bacteria use meiosis to form spores, which then unite to produce a zygote

Answer 151

a virus transduces DNA from one bacterium to another

Question 152

One of the main goals of wastewater treatment is to reduce the BOD in wastewater. Why is it bad
to have a high BOD in water released to the environment?
A. Bio-organismal diseases can result from drinking water with high BOD.
B. High phosphate and nitrogen levels lead to eutrophication of lakes and rivers.
C. Too much oxygen can alter the population balance in sensitive ecosystems.
D. BOD toxins can accumulate in the food chain and are hard to eliminate.
E. BOD has an offensive odor, and people in nearby communities complain.

Answer 152

High phosphate and nitrogen levels lead to eutrophication of lakes and rivers.

Question 153

The secondary stage of sewage treatment . . .
A. must be done in concrete tanks that have no contact with the environment
B. precipitates PO4
-3
as calcium phosphate
C. produces an effluent with very low fecal coliform levels
D. is an entirely anaerobic process
E. turns organic nutrients into bacterial biomass, which is recoverable as flocs

Answer 153

turns organic nutrients into bacterial biomass, which is recoverable as flocs

Question 154

Which of the following would be desirable in an organism that you plan to use as a fecal indicator?
A. It should be much easier to kill than true pathogens.
B. It should be found commonly in soil and the environment.
C. It should be a native flora of the digestive tract.
D. It must be able to be detected in water with a single test.
E. It should be an obligate anaerobe that produces endospores.

Answer 154

It should be a native flora of the digestive tract.

Question 155

Which of the following statements about the typical sewage treatment process as performed in the
United States is correct?
A. Removal of BOD is mainly through aerobic metabolism and biofilm formation.
B. The primary treatment step involves chlorination or ozonation to kill pathogens.
C. Anaerobic digestion can be performed on the solid precipitate after tertiary treatment.
D. The primary stage can be replaced with a wetland, but not the secondary or tertiary stages.
E. A major component of BOD is removed by sulfate reducing bacteria.

Answer 155

Removal of BOD is mainly through aerobic metabolism and biofilm formation.

Question 156

How does sewage treatment remove the majority of BOD from a sewage sample?
A. It doesn’t; BOD is added during sewage treatment.
B. By chlorination during the primary treatment stage
C. By adding Ca++ during the tertiary treatment stage
D. In an anaerobic sludge digester
E. By precipitation of flocs during the secondary treatment stage.

Answer 156

By precipitation of flocs during the secondary treatment stage.

Question 157

Which of the following features would you expect to find in a coliform that is used as a fecal
indicator bacterium?
A. It should be easy to kill.
B. It should produce gas.
C. It should be common in most natural environments.
D. It should grow very slowly.
E. It should be a pathogen.

Answer 157

It should produce gas.

Question 158

A chemical with which of the following properties would likely biomagnify in the environment?
A. chlorinated
B. chlorinated and hydrophilic
C. chlorinated and hydrophobic
D. methylated phenol ring
E. hydrogenated

Answer 158

chlorinated and hydrophobic

Question 159

For a bioremediation project to be successful, we frequently have to supplement what is already
present in the environment. Which of the following is a typical supplement?
A. PO4
-3
B. Carbon
C. Energy
D. Bacteria
E. N2

Answer 159

Bacteria

Question 160

Which of the following is involved in the process of transduction?
A. Ribosomes
B. Persister cells
C. The F plasmid
D. Bacteriophage
E. Electron transport chains

Answer 160

Bacteriophage

Question 161

Water with high BOD would be expected to . . .
A. support much growth of cyanobacteria
B. have low nutrient levels
C. have high oxygen levels
D. be oligotrophic
E. be good for sport fishing

Answer 161

support much growth of cyanobacteria

Question 162

Formation of flocs in a sewage treatment plant depends on . . .
A. methanogenesis in tertiary treatment steps
B. heavy solids in the sewage that initiate biofilm formation
C. anaerobic fermentation of nutrients in the sewage
D. growth of aerobic heterotrophs with hydrolytic enzymes
E. absence of inhibitors like Ca++ and NH4
+
in the sewage

Answer 162

growth of aerobic heterotrophs with hydrolytic enzymes

Question 163

Why do city water treatment plants keep count of the coliforms in the water?
A. Coliforms are pathogens.
B. Coliforms indicate fecal contamination of the water.
C. Coliforms indicate elevated BOD in the water.
D. The gas produced by coliforms is toxic.
E. Epidemiologists use the data to trace specific pathogen strains in case of an epidemic

Answer 163

Coliforms indicate fecal contamination of the water.

Question 164

Which of the following are most likely to biomagnify in the environment?
A. Chlorinated, fat-soluble compounds
B. Highly branched hydrocarbon compounds
C. Brominated, water-soluble compounds
D. Compounds with aromatic rings
E. Compounds that contain phosphate groups

Answer 164

Chlorinated, fat-soluble compounds

Question 165

How do bacteria naturally develop the ability to bioremediate pollutants?
A. They don’t. We have to engineer them.
B. Bacteria evolve rapidly once they are exposed to a pollutant.
C. HGT of genes that catabolize plant flavonoids builds natural degradative pathways.
D. The evolutionary selective pressure is resistance against viruses present in soil.
E. The evolutionary selective pressure is increased virulence toward plant hosts.

Answer 165

HGT of genes that catabolize plant flavonoids builds natural degradative pathways.

Question 166

Water with high BOD . . .
A. does not support much microbial growth
B. also has a high concentration of dissolved oxygen
C. is considered to be polluted
D. is oligotrophic
E. is especially deficient in NO3
-
and PO4
-3

Answer 166

is considered to be polluted

Question 167

The main purpose for the secondary step in sewage treatment is . . .
A. to anaerobically digest sludge and produce methane
B. to kill bacterial contaminants that would otherwise be released into the environment
C. to add oxygen to water before it is released to the river
D. to remove phosphate and ammonia, which have a bad odor
E. to turn organic nutrients into precipitable biomass

Answer 167

to turn organic nutrients into precipitable biomass

Question 168

A fecal indicator organism should . . .
A. be common in the soil as well as in humans
B. be harder to kill than most pathogens
C. be an auxotroph
D. produce acid and gas
E. have enough I/C factors, PAIs, etc. for it to be a pathogen

Answer 168

produce acid and gas

Question 169

Somehow, pathogen growth must be minimized during food preparation involving microbes. Which
of the following is NOT used to reduce pathogen growth?
A. The food is allowed to become acidic.
B. The food is frozen to kill pathogens.
C. The food is cultured in salt brine.
D. The food is prepared with thermophilic organisms.
E. SO2 gas is added to inhibit growth of spoilage organisms

Answer 169

The food is frozen to kill pathogens.

Question 170

Which of the following would NOT be an effective way to prevent spoilage organisms from
growing in food?
A. Reduce the water activity to 0.5 or less
B. Freeze the food
C. Lower the pH below 4
D. Raise the pH above 12
E. Keep oxygen out of the food

Answer 170

Keep oxygen out of the food

Question 171

Oh no!! You forgot to put away the leftovers after dinner, and now you’re afraid they’ve been
sitting out long enough to have spoiled. If you reheat the food before you eat it, you would be safe
from all of the following EXCEPT . . .
A. Campylobacter jejuni
B. Vibrio parahemolyticus
C. Clostridium botulinum
D. Staphylococcus aureus
E. Listeria monocytogenes

Answer 171

Staphylococcus aureus

Question 172

A foodborne pathogen associated with jam or jelly is most likely to be . . .
A. a fungus
B. present as a biofilm
C. a Staphylococcus
D. halophilic
E. a Pseudomonas

Answer 172

a fungus

Question 173

During the manufacture of yogurt, how is the growth of pathogens inhibited?
A. Salt and sugar are added to inhibit bacterial growth by lowering the aw.
B. Pathogens are allowed to grow, but the yogurt is later pasteurized.
C. The fermentation is thermophilic; pathogens are inhibited by the high temperature.
D. Probiotic bacteria are added to compete with the pathogens.
E. The yogurt is frozen briefly to kill all the bacteria, and then “good” bacteria are added
back to the final product.

Answer 173

The fermentation is thermophilic; pathogens are inhibited by the high temperature.

Question 174

Acetobacter can be a valuable and desirable bacterium in the food industry. Why?
A. It is one of the organisms whose secondary metabolites give flavor to wine.
B. It is one of the organisms that begins lactic acid fermentation to make cheese.
C. The CO2 it produces is what makes bread rise.
D. It is used to make vinegar from alcohol by acid fermentation.
E. It is a probiotic that is added to many food products to boost the immune response

Answer 174

It is used to make vinegar from alcohol by acid fermentation.

Question 175

Food spoilage bacterium that produces cellulases to degrade plant cell walls.
A. Aspergillus
B. Staphylococcus aureus
C. Erwinia
D. Bacillus cereus
E. Rhizopus

Answer 175

Erwinia

Question 176

How and why is it important in the food industry to be able to regulate water activity (aw)?
A. aw is reduced to produce a hypertonic environment and cause bacterial plasmolysis
B. aw is kept low so that water rushes into the bacterial cell and causes it to lyse
C. aw is increased by evaporation, so that aqueous enzymatic reactions can no longer occur
D. aw is kept high to produce a hypotonic environment and lyse susceptible bacteria
E. aw is increased with salt, which makes the environment hypotonic to bacterial cytoplasm

Answer 176

aw is reduced to produce a hypertonic environment and cause bacterial plasmolysis

Question 177

Spores of this organism can germinate in improperly processed foods in which anaerobic pockets
are allowed to form. A toxin causes severe neuroparlaysis
A. Aspergillus
B. Clostridium botulinum
C. Vibrio parahemolyticus
D. Bacillus cereus
E. Rhizopus.

Answer 177

Clostridium botulinum

Question 178

What microorganisms are used most extensively in the food industry, being required in the
production of such diverse foods as cheese, sauerkraut, yogurt and pepperoni sausage?
A. Molds like Penicillium
B. Halophilic bacteria
C. Thermophilic bacteria
D. Lactic acid bacteria
E. Yeasts like Saccharomyces

Answer 178

Lactic acid bacteria

Question 179

How are microbes involved in bread making?
A. Enzymes from the microbes are required to extract nutrients from the grain.
B. Fungal filaments are used as a binder to hold the flour together.
C. O2 produced during respiration gives the bread a light, soft texture.
D. Fermentation acids are required to soften the flour and prepare it for aeration.
E. The CO2 produced from alcohol fermentation makes the bread rise.

Answer 179

The CO2 produced from alcohol fermentation makes the bread rise.

Question 180

Which of the following is NOT a method used to prevent spoilage in the indicated food?
A. The halophiles used to make bread can grow in the salty gluten, but other bacteria cannot.
B. Pepperoni is smoked after fermentation to reduce aw.
C. Thermophilic fermentation is used to prevent pathogen growth in yogurt.
D. Sulfites are added to wine to prevent growth of Acetobacter.
E. Lactic acid bacteria produce enough acid in sauerkraut to prevent growth of pathogens.

Answer 180

The halophiles used to make bread can grow in the salty gluten, but other bacteria cannot.

Question 181

The growth of Aspergillus on grains that will be part of the food supply is . . .
A. bad, because it produces an acid that kills the plants
B. good, because it produces antibiotics that kill pathogenic bacteria.
C. bad, because it produces a carcinogenic toxin
D. good, because it produces enzymes that promote plant growth
E. bad, because it has a Type III secretion system that damages the grains

Answer 181

bad, because it produces a carcinogenic toxin

Question 182

More than 1000 people in Florida recently developed symptoms of bloody dysentery. Ten
experienced kidney failure, and three died. The illness was found to be due to a toxemia, and was
traced to contaminated bagged lettuce. Which of the following organisms caused this outbreak?
A. Campylobacter jejuni
B. Cryptosporidium parvum
C. Salmonella enteritidis
D. Escherichia coli O157:H7
E. Vibrio parahemolyticus

Answer 182

Escherichia coli O157:H7

Question 183

Bacteria are used in the food industry, but the growth of potential pathogens must be inhibited.
Frequently, a product of the “good” bacteria inhibits the “bad” ones. But one of the following foods
must be processed further after the “good” bacteria have finished growing, because the fermentation
process does not completely kill the pathogens. Which is it?
A. Cheese
B. Pepperoni
C. Sauerkraut
D. Yogurt
E. Beer

Answer 183

Pepperoni

Question 184

How is fermentation involved in the bread making process?
A. It produces a gas that allows the bread to rise.
B. It produces acid, which flavors the bread.
C. It produces acid, which kills pathogens that may be present on the grain.
D. It produces the gluten that is necessary for the bread to rise.
E. It produces alcohol, which kills pathogens that may be present on the grain.

Answer 184

It produces a gas that allows the bread to rise.

Question 185

Organisms that survive at the lowest water activities are . . .
A. thermophilic bacteria
B. xerophilic fungi
C. halophilic Archaea
D. halophilic bacteria
E. acidophilic fungi

Answer 185

xerophilic fungi

Question 186

There is an increased danger of getting botulism from . . .
A. foods that have been processed in a commercial cannery
B. foods that have been prepared by lactic acid fermentation
C. foods with a naturally neutral pH
D. foods that have been dried under aerobic conditions
E. any foods that are thick and contain facultative anaerobes

Answer 186

foods with a naturally neutral pH

Question 187

Several people experienced a 24-hour “stomach bug,” with nausea, vomiting and diarrhea, after
eating spaghetti and meatballs at a restaurant. Which of the following are the most likely culprits?
A. Vibrio and Norovirus
B. E. coli and Botulism
C. Staph aureus and Bacillus cereus
D. Campylobacter and Salmonella
E. Listeria and E. coli

Answer 187

Staph aureus and Bacillus cereus

Question 188

Lactic acid fermentation is used in the production of all of the following foods EXCEPT . . .
A. cheese
B. bread
C. sauerkraut
D. pepperoni
E. yogurt

Answer 188

bread

Question 189

What organism can spoil wine, and how is its growth prevented?
A. Fusarium – by adding an alcoholic must to kill the bacteria
B. Botrytis – by adding sulfite to kill the virus
C. Penicillium – by lowering the pH to kill the fungus
D. Acetobacter – by adding sulfite to inhibit bacterial growth
E. Malolactic bacteria – by adding an alcoholic must to kill them

Answer 189

Acetobacter – by adding sulfite to inhibit bacterial growth

Question 190

Which of the following combinations of food and contaminating organism is not possible?
A. Bread contaminated by Staphylococcus
B. Cured ham contaminated by mold
C. Jelly contaminated by Pseudomonas
D. Cereal grain contaminated by Aspergillus
E. Fresh lettuce leaves contaminated by Salmonella

Answer 190

Jelly contaminated by Pseudomonas

Question 191

Oops! You ate at one of those places that the Health Inspector flagged for having the rice on the
sushi bar at room temperature. You might have gotten food poisoning. What symptoms can you
expect?
A. Watery diarrhea for about a week
B. Nausea, diarrhea and vomiting for a day
C. Gut cramping, but possibly neural paralysis and death
D. Vomiting, but no diarrhea or other symptoms
E. Diarrhea, gut inflammation and potential kidney damage

Answer 191

Nausea, diarrhea and vomiting for a day

Question 192

Which of the following is NOT used to prevent the growth of food spoilage organisms during the
cheese making process?
A. Heat
B. Salt
C. Acid
D. Sulfite
E. Competition from other organisms

Answer 192

Sulfite

Question 193

Bacteria can directly enhance plant hardiness by . . .
A. producing auxin in leaf and stem tissue
B. producing gibberellic acid in stems
C. growing within xylem or phloem tissue
D. producing cellulase
E. inhibiting ethylene production after germination

Answer 193

inhibiting ethylene production after germination

Question 194

Which of the following is NOT a characteristic of plant-growth-promoting rhizobacteria (PGPR)?
A. They are only able to help the plant avoid root diseases.
B. They have evolved to use flavonoids as carbon sources.
C. They can form biofilms on plant root surfaces.
D. They can live within plant root cells.
E. They can produce antimicrobial proteins.

Answer 194

They are only able to help the plant avoid root diseases.

Question 195

PGPR bacteria are effective at reducing root rot caused by Pythium. The bacteria could reduce
Pythium root damage by all of the following mechanisms, EXCEPT . . .
A. parasitizing the Pythium pathogen
B. binding iron and keeping it from the Pythium pathogen
C. producing phytohormones to strengthen the roots
D. colonizing the root hairs so there is no room for Pythium to colonize
E. producing antibiotics that inhibit growth of the Pythium

Answer 195

parasitizing the Pythium pathogen

Question 196

Why do cows need rumen microflora?
A. They produce the methane that the cow uses to regulate its temperature.
B. They produce ATP for the cow.
C. They ferment cellulose directly without first saccharifying it.
D. They produce volatile fatty acids from which the cow gets most of its energy.
E. The same reason we need gut microflora - they protect the cow from pathogens.

Answer 196

They produce volatile fatty acids from which the cow gets most of its energy.

Question 197

This potato was infected after a period of very wet weather. What likely infected it?
A. Verticillium
B. Pseudomonas syringae
C. Agrobacterium tumifaciens
D. A basidiomycete
E. Phytophthora

Answer 197

Phytophthora

Question 198

PGPR bacteria can enhance plant hardiness by . . .
A. producing auxin in leaf and stem tissue
B. inserting a plasmid called Ti to increase the plant cell growth rate
C. producing gibberellic acid in root hairs
D. growing within xylem or phloem tissue
E. inhibiting ethylene production until seeds have germinated

Answer 198

producing gibberellic acid in root hairs

Question 199

Which of the following is NOT a characteristic of PGPR bacteria?
A. They have evolved to use flavonoids as carbon sources.
B. They have a strictly anaerobic metabolism.
C. They form biofilms on plant root surfaces.
D. They can produce bacteriocins.
E. They can produce the phytohormones auxin and gibberellic acid.

Answer 199

They have a strictly anaerobic metabolism.

Question 200

Bacteria that produce the enzyme ACC deaminase have been added as special coatings around
plant seeds. What is the purpose of this technology?
A. to protect the seeds from harsh soil conditions and allow earlier planting
B. to carry out ethanol fermentation for production of cellulosic fuel
C. to reduce the amount of ethylene at the right time to encourage root elongation
D. to allow the bacteria to colonize the plant roots and perform nitrogen fixation
E. to have the bacteria digest the seed coat so the plant can germinate faster

Answer 200

to reduce the amount of ethylene at the right time to encourage root elongation

Question 201

Reducing the odor from a hog farm can be done by the use of nitrifying and denitrifying bacteria,
but it required some skilled engineering to get these bacteria to grow together. Why?
A. One produces antiquoromones to inhibit the growth of the other
B. They carry out opposite steps in the nitrogen cycle, so one reverses the action of the other
C. One is an organotroph, and the other is a lithotroph
D. They are natural “enemies” - one produces antibodies against the other
E. One requires an aerobic environment; the other an anaerobic environment

Answer 201

One requires an aerobic environment; the other an anaerobic environment

Question 202

Which of the following is found in wet soil and causes root
damage shortly after germination, which leads to growth “damping off”
and plant stunting, as seen in the picture?
A. Agrobacterium
B. Mosaic viruses
C. Verticillium
D. Pythium
E. Pseudomonas syringae

Answer 202

Pythium

Question 203

How does the bacterial regulation of ethylene production affect plant hardiness?
A. Bacterial ethylene production increases the growth of plant stems.
B. Bacterial ethylene production causes damage to phloem and stunts plant growth.
C. Bacterial ethylene production prevents colonization of plant roots by pathogenic fungi.
D. Bacterial inhibition of plant ethylene production reduces the fruit ripening time.
E. Bacterial inhibition of plant ethylene production at the right time can enhance root growth.

Answer 203

Bacterial inhibition of plant ethylene production at the right time can enhance root growth.

Question 204

Which of the following bacteria is a plant pathogen that inserts one of its plasmids into plant cells,
and is therefore used frequently in plant genetic engineering?
A. Erwinia carotovora
B. Pseudomonas syringae
C. Agrobacterium tumifaciens
D. Acetobacterium woodii
E. Spiroplasma

Answer 204

Agrobacterium tumifaciens

Question 205

The tree at right is infected by an organism that
grows in and damages xylem tissue. The organism is
most likely . . .
A. Pythium
B. Agrobacterium
C. Erwinia
D. Verticillium
E. Maple Mosaic Virus

Answer 205

Verticillium

Question 206

Which of the following does not typically occur much in a healthy rumen?
A. Volatile fatty acid fermentation
B. Hydrolysis of cellulose
C. Methanogenesis
D. Hydrolysis of starch
E. Lactic acid fermentation

Answer 206

Lactic acid fermentation

Question 207

Which of the following statements about Agrobacterium is NOT true?
A. It contains a useful natural cloning vector
B. It infects xylem tissue in plant stems
C. It contains genes for the production of auxin
D. It injects a piece of its DNA into plant cells
E. It causes crown gall tumors in plants

Answer 207

It contains genes for the production of auxin

Question 208

How do Ascomycete fungi like Fusarium and Rice Blast enter plant cells?
A. They enter as spores through plasmodesmata.
B. They swim through open stomata during gas exchange.
C. Turgor pressure in fungal appressoria pokes a hole in the plant cell.
D. Their yeast forms are carried in insect mouthparts.
E. They don’t. These fungi just grow on the surface of the plant.

Answer 208

Turgor pressure in fungal appressoria pokes a hole in the plant cell.

Question 209

Which of the following is true about plant viral infections?
A. They can appear as in the picture at the right.
B. They are usually caused by enveloped viruses.
C. Plants have no defense mechanisms.
D. They typically kill the plant quickly.
E. They often produce a gray fuzzy growth called “smut.”

Answer 209

They can appear as in the picture at the right.

Question 210

How does a plant’s immune system compare to ours?
A. It’s pretty much the same, with humoral, cellular and innate branches.
B. It produces T cells in response to specific pathogens, but no antibodies.
C. It recognizes PAMPs and secretes antibacterial compounds in response.
D. It has macrophages that engulf and digest bacterial invaders.
E. Plants do not have an immune system.

Answer 210

It recognizes PAMPs and secretes antibacterial compounds in response.

Question 211

How do ascomycete fungi gain entry to plant leaves?
A. Their spores are deposited from the mouthparts of chewing insects.
B. They produce cellulases that digest plant cells and make holes in leaves.
C. Their type III secretory systems inject effectors that induce membrane ruffling.
D. They have an organelle that uses turgor pressure to poke a hole into the plant cell.
E. They enter via communication channels called plasmodesmata.

Answer 211

They have an organelle that uses turgor pressure to poke a hole into the plant cell.

Question 212

Which of the following would be considered a PGPR organism?
A. Pythium
B. Fusarium
C. Xanthomonas
D. Spiroplasma
E. Paenibacillus

Answer 212

Paenibacillus

Question 213

PGPR organisms can benefit plant cells by all of the following EXCEPT . . .
A. Sensitizing the immune system by inducing azalaic acid secretion
B. Producing antibiotics to kill pathogenic bacteria
C. Producing auxins while they are living on plant root tissues
D. Producing large amounts of gibberellic acid in plant stems and shoots
E. Competing for space and resources with pathogenic bacteria and fungi

Answer 213

Producing large amounts of gibberellic acid in plant stems and shoots

Question 214

What is the importance of volatile fatty acids in ruminant microbiology?
A. They are fed to cattle as a supplement to increase the growth of rumen bacteria.
B. They are important contaminants involved in the initial souring of milk.
C. They are produced in excess when a cow is switched from grass-fed to grain-fed.
D. They are dangerous acids that can decrease the pH of the rumen.
E. They are the main carbon source produced in the rumen for the cow’s nutrition.

Answer 214

They are the main carbon source produced in the rumen for the cow’s nutrition.

Question 215

Plants and humans share all of the following immune response functions EXCEPT . . .
A. Pattern Recognition Receptors
B. Antimicrobial defense molecules
C. Native Flora
D. Cells that kill infected self cells
E. Molecules that signal the presence of a pathogen

Answer 215

Cells that kill infected self cells

Question 216

What is the purpose of coating seeds with delayed-release bacteria that produce ACC deaminase?
A. ACC deaminase blocks pathogen entry into roots
B. ACC deaminase is a plant hormone that promotes stem growth
C. ACC deaminase is the enzyme that fixes nitrogen in plant roots
D. ACC deaminase blocks the production of ethylene after the seed has germinated
E. ACC deaminase stimulates growth of fusarium

Answer 216

ACC deaminase blocks the production of ethylene after the seed has germinated

Question 217

Microbial production of ethanol from cellulosic sources is an unrealized goal so far. We would be
much closer to the goal if we had ________________, but we don’t yet.
A. yeast that could ferment sugar
B. yeast that could ferment pentoses
C. bacteria that could digest cellulose
D. bacteria that could survive in 10% ethanol
E. bacteria that could ferment pentoses

Answer 217

bacteria that could survive in 10% ethanol

Question 218

Which of the following would NOT be a potential application of DNA-based microarray
technology?
A. Personalized therapy based on which cytochrome P450 enzyme variant a patient has
B. Identification of bacteria that can colonize plant roots and promote growth
C. Identifying which cytokines are degraded by a particular drug
D. Diagnosis of a bacterial respiratory tract infection
E. Identify which genes are involved in formation of a tumor

Answer 218

Identifying which cytokines are degraded by a particular drug

Question 219

A throat sample was isolated from an asymptomatic patient. 16S rRNA primers flanking a unique
region were added and PCR was performed. The PCR product was fluorescently labeled and
hybridized to a diagnostic chip. The array spot corresponding to Streptococcus pneumoniae showed
fluorescence, along with several dozen others. How would you interpret this result?
A. The patient has Strep throat.
B. The use of 16S rRNA resulted in a false positive test.
C. The primers were not specific enough, and too many rRNAs were amplified.
D. The oligonucleotides on the chip are not specific enough.
E. Streptococcus pneumoniae is one of many organisms in normal oral flora.

Answer 219

Streptococcus pneumoniae is one of many organisms in normal oral flora.

Question 220

Which of the following is the LEAST efficient technology for potentially producing combustible
fuel from renewable sources?
A. Butanol from Clostridial fermentation
B. Ethanol from cellulosic sources
C. Methane from anaerobic digestion of biological waste
D. Ethanol from starchy grains
E. Petroleum from aquatic photoautotrophs

Answer 220

Ethanol from cellulosic sources

Question 221

The most promising microbial fuel cells involve bacteria that can . . .
A. form a biofilm on the anode with protein nanowires
B. ferment pentoses as well as hexoses
C. serve as electron shuttles between the anode and cathode chambers
D. simultaneously degrade cellulose and ferment the sugar to ethanol
E. harvest electrons efficiently from a wide variety of electron donors

Answer 221

form a biofilm on the anode with protein nanowires

Question 222

What was the rationale for Roche pharmaceuticals to develop the P450 microarray?
A. They wanted to screen 450 bacteria for new antibiotic production.
B. They wanted to diagnose potential infections with many different pathogens.
C. It is a protein array to detect how certain drugs affect cytochrome profiles in a patient.
D. They used it to clone the insecticide gene from BT into plant cells.
E. It detects a cytochrome variant that determines how some patients metabolize certain
drugs.

Answer 222

It detects a cytochrome variant that determines how some patients metabolize certain
drugs.

Question 223

One major advantage to using bacteria for fuel ethanol production rather than yeast is that. . .
A. bacteria can ferment pentose sugars; so far, yeast still cannot
B. bacteria are much more ethanol tolerant than yeast are
C. bacteria can produce crude oil in addition to the ethanol
D. bacteria can produce ethanol from cellulosic fuel crops
E. bacteria are already used more for industrial fermentation than are yeast

Answer 223

bacteria can produce ethanol from cellulosic fuel crops

Question 224

What is the science of “metagenomics”?
A. The study of all the genes in a mixed bacterial population
B. The study of how bacteria impact the soil environment
C. The use of the human genome to understand what diseases affect different people
D. The technological development of microarrays
E. A series of methods to clone genes into multiple host cells simultaneously

Answer 224

The study of how bacteria impact the soil environment

Question 225

On what principle is a microbial fuel cell based?
A. Yeast can produce ethanol from cellulose in an enclosed chamber.
B. Bacteria can donate respiratory electrons to an oxidized anode.
C. Bacteria can transfer electrons across a wide gap because of electrical attraction.
D. Electrons can build up to a high concentration inside bacteria.
E. Bacteria are capable of simultaneous saccharification and fermentation.

Answer 225

Bacteria can donate respiratory electrons to an oxidized anode.

Question 226

What bacterial molecule is usually used to produce diagnostic microarrays? Why?
A. Antibodies, since they are highly variable and can be attached to the array easily.
B. Cytochrome P450, since only some bacteria have cytochrome P in their electron transport
chain.
C. DNA from each gene on the bacterial chromosome, since this allows us to determine which
genes are transcribed under various environmental conditions.
D. 16S rRNA because the unique regions can be amplified by PCR using primers made against
the similar regions.
E. Capsular polysaccharides, since they are highly antigenic and we produce antibodies against
them readily.

Answer 226

16S rRNA because the unique regions can be amplified by PCR using primers made against
the similar regions.

Question 227

In a recent experiment designed by the Woods Hole Oceanographic Institute, thousands of tons of
iron is being added to areas of the world’s oceans. Why?
A. This will fertilize the oceans and result in more production of krill and other plankton.
B. This is an attempt to get rid of scrap iron by having bacteria use it to make cytochromes.
C. They are hoping to stimulate photoautotrophic growth more than heterotrophic growth.
D. If iron can shade the oceans from sunlight, the water temperature may decrease.
E. By oxidizing the iron to iron oxide, they hope to reduce CO2 to CH4.

Answer 227

They are hoping to stimulate photoautotrophic growth more than heterotrophic growth.

Question 228

Though microbial fuel cell (MFC) technology is still in its infancy, some ways to improve MFCs
have already become obvious. What is one way that could be used to increase the efficiency of MFCs?
A. Thoroughly aerate the anode of the fuel cell by blowing O2 into
the chamber.
B. Try to increase bacterial production of pili and nanowires.
C. Use a redox mediator that is higher on the right-hand side
of the redox chart than the electron donor is on the left-hand side.
D. Get the bacteria to perform simultaneous saccharification and
fermentation (SSF)
E. Use aquatic phototrophs as the fuel source for the fuel cell.

Answer 228

Try to increase bacterial production of pili and nanowires.

Question 229

A saliva sample was isolated from a patient and heated to 95oC.
Primers that recognized constant regions of 16S rRNA were added and the temperature was lowered to
60oC. A thermostable DNA polymerase was added and the temperature was raised to 72oC. The
heating, primer annealing and polymerase steps were repeated 35 times. Then the product of this
reaction was labeled fluorescently and added to a diagnostic microarray. Spots on the array
representing Haemophilus influenzae, Streptococcus mutans and Corynebacterium diphtheriae
appeared fluorescent. What can you conclude from this exercise?
A. Nothing – the PCR reaction was done incorrectly.
B. Nothing – the PCR primers should have recognized unique regions of the 16S rRNA.
C. Nothing – the pathogens named above are not transmitted in saliva.
D. Nothing – you need to hybridize two different nucleic acid samples to a microarray.
E. This patient is underimmunized and has somehow been exposed to Diphtheria.

Answer 229

This patient is underimmunized and has somehow been exposed to Diphtheria.

Question 230

Which of the following would provide the greatest improvement to microbial fuel cell technology?
A. using microbes capable of simultaneous saccharification and fermentation
B. developing yeast that were capable of fermentation of pentose sugars
C. developing bacteria that could withstand exposure to 20% ethanol
D. increasing the efficiency of bacterial adhesion to the anode of the fuel cell
E. using an electron shuttle in the cathode compartment as well as in the anode compartment

Answer 230

increasing the efficiency of bacterial adhesion to the anode of the fuel cell

Question 231

What does the field of pharmacogenetics deal with?
A. Using gene therapy to treat immunodeficiency diseases
B. Development of DNA-based vaccines
C. Antimicrobial drugs based on nucleoside analogs
D. Using DNA to identify what pathogen is causing an infection
E. Developing treatments specific to a patient’s genotype

Answer 231

Developing treatments specific to a patient’s genotype

Question 232

What’s the idea behind the experiment to fertilize the oceans with iron?
A. To increase the growth of all bacteria in the oceans
B. To decrease the growth of all bacteria in the oceans
C. To selectively increase the growth of autotrophs in the oceans
D. To enhance the respiratory part of the carbon cycle
E. To get bacteria to form biofilms on the iron particles

Answer 232

To selectively increase the growth of autotrophs in the oceans

Question 233

What still needs to be done in order to use bacteria for the production of cellulosic
ethanol?
A. Develop bacteria that are more ethanol tolerant
B. Develop bacteria that can hydrolyze cellulose
C. Develop bacteria that can ferment pentose sugars
D. Develop bacteria that can perform alcohol fermentation
E. Enhance the aerobic growth rate of bacteria

Answer 233

Develop bacteria that are more ethanol tolerant

Question 234

(BONUS) What is the purpose of a microbial fuel cell?
A. To produce oil from algae like Botryococcus
B. To produce butanol from fungal fermentations
C. To produce hydrogen gas from bacterial fermentations
D. To harvest electrons from bacterial electron transport chains
E. To produce fuel additives called “mediators”

Answer 234

To harvest electrons from bacterial electron transport chains

Question 235

We mentioned a viral diagnostic microarray called the “Virochip.” There is a lot of work on
similar bacterial arrays, and many have been developed, though none has been approved yet. What is a
difference between the viral array and bacterial diagnostic arrays?
A. Viral genomes are much harder to sequence than bacteria are.
B. The viral array would have more spots since there are more viruses than bacterial species.
C. The bacterial array would be spotted with oligos that recognize 16S rRNA.
D. Bacterial arrays would have to be hybridized to two DNAs, one red and one green.
E. Bacterial arrays would be spotted with proteins rather than with oligonucleotide probes.

Answer 235

The bacterial array would be spotted with oligos that recognize 16S rRNA.

Question 236

Cytokine microarrays are used in the pharmaceutical industry as a first screen to determine
whether newly developed drugs will cause an adverse reaction. How do such arrays work?
A. Cytokines on the array bind to and induce immune cells in the sample.
B. Anti-cytokine antibodies on the array detect cytokines in the sample.
C. Staph protein A on the array detects anti-cytokine antibodies in the sample.
D. Oligonucleotides on the array detect cytokine gene expression in the sample.
E. Cytokines on the array detect anti-cytokine antibodies in the sample.

Answer 236

Anti-cytokine antibodies on the array detect cytokines in the sample.

Question 237

What is the goal of an “artificial leaf”?
A. To produce electricity directly from sunlight
B. To produce glucose from CO2
C. To use PS-II and sunlight to produce O2
D. To use PS-I and PS-II to produce ATP
E. To use sunlight, PS-II and a metal catalyst to produce H2

Answer 237

To use sunlight, PS-II and a metal catalyst to produce H2

Question 238

All of the following could be considered “second generation” biofuels EXCEPT . . .
A. ethanol from fermentation of corn starch
B. ethanol from fermentation of algal cellulose
C. biodiesel from a cloned bacterial plasmid
D. crude oil from Botryococcus
E. butanol from ABE fermentation

Answer 238

ethanol from fermentation of corn starch

Question 239

Which of the following is absolutely essential in a microbial fuel cell (MFC)?
A. Bacteria that produce nanowires
B. Bacteria with a respiratory chain
C. Simultaneous saccharification and fermentation
D. Bacteria that form biofilms on the anode
E. Chemical electron shuttles (“mediators”)

Answer 239

Bacteria with a respiratory chain

Question 240

Which of the following is still “science fiction” (is still theoretical; has not yet been done)?
A. Using bacterial scrubbers to reduce CO2 emissions from factories
B. Combining hydrolysis and fermentation capabilities in the same organism
C. Generating electricity from a bacterial PMF
D. Knowing every gene in a bacterium, even though we can’t grow the bacterium
E. Nanoassembly of biological components using specially folded DNA to bring all the
components together

Answer 240

Combining hydrolysis and fermentation capabilities in the same organism

Question 241

The main energy product produced by an “artificial leaf” is . . .
A. H2
B. electrons
C. glucose
D. CO2
E. ethanol

Answer 241

H2

Question 242

There are many advantages in using bacteria rather than yeast to produce biofuels. Which of the
following is NOT an advantage of bacteria?
A. Bacteria can ferment pentose sugars.
B. Bacteria can hydrolyze b-1,4-glycosidic bonds
C. Bacteria can survive higher ethanol concentrations.
D. Bacteria can produce butanol.
E. The greater evolutionary potential of bacteria means that they can be used to produce
many different biofuel products.

Answer 242

Bacteria can survive higher ethanol concentrations.