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دنیای میکروب ها - تست های چهارجوابی میکروبیولوژی
نمونه سئوالات درس باکتری ۲

1 - كليه مطالب ذيل دررابطه باسويه هاي Enterotoxigenic E.coli صحيح است ,بجز :

الف – ژن مسئول توليدتوكسين LT وST تحت كنترل پلاسميد است.

ب- GM1 رسپتور قسمت B از سم  LT  است.  

ج- ژن هاي پلاسميدي توليدكننده LT و ST ممكن است حامل ژنهاي كلونيزاسيون نيزباشند.  

د- هردوتوكسين LT  و ST بامكانيسمي كاملا مشابه عمل مي كنند.

 

2- دربين شاخص هاي ويرولانس E.coli به ترتيب كدام دوفاكتور ادهسين واگرسين هستند : :

الف- پيلي K - انتروكلين    

ب- فاكتوركلني سازI- پيلي K    

ج- Kكپسولي- انتروكلين     

د- انتروكلين- فاكتوركلني سازII

 

3- E.coli شايعترين ارگانيسم مولدعفونتهاي ادراري درانسان است.توجيه اين مطلب اين است كه ‚ E.coli :

الف- فلور نرمال مثانه است.                  

ج- به گيرنده هاي خاصي درسطح سلول هاي اپيتليال مجاري ادراري مي چسبد.

ب- توسط آنزيم اوره آز ‚ اوره راهيدروليزمي كند.        

د- به اكثرموادضدميكروبي دستگاه ادراري مقاوم است.

 

4- كدام يك از عبارات زير در مورد سالمونلاتيفي موريوم غلط است :

الف- باكتري داراي مخازن حيواني متعدد است.         

ب- يكي از عوامل شايع انتروكوليت است.

ج- تخمير كننده لاكتوز  است.                                 

د- باكتري گرم منفي، متحرك و داراي اندوتوكسين است.

 

5- كلني ويبريون وبا ،بر روي محيط T.C.B.S چگونه رشد مي كند :

الف-كلني هاي بنفش رنگ كه گاهي جلاي فلزي داشته و مركز آنها سياه است.

ب-كلني هاي گرد و برجسته بيرنگ تا كرمي ،مركز كدر و لبه شفاف و يك هاله ابري در اطراف

ج-كلني هاي گرد و خيلي برجسته موكوئيد و خاكستري رنگ

د-كلني گرد وبرجسته متوسط زرد رنگ در وسط كدر ولبه شفاف

 

Questions :

 You have been asked to design a nucleic acid amplification test for a rarely isolated bacterium. There are several questions that you must ask in order to develop a test that could be used to diagnose disease.


 1.  Early attempts at the polymerase chain reaction (PCR) used E. coli DNA polymerase. This was replaced with DNA polymerase from Thermus aquaticus (“Taq” polymerase). The primary advantage in using this enzyme is

a. It is cheaper than E. coli polymerase

b. Specificity is increased because nonspecific hybridization of primers does not occur

c. Use of Taq polymerase results in fewer PCR cycles

d. Use of Taq polymerase enables lower temperatures to be used

e. Upon repeated cycling, Taq polymerase becomes denatured, which causes less interference with the hybridization process

 

2. Assume, initially, that the polymerase chain reaction (PCR) will amplify any DNA, human or microbial. The best way to prevent contamination of the PCR process is to

a. Wear gloves

b. Wash benches with bleach

c. Use universal precautions

d. Incorporate self-sterilizing agents into the PCR mixture

e. Do all of the work under a hood

 

3. You must choose primers for this PCR. Primers are small pieces of nucleic acid that recognize a pair of unique sites on the bacterial chromosome. For an optimum test to be developed, which of the following characteristics is the least desirable?

a. Ability to be constructed by a synthesizer

b. Uniqueness to the organism that you wish to detect

c. Complementary to sequences on the bacterial chromosome

d. Ability to serve as a template for replication

e. That the sequences are widely recognized by many bacterial species

 

4. You have chosen the primers for the PCR that you have designed. You have also developed a reaction mixture that contains, among other substances, a polymerase enzyme. After the primer pairs have been amplified, they must be detected. Which of the following detection methods is most sensitive (that is, will detect the highest number of amplicons)?

 a. Southern blot 

b. Ethidium staining of the amplified products (amplicons)

c. Microscopy

d. Capture of the amplicons on a solid phase followed by an enzyme immunoassay

e. Labeling of the amplicons with fluorescent dyes

 

 5.  The purpose of gene cloning is to produce large amounts of genes in pure form. The sequence of the cloning process is critical to the production of clones. Which of the following steps initializes the cloning process?

a. Isolation and fragmentation of source DNA 

b. Amplification of source DNA

c. Detection and purification of clones

d. Joining of host DNA to a cloning vector

e. Incorporation of a cloning vector into the host cell

 

6. Nucleic acid probes are not only useful for searching for genes in the cloning host but also for searching for genes or gene fragments in patient specimens. Which one of the following statements is true of nucleic acid probes?

a. Only DNA can be used as a probe

b. Primers are labeled to allow detection, but probes are unlabeled

c. Nucleic acid probes are not as sensitive as traditional culture methods for detection of pathogenic microorganisms

d. Probes can be designed so that they can detect very specific pieces of a nucleic acid, for example, a penicillin-resistant gene

e. Probes may contain any part of the base sequence of the gene of interest

 

7. DNA from a host sample can be amplified by a process known as the polymerase chain reaction (PCR). Which of the following is required for PCR?

a. Knowledge of the genetic sequence to be amplified 

b. An single nucleotide primer

c. An ultracentrifuge

d. A universal probe to detect the amplified product

e. A heat-sensitive DNA polymerase enzyme

 

Questions :

The following diagram illustrates the amplification of DNA by the polymerase chain reaction (PCR). There are at least four points in the PCR process (A–D) that are critical to the reaction.

8. The Southern blot detection system for amplified PCR products fails to function. Which one of the following would be affected?

a. A          b. B          c. C         d. D

 

9. DNA does not hybridize with the primers. Which one of the following would be affected?

a. A          b. B          c. C         d. D

 

10. The laboratory observes a series of false-positive results. Which one of the following processes would you suspect to be faulty?

a. A          b. B          c. C         d. D

 

11. The DNA strands fail to reanneal. Which one of the following processes would you suspect to be faulty?

a. A          b. B          c. C         d. D

 

12. The laboratory observes a series of false-negative results. Which one of the following processes would you suspect to be faulty?

a. A          b. B          c. C         d. D


+ نوشته شده در  سه شنبه 23 شهریور1389ساعت 23:8  توسط رضائیان - شاه ایلی 

 

۱- كداميك از اسيد آمينه هاي زير داراي ايزومرنوري نمي باشد.

الف) اورني تين    ب) تره اونين    ج) ايزولوسين    د) گلايسين


۲- كدام اسيد آمينه از اسيد آمينه هاي زير در تثبيت و تشكيل و استحكام ساختمان فضايي پروتئينها نقش كمتري دارد.

الف)Lys    ب) Pro    ج)Cys    د) Ala


۳- كداميك از آمينو اسيدهاي زير داراي گروه SH – مي باشد.

الف)Methionin ( ميتونين )      ب)Cystin ( سيستين )           ج)سيتئين               د) هر سه مورد


۴- در يك پروتئين

الف)فقط اسيد آمينه نوع L و يا فقط نوع D وجود دارد.

ب)ممكن است قسمتي - هليكس راست گرد و قسمتي چپ گرد باشد.

ج) ممكن است ناحيه آلفا - هليكسي وجود داشته باشد كه همه داراي اسيد آمينه نوع L و هم D باشد.

د) ممكن است در بعضي از قسمتهاي صفحات محكم پپتيدي وجود نداشته باشد.


۵- پرولين باعث تثبيت كداميك از ساختمانهاي زير مي گردد.

الف) - كراتين     ب)فيبروئين     ج)كلاژن     د) الاستين

ادامه مطلب
+ نوشته شده در  یکشنبه 2 خرداد1389ساعت 1:53  توسط رضائیان - شاه ایلی 

 

1- Which statement(s) is / are not true of the organisms in the domain Archaea?

a. These organisms lack peptidoglycan in their cell walls            

 b. These organisms contain ether-Iinked lipids

c. These organisms have simple RNA polymerases.                    

d. All of the above

 

2- Organisms in the domain Archaea are grouped into kingdoms according to their

a. 16S rRNA        b. 16S mRNA     c. 18S rRNA     d. 18S mRNA

 

3- Which statement is true?

a. The methanogens are obligate aerobes; the extreme halophiles are obligate anaerobes

b. The methanogens are obligate anaerobes; the extreme halophiles are obligate aerobes

c. Both the methanogens and the extreme halophiles are obligate aerobes

d. Both the methanogens and the extreme halophiles are obligate anaerobes

 

4- Methanogens :

a. Produce methane as a part of their energy metabolism                    

b. Utilize methane as an energy source

c. Process and store methane as a part of their repair mechanism       

d. Do none of the above

 

5- Most known methanogens are :

a. Psychrophiles        b. Mesophiles    

c. Thermophiles        d. Extremophiles (at either the psychrophilic or thermophilic end)

 

6- Acid-fast organisms such as Mycobacterium tuberculosis resist decolorization by an acid-alcohol wash because of the high concentration of _____ in their cell walls.

a. proteins       b. carbohydrates        c. lipids         d. peptidoglycan

 

7- When smears of microorganisms are stained the smear is heat fixed in order to:

a. kill the organism         b. attach the organism firmly to the slide

c. both a and b                d. neither a or b

 

8- The lipopolysaccharide (LPS) that is found in the other membrane of                gram-negative bacteria is also known as:

a. exotoxin        b. teichoic acid        c. murein        d. endotoxin

 

9- Chemotaxis implies that bacteria:

a. move towards an attractant      b. move away from a repellent     

c. both a and b                           d. neither a nor b

 

10- The term used to describe bacteria that are shaped like curved rods is:

a. coccus      b. bacillus      c vibrio      d. coccobacillus

 

11- Bacteria are called _______ if they can metabolise only methane, methanol, carbon monoxide, formic acid and a few related one-carbon molecules.

a. methylotrophs      b. carbotrophs       c. monotrophic       d. autotrophic

 

12- Mannitol salt agar (MSA) only allows the growth of halophiles. Among the halophiles, mannitol fermenters release acid that turns the pH indicator yellow; mannitol nonfermenters leave the medium red. Onto MSA you inoculate a halophilic mannitol fermenter and a nonhalophilic mannitol nonfermenter. Here the medium acts as a _____ medium.

a. selective      b. differential       c. both a and b       d. neither a nor b

 

13- Organisms that do not require oxygen for growth but grow better in its presence are called:

a. facultative anaerobes       b. microaerophiles        c. aerotolerant       d. anoxygenic

 

14- Organisms that are damaged by the normal atmospheric levels of oxygen (20%) but require oxygen at levels of 2-10% for growth are called:

a. facultative anaerobes       b. microaerophiles       c. aerotolerant       d. anoxygenic

 

15- If you formed antibodies against O antigen of certain bacterial strains, where would the antibody be found to bind to the bacterial cell?

a. nucleoid       b. ribosome       c. capsule       d. outer membrane of cell wall

 

16- Which of the following components of various pathogenic microbes does not play a role in the attachment of pathogens to surfaces of the body?

a. fimbrae      b. flagella       c. capsule       d. glycocalax       e. spike

 

+ نوشته شده در  چهارشنبه 11 شهریور1388ساعت 1:51  توسط رضائیان - شاه ایلی  | 

 

1-  کدام  يک  از اصطلاحات زير به رابطه  تعاملي  بين  قارچ  و جلبک  در يک  گلسنگ  اطلاق  مي شود؟

 الف- انگلي      ب- همزيستي   (Symbiosis)     ج- Endosymbiosis     د-  Endoparasitism

  

2-    کدام  يک  از موجودات  زير فاقد اسيد نوکلئيک  است ؟

الف- باکتري ها     ب- ويروسها      ج- ويروئيدها     د- پريونها

 

3- کدام  يک  از گزينه هاي  زير جزء آغازيان  نيست ؟

الف- باکتريها     ب- جلبک      ج- تک ياخته      د- قارچها

 

4- کدام  يک  از موجودات  زير به  طور همزمان  داراي  DNA  و  RNA  است ؟

الف- باکتريها     ب- ويروسها     ج- ويروئيدها      د- پريونها

 

5- يک  مرد 65 ساله  دچار دمانس  مي شود، بيماري  وي  ظرف  چندين  ماه  پيشرفت  مي کند و با  بي تعادلي  (آتاکسي ) و خواب آلودگي  همزاه  مي گردد. در نوار مغز، امواج  کندي  با ولتاژ بالا ديده   مي شوند که  به  نفع  بيماري  کروتز فلدژاکوب  مي باشد. اين  بيماري  توسط  کدام  يک  از عوامل   زير ايجاد مي شود؟

 الف- باکتري       ب- ويروس       ج- ويروئيد      د-  پريون

 

 

+ نوشته شده در  چهارشنبه 4 شهریور1388ساعت 1:22  توسط رضائیان - شاه ایلی  | 

 

1. Biochemical synthesis of new cell material is called ……..

A. Metabolism           B. Anabolism           C. Catabolism           D. Synthatabolism

 

 2. Chemoorganotrophs use which of the following as an energy source?

A. Organic compounds                                   B. Inorganic compounds         

C. Both organic and inorganic compounds        D. Light

 

 3. A fastidious organism is ……..

A. oxygen sensitive                  B. temperature sensitive      

C. nutritionally demanding        D. atmospheric pressure sensitive

 

4. In an electron carrier system, the net energy change is determined by the difference in reduction potentials between the

A. primary electron donor and the terminal electron donor.

B. primary electron acceptor and the terminal electron acceptor.

C. primary electron acceptor and the terminal electron donor.

D. primary electron donor and the terminal electron acceptor.

 

5. The Embden-Meyerhof Pathway is another name for ………

A. the citric acid cycle        B. glycolysis       C. electron transport        D. NADH production

 

6. In glycolysis …….

A. the crucial product is ATP; the fermentation products are waste products.

B. the crucial product is ethanol or lactate; ATP is a waste product.

C. the crucial product is CO2; ATP is a waste product.

D. the crucial product is not relevant because glycolysis is not a major pathway.

 

7. The chemical substance that enters the citric acid cycle for further metabolism is ……..

A. ethyl alcohol          B. acetyl-CoA          C. adenosine triphosphate          D. pyruvic acid

 

8. Which of the following occurs in the absence of oxygen?

A. Fermentation                             B. Anaerobic respiration         

C. Anoxygenic photosynthesis          D. All of the above.

 

9. Most chemolithotrophs are ……..

A. phototrophs          B. autotrophs           C. heterotrophs          D. organotrophs

 

10. For a carbon source, chemoorganotrophs generally use such compounds as ……..

A. glucose           B. carbon dioxide          C. triglycerides           D. sunlight

 

11. For each molecule of pyruvate that enters the citric acid cycle, how many molecules of CO2 are generated?

A. 1          B. 2          C. 3           D. 6

 

12. Whether an organism is classified as a photoheterotroph or a photoautoroph depends on its …….

A. energy source.                    B. carbon source.         

C. oxygen requirements.          D. All of the above.

 

13. How many ATP result from the transfer of electrons from NADH to O2 through the electron transport chain?

A. 1          B. 2          C. 3          D. 6

 

14. Which statement is true?

A. The cytochromes contain iron; chlorophyll contains magnesium.

B. The cytochromes contain magnesium; chlorophyll contains iron.

C. Both the cytochromes and chlorophyl contain iron but not magnesium.

D. Both the cytochromes and chlorophyl contain magnesium but not iron.

 

15. The Calvin cycle …..

A. is responsible for the fixation of CO2.                                           B. utilizes only ATP.

C. requires phosphofructokinase and pyruvate decarboxylase             D. all of the above

 

16. Compounds produced by cyanobacteria that are responsible for the earthy odors in water supplies contaminated by these organisms are called

A. geobacteria          B. gleothece          C. Geosmins         D. geodecans

 

+ نوشته شده در  دوشنبه 2 شهریور1388ساعت 5:37  توسط رضائیان - شاه ایلی  | 

 

1- Who first described microorganisms such as bacteria?

a. Louis Pasteur          b. Robert Koch        c. Fannie Hesse        d. Anton von Leeuwenhoek

 

2- Who first developed the process of colony purification on solid media?

a. Louis Pasteur         b. Robert Koch          c. Fannie Hesse         d. Anton von Leeuwenhoek

 

3- What was the first successful solid medium for colony purification of bacteria?

a. Agar          b. Potato          c. Gelatin         d. Meat

 

4- Who first suggested using the thickening agent most commonly used for colony purification today?

a. a glass barrier prevented contamination.

b. heating media prevented microbial growth.

c. fresh air could directly contact the medium.

d. the experimenter could look for contamination without disturbing the experiment.

 

5- Credit for the first vaccine for the prevention of human disease is generally given to:

a. Edward Jenner for the prevention of small pox

b. Louis Pasteur for the prevention of rabies

c. Louis Pasteur for the prevention of anthrax

d. Robert Koch for the prevention of tuberculosis

 

6- To make a vaccine against chicken cholera that would not kill the chicken, Pasteur

a. treated the sample with heat to kill the microorganisms

b. attenuated the strain by repeatedly passaging it in culture

c. used a related but different microorganism from animals

d. used very small, non-lethal amounts of material

 

7- When Louis Pasteur first tried his vaccine on a young boy, there was a possibility that the vaccine itself could kill the child. This was permissible under the standards of the day because

a. the importance of the Science was worth the risk

b. less value was placed on human life than today

c. the child was from a poor family

d. the child had rabies, which was always fatal

 

8- Agostino Bassi first showed that a disease, in silkworms, was caused by microorganism. What kind of microorganism caused the disease:

a. Virus          b. Bacterium          c. Fungus          d. Protozoan

 

9- What was the first bacterium shown to cause human disease?

a. Anthrax          b. Mycobacterium          c. Diphtheria           d. d. Streptococcus

 

10- What was the first virus shown to cause disease?

a. Polio          b. Hepatitis           c. Tobacco mosaic virus         d. Potato blight

 

11- The primary use of Koch's postulates is to

a. clearly identify and characterize a particular microorganism           

b. isolate microorganisms from diseased animals

c. demonstrate that a disease is caused by a microorganism          

d. develop vaccines for specific diseases

 

12- Which of the following is NOT part of Koch's postulates?

a. the microorganism is never found in healthy animals                 

b. the microorganisms is always found in diseased animals

c. the microorganism must cause disease in healthy animals          

d. the microorganism must secrete a toxin in culture

 

 13- The role of antibodies in fighting disease was first demonstrated by:

a. vaccination of humans with rabies                              

 b. injection of rabbit "antitoxin" to protect against diphtheria.

c. attenuation of rabies by passage in atypical host           

 d. observation of phagocytosis of bacteria

 

14- The role of blood cells in fighting disease was first demonstrated by

a. Pasteur with his swan necked flasks                               

b. Koch with acid fast staining of mycobacteria

c. Metchnikoff with his observation of phagocytosis       

d. Chamberland with his filtration of virus through porcelain

 

15- The first observation that bacteria-like organisms could be found in normal air was by

a. Anton Leeuwenhoek          b. Louis Pasteur           c. Robert Koch          d. Joseph Meister

 

16- The first physician to make practical application of the germ theory of disease to surgery was

a. Louis Pasteur          b. Robert Koch          c. Joseph Lister          d. Edward Jenner

 

17- Louis Pasteur's studies on the unwanted production of acid from beet sugar was the first demonstration that

a. sugars are unstable and can breakdown into either ethanol or acid

b. bacteria can cause specific chemical reactions

c. ethanol is unstable and can convert to acid

d. microorganisms can be found in air

 

18- Which of the following discoveries is NOT attributed to Sergei Winogradsky?

a. Colony isolation on solid phase medium                           

b. Colony enrichment on selective medium

c. Bacteria oxidation of iron and sulfur to obtain energy             

d. CO2 fixation by non-photosynthetic microorganisms

 

+ نوشته شده در  یکشنبه 1 شهریور1388ساعت 5:34  توسط رضائیان - شاه ایلی  |