Writing NBDE Part 1 in March or April 2010

[Truth seeker]

Final days of preparation . Anybody who has scheduled to take the exam in a few weeks from now by end of March or April, please come together and discuss questions and clear as many doubts as possible . This thread is to motivate and share experience and elaborate on those aspects of part 1 that are tricky .

A request to people who are looking for study partners , kindly do not post in this thread, else this thread will again end up there .

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[Truth seeker]

Q1 . Reactions that have unfavorable energetics (i.e +free energy) in metabolic pathways may be driven to completion by which of the following processes ?
-coupling
-allosterism
-modification
-microscopic reversibility

Q2. The discharge of impulses in small motor (fusimotor) neurons innervating muscle spindles serves to
- inhibit extrafusal muscle contraction
- sustain extrafusal muscle contraction
- protect muscle from excessive strain
- inhibit discharge of impulses in large motor fibers
- inhibit discharge of impulses in small motor fibers

Q3. infusion of hypertonic NaCl solution will
- increase extracellular osmolarity only
- decrease intracellular osmolarity only
- decrease extracellular volume and increase extracellular volume
- increase both intracellular and extracellular volumes
- decrease both intracellular and extracellular volumes

Q4. Reflex after-discharge can be explained in terms of
- ant. horn cells
- afferent nerve fibers
- neuromuscular junction
- internuncial pool circuit
- none of the above

Q5.Iron-porphyrin protein structures are components of
- myoglobin
- b vitamin
- hemoglobin
- cytochromes
- pyridine dinucleotides

Q6. Upon complete hydrogenation , oleic , linoleic and linolenic acids yield
- stearic acid
- myristic acid
- palmitoleic acid
- arachidonic acid
- multiple acetate fragements

Q7. If two vessels are connected in parallel, their total resistance to blood flow is
- the sum of their individual resistances
- the average of their individual resistances
- greater than if they were connected in series
- equal to the resistance of smaller vessel
- less than the resistance of either vessel

Please explain the concepts related to these questions with answers. any help is greatly appreciated .

 

[wadent]

Q1 . Reactions that have unfavorable energetics (i.e +free energy) in metabolic pathways may be driven to completion by which of the following processes ?
-coupling
-allosterism
-modification
-microscopic reversibility

Q2. The discharge of impulses in small motor (fusimotor) neurons innervating muscle spindles serves to
- inhibit extrafusal muscle contraction
- sustain extrafusal muscle contraction
- protect muscle from excessive strain
- inhibit discharge of impulses in large motor fibers
- inhibit discharge of impulses in small motor fibers

Q3. infusion of hypertonic NaCl solution will
- increase extracellular osmolarity only
- decrease intracellular osmolarity only
- decrease extracellular volume and increase extracellular volume
- increase both intracellular and extracellular volumes
- decrease both intracellular and extracellular volumes

Q4. Reflex after-discharge can be explained in terms of
- ant. horn cells
- afferent nerve fibers
- neuromuscular junction
- internuncial pool circuit............answer
- none of the above

Q5.Iron-porphyrin protein structures are components of
- myoglobin
- b vitamin
- hemoglobin
- cytochromes.........................answer
- pyridine dinucleotides

Q6. Upon complete hydrogenation , oleic , linoleic and linolenic acids yield
- stearic acid
- myristic acid
- palmitoleic acid.................answer
- arachidonic acid
- multiple acetate fragements

Q7. If two vessels are connected in parallel, their total resistance to blood flow is
- the sum of their individual resistances
- the average of their individual resistances
- greater than if they were connected in series
- equal to the resistance of smaller vessel............answer
- less than the resistance of either vessel

Please explain the concepts related to these questions with answers. any help is greatly appreciated .

hey pls correct if iam wrong,,havent started bio/physio studies yet ,,but thats what i can find as logocal answers !! pls correct if iam wrong

 

[terminal]

hey pls correct if iam wrong,,havent started bio/physio studies yet ,,but thats what i can find as logocal answers !! pls correct if iam wrong

Q7. If two vessels are connected in parallel, their total resistance to blood flow is
- the sum of their individual resistances
- the average of their individual resistances
- greater than if they were connected in series
- equal to the resistance of smaller vessel
- less than the resistance of either vessel............answer

in parallel flow total resistance is sum of reciprocals...thus indiviual resistances are less than total resistance.

 

[terminal]

hey wadent can u explain internuncial pool circuit..

 

[terminal]

Upon complete hydrogenation , oleic , linoleic and linolenic acids yield
- stearic acid.................answer
- myristic acid
- palmitoleic acid
- arachidonic acid
- multiple acetate fragements

 

[drdds2009]

Q7. If two vessels are connected in parallel, their total resistance to blood flow is
- the sum of their individual resistances
- the average of their individual resistances
- greater than if they were connected in series
- equal to the resistance of smaller vessel
- less than the resistance of either vessel............answer

in parallel flow total resistance is sum of reciprocals...thus indiviual resistances are less than total resistance.

http://www.cvphysiology.com/Hemodynamics/H005.htm

 

[Truth seeker]

thanks for taking time to reply and please do share more thoughts on the concepts asked in other questions .
wadent , drdds2009 (thank you for the link) and terminal.... thanks you all !
lets share more questions as we get closer to our Exam.

 

[terminal]

on fracture of the condyle neck where would it still recieve its blood supply from?>

 

[Truth seeker]

on fracture of the condyle neck where would it still recieve its blood supply from?>

primary vascular supply to TMJ : superficial temporal a. br of ECA
in case thats cut off due to trauma , the other arteries in the vicinity : masseteric and deep temporal artery .
Also maxillary a. runs medial to it .

When these are affected in trauma too , then periosteal blood supply remains intact.

i guess periosteal is the answer, what are the options .
also please correct me if wrong .

 

[Truth seeker]

Q1.A 25 year old person will have which type of which pulp tissue..?
a. loose areolar
b. dense regular

Q2.Which of the following is an antimicrobial agent that primarily inactivates cellular DNA
1)Phenols
2)Chlorhexidine
3)Ethylene oxide
4)70 percent isopryl alcohol
5)Alkaline glutaraldehyde

 

[terminal]

Q1.A 25 year old person will have which type of which pulp tissue..?
a. loose areolar
b. dense regular

Q2.Which of the following is an antimicrobial agent that primarily inactivates cellular DNA
1)Phenols
2)Chlorhexidine
3)Ethylene oxide
4)70 percent isopryl alcohol
5)Alkaline glutaraldehyde

its loose areolar for first ques.....not sure about the second one..its between ethylene oxide and alk glutaraldehyde(rather both seem true as these cause alkylation of nucleic acids and proteins..)rest all just disrupt cell memb......do u have the answers?

 

[Truth seeker]

its loose areolar for first ques.....not sure about the second one..its between ethylene oxide and alk glutaraldehyde(rather both seem true as these cause alkylation of nucleic acids and proteins..)rest all just disrupt cell memb......do u have the answers?

Hey terminal,

For Q2. i thought its dense regular, in a young pulp , coz as pulp ages cells decrease in number. please correct me if am wrong anywhere

Coming to Q1. I guess glutaraldehyde is more appropriate

No i do not have answers for the same.

 

[terminal]

Hey terminal,

For Q2. i thought its dense regular, in a young pulp , coz as pulp ages cells decrease in number. please correct me if am wrong anywhere

Coming to Q1. I guess glutaraldehyde is more appropriate

No i do not have answers for the same.

hey i hve done this ques smwhr n rembr very well the ans is loose areolar.....

for reference i searched net...

Light Microscopy
Figs. 1A, 1B, and 1C show the hematoxylin-eosin staining results. Fig. 1A shows that deciduous pulp, obtained from a six-year-old child, is composed of ground substance and contains many cell types. Fibroblasts, blood cells, and aggregates of sizeable mononuclear cells are scattered within this mesenchymal-like stroma. Furthermore, aggregates of mononuclear cells tend to form cylinder-like structures, often delimiting a lumen (arrows). However, in a 26-year-old patient (Fig. 1B), sizeable cell aggregates have disappeared from the dental pulp, and the dental pulp shows an increase in the number of differentiated cells, such as spindle-shaped fibroblasts and fibrocytes. The fibrils and extracellular matrix are arranged to form a loose connective tissue. Fig. 1C shows a tooth slice from a 60-year-old patient in which the cell population, greatly decreased, appears to be exclusively composed of fibrocytes spread within the compact connective tissue.

hope this helps.

 

[Truth seeker]

Hey terminal,
thanks for the clarification.

From what i knew , as pulp ages, cells decrease and fibers increase , and the size of pulp chamber decreases too , so keeping all of these in mind ,
young pulp = less dense = loose areolar
older pulp = more dense = dense conn. tissue ?

i hope am in the right direction !

Also lets keep the discussion going and questions coming .

 

[terminal]

yes you are right on ur explanation...
though it gets dense with age but never regular!
regular stand basically for ligaments and tendons...
hope this clarifies...

 

[Truth seeker]

yes you are right on ur explanation...
though it gets dense with age but never regular!
regular stand basically for ligaments and tendons...
hope this clarifies...

tons of thanks to you .
When is ur exam , i just thought , how about posting a few q's each day and discussing them ?
I have already started freaking out , i have roughly 3 weeks or so !

 

[Truth seeker]

Q. Thymic hypoplasia may result in an absence of plasma cells .

can somebody please explain how this is possible ?

 

[Truth seeker]

1.What is opsonic index ?
2.What is Bordet-Gengou phenomenon ?

Somebody pls help with these terms

 

[terminal]

sorry i too was confused on these....
CAN SMONE EXPLAIN THIS QUES..
Pieces off dog parotid gland and of pancreas are tranplanted under the skin of the donor animal.After re establishment of circulation ,ingestion of food wil result secretion from-
a both parotid n pancreatic transplant
b fragment of parotid only
c fragment of pancreas only
d neither fragment ..

asda says its only PANCREAS but how????couldnt get this one

 

[terminal]

1.What is opsonic index ?
2.What is Bordet-Gengou phenomenon ?

Somebody pls help with these terms

this is what i found on net

Bordet-gengou phenomenon
The phenomenon of complement fixation; when alexin (complement)-containing serum is added to a mixture of bacteria and specific antibody, the alexin is removed (fixed) and is not available to lyse subsequently added erythrocytes sensitised with specific antibody.



opsonic index a measure of opsonic activity determined by the ratio of the number of microorganisms phagocytized by normal leukocytes in the presence of serum from an individual infected by the microorganism, to the number phagocytized in serum from a normal individual.

 

[lotexigeus]

sorry i too was confused on these....
CAN SMONE EXPLAIN THIS QUES..
Pieces off dog parotid gland and of pancreas are tranplanted under the skin of the donor animal.After re establishment of circulation ,ingestion of food wil result secretion from-
a both parotid n pancreatic transplant
b fragment of parotid only
c fragment of pancreas only
d neither fragment ..

asda says its only PANCREAS but how????couldnt get this one

I remember this question, no clue how to explain it though.

 

[wadent]

upon complete hydrogenation , oleic , linoleic and linolenic acids yield
- stearic acid.................answer
- myristic acid
- palmitoleic acid
- arachidonic acid
- multiple acetate fragements

hey terminal can u pls explain why stearic acid is the answer pls !!!!!!!

 

[Truth seeker]

sorry i too was confused on these....
CAN SMONE EXPLAIN THIS QUES..
Pieces off dog parotid gland and of pancreas are tranplanted under the skin of the donor animal.After re establishment of circulation ,ingestion of food wil result secretion from-
a both parotid n pancreatic transplant
b fragment of parotid only
c fragment of pancreas only
d neither fragment ..

asda says its only PANCREAS but how????couldnt get this one

it is Pancreas indeed 'coz parotid is under neural stimulation , but in pancreas , the graft piece would be viable by just gaining vascularization and then secretin and CCK act locally due to presence of chyme upon ingestion of food,to bring about pancreatic secretion . Please correct me if am wrong somewhere .

 

[Truth seeker]

this is what i found on net

Bordet-gengou phenomenon
The phenomenon of complement fixation; when alexin (complement)-containing serum is added to a mixture of bacteria and specific antibody, the alexin is removed (fixed) and is not available to lyse subsequently added erythrocytes sensitised with specific antibody.



opsonic index a measure of opsonic activity determined by the ratio of the number of microorganisms phagocytized by normal leukocytes in the presence of serum from an individual infected by the microorganism, to the number phagocytized in serum from a normal individual.

Thanks terminal . I still cannot follow the Bordet-Gengou phenomenon, can you pls explain in simpler terms......?

 

[anniestar]

hey truthseeker,
good one on parotid pancreas question.i liked the reasoning.keep going.

 

[dr.internationa]

good job truthseeker..

 

[Truth seeker]

my pleasure guys ! lets keep discussing and motivating each other to keep the spirit of studying ON!!!!!!!

 

[terminal]

this is what i found on net

Bordet-gengou phenomenon
The phenomenon of complement fixation; when alexin (complement)-containing serum is added to a mixture of bacteria and specific antibody, the alexin is removed (fixed) and is not available to lyse subsequently added erythrocytes sensitised with specific antibody.



opsonic index a measure of opsonic activity determined by the ratio of the number of microorganisms phagocytized by normal leukocytes in the presence of serum from an individual infected by the microorganism, to the number phagocytized in serum from a normal individual.

hey truth seeker this means that as the complement is bound to bacteria it is not free to break up or lyse erythrocytes....so there is no change,,,,
hope this clears...

 

[terminal]

hey terminal can u pls explain why stearic acid is the answer pls !!!!!!!

oleic , linoleic and linolenic acids are 18C unsaturated fatty acids on hydrogenation they yeild 18C saturated fatty acid and i.e. stearic acid!

 

[terminal]

it is Pancreas indeed 'coz parotid is under neural stimulation , but in pancreas , the graft piece would be viable by just gaining vascularization and then secretin and CCK act locally due to presence of chyme upon ingestion of food,to bring about pancreatic secretion . Please correct me if am wrong somewhere .

thanks!

 

[anniestar]

hi terminal,
this one pls
Clinical examination reveals that lingual cusp of tooth#5 is brokn off.this is most likely due to which mandibular movement??
1.left mesiotrusive
2.right mesiotrusive
3.left laterotrusive
4.right laterotrusive

the answer is A but i fail to understand.
when we talk about left mesiotrusive does it not mean that it is right laterotrusive??

pls explain

 

[wadent]

Thanks terminal (shukriat ! )

 

[terminal]

hi terminal,
this one pls
Clinical examination reveals that lingual cusp of tooth#5 is brokn off.this is most likely due to which mandibular movement??
1.left mesiotrusive
2.right mesiotrusive
3.left laterotrusive
4.right laterotrusive

the answer is A but i fail to understand.
when we talk about left mesiotrusive does it not mean that it is right laterotrusive??

pls explain

EVEN I DONT GET IT....any one please come up with an explanation!!

 

[anniestar]

in relative insulin insufficiency,acetyl co A is channelled into
1.ketone body
2.cholesterol
3.fatty acid
4.kreb cycle

answer gvn is ketone body.but if there are low levels of insulin it means high levels of glucose,then why ktone body formation????
plsexplain

 

[Truth seeker]

in relative insulin insufficiency,acetyl co A is channelled into
1.ketone body
2.cholesterol
3.fatty acid
4.kreb cycle

answer gvn is ketone body.but if there are low levels of insulin it means high levels of glucose,then why ktone body formation????
plsexplain

Hey you are thinking in the correct direction, just try to look at it this way !
Insulin insufficiency = high glucose ; and high blood glucose = Diabetes , here glucose is not available for utilization and uptake , hence fasted state of body and thus -ketogenesis - a state where ketone bodies bodies form .

 

[Truth seeker]

Any explanations for these q's pls

Q1. The discharge of impulses in small motor (fusimotor) neurons innervating muscle spindles serves to
- inhibit extrafusal muscle contraction
- sustain extrafusal muscle contraction
- protect muscle from excessive strain
- inhibit discharge of impulses in large motor fibers
- inhibit discharge of impulses in small motor fibers

Q2. infusion of hypertonic NaCl solution will
- increase extracellular osmolarity only
- decrease intracellular osmolarity only
- decrease extracellular volume and increase extracellular volume
- increase both intracellular and extracellular volumes
- decrease both intracellular and extracellular volumes

Q3.In an ideal intercuspal relation the lingual cusp of max 2nd premolar cntacts the
-distal fossa of mand 2nd premolar
-mesial marginal ridge of mand 1st molar
-distal marginal ridge of mand 2nd molar
-distal marginal ridge of mand 1st premolar

 

[Truth seeker]

hey truth seeker this means that as the complement is bound to bacteria it is not free to break up or lyse erythrocytes....so there is no change,,,,
hope this clears...

Thankyou

 

[anniestar]

hey you are thinking in the correct direction, just try to look at it this way !
Insulin insufficiency = high glucose ; and high blood glucose = diabetes , here glucose is not available for utilization and uptake , hence fasted state of body and thus -ketogenesis - a state where ketone bodies bodies form .

thanks

 

[colours99]

it is Pancreas indeed 'coz parotid is under neural stimulation , but in pancreas , the graft piece would be viable by just gaining vascularization and then secretin and CCK act locally due to presence of chyme upon ingestion of food,to bring about pancreatic secretion . Please correct me if am wrong somewhere .

Isn't the answer because pancreas is an endocrine organ and parotid is not?

 

[papu]

Q2. infusion of hypertonic NaCl solution will
- increase extracellular osmolarity only ans
- decrease intracellular osmolarity only
- decrease extracellular volume and increase extracellular volume
- increase both intracellular and extracellular volumes
- decrease both intracellular and extracellular volumes

i think there is some mistake with 3rd option
increase in extracellular volume and decrease in intracellular volume (i guess this option can be the ans)

 

[anniestar]

The epidemic of HIV-related disease bears major responsibility for the resurgence of which respiratory pathogen?

A. Streptococcus pneumoniae
B. Hemophilus infuenzae
C. Streptococcus pyogenes
D. Mycobacterium tuberculosis
E. Mycoplasma pneumoniae

hey anyone,
ay idea what is the correct answer.
thanks

 

[doit22]

The epidemic of HIV-related disease bears major responsibility for the resurgence of which respiratory pathogen?

A. Streptococcus pneumoniae
B. Hemophilus infuenzae
C. Streptococcus pyogenes
D. Mycobacterium tuberculosis
E. Mycoplasma pneumoniae

hey anyone,
ay idea what is the correct answer.
thanks

hey i thnk its myco bacterium tuberculosis...correct me if im wrong.....

 

[rose82]

Are you sure ketone bodies is the answer?I'm not sure,but I think the answer is kreb's cycle.Im saying this because of acetyl coA fate.it either enters krebs or used for fatty acid synthesis.the latter takes place if insulin is there.the former takes place without any hormones.please confirm,I may be wrong.

 

[anniestar]

i think the answer is ketone bodies,that is the answer given in ASDA papers and the hint is they r saying insulin defciency pointing out to a diseased state so we hve to think about diabetes mellitus.even i didn't understand in the beginning but now i get it coz i think with the exception of few mostly all ADA answers are right but we take time to understand.

 

[Truth seeker]

Q2. infusion of hypertonic NaCl solution will
- increase extracellular osmolarity only ans
- decrease intracellular osmolarity only
- decrease extracellular volume and increase extracellular volume
- increase both intracellular and extracellular volumes
- decrease both intracellular and extracellular volumes

i think there is some mistake with 3rd option
increase in extracellular volume and decrease in intracellular volume (i guess this option can be the ans)

sorry it was a typo , the correct option in Q was
decrease intracellular and increase extracellular . i dunno i guess am freaking out coz of exam.......getting closer, got it cleared . thankyou very much

 

[Truth seeker]

In an ideal intercuspal relation the lingual cusp of max 2nd premolar cntacts the
-distal fossa of mand 2nd premolar (ans given )
-mesial marginal ridge of mand 1st molar
-distal marginal ridge of mand 2nd molar
-distal marginal ridge of mand 1st premolar

Please help me clarify this.
Acc to book, lingual cusp of Max 2nd pm contacts DMR of Mand 2nd pm and MMR of mand 1st molar , i dunno how to go ahead with this !

 

[Truth seeker]

hey i thnk its myco bacterium tuberculosis...correct me if im wrong.....

seems like M. tuberculosis is most appropriate amongst these options

 

[papu]

sorry it was a typo , the correct option in Q was
decrease intracellular and increase extracellular . i dunno i guess am freaking out coz of exam.......getting closer, got it cleared . thankyou very much

hi truth seeker did u get the answer for this
Q1. The discharge of impulses in small motor (fusimotor) neurons innervating muscle spindles serves to
- inhibit extrafusal muscle contraction
- sustain extrafusal muscle contraction
- protect muscle from excessive strain
- inhibit discharge of impulses in large motor fibers
- inhibit discharge of impulses in small motor fibers

 

[BIGDENT]

The answer is ketone bodies. Insulin insufficiency can be due to two possibilities...Diabetes mellitus or starved state of the body. During either of these fat stored and TAG is the only sufficient source of energy past a single day, with the idea in mind that protein catabolism will just lead to death. Fatty acid lipolysis and eventual beta oxidation pass through acetyl Coa and eventually fatty pathway to ketone bodies (in liver). Krebs is not an option with insulin insuff. due do the fact that OAA which is needed for acetyl CoA to entry krebs will be depleted through gluconeogenisis. this depletion of OAA will take precedence over Krebs cycle due to the bodies drive for brain nutrition first and foremost. promoters (insulin promoting Act CoA to Malonyl CoA) and Inhibitors on pathways only apply in functional and nutritional sufficiency at all levels.