Block 6 GI Embryo & Nitrgn Metab MCQ's
Questions and Answers
- 1.
A 2 month old baby boy presents with a swollen umbilicus that has failed to heal properly. The umbilicus drains secretions and there is passage of fecal matter through the umbilicus at times. What is the most likely diagnosis?
- A.
Gastroschisis
- B.
Anal agenesis
- C.
Ileal diverticulum
- D.
Omphalocele
- E.
Intestinal volvulus
Correct Answer
C. Ileal diverticulumExplanation
The most likely diagnosis for a 2-month-old baby boy with a swollen umbilicus that has failed to heal properly, drainage of secretions, and passage of fecal matter through the umbilicus is ileal diverticulum. Ileal diverticulum is a rare congenital abnormality where a pouch or sac forms in the wall of the small intestine. It can lead to various symptoms such as abdominal pain, obstruction, and infection. In this case, the presentation of a swollen umbilicus with drainage and fecal matter passage suggests the presence of an ileal diverticulum.Rate this question:
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- 2.
A five month old female infant presented at the pediatric unit due to yellow pigmentation of the skin which had developed on the 3rd day of life. Clinical examination showed jaundice with mild abdominal distention and hepatosplenomegaly and no ascites (fluid accumulation in abdominal cavity). The lungs and the heart were essentially normal. Stool was clay colored. Infection screen and hepatitis markers were negative. Bile salts and bile pigments were detected in the urine. What is the most likely diagnosis?
- A.
Duodenal stenosis
- B.
Pyloric stenosis
- C.
Extra hepatic biliary atresia
- D.
Neonatal hemochromatosis
- E.
Viral hepatitis
Correct Answer
C. Extra hepatic biliary atresiaExplanation
The most likely diagnosis in this case is extra hepatic biliary atresia. This is supported by the clinical findings of jaundice, hepatosplenomegaly, and clay-colored stools, which are characteristic of biliary obstruction. The absence of ascites suggests that the obstruction is extrahepatic rather than intrahepatic. Additionally, the negative infection screen and hepatitis markers make viral hepatitis less likely as a cause.Rate this question:
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- 3.
Periodontal ligaments are derived from
- A.
Ectoderm
- B.
Oral epithelium
- C.
Odontoblasts
- D.
Mesoderm
- E.
Neural crest cells
Correct Answer
E. Neural crest cellsExplanation
Periodontal ligaments are derived from neural crest cells. Neural crest cells are a group of cells that originate from the neural tube during embryonic development. These cells migrate to various regions of the body, including the developing teeth and surrounding tissues. In the case of periodontal ligaments, neural crest cells migrate to the developing tooth sockets and differentiate into the specialized cells that make up the ligaments. This process is crucial for the proper formation and function of the periodontal ligaments, which help to anchor the teeth to the surrounding bone.Rate this question:
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- 4.
Which of the following events in the development of the abdominal cavity is affected by the rapid growth of the liver?
- A.
Formation of greater omentum
- B.
Formation of lesser sac
- C.
Physiological herniation of the midgut loop
- D.
Urorectal septum formation
- E.
Formation of pancreas
Correct Answer
C. Physiological herniation of the midgut loopExplanation
The rapid growth of the liver affects the physiological herniation of the midgut loop. During development, the midgut loop normally herniates into the umbilical cord, and then returns to the abdominal cavity as it grows. The liver grows rapidly and occupies a significant portion of the abdominal cavity, which limits the space available for the midgut loop to return. This results in the physiological herniation of the midgut loop. Therefore, the rapid growth of the liver directly affects this event in the development of the abdominal cavity.Rate this question:
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- 5.
Prenatal ultrasound revealed polyhydramnios at 36 weeks, and at birth the infant had excessive fluids in its mouth and difficulty breathing. Which of the following is the most likely cause for these conditions?
- A.
Pyloric stenosis
- B.
Enterocystoma
- C.
Annular pancreas
- D.
Esophageal atresia with tracheoesophageal fistula
- E.
Meckel's diverticulum
Correct Answer
D. Esophageal atresia with tracheoesophageal fistulaExplanation
Esophageal atresia with tracheoesophageal fistula is the most likely cause for the conditions described. Esophageal atresia is a congenital condition where the esophagus does not develop properly, and tracheoesophageal fistula is an abnormal connection between the esophagus and the trachea. This can lead to excessive fluids in the mouth and difficulty breathing, as the fluids can pass from the esophagus into the trachea and lungs. Prenatal ultrasound revealing polyhydramnios further supports this diagnosis, as it is often associated with esophageal atresia.Rate this question:
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- 6.
The chorda tympani nerve, a derivative of the facial nerve, transmits taste fibers from the anterior two-thirds of the tongue to the brain. What is the best embryological reason for this anatomical pattern?
- A.
Contribution of the copula from pharyngeal arch II to the formation of the adult tongue
- B.
Contribution of the hypopharyngeal eminence from pharyngeal arch III to the formation of the adult tongue
- C.
A pretrematic branch from the nerve of pharyngeal arch II to arch I
- D.
A pretrematic branch from the nerve of pharyngeal arch III to arch II
- E.
A pretrematic branch from the nerve of pharyngeal arch IV to arch III
Correct Answer
C. A pretrematic branch from the nerve of pharyngeal arch II to arch IExplanation
The best embryological reason for the anatomical pattern of the chorda tympani nerve transmitting taste fibers from the anterior two-thirds of the tongue to the brain is the contribution of the copula from pharyngeal arch II to the formation of the adult tongue. This suggests that during embryonic development, the nerve of pharyngeal arch II sends a pretrematic branch to arch I, allowing taste fibers to be transmitted from the anterior two-thirds of the tongue to the brain through the chorda tympani nerve.Rate this question:
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- 7.
Meckel's diverticulum is a remnant of the
- A.
Ventral mesentery
- B.
Allantois
- C.
Lesser sac
- D.
Vitelline duct
- E.
Cloaca
Correct Answer
D. Vitelline ductExplanation
Meckel's diverticulum is a congenital abnormality that occurs when the vitelline duct, which connects the developing intestines to the yolk sac during fetal development, fails to fully close. This results in a small pouch or diverticulum that protrudes from the small intestine. The vitelline duct is responsible for transporting nutrients from the yolk sac to the developing embryo, but it typically degenerates and disappears by the 7th week of gestation. However, in some cases, remnants of the duct can persist, leading to the formation of Meckel's diverticulum.Rate this question:
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- 8.
Which of the following structures is derived from hindgut?
- A.
Liver
- B.
Ascending colon
- C.
Descending colon
- D.
Appendix
- E.
Cecum
Correct Answer
C. Descending colonExplanation
The descending colon is derived from the hindgut. The hindgut is the last part of the embryonic digestive tract and gives rise to the lower portion of the large intestine. The descending colon is a segment of the large intestine that extends from the transverse colon to the sigmoid colon. It is responsible for absorbing water and electrolytes from the remaining indigestible food matter, forming solid waste that will eventually be eliminated from the body.Rate this question:
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- 9.
Which of the following structures is derived from the midgut?
- A.
Liver
- B.
Descending colon
- C.
Appendix
- D.
Gallbladder
- E.
Spleen
Correct Answer
C. AppendixExplanation
The appendix is derived from the midgut. During embryonic development, the midgut gives rise to several structures including the small intestine, cecum, and appendix. The appendix is a small, finger-like pouch attached to the cecum, which is the first part of the large intestine. It is considered to be a vestigial organ with no known essential function in humans.Rate this question:
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- 10.
Appendix is derived from the
- A.
Dorsal mesentery
- B.
Ventral mesentery
- C.
Foregut
- D.
Hindgut
- E.
Midgut
Correct Answer
E. MidgutExplanation
The appendix is derived from the midgut. During embryonic development, the midgut undergoes a process called rotation, which results in the formation of the appendix as a small, finger-like extension of the cecum. The midgut is responsible for the digestion and absorption of nutrients, and the appendix is believed to have a minor role in the immune system.Rate this question:
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- 11.
Which of the following structures can be found at the free margin of falciform ligament?
- A.
Portal triad
- B.
Median umbilical ligament
- C.
Superior mesenteric artery
- D.
Round ligament of the liver
- E.
Cystic duct
Correct Answer
D. Round ligament of the liverExplanation
The falciform ligament is a ligament that attaches the liver to the anterior body wall. It is a broad and thin antero-posterior peritoneal fold, falciform (Latin "sickle-shaped"), its base being directed downward and backward and its apex upward and backward. The falciform ligament droops down from the hilum of the liver. It is a remnant of the umbilical vein of the fetus and a derivative of the embryonic ventral mesentary. It is situated in an antero-posterior plane but lies obliquely, so that one surface faces forward and is in contact with the peritoneum behind the right rectus and the diaphragm, while the other is directed backward and is in contact with the left lobe of the liver. It is attached by its left margin to the under surface of the diaphragm and the posterior surface of the sheath of the right Rectus as low down as the umbilicus; by its right margin it extends from the notch on the anterior margin of the liver, as far back as the posterior surface. It is composed of two layers of peritoneum closely united together. Its base/free edge contains between its layers the ***ROUND LIGAMENT*** and the paraumbilical veins. Becomes canalised if the individual is suffering from portal hypertension, due to the increase in venous congestion blood is pushed down from the liver towards the anterior abdominal wall and pools resulting in periumbilical bruising.Rate this question:
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- 12.
Which of the following amino acids is both essential and glucogenic?
- A.
Alanine (Ala, A)
- B.
Methionine (Met, M)
- C.
Leucine (Leu, L)
- D.
Proline (Pro, P)
- E.
Lysine (Lys, K)
Correct Answer
B. Methionine (Met, M)Explanation
Methionine is the correct answer because it is an essential amino acid, meaning that it cannot be synthesized by the body and must be obtained through diet. It is also glucogenic, which means that it can be converted into glucose through various metabolic pathways. This makes methionine a versatile amino acid that can be used for energy production in addition to its role in protein synthesis.Rate this question:
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- 13.
K.L. was born in Ville de Saguenay (Quebec), birth was uneventful. However, she failed to thrive. Suddenly at the age of 5 month her condition deteriorated rapidly and she was transferred to an emergency room. Organ function tests indicated failure of liver and kidney, attending physicians noticed a strong cabbage-like smell originating from her. The most likely diagnosis is
- A.
Hyperlysinemia
- B.
Cystinuria
- C.
Methylmalonic aciduria
- D.
Tyrosinemia I
- E.
Glycine cleavage enzyme deficiency
Correct Answer
D. Tyrosinemia IExplanation
The most likely diagnosis for K.L. based on the given information is Tyrosinemia I. This is suggested by the symptoms of liver and kidney failure, as well as the strong cabbage-like smell originating from her. Tyrosinemia I is a rare genetic disorder that affects the body's ability to break down the amino acid tyrosine. This leads to a buildup of toxic substances in the body, causing liver and kidney damage. The symptoms typically appear in infancy and can be life-threatening if not treated promptly.Rate this question:
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- 14.
The presence of phenylpyruvate and phenylketones in a child's blood are indications of the genetic disorder Phenylketonuria. How does this compound accumulate? This is a disorder of phenyalanine metabolism which results from:
- A.
Too little product formation of a metabolic pathway
- B.
Too much substrate accumulation for an enzymatic reaction
- C.
An undersupply of tyrosine for protein translation
- D.
An oversupply of homogentisic acid
- E.
Modification of blood proteins by metabolic acids
Correct Answer
B. Too much substrate accumulation for an enzymatic reactionExplanation
Phenylketonuria is a genetic disorder that affects the metabolism of phenylalanine. The correct answer states that the presence of phenylpyruvate and phenylketones in a child's blood indicates too much substrate accumulation for an enzymatic reaction. In individuals with phenylketonuria, there is a deficiency or absence of the enzyme phenylalanine hydroxylase, which is responsible for converting phenylalanine into tyrosine. As a result, phenylalanine accumulates in the body and is converted into phenylpyruvate and phenylketones. Therefore, the excessive accumulation of phenylalanine leads to the presence of these compounds in the blood, indicating the presence of phenylketonuria.Rate this question:
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- 15.
Coconut protein is biologically inferior because it is lacking many essential amino acids. In your efforts to make transgenic coconuts with protein of high biological value, you should definitely ensure that your coconut protein has an adequate amount of:
- A.
Glutamine
- B.
Arginine
- C.
Phenylalanine
- D.
Tyrosine
- E.
Serine
Correct Answer
C. PhenylalanineExplanation
Coconut protein is considered biologically inferior because it lacks many essential amino acids. Phenylalanine is one of the essential amino acids that is lacking in coconut protein. Therefore, in order to enhance the biological value of the protein in transgenic coconuts, it is important to ensure that the coconut protein has an adequate amount of phenylalanine.Rate this question:
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- 16.
High homocysteine levels are associated with an increased risk of atherosclerosis. A deficiency of which of the following enzymes would result in high blood levels of homocysteine (and also methionine)?
- A.
Tyrosine hydroxylase
- B.
Cystathionine synthase
- C.
Threonine dehydratase
- D.
Glutathione reductase
- E.
L-amino acid oxidase
Correct Answer
B. Cystathionine synthaseExplanation
Cystathionine synthase is the correct answer because it is an enzyme that is responsible for converting homocysteine to cystathionine. A deficiency of this enzyme would result in the accumulation of homocysteine in the blood, leading to high blood levels of homocysteine. This can increase the risk of atherosclerosis, a condition characterized by the buildup of plaque in the arteries, which can lead to heart disease and other cardiovascular problems.Rate this question:
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- 17.
A negative nitrogen balance is most likely in:
- A.
A heavyweight boxer training for the world championship
- B.
A fast-growing teenager who eats 3500 calories of junk food every day
- C.
A political prisoner who went on a hunger strike
- D.
A woman who is 8 months pregnant
- E.
A patient who is recovering from successful cancer surgery and chemotherapy
Correct Answer
C. A political prisoner who went on a hunger strikeExplanation
A negative nitrogen balance occurs when the body is breaking down more protein than it is synthesizing. This can happen during periods of starvation or extreme calorie restriction. In the given options, a political prisoner who went on a hunger strike is most likely to have a negative nitrogen balance because they are not consuming any food or nutrients. The other options involve individuals who may have higher calorie needs or are in a state of growth or recovery, which would not typically result in a negative nitrogen balance.Rate this question:
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- 18.
A 2-week-old infant presents with vomiting, lethargy and convulsions without evidence of an infectious process. Laboratory examination reveals hyperammonemia with alkalosis. Glutamine, citrulline and arginine are found elevated in the blood. The enzyme that is most likely deficient in this patient is:
- A.
Arginase
- B.
Carbamoyl-phosphate synthetase I
- C.
Arginosuccinate lyase
- D.
Ornithine transcarbamoylase
- E.
Arginosuccinate synthetase
Correct Answer
A. ArginaseExplanation
The presentation of vomiting, lethargy, and convulsions without evidence of an infectious process, along with laboratory findings of hyperammonemia with alkalosis and elevated levels of glutamine, citrulline, and arginine in the blood, suggests a urea cycle disorder. Among the given options, the enzyme that is deficient in this patient is most likely arginase. Arginase is responsible for the final step in the urea cycle, converting arginine to ornithine and urea. Deficiency of arginase leads to the accumulation of arginine and subsequent elevation of glutamine and citrulline.Rate this question:
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- 19.
A newborn with acute encephalopathy is found to have hypoglycemia and ketonuria. Plasma leucine, isoleucine and valine are markedly elevated, but plasma ammonia is normal. This is most likely a case of:
- A.
Ornithine transcarbamoylase deficiency
- B.
Long-chain acyl-CoA dehydrogenase deficiency
- C.
Methylmalonic acidemia
- D.
Vitamin B12 deficiency
- E.
Maple syrup urine disease
Correct Answer
E. Maple syrup urine diseaseExplanation
I Love Vermont, (isolucine, lucine, Valine) =branched chain A.A.'s maple syrup from Vermont comes from Maple trees, which have branches.Rate this question:
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- 20.
A nurse notices that the urine produced by a newborn infant has the odor of maple syrup. Which of the following pathways is most likely defective?
- A.
Metabolism of branched-chain amino acids
- B.
Metabolism of aromatic amino acids
- C.
Metabolism of sulfur-containing amino acids
- D.
Transformation of carbohydrates to amino acids
- E.
One-carbon transfer reactions
Correct Answer
A. Metabolism of branched-chain amino acidsExplanation
The correct answer is the metabolism of branched-chain amino acids. The odor of maple syrup in the urine is a characteristic symptom of a rare genetic disorder called maple syrup urine disease (MSUD). This disorder affects the metabolism of branched-chain amino acids, specifically leucine, isoleucine, and valine. In individuals with MSUD, the body is unable to break down these amino acids properly, leading to a buildup of toxic byproducts. This results in the distinctive sweet smell in the urine.Rate this question:
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- 21.
A 1-year-old child with mental retardation has a deficiency of dihydrobiopterin reductase. This enzyme deficiency leads to an increased blood level of:
- A.
Tyrosine
- B.
Methionine
- C.
Glucocerebroside
- D.
Glycine
- E.
Phenylalanine
Correct Answer
E. PhenylalanineExplanation
Hawkinsinuria, increased Cl- in urine (swimming pool urine)Rate this question:
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- 22.
A.B. is transferred into the emergency room of a local hospital. Upon investigation high levels of glutamate:oxaloacetate transaminase (GOT) and glutamate:pyruvate transaminase (GPT) are found in his serum. His problems probably involve the following organ:
- A.
Heart
- B.
Brain
- C.
Liver
- D.
Muscle
- E.
Lungs
Correct Answer
C. LiverExplanation
Based on the information provided, the high levels of glutamate:oxaloacetate transaminase (GOT) and glutamate:pyruvate transaminase (GPT) in A.B.'s serum suggest that his problems likely involve the liver. GOT and GPT are enzymes that are primarily found in the liver, and elevated levels of these enzymes in the bloodstream can indicate liver damage or dysfunction. Therefore, it can be inferred that A.B.'s organ involvement is the liver.Rate this question:
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