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GIT — Biochemistry MCQs
RMU · 152 MCQs with clinical pearls · Prof Jariya
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Sections in this rmu
- Protein Digestion — 23 MCQs
- Carbohydrate Digestion — 22 MCQs
- Carbohydrate Digestion and Absorption — 22 MCQs
- Protein Digestion and Absorption — 21 MCQs
- Gastrointestinal Secretions and Regulation — 18 MCQs
- Gastrointestinal Secretions — 18 MCQs
- Lipid Digestion — 14 MCQs
- Lipid Digestion and Absorption — 14 MCQs
Sample MCQs with clinical pearls
A lean teenager experiences excessive flatulence ,borborygmic sounds, abdominal discomfort and diarrhea after consumption of dairy products. The likely diagnosis is:
A) Adult hypolactasia ✔
B) Celiac disease
C) Fructose intolerance
D) Galactosemia
E) Lactose intolerance
ADULT HYPOLACTASIA is the normal mammalian pattern: lactase activity is high at birth and declines after weaning. It affects most adults of Asian, African and Mediterranean descent - lactase PERSISTENCE is the genetic variant, not the deficiency. Undigested lactose draws water osmotically and is fermented by colonic bacteria to hydrogen, methane and short-chain fatty acids, giving flatulence, borborygmi and diarrhoea. Diagnosis is by hydrogen breath test. MEMORY: 'Losing lactase after weaning is normal; keeping it is the mutation.'
A young man presents with diarrhea, excessive flatulence ,borborygmic sounds and abdominal discomfort after an ice cream party, The likely cause of excessive flatulence are, undigested:
A) Disaccharides ✔
B) Heteropolsaccharides
C) HomoPolysaccharides
D) Monosaccharides
E) Oligosaccharides
Symptoms appearing after a meal rich in DISACCHARIDES point to a brush border disaccharidase deficiency. Undigested disaccharide is osmotically active and is fermented by colonic bacteria, producing gas and short-chain fatty acids - hence flatulence, borborygmi and osmotic diarrhoea. The commonest is lactase deficiency; sucrase-isomaltase deficiency gives the same picture after sucrose and starch. MEMORY: 'Undigested sugar reaching the colon always means gas and water.'
For digestion of starch enzyme is present in :
A) Gastric & deudenal secretions
B) Gastric & intestinal secretions
C) Gastric & pancreatic secretions
D) Saliva & gastric secretions
E) Saliva & pancreatic secretions ✔
Starch digestion uses alpha-amylase from TWO sources: SALIVARY amylase, which starts it in the mouth and is destroyed by gastric acid, and PANCREATIC amylase, which does most of the work in the duodenum. Both hydrolyse internal alpha-1,4 bonds. Note there is NO gastric amylase - the stomach contributes acid and pepsin, not carbohydrate digestion. MEMORY: 'Amylase comes from mouth and pancreas, never from the stomach.'
152 MCQs are arranged to the learning outcomes of this rmu.
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