{"questions":[{"id":"mdcat-bio-enz-01","v":1,"subject":"biology","chapter":"enzymes","seed":true,"difficulty":1,"stem":"Enzymes speed up a chemical reaction by:","options":["Raising the temperature","Lowering the activation energy","Changing the equilibrium position","Supplying extra substrate"],"answer":1,"explain":{"en":"An enzyme provides another reaction pathway with a lower activation energy, so more molecules can react at body temperature. It does not change the equilibrium or the overall energy change of the reaction, and it is not used up.","ur":"انزائم ایک ایسا راستہ فراہم کرتا ہے جس میں ایکٹیویشن انرجی کم ہوتی ہے، اس لیے جسم کے درجہ حرارت پر زیادہ مالیکیول ردعمل کر پاتے ہیں۔ یہ توازن نہیں بدلتا اور خود استعمال نہیں ہوتا۔"},"source":{"kind":"parcha-original"},"status":"sample","exam":"mdcat"},{"id":"mdcat-bio-enz-02","v":1,"subject":"biology","chapter":"enzymes","difficulty":3,"stem":"A non-protein organic group that is tightly (often covalently) bound to an enzyme is called:","options":["A coenzyme","An apoenzyme","A prosthetic group","An activator"],"answer":2,"explain":{"en":"A prosthetic group (for example haem) is permanently bound to its enzyme. A coenzyme (such as NAD) binds loosely and leaves after the reaction. An apoenzyme is the protein part alone, and activators are usually metal ions.","ur":"پروستھیٹک گروپ (مثلاً ہیم) انزائم سے مستقل جڑا رہتا ہے۔ کوانزائم (جیسے NAD) ڈھیلا جڑتا ہے اور ردعمل کے بعد الگ ہو جاتا ہے۔ ایپو انزائم صرف پروٹین والا حصہ ہے۔"},"source":{"kind":"parcha-original"},"status":"sample","exam":"mdcat"},{"id":"mdcat-bio-enz-03","v":1,"subject":"biology","chapter":"enzymes","difficulty":2,"stem":"A competitive inhibitor works by:","options":["Binding to the active site","Denaturing the enzyme","Binding only to the product","Raising the optimum pH"],"answer":0,"explain":{"en":"A competitive inhibitor looks like the substrate and occupies the active site, so substrate and inhibitor compete. Adding more substrate reduces its effect. A non-competitive inhibitor binds elsewhere and changes the enzyme's shape.","ur":"مسابقتی رکاوٹ ڈالنے والا مادہ سبسٹریٹ جیسا ہوتا ہے اور ایکٹو سائٹ پر بیٹھ جاتا ہے، اس لیے دونوں میں مقابلہ ہوتا ہے۔ سبسٹریٹ بڑھانے سے اس کا اثر کم ہوتا ہے۔"},"source":{"kind":"parcha-original"},"status":"sample","exam":"mdcat"},{"id":"mdcat-bio-enz-04","v":1,"subject":"biology","chapter":"enzymes","difficulty":2,"stem":"The lock-and-key model of enzyme action was proposed by:","options":["Daniel Koshland","Louis Pasteur","Emil Fischer","Eduard Buchner"],"answer":2,"explain":{"en":"Emil Fischer proposed the lock-and-key model in 1894: the substrate fits a rigid active site exactly. Daniel Koshland later proposed the induced-fit model, in which the active site changes shape slightly as the substrate binds.","ur":"ایمل فشر نے 1894 میں لاک اینڈ کی ماڈل پیش کیا: سبسٹریٹ ایک سخت ایکٹو سائٹ میں بالکل فٹ ہوتا ہے۔ بعد میں ڈینیئل کوشلینڈ نے انڈیوسڈ فٹ ماڈل دیا جس میں ایکٹو سائٹ تھوڑی شکل بدلتی ہے۔"},"source":{"kind":"parcha-original"},"status":"sample","exam":"mdcat"},{"id":"mdcat-bio-enz-05","v":1,"subject":"biology","chapter":"enzymes","difficulty":1,"stem":"Most enzymes in the human body work best at about:","options":["25 °C","37 °C","50 °C","70 °C"],"answer":1,"explain":{"en":"Human enzymes have an optimum near normal body temperature, about 37 °C. Above the optimum, activity falls quickly as the enzyme denatures; below it, molecules move more slowly and collide less often.","ur":"انسانی انزائم جسم کے عام درجہ حرارت یعنی تقریباً 37 °C پر بہترین کام کرتے ہیں۔ اس سے زیادہ گرمی پر انزائم ڈی نیچر ہو جاتا ہے اور کم پر مالیکیول آہستہ حرکت کرتے ہیں۔"},"source":{"kind":"parcha-original"},"status":"sample","exam":"mdcat"},{"id":"mdcat-bio-enz-06","v":1,"subject":"biology","chapter":"enzymes","difficulty":2,"stem":"Pepsin, which digests protein in the stomach, has an optimum pH of about:","options":["2","7","8","11"],"answer":0,"explain":{"en":"Pepsin works in the acidic stomach (hydrochloric acid), with an optimum near pH 2. Trypsin in the small intestine works best near pH 8.","ur":"پیپسن معدے کے تیزابی ماحول (ہائیڈروکلورک ایسڈ) میں کام کرتا ہے، اس کا بہترین pH تقریباً 2 ہے۔ چھوٹی آنت کا ٹرپسن تقریباً pH 8 پر بہترین کام کرتا ہے۔"},"source":{"kind":"parcha-original"},"status":"sample","exam":"mdcat"}]}