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MDCAT 2025
Biology XII
MCQs with Answers
Practice Test 1
MDCAT BOOSTER TEST SERIES 20251. Which lipid type has no c-c linkages?
● Fats & oil ✅
o Phospholipids
o Terpenoids
o All of these
2. Carbohydrates are:
o Polyhydroxy ketones
o Polyhydroxy aldehydes
● Polyhydroxy carbonyls ✅
o Polyhydroxy esters
3. True statements regarding oligosaccharides are:
o Comparatively less sweat in taste
o Comparatively less soluble in water
o They can hydrolyze
● All of these ✅
4. Refinose is among:
o Reducing sugars
● Non-reducing sugars ✅
o Either reducing or non-reducing sugars depending on the form
o It's not a sugar
5. What are the reasons that plant non-reducing sugars as transport food from?
o More energy
o No oxidation or reacting
o No Intermediate reaction
● All of these ✅
6. Most of the sugars in our body are:
● Right handed ✅
o Left handed
o Both right and left handed sugars are in equal quantity
o our body have no sugars
7. The diabetic patients use left hand sugars which have no calories. Reason for zero calories is/are:
o No enzymes are present in our body for their digestion
o They don't fit onto the catalytic site hence no metabolism
o The don't have zero calories
● Both A & B ✅
8. The protein chain can be broken into small chain of more than 10 amino acids called:
o Polypeptide chain
● Pephone ✅
o Peptide
o B & C
o All of these
9. In a person's blood protein, an amino acid sequence is changed as that glutamic acid is replaced by valine at sixth position. What are the possible consequences of this change?
o Sickle cell anemia
o Insufficient oxygen carrying capacity
o Death
● All of the above ✅
o No any significant consequences
10. Regarding waxes, choose the correct statements:
o Considerable commercial importance
o Sperm whales are the principle source
o Water repellent & non-reactive
● All of these ✅
o None of these
11. Which one of the following structural work as a cell surface protein?
● Amyloid ✅
o Fibroin
o Fibrillin
o All of these
o None of these
12. Enzymes are defined as:
o organic molecules capable of synthesizing specific chemical reactions
o Inorganic molecules capable of synthesizing specific chemical reactions
● organic molecules capable of catalyzing Specific chemical reactions ✅
o Inorganic molecules capable of catalyzing specific chemical reactions
13. Regarding active site, what's the correct:
o It's charged place to fit the substrate
o Its shape is complementary to these substrate's shape
o Both charge & shape is formed by the site's polypeptide chain
o Both A & B
● All of these ✅
14. Detachable co-factors are:
o Metallic ions
o Inorganic co-factors
o organic co-factors
● Both A & B ✅
o Both A & C
15. Choose the correct combination:
o Pepsin + Polypeptide Chain = Pepsinogen
o Pepsinogen + HCl = Pepsin
o Pepsinogen + Polypeptide chain = Pepsin
● A & B ✅
o None of these
16. Lock & Key model, describes the characteristic of enzymes as:
o Flexible shape
o Complementary distribution of charge
o Absolute specificity
o A & C
● B & C ✅
17. Enzymes with what optimum temperature are used in biological washing powder?
o 37 °C
o 0
o 25 °C to 42 °C
● 72 °C or higher ✅
18. There's a slight change in the pH if the environment:
What would be its effect on the enzyme?
o Ionization of amino acids of enzyme
o Enzyme become inactive
● Both A & B ✅
o Not any significant effects as the change is narrow
19. Feedback inhibition is an example of:
o Competitive inhibition
● Non-competitive inhibition ✅
o Un-competitive inhibition
o None of these
20. What are the significance of enzyme inhibition?
o Major control mechanism
o Strategy for drug recovery
o Knowledge about metabolic pathway
o Screening of diseases
● All of these ✅
21. Most of the enzymatic pathways are shutdown by feedback inhibition by:
o Inactive state of active site
o End product binds at active site of pathway's first enzyme
o End product binds at active site of pathway's last enzyme
● End product binds at allosteric site of pathway's first enzyme ✅
o End product binds at allosteric site of pathway's last*enzyme
22. Allosteric activator:
o bound covalently to the enzymes
● Their interaction with enzyme is reversible ✅
o they are not influenced by thermal factors
o All of these
23. Choose the incorrect statement(s):
o All biological membranes have same chemical composition
o Biological membranes have approximately equal percentage of lipids proteins by weight
● Carbohydrates are not present in the biological membranes ✅
o A & C
o B & C
24. Regarding structure of plasma membrane, what's the correct?
o Lipid bilayer is sandwiched between two protein layers i.e. inside & outside
● Lipid molecules can rotate & vibrate within the layers of membrane ✅
o Lipid molecules are arranged like icebergs in the sea
o All of these
o None of these
25. These proteins act as channels in plasma membrane:
o Integral proteins
o Peripheral proteins
o Intrinsic proteins
● A & C ✅
26. Mitochondria:
● Constantly moving in living cells ✅
o Centers of anaerobic respiration
o Universally present in all cells
o A & C
o A & B
27. Liver & spleen enlargement due to LSD:
● Gaucher's disease ✅
o Tay-Sachs disease
o Krabbe's disease
o Cytopenia
28. Lysosome while performing their functions are called as:
o Endosomes
o Secondary lysosomes
o Primary lysosomes
● A & B ✅
o Either of these
29. Interstitial cells contains large number of:
● SER ✅
o RER
o No ER
o Both SER & RER in equal quantity
30. What are the functions of cholesterol in cell membrane?
o Regulation of cell membrane fluidity according to the varying temperatures
o Preventing the passage of H+ & N+ ions across membrane
o Synthesis of membrane lipids
● A & B ✅
o All of these
31. Part of cytoplasm near the nucleus is called:
● Cytosol ✅
o Cell sap
o Cytogel
o Both A & B
32. Regarding endoplasmic reticulum:
o Lipoprotein
o Channels
o Network throughout the cell
o B & C
● All of these ✅
33. Fungal cell wall is made up of:
o Peptidoglycan
o Pure chitin
● Modified chitin ✅
o Cellulose
34. Detection HIV viruses can be done by:
o Blood sample
o Saliva sample
o NATs
● All of these ✅
35. AIDS leads to:
o Compromised immune system o Kaposi sarcoma
o Death
● All of these ✅
36. Viruses resist from host cell immune system by:
o Degrading host cell Genome
o Deactivating the complement system
o Inactivation of MHC
● All of these ✅
37. Regarding CoVID-19 virus, what's correct?
o Enveloped
o Spherical
o Zophage
o B & C
● All of these ✅
38. Regarding viral envelope, what's not correct?
o Provided with glycoprotein spikes
● Derived from viral surface capsid ✅
o Contain virtually encoded proteins
o A & C
o B & C
39. What's not related to viruses?
o Energy generation
o Cell organelles
o Metabolism
o A & B
● All of these ✅
40. Regarding the genetic material of the virus. what's correct?
o Either DNA or RNA
o Determines virus' functionality
o Biomolecules formation
o A & B
● All of these ✅
41. Polio Viruses are
o Non-enveloped viruses
o Enveloped viruses
o More resistant to environmental stresses
● A & C ✅
o B & C
42. Inner core of viruses may contain:
o Genetic material
o Enzymes
o Proteins
o A & B
● All of these ✅
43. Shape of capsid of HIV virus is:
● Circular ✅
o Helical
o Polyhedron
o Spherical
44. Hepatitis can't be transmitted through:
o Blood
o Fecal
o Sexual activities
● All of these are the routes of transmission ✅
45. In which part of the cell does the citric acid cycle occur?
o Cytoplasm
o Nucleus
● Mitochondrial matrix ✅
o Endoplasmic reticulum
46. What is the primary role of NADH and FADH2 cellular respiration?
● To provide electrons to the electron transport chain ✅
o To directly produce ATP
o To synthesize glucose
o To convert pyruvate to lactic acid
47. Which process produces the most ATP per molecule of glucose?
o Glycolysis
o Citric acid cycle
o Fermentation
● Oxidative phosphorylation ✅
48. Which molecule is an end product of the citric acid cycle?
o Glucose
o Pyruvate
o Acetyl CoA
● Co2 ✅
49. Which molecule is generated during the breakdown of fatty acids in beta-oxidation?
o Glucose
o Pyruvate
● Acetyl-CoA ✅
o Lactic acid
50. Where does the conversion of pyruvate to acetyl-CoA occur?
o Cytoplasm
● Mitochondrial matrix ✅
o Inner mitochondrial membrane
o Endoplasmic reticulum
51. which component of the electron transport chain is responsible for pumping protons across the mitochondrial membrane.
o Ubiquinone
o Cytochrome c
o ATP synthase
● Complex I, III & IV ✅
52. What is the role of coenzyme A in cellular respiration?
o To carry out electrons to the electron transport chain
● To transfer acetyl groups into the citric acid cycle ✅
o To regenerate NAD+
o To produce ATP directly
53. Which of the following molecules serves as a major carrier of high-energy electrons?
o ATP
o NADH
o FADH2
● Both B & C ✅
o AoT
54. Which process generates ATP through chemiosmosis?
o Glycolysis
o Citric acid cycle
● Oxidative phosphorylation ✅
o Lactic acid fermentation
55. Which process occurs in the mitochondria but does not involve oxygen?
o Glycolysis
● Citric acid cycle ✅
o Electron transport chain
o None of these
56. Which of the following is incorrect regarding Large Intestine:
o It's last segment of digestive system
o Reabsorption of water & minerals
o Synthesis of vitamins
● It contains villi ✅
57. Gall bladder is stimulated by _____ which is released by _____:
o Secretin, duodenum
● Cholecystokinin, duodenum ✅
o Cholecystokinin, stomach
o Secretin, stomach
58. The three secretions meeting the food in the small intestine are:
● Bile, pancreatic juice, intestinal juice ✅
o Pancreatic juice, intestinal juice, gastric juice
o Bile, pancreatic juice, gastric juice
o Bile, gastric juice, saliva
59. All are components of pancreatic juice except:
o NaHCo3
o Amylopsin
o Chymotrypsin
● Ptyalin ✅
60. It is not correct about bile juice:
o It neutralizes, and turns acidic chyme into alkaline
o It neutralizes, and turns acidic chyme into alkaline
o It's yellowish in colour
● It contains different enzymes ✅
o Its salt are involved in emulsification of fats
61. Which enzyme acts on fats to form fatty acids and glycerol?
o Erypsin
o Maltase
o Lactase
● Lipase ✅
62. Liver performs the function of:
o Conversion of glucose into glycogen
o Deamination
o Conversion of glycogen into glucose
● All of these ✅
Prepared by: Dr. Ashfaque Jokhio Dated: 17th August 2025
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