Mock Test 6

Mock Test 06: Cell Biology (75 Questions)

180:00

Test Completed

PART A: General Aptitude

1. Next in series: 5, 11, 23, 47, 95, ? A) 189 B) 191 C) 195 D) 199

Ans: B. Pattern: (x * 2) + 1. 95 * 2 + 1 = 191.

2. A train running at 54 km/h crosses a 150m platform in 20 seconds. Length of the train is: A) 100m B) 150m C) 200m D) 250m

Ans: B. Speed = 54*(5/18) = 15 m/s. Distance = 15*20 = 300m. Train = 300-150 = 150m.

3. Pointing to a woman, a man says, "Her mother is the only daughter of my mother." How is the man related to the woman? A) Father B) Brother C) Uncle D) Grandfather

Ans: C. The only daughter of his mother is his sister. The woman is his sister's daughter, making him her maternal uncle.

4. Sum of ages of A and B is 40. 5 years ago, A was twice as old as B. Present age of A is: A) 15 B) 20 C) 25 D) 30

Ans: C. A+B=40. A-5 = 2(B-5). Solving gives A=25, B=15.

5. Two dice are tossed. Probability that the total score is a prime number is: A) 1/6 B) 5/12 C) 1/2 D) 7/9

Ans: B. Primes: 2,3,5,7,11. Total pairs = 15. Prob = 15/36 = 5/12.

6. In a row of 40 students, Rahul is 15th from left. His position from the right is: A) 24th B) 25th C) 26th D) 27th

Ans: C. Right Pos = (Total - Left) + 1 = (40 - 15) + 1 = 26th.

7. 12 men complete a work in 9 days. After 3 days, 6 more men join. How many days to complete remaining work? A) 3 B) 4 C) 5 D) 6

Ans: B. Total work = 108 units. Done in 3 days = 36. Rem = 72. New workforce = 18. Days = 72/18 = 4.

8. A shopkeeper gives 10% discount and still gains 20%. If marked price is Rs 400, cost price is: A) Rs 300 B) Rs 320 C) Rs 360 D) Rs 280

Ans: A. SP = 400 * 0.9 = 360. CP = 360 / 1.2 = 300.

9. Find the odd one out: 16, 25, 36, 72, 144, 196, 225. A) 36 B) 72 C) 144 D) 196

Ans: B. All others are perfect squares.

10. At what angle are the hands of a clock inclined at 20 minutes past 6? A) 70° B) 80° C) 60° D) 50°

Ans: A. Angle = |30*6 - 5.5*20| = |180 - 110| = 70°.

11. A man travels 3 km East, turns South to travel 4 km. How far is he from the start? A) 7 km B) 5 km C) 1 km D) 6 km

Ans: B. Pythagoras theorem: sqrt(3^2 + 4^2) = 5.

12. Volume of a cylinder is 1540 cubic cm. If height is 10 cm, radius of base is: A) 7 cm B) 14 cm C) 21 cm D) 10 cm

Ans: A. V = πr^2h. 1540 = (22/7)*r^2*10. r^2 = 49 => r = 7.

13. In a code, BRAIN is written as CQBJO. How is MAKER written? A) NBLFS B) NZLFS C) NBLFQ D) NBLFR

Ans: A. Each letter shifts +1. M->N, A->B, K->L, E->F, R->S.

14. Ratio of radii of two spheres is 2:3. Ratio of their surface areas is: A) 2:3 B) 4:9 C) 8:27 D) 16:81

Ans: B. Area ratio is square of radius ratio: 2^2 : 3^2 = 4:9.

15. From a pack of 52 cards, 1 card is drawn. Probability of getting a face card is: A) 1/13 B) 3/13 C) 4/13 D) 1/4

Ans: B. Face cards = 12 (J,Q,K of 4 suits). Prob = 12/52 = 3/13.

16. If 15% of x is equal to 20% of y, then x:y is: A) 3:4 B) 4:3 C) 5:4 D) 4:5

Ans: B. 15x = 20y => x/y = 20/15 = 4/3.

17. Average of 5 consecutive odd numbers is 61. What is the highest number? A) 63 B) 65 C) 67 D) 69

Ans: B. Middle number is 61. Numbers are 57, 59, 61, 63, 65.

18. A pipe fills a tank in 10h, another empties it in 15h. If both open, time to fill is: A) 25h B) 30h C) 12h D) 20h

Ans: B. Net rate = 1/10 - 1/15 = 1/30. Time = 30 hours.

19. Find simple interest on Rs 4000 at 5% p.a for 3 years. A) Rs 600 B) Rs 500 C) Rs 750 D) Rs 800

Ans: A. SI = (4000*5*3)/100 = 600.

20. What is 25% of 25% of 1000? A) 62.5 B) 6.25 C) 625 D) 0.625

Ans: A. 0.25 * 0.25 * 1000 = 0.0625 * 1000 = 62.5.

21. 30% of students failed in a class. If 140 passed, total students are: A) 200 B) 180 C) 250 D) 300

Ans: A. 70% passed. 0.7x = 140 => x = 200.

22. The least number divisible by 12, 15, and 20 is: A) 40 B) 50 C) 60 D) 120

Ans: C. LCM of 12, 15, 20 is 60.

23. In a triangle, angles are in ratio 2:3:4. The largest angle is: A) 60 B) 80 C) 100 D) 120

Ans: B. 2x+3x+4x=180 => 9x=180 => x=20. Largest = 4*20 = 80°.

24. Cost price of 20 articles = Selling price of 16 articles. Gain % is: A) 20% B) 25% C) 16% D) 30%

Ans: B. Gain = (20-16)/16 * 100 = 25%.

25. A polygon has 54 diagonals. The number of sides is: A) 10 B) 12 C) 14 D) 9

Ans: B. Diagonals = n(n-3)/2. 54*2 = n^2-3n => n^2-3n-108=0 => (n-12)(n+9)=0. n=12.

PART B: Core Cell Biology

26. Which of the following lipids is most abundant in the eukaryotic plasma membrane? A) Sphingomyelin B) Phosphatidylcholine C) Cardiolipin D) Phosphatidylinositol

Ans: B. PC is the primary structural phospholipid in most eukaryotic membranes.

27. Which motor protein drives movement toward the minus-end of microtubules? A) Kinesin B) Dynein C) Myosin D) Dynamin

Ans: B. Dyneins are minus-end directed, while most kinesins are plus-end directed.

28. The KDEL sequence at the C-terminus of a protein ensures it is retained in the: A) Nucleus B) Lysosome C) Endoplasmic Reticulum D) Golgi

Ans: C. KDEL is the ER retrieval sequence.

29. The main functional units of gap junctions are called: A) Cadherins B) Connexons C) Claudins D) Integrins

Ans: B. Gap junctions consist of connexons, which are formed by connexin hexamers.

30. Which phase of the cell cycle is characterized by DNA replication? A) G1 B) G2 C) S phase D) M phase

Ans: C. Synthesis (S) phase is when the genome is duplicated.

31. What is the role of the nucleolus? A) Lipid synthesis B) Ribosome subunit assembly C) ATP production D) Protein degradation

Ans: B. rRNA transcription and ribosome subunit assembly occur here.

32. COPII-coated vesicles transport cargo from the: A) Golgi to ER B) Plasma membrane to Endosome C) ER to Golgi D) TGN to Lysosome

Ans: C. COPII is for anterograde ER-to-Golgi transport.

33. Which of the following relies on a proton (H+) gradient to maintain a highly acidic interior (pH ~5.0)? A) Peroxisome B) Nucleus C) Mitochondria matrix D) Lysosome

Ans: D. V-type ATPases pump protons into the lysosome.

34. A G-protein coupled receptor (GPCR) typically has how many transmembrane alpha-helices? A) 1 B) 5 C) 7 D) 12

Ans: C. GPCRs are strictly 7-transmembrane (7TM) receptors.

35. Which organelle is responsible for the beta-oxidation of very long-chain fatty acids (VLCFAs)? A) Mitochondria B) Smooth ER C) Peroxisome D) Lysosome

Ans: C. VLCFAs are too long for mitochondria and are initially broken down in peroxisomes.

36. The major protein constituent of microfilaments is: A) Tubulin B) Actin C) Keratin D) Myosin

Ans: B. Microfilaments are composed of polymerized G-actin monomers.

37. Mannose-6-phosphate is a targeting signal for enzymes destined for the: A) Nucleus B) Lysosome C) Mitochondria D) Chloroplast

Ans: B. M6P tags target hydrolytic enzymes to the lysosome.

38. In which cell cycle phase does the mitotic spindle begin to assemble? A) Interphase B) Prophase C) Metaphase D) Anaphase

Ans: B. Centrosomes separate and spindle fibers form during prophase.

39. Which enzyme cleaves PIP2 into the second messengers IP3 and DAG? A) Adenylyl cyclase B) Phospholipase C C) Protein Kinase A D) Phosphoinositide 3-kinase (PI3K)

Ans: B. Phospholipase C (PLC) generates IP3 and DAG.

40. Caspases, the executioners of apoptosis, are essentially: A) Serine proteases B) Cysteine proteases C) Tyrosine kinases D) Phosphatases

Ans: B. Caspases are Cysteine-dependent Aspartate-directed Proteases.

41. The inner mitochondrial membrane is highly impermeable due to the presence of: A) Cholesterol B) Cardiolipin C) Porins D) Sphingomyelin

Ans: B. Cardiolipin tightens the membrane to prevent proton leakage.

42. Fibronectin and laminin are major components of the: A) Cytoskeleton B) Extracellular matrix (ECM) C) Nuclear lamina D) Plasma membrane

Ans: B. These are key adhesive glycoproteins in the ECM.

43. Maturation Promoting Factor (MPF) is a complex of: A) Cyclin E and Cdk2 B) Cyclin B and Cdk1 C) Cyclin D and Cdk4 D) Cyclin A and Cdk2

Ans: B. MPF drives the cell into mitosis.

44. Desmosomes link to which cytoskeletal element? A) Microtubules B) Actin filaments C) Intermediate filaments D) Myosin

Ans: C. Desmosomes connect to intermediate filaments (like keratin).

45. Which vesicle coat protein is involved in endocytosis at the plasma membrane? A) COPI B) COPII C) Clathrin D) Retromer

Ans: C. Clathrin, along with AP-2, mediates endocytosis.

46. The nucleolus disappears during which phase of mitosis? A) Prophase B) Metaphase C) Anaphase D) Telophase

Ans: A. The nucleolus breaks down in prophase and reforms in telophase.

47. Which organelle modifies, sorts, and packages proteins for secretion? A) ER B) Golgi apparatus C) Endosome D) Ribosome

Ans: B. The Golgi is the sorting and packaging center.

48. Signal peptides targeting proteins to the ER are typically located at the: A) N-terminus B) C-terminus C) Middle of the protein D) Only on RNA

Ans: A. The ER signal sequence is usually a hydrophobic stretch at the N-terminus.

49. Receptor Tyrosine Kinases (RTKs) generally require what event for activation? A) Cleavage B) Binding to G-proteins C) Dimerization D) Internalization

Ans: C. Ligand binding induces receptor dimerization and trans-autophosphorylation.

50. A hallmark of apoptosis on an agarose gel is: A) A single high MW DNA band B) A DNA ladder of ~200bp increments C) Complete RNA smear D) No DNA

Ans: B. Caspase-activated DNase (CAD) cleaves DNA between nucleosomes, creating a ladder.

PART C: Advanced / Analytical Cell Biology

51. In a FRAP experiment on a GFP-tagged membrane receptor, the fluorescence fails to recover fully, plateauing at 60%. This indicates that: A) 60% of the receptors are immobile B) 40% of the receptors are tethered/immobile C) The fluorophore has a short half-life D) The membrane is purely fluid

Ans: B. The recovery extent (mobile fraction) is 60%, meaning 40% cannot diffuse (e.g., tethered to the cytoskeleton).

52. Cholera toxin locks the Gs alpha subunit in its active state by: A) Phosphorylating it B) Cleaving it C) ADP-ribosylation, inhibiting GTP hydrolysis D) Promoting GDP binding

Ans: C. ADP-ribosylation of an Arginine residue in Gs-alpha destroys its intrinsic GTPase activity.

53. Zellweger syndrome, which causes death in infancy, is caused by mutations in PEX genes leading to: A) Empty peroxisomes due to import failure B) Lysosomal rupture C) Defective mitochondrial electron transport D) Failure of ER-to-Golgi transport

Ans: A. PEX mutations disrupt the import of peroxisomal matrix proteins, leaving peroxisomes as empty "ghosts".

54. During vesicular fusion, the SNARE complex must be unraveled for recycling. This is driven by: A) Dynamin and GTP B) NSF and alpha-SNAP using ATP C) Clathrin ATPase D) Rab-GEF

Ans: B. The AAA-ATPase NSF uses ATP hydrolysis to untangle the highly stable 4-helix SNARE bundles.

55. A cell with a mutant Wee1 kinase will likely exhibit which phenotype? A) Arrest in G2 B) Arrest in M phase C) Smaller cell size due to premature entry into mitosis D) Giant cells that cannot divide

Ans: C. Wee1 puts inhibitory phosphates on M-Cdk. Without Wee1, cells divide before growing adequately, becoming "wee" (small).

56. In the DNA damage response, ATM kinase phosphorylates p53, stabilizing it by preventing its interaction with: A) p21 B) Rb C) MDM2 D) E2F

Ans: C. MDM2 is an E3 ubiquitin ligase that normally degrades p53. Phosphorylation of p53 blocks MDM2 binding.

57. The APC/C triggers anaphase by ubiquitinating: A) Separase B) Securin C) Cohesin D) Condensin

Ans: B. APC/C degrades Securin, which frees Separase to cleave the Cohesin rings holding chromatids together.

58. The oncogenic Ras G12V mutation causes cancer because the Ras protein: A) Cannot bind GTP B) Cannot hydrolyze GTP, remaining permanently active C) Stays locked to the receptor D) Directly phosphorylates MEK

Ans: B. The G12V mutation destroys intrinsic GTPase activity, locking Ras in the "on" state.

59. In the Wnt pathway, beta-catenin is marked for degradation by the destruction complex. Which kinases phosphorylate beta-catenin in this complex? A) PKA and PKC B) GSK-3 and CK1 C) MEK and ERK D) PI3K and Akt

Ans: B. Casein Kinase 1 (CK1) and Glycogen Synthase Kinase-3 (GSK-3) sequentially phosphorylate beta-catenin.

60. Notch signaling is highly direct. Upon ligand binding, the Notch receptor is cleaved by: A) Gamma-secretase B) Caspase-3 C) MMPs D) Calpain

Ans: A. Regulated Intramembrane Proteolysis (RIP) by gamma-secretase releases the Notch Intracellular Domain (NICD).

61. Smac/DIABLO promotes apoptosis by: A) Forming pores in the mitochondria B) Binding and inhibiting IAPs (Inhibitors of Apoptosis) C) Activating Caspase-8 D) Cleaving DNA

Ans: B. Released from mitochondria, Smac neutralizes IAPs, allowing caspases to function freely.

62. During macroautophagy, which ubiquitin-like protein is lipidated to phosphatidylethanolamine to form the autophagosome? A) Beclin-1 B) LC3 (ATG8) C) ATG5 D) p62

Ans: B. LC3-I is conjugated to PE to become LC3-II, a classic marker of autophagosome membranes.

63. Dynamic instability vs Treadmilling: Which correctly pairs the polymer with its dominant behavior? A) Microtubules = Treadmilling; Actin = Dynamic instability B) Microtubules = Dynamic instability; Actin = Treadmilling C) Both treadmill equally D) Intermediate filaments = Dynamic instability

Ans: B. Microtubules switch rapidly between growth and catastrophe (dynamic instability), while actin flux maintains length (treadmilling).

64. Nocodazole and Taxol both arrest cells in mitosis, but their mechanisms are opposite. Taxol works by: A) Depolymerizing microtubules B) Stabilizing microtubules C) Inhibiting actin polymerization D) Destroying centrosomes

Ans: B. Taxol binds and stabilizes microtubules, preventing the spindle disassembly necessary for anaphase.

65. Integrin "inside-out" signaling is initiated by the binding of which intracellular protein to the integrin beta tail? A) FAK B) Talin C) Src D) Vinculin

Ans: B. Talin binds the beta tail, separating it from the alpha tail and extending the extracellular domain into an active conformation.

66. The "Warburg Effect" in cancer relies on the upregulation of a specific Pyruvate Kinase splice variant that is kept in a low-activity state. Which variant? A) PKM1 B) PKM2 C) PKL D) PKR

Ans: B. PKM2 dimerizes into a low-activity form, creating a glycolytic bottleneck that diverts intermediates for biomass synthesis.

67. I-cell disease results from extracellular secretion of lysosomal enzymes. The primary genetic defect is in: A) GlcNAc-1-phosphotransferase B) Hexosaminidase A C) AP-1 clathrin adaptor D) Mannose-6-phosphate receptor

Ans: A. This enzyme is required to form the M6P tag; without it, enzymes follow the default secretory pathway.

68. Telomerase reactivation in cancers like glioblastoma is most frequently caused by: A) Point mutations in the TERT promoter B) TERC RNA amplification C) Alternative Lengthening of Telomeres (ALT) D) Loss of Shelterin

Ans: A. TERT promoter mutations create new transcription factor binding sites, massively upregulating telomerase expression.

69. A widely used biochemical marker to detect senescent cells in tissues is: A) Cleaved caspase-3 B) SA-beta-galactosidase at pH 6.0 C) Phospho-Akt D) Ki-67

Ans: B. Expanded lysosomal compartments in senescent cells exhibit detectable beta-gal activity at a suboptimal pH of 6.0.

70. G-protein coupled receptor desensitization prevents overstimulation. Beta-arrestin binding to the phosphorylated receptor also scaffolds: A) PKA B) MAPK (ERK) cascades C) Adenylyl cyclase D) Phospholipase C

Ans: B. Beta-arrestin mediates G-protein-independent signaling by acting as a scaffold for MAP kinases.

71. Cytochrome c release from mitochondria initiates the apoptosome. Which Bcl-2 family proteins directly form the pore for its release? A) Bcl-2 and Bcl-xL B) Bax and Bak C) Bid and Bim D) Puma and Noxa

Ans: B. Bax and Bak oligomerize in the outer mitochondrial membrane to form the pore.

72. Which transport vesicle moves proteins from the Trans-Golgi Network (TGN) to the late endosome? A) COPI B) COPII C) Clathrin with AP-1 D) Clathrin with AP-2

Ans: C. AP-1 acts as the adaptor for clathrin at the TGN, while AP-2 is used for endocytosis at the plasma membrane.

73. PTEN antagonizes the PI3K/Akt pathway by acting as a: A) Lipid kinase B) Lipid phosphatase C) Protein kinase D) Protease

Ans: B. PTEN removes the phosphate from PIP3, converting it back to PIP2 and halting Akt recruitment.

74. The Signal Recognition Particle (SRP) relies on which molecule to function as a scaffold for its proteins? A) 5S rRNA B) 7SL RNA C) U1 snRNA D) snoRNA

Ans: B. The 7SL RNA molecule acts as the structural backbone for the SRP complex.

75. Extrinsic apoptosis relies on the Death-Inducing Signaling Complex (DISC). Which domain connects the Fas receptor to the FADD adaptor? A) Death Effector Domain (DED) B) CARD Domain C) Death Domain (DD) D) BIR Domain

Ans: C. The homotypic interaction between the Death Domains (DD) of Fas and FADD initiates the complex formation.