HorthooZ – Kerala GK, PSC Questions & Onam Quiz

Q1 Multiple Choice Question

In addition to the nucleolus, the interphase nucleoplasm contains various specialized non-membranous nuclear bodies; what are the primary functional roles of 'Nuclear Speckles' (interchromatin granule clusters) and 'Cajal Bodies' respectively?

A Nuclear speckles store pre-mRNA splicing factors; Cajal bodies assemble and modify small nuclear ribonucleoproteins (snRNPs) and telomerase B Nuclear speckles synthesize ATP; Cajal bodies perform cellular respiration C Nuclear speckles store calcium ions; Cajal bodies assemble mitotic spindles D Nuclear speckles digest nuclear DNA; Cajal bodies form ribosomes

Q2 Multiple Choice Question

Newly synthesized lysosomal acid hydrolase enzymes are sorted and directed from the cis-Golgi network to nascent lysosomes through the covalent addition of which specific molecular address tag?

A Terminal sialic acid residues B Mannose-6-Phosphate (M6P) tag added by cis-Golgi N-acetylglucosamine-1-phosphotransferase C Myristoyl lipid anchors D Tri-phosphate 5' nucleotide caps

Q3 Multiple Choice Question

During ribosomal elongation cycle steps, after an aminoacyl-tRNA is delivered into the A-site by Elongation Factor Tu (EF-Tu) in a GTP-dependent step, what precise conformational movement must occur before peptide bond formation?

A Immediate dissociation of the small ribosomal subunit into free RNA strands B Hydrolysis of all cellular ribosomal RNA into mononucleotides C Complete circularization of mRNA into a closed loop D Accommodation (the aminoacyl-tRNA swings into the peptidyl transferase center, aligning the amino acid ester group with the P-site peptidyl-tRNA)

Q4 Multiple Choice Question

What are the precise large and small sedimentation subunit constituents of a eukaryotic cytoplasmic 80S ribosome?

A 50S large subunit and 30S small subunit B 40S large subunit and 20S small subunit C 60S large subunit and 40S small subunit D 70S large subunit and 40S small subunit

Q5 Multiple Choice Question

Which specific eukaryotic RNA Polymerase is exclusively localized within the nucleolus to transcribe large ribosomal RNA precursor molecules (45S pre-rRNA)?

A RNA Polymerase II B RNA Polymerase III C DNA Polymerase alpha D RNA Polymerase I

Q6 Multiple Choice Question

In bacterial translation initiation, how does the 30S ribosomal small subunit accurately locate and bind to the correct translation start site on mRNA molecules?

A Recognition of a 5' 7-methylguanosine cap structure by ribosomal proteins B Spontaneous random collision until an AUG codon is hit C Base-pairing between the pyrimidine-rich Shine-Dalgarno sequence (AGGAGG) on the mRNA and the complementary purine-rich sequence at the 3' end of 16S rRNA D Direct binding to poly-A tail sequences at the extreme 3' terminus

Q7 Multiple Choice Question

The extreme resistance of lysosomal membrane proteins (LAMP-1 and LAMP-2) against proteolytic degradation by high concentrations of active luminal proteases is primarily attributed to:

A An extensive, densely packed web of O-linked and N-linked complex oligosaccharides forming a protective glycocalyx brush border B A solid crystalline outer coat composed entirely of calcium phosphate C An impenetrable outer envelope made of plant sporopollenin D A complete absence of all peptide bonds in their backbone

Q8 Multiple Choice Question

The 'Cross-Correction Phenomenon' observed in cultured fibroblast cells from mucopolysaccharidosis patients demonstrates that:

A Cells can spontaneously convert mutant DNA into wild-type DNA via reverse transcription B Ribosomes can substitute for missing lysosomal acid hydrolases C Lysosomes can fuse directly with the plasma membrane to expel all undigested waste permanently D Deficient cells can take up functional lysosomal enzymes secreted into the extracellular medium by normal cells via Mannose-6-Phosphate receptor-mediated endocytosis

Q9 Multiple Choice Question

Specifically which multi-protein electron transport chain complexes (ETS) and ATP synthase particles are embedded directly along the inner mitochondrial cristae membranes?

A Complexes I, II, III, IV and F1F0 ATP synthase (Oxysomes / Inner membrane particles) B Photosystem I and II reaction centers C Cellulose microfibril synthetase complexes D Ribosomal 30S and 50S subunits exclusively

Q10 Multiple Choice Question

When a cell selectively targets and degrades damaged, depolarized mitochondria through autophagy to maintain metabolic quality control, this specialized pathway is known as:

A Pexophagy B Mitophagy (selective autophagic degradation of damaged mitochondria via Pink1 and Parkin pathways) C Ribophagy D Reticulophagy

Q11 Multiple Choice Question

Human mitochondrial DNA (mtDNA) is a circular double-stranded molecule of 16,569 base pairs containing a non-coding control region known as the D-Loop (Displacement Loop), which serves as the primary site for:

A Proteolytic degradation of damaged nuclear chromosomes B Initiation of both heavy-strand DNA replication and bidirectional transcription promoters C Synthesis of ribosomal RNA subunits D Attachment to mitotic spindle microtubules during cell division

Q12 Multiple Choice Question

In lysosomal maturation dynamics, what is the fundamental functional difference between a 'Primary Lysosome' and a 'Secondary Lysosome'?

A Primary lysosomes bud from Golgi and contain newly synthesized inactive enzymes; Secondary lysosomes are formed by fusing with vesicles containing target materials to actively digest them B There is no structural or functional distinction C Primary lysosomes are found only in plants; Secondary only in bacteria D Primary lysosomes synthesize ATP; Secondary lysosomes synthesize DNA

Q13 Multiple Choice Question

Located inside the eukaryotic nucleus as a dense, spherical, non-membranous sub-compartment discovered by Felice Fontana, the Nucleolus functions primarily as the cell's:

A Ribosomal RNA (rRNA) synthesis and ribosome subunit assembly factory B Storage vacuole for toxic plant waste crystals C Primary site of ATP oxidative phosphorylation D Anchoring center for mitotic spindle microtubules

Q14 Multiple Choice Question

While standard eukaryotic translation initiation requires 5' cap recognition by eIF4E, some viral and cellular mRNAs initiate translation independently of the 5' cap by utilizing structured RNA elements called:

A TATA promoter boxes B Shine-Dalgarno sequences C IRES (Internal Ribosome Entry Sites) D Kozak consensus boxes

Q15 Multiple Choice Question

During mitochondrial oxidative phosphorylation, the rotary motor F1F0-ATP Synthase couples proton translocation down the electrochemical gradient from the intermembrane space into the matrix to drive the synthesis of ATP by:

A Enzymatic cleavage of mitochondrial DNA rings B Direct thermal boiling of inorganic phosphate molecules onto lipid bilayers C Direct reduction of oxygen gas into water without proton involvement D Rotational catalysis driven by proton flux through the F0 membrane-spanning rotor, inducing conformational changes in the F1 catalytic head to phosphorylate ADP into ATP

Q16 Multiple Choice Question

Discovered by George Emil Palade in 1953 using electron microscopy, which non-membranous cytoplasmic ribonucleoprotein granules are universally designated as the 'Protein Factories of the Cell'?

A Centrosomes B Peroxisomes C Ribosomes (Protein Factories) D Lysosomes

Q17 Multiple Choice Question

Because the inner mitochondrial membrane is strictly impermeable to cytosolic NADH produced during glycolysis, how do eukaryotic cells transfer reducing equivalents into the mitochondrial matrix?

A Passive diffusion of intact NADH molecules across phospholipid head groups B Direct active transport through membrane porin channels without carrier proteins C Conversion of NADH directly into carbon dioxide gas D Via intracellular shuttle systems such as the Malate-Aspartate shuttle and Glycerol-3-phosphate shuttle

Q18 Multiple Choice Question

In the functional spatial organization of the interphase nucleus, active RNA Polymerase II complexes and their associated transcription machinery are not distributed uniformly but concentrate in dynamic foci known as:

A Nuclear Envelope Lamina Pores B Transcription Factories C Nucleolar Organizer Regions D Heterochromatic Silencing Hubs

Q19 Multiple Choice Question

In eukaryotic cells, what is the primary functional difference between free ribosomes floating in the cytosol and bound ribosomes attached to the Rough Endoplasmic Reticulum (RER)?

A Free ribosomes contain 70S; bound ribosomes contain 80S exclusively B Free ribosomes synthesize cytosolic/intracellular proteins, whereas bound ribosomes synthesize membrane, lysosomal, and secretory proteins C Free ribosomes synthesize lipids; bound ribosomes synthesize carbohydrates D There is zero functional difference between the two pools

Q20 Multiple Choice Question

In contrast to macroautophagy which utilizes double-membrane vesicles, 'Chaperone-Mediated Autophagy' (CMA) selectively targets soluble cytosolic proteins containing a KFERQ-like motif for direct translocation across the lysosomal membrane via:

A Nuclear pore complex reverse transport gates B Microtubule-dependent flagellar dynein motors C LAMP-2A (Lysosomal-Associated Membrane Protein 2A) receptor complexes assisted by cytosolic Hsc70 chaperones D Endocytotic caveolae invaginations

Cell Structure & Organelles