HorthooZ – Kerala GK, PSC Questions & Onam Quiz

Q1 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

Q2 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

Q3 Multiple Choice Question

In highly active mammalian striated skeletal muscle fibers (which require massive bursts of ATP), mitochondria cluster densely beneath the sarcolemma and around contractile myofibrils; these are known respectively as:

A Cortical and Stromal mitochondria B Primary and Secondary mitochondria C Endosomal and Peroxisomal mitochondria D Subsarcolemmal and Intermyofibrillar mitochondria

Q4 Multiple Choice Question

Proteins synthesized in the cytoplasm that must be imported into the nucleus (such as histones and transcription factors) are recognized and directed across nuclear pore complexes through the presence of:

A A polyadenylated 3' RNA trailer sequence B A covalently attached myristoyl lipid tail C A hydrophobic N-terminal signal anchor peptide targeting the rough ER D A Nuclear Localization Signal (NLS) rich in positively charged basic amino acids (Lysine and Arginine)

Q5 Multiple Choice Question

Immediately underlying the inner nuclear membrane, a dense fibrillar network known as the 'Nuclear Lamina' provides mechanical stability and chromatin attachment sites; this lamina is composed primarily of:

A Type V intermediate filament proteins known as Lamins (Lamins A, B, and C) B Tubulin alpha-beta heterodimeric microtubules C Collagen and elastin extracellular matrix fibrils D Actin microfilaments and Myosin motor complexes

Q6 Multiple Choice Question

Within the eukaryotic interphase nucleus, which chromatin region is loosely packed, transcriptionally active, and stains lightly, contrasted with densely packed, transcriptionally inactive heterochromatin?

A Telomeric repeats B Heterochromatin C Euchromatin D Centromeric satellite DNA

Q7 Multiple Choice Question

During interphase, microscopy and chromosome conformation capture (Hi-C) techniques demonstrate that individual chromosomes do not intermingle randomly in the nucleoplasm but instead occupy discrete physical spaces known as:

A Heterochromatic Centromeric Plates B Nucleolar Organizer Regions C Chromosome Territories D Lamina-Associated Spheres

Q8 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

Q9 Multiple Choice Question

The control center of the eukaryotic cell containing hereditary genetic information enclosed within a double-membrane nuclear envelope was discovered in 1831 by:

A George Palade B Robert Brown C Christian de Duve D Camillo Golgi

Q10 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

Q11 Multiple Choice Question

Unlike nuclear DNA which is packaged around histones, mitochondrial circular DNA is packaged into compact nucleoid structures primarily by binding which high-mobility group protein?

A RNA Polymerase II B TFAM (Mitochondrial Transcription Factor A) C DNA Ligase IV D Topoisomerase I

Q12 Multiple Choice Question

At the conclusion of mitosis (telophase), the de-phosphorylation of nuclear lamins and nuclear envelope membrane proteins by specific phosphatases triggers:

A The immediate fusion of mitochondria with the plasma membrane B The complete cessation of all cellular transcription permanently C The permanent destruction of all genomic DNA strands D The structural reassembly of the nuclear envelope and reformation of the nuclear lamina around separated daughter chromosome sets

Q13 Multiple Choice Question

Which double-membrane-bound cell organelle is universally known as the 'Powerhouse of the Cell' because it generates chemical energy in the form of ATP via aerobic cellular respiration?

A Ribosome B Lysosome C Mitochondria D Golgi apparatus

Q14 Multiple Choice Question

When a ribosome translating a secretory protein pauses its translation upon recognizing an N-terminal signal peptide via Signal Recognition Particle (SRP), where does the ribosome dock to accomplish co-translational translocation?

A The Golgi cis-cisternae rim B The nuclear pore complex basket C The Sec61 translocon channel complex embedded in the Rough Endoplasmic Reticulum membrane D The mitochondrial outer membrane porin channel

Q15 Multiple Choice Question

Popularized profoundly by Lynn Margulis in 1967, which evolutionary theory explains the origin of eukaryotic Mitochondria and Chloroplasts from engulfed ancient prokaryotic cells?

A Mutation Theory of Evolution B Endosymbiotic Theory C Theory of Special Creation D RNA World Hypothesis

Q16 Multiple Choice Question

In the 23S rRNA of the bacterial large ribosomal subunit, which universally conserved nucleotide residue is structurally indispensable for catalyzing peptide bond formation at the peptidyl transferase center?

A Guanine 500 B Cytosine 100 C Adenine 2451 (A2451 in E. coli numbering) D Uracil 3000

Q17 Multiple Choice Question

In human cytogenetics, the specific chromosomal regions containing clusters of tandemly repeated genes for 45S pre-rRNA that directly organize the assembly of the nucleolus during telophase are called:

A Autonomous Replicating Sequences (ARS) B Telomeric ends of chromosomes C Nucleolar Organizer Regions (NORs, located on human acrocentric chromosomes 13, 14, 15, 21, and 22) D Centromeric kinetochore plates

Q18 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

Q19 Multiple Choice Question

Popularly termed the 'Suicidal Bags' of the cell, Lysosomes contain hydrolytic digestive enzymes that function most efficiently in which acidic pH environment?

A Strictly neutral pH 7.0 B Extreme hyper-saline pH 12.0 C Alkaline pH around 8.5 to 9.0 D Acidic pH around 4.5 to 5.0

Q20 Multiple Choice Question

Wolman disease is a fatal autosomal recessive lysosomal storage disorder directly caused by the inherited deficiency of which lysosomal lipid-degrading enzyme?

A Lysosomal Acid Lipase (LAL) B Alpha-glucosidase C Hexosaminidase A D Acid phosphatase

Cell Structure & Organelles