Free NEET Biology multiple-choice questions on Cell Organelles. Attempt each question and reveal the answer with a full explanation.
The smallest cell of size 0.3 , m in length is Mycoplasma Bacteria Ostrich egg Red Blood Cell The movement of a solvent through a semipermeable membrane from a region of low solute concentration to high solute concentration is called: Osmosis Diffusion Active transport Facilitated diffusion A vital stain used to specifically visualize mitochondria in living cells is: Janus Green B Acetocarmine Safranin Methylene Blue Identify the structure of Lecithin, a phospholipid found in cell membranes, based on its components. Glycerol + 2 Fatty Acids + Phosphate + Choline Glycerol + 3 Fatty Acids Glycerol + 2 Fatty Acids + Serine Sphingosine + 1 Fatty Acid + Phosphate + Choline The perinuclear space, which forms a barrier between the materials present inside the nucleus and that of the cytoplasm, typically measures: 10 to 50 nm 100 to 200 nm 1 to 5 m 0.1 to 0.5 nm Which of the following bonds connects the phosphate group to the 5' carbon of a nucleoside sugar? Phosphoester bond Phosphodiester bond Glycosidic bond Hydrogen bond The motor protein responsible for the sliding movement of microtubules in cilia and flagella is: Dynein Kinesin Myosin Tubulin The bond formed between two nucleotides in a single strand of DNA is the: 3'-5' phosphodiester bond 5'-3' phosphodiester bond Glycosidic bond Hydrogen bond Which of the following plastids store proteins? Aleuroplasts Elaioplasts Amyloplasts Chromoplasts The middle lamella is a layer mainly of calcium pectate which holds the different neighboring cells together. Which other ion is often found in the pectates of the middle lamella? Magnesium Potassium Sodium Iron The 'forming face' of the Golgi apparatus, where vesicles from the ER fuse, is also known as the: Cis face Trans face Maturing face Concave face The movement of ions or molecules across a membrane against their concentration gradient, which requires energy in the form of ATP , is called: Active transport Facilitated diffusion Simple diffusion Osmosis Which of the following describes the function of 'Elaioplasts'? Storage of fats and oils Storage of starch Storage of proteins Photosynthesis A cell examined under the microscope shows no nuclear membrane, yet it contains 70S ribosomes and a circular DNA molecule. This cell is most likely a: Bacterium Fungal cell Plant cell Animal cell What is the name of the process by which animal cells typically undergo cytokinesis? Cell furrowing Cell plate formation Spindle contraction Budding The largest isolated single cell is: Egg of an ostrich Human nerve cell Acetabularia Mycoplasma Which of the following structural components of the cell wall is unique to bacteria and absent in plant cell walls? Peptidoglycan Cellulose Hemicellulose Pectin Select the incorrect statement regarding the Smooth Endoplasmic Reticulum ( SER ): It is involved in protein synthesis It is the major site for lipid synthesis In animal cells, lipid-like steroidal hormones are synthesized in SER It lacks ribosomes on its surface Which organelle is responsible for the 'sorting' and 'tagging' of proteins before they are sent to their final destinations? Golgi apparatus Ribosome Lysosome Peroxisome If a bacterial cell is placed in a solution and it does not burst despite high internal pressure, it is primarily due to the presence of: Cell wall Plasma membrane Capsule Glycocalyx Which of the following inclusion bodies are responsible for providing buoyancy to purple and green photosynthetic bacteria? Gas vacuoles Phosphate granules Cyanophycean granules Glycogen granules The presence of a 'thin outer layer' in animal cells, which we now know as the plasma membrane, was first reported by: Theodore Schwann Matthias Schleiden Rudolf Virchow Robert Brown The enzymes present in lysosomes, such as lipases and proteases, are optimally active at: Acidic pH Basic pH Neutral pH Variable pH Which one of the following is a polysaccharide found in the exoskeleton of arthropods? Chitin Glucosamine Glycogen Cellulose In a chloroplast, the flattened membranous sacs are called thylakoids. When these thylakoids are arranged in stacks like piles of coins, they are called: Grana Stroma Lumen Envelope A cell organelle containing hydrolytic enzymes, which are formed by the process of packaging in the Golgi apparatus, is: Lysosome Vacuole Peroxisome Glyoxysome The bacterial cell envelope consists of a tightly bound three-layered structure. From the outermost to the innermost, the correct sequence is: Glycocalyx → Cell wall → Plasma membrane Cell wall → Glycocalyx → Plasma membrane Plasma membrane → Cell wall → Glycocalyx Glycocalyx → Plasma membrane → Cell wall A major difference between a plant cell and an animal cell during cytokinesis is that: Plant cells form a cell plate, while animal cells form a cleavage furrow. Plant cells undergo karyokinesis only. Animal cells form a cell plate from the center outwards. Plant cells divide by the contraction of a ring of actin filaments. Which of the following is NOT a component of the cytoskeleton? Mesosomes Microtubules Microfilaments Intermediate filaments Which of the following cell organelles is double membrane-bound and contains its own genetic material? Chloroplast Lysosome Endoplasmic Reticulum Golgi Complex In some bacteria, the glycocalyx is a loose sheath called the: Slime layer Capsule Cell wall Mesosome In some bacteria, the cell envelope includes small, circular, self-replicating extrachromosomal DNA molecules. These are known as: Plasmids Nucleoids Mesosomes Genophores In the chloroplast, the water-soluble enzymes required for the synthesis of carbohydrates and proteins are located in the: Stroma Thylakoid lumen Grana Inner membrane The concentration of Ca 2+ ions in the middle lamella is high because it is primarily composed of: Calcium pectate Calcium carbonate Calcium oxalate Hemicellulose The formation of a cluster of ribosomes on a single mRNA strand for the simultaneous production of several copies of a polypeptide is called a: Polysome Phagosome Lysosome Centrosome Which of the following organelles is known to be 'semi-autonomous' as it contains its own DNA , RNA , and 70S ribosomes? Mitochondria Golgi apparatus Endoplasmic reticulum Lysosomes In a prokaryotic cell, the genomic DNA is not enclosed by a nuclear membrane. This region where the DNA is located is termed the: Nucleoid Nucleolus Genophore Plasmid Proteins that span the entire thickness of the lipid bilayer and are difficult to extract from the membrane are called: Integral proteins Peripheral proteins Extrinsic proteins Linker proteins A small, circular, double-stranded DNA molecule in bacteria that often carries genes for antibiotic resistance is called a: Plasmid Mesosome Nucleoid Inclusion body What is the correct sequence of organelles involved in the process of photorespiration? Chloroplast Peroxisome Mitochondria Chloroplast Vacuole Peroxisome Chloroplast Mitochondria Peroxisome Chloroplast Cytoplasm Mitochondria The F 1 headpiece of the ATP synthase complex ( F 0-F 1 ) is characterized as a/an: Peripheral membrane protein complex Integral membrane protein complex Channel for proton diffusion Lipid-soluble carrier In the photorespiratory pathway ( C 2 cycle), the conversion of two molecules of Glycine into one molecule of Serine, CO 2 , and NH 3 takes place in which organelle? Mitochondria Peroxisome Chloroplast Glyoxysome What is the specific name of the 20-amino acid protein-rich structure that acts as the 'spool' around which DNA is wound in a eukaryotic cell? Histone Octamer Kinetochore Centriole Nucleoside While the genetic code is nearly universal, which of the following organelles has been found to have its own unique variations in the code? Mitochondria Golgi Apparatus Endoplasmic Reticulum Lysosome The histone octamer consists of which of the following pairs of histones? H2A, H2B, H3, H4 H1, H2A, H2B, H3 H1, H2, H3, H4 H2, H3, H4, H5 In a bacterial cell, a 'Polysome' refers to: Several ribosomes attached to a single mRNA A complex of RNA and DNA polymerase The nucleoid region of the cell A ribosome attached to the cell membrane Which RNA polymerase is responsible for the transcription of tRNA in eukaryotes? RNA Polymerase III RNA Polymerase I RNA Polymerase II RNA Polymerase IV The sequence of nitrogenous bases in a strand of DNA is 5'-ATGCATGC-3' . What will be the sequence of the complementary RNA strand? 3'-UACGUACG-5' 5'-UACGUACG-3' 3'-TACGTACG-5' 5'-AUGCUAGC-3' Under which condition will the Lac operon be switched 'on'? Lactose is present and binds to the repressor Glucose is present and binds to the promoter Lactose is absent and the repressor binds to the operator Repressor binds to the structural genes The process of 'charging of tRNA' or aminoacylation is essential for: Translation Transcription Replication Splicing In eukaryotes, the process of removing introns and joining exons in a defined order is called: Splicing Capping Tailing Transformation During the processing of hnRNA in eukaryotes, the 'tailing' process involves the addition of: Adenylate residues at 3' end Methyl guanosine triphosphate at 5' end Adenylate residues at 5' end Methyl guanosine triphosphate at 3' end Select the correct statement regarding the mechanism of translation. The UTRs (Untranslated Regions) are required for efficient translation process. Aminoacylation of tRNA requires GTP as an energy source. The small subunit of ribosome binds to the mRNA to start translation at the 3' end. The peptide bond formation is catalyzed by RNA polymerase. In a polynucleotide chain, the 5' end is identified by the presence of a: Free phosphate group at the 5' carbon of the sugar Free hydroxyl group at the 5' carbon of the sugar Nitrogenous base attached to the 5' carbon Methyl group at the 5' carbon The RNA polymerase holoenzyme requires which factor for the specific initiation of transcription in prokaryotes? Sigma factor ( σ ) Rho factor ( ρ ) Gamma factor ( γ ) Beta factor ( β ) DNA sequences that are repeated many times and form a large portion of the eukaryotic genome, often found in centromeres, are called: Satellite DNA Exons Introns Structural genes The cell membranes are mainly composed of :- Phospholipids Proteins Fats Carbohydrates The genetic code is nearly universal. However, some exceptions have been found in: Mitochondria and some protozoans Bacteria and viruses Chloroplasts of all plants Fungi only Which complex is formed by the association of snRNPs (small nuclear ribonucleoproteins) with the hnRNA to remove introns? Spliceosome Nucleosome Polysome Ribosome The Untranslated Regions (UTRs) are present in mRNA at: Both 5' end (before start codon) and 3' end (after stop codon) Only at the 5' end Only at the 3' end In the middle of the coding sequence DNA is chemically more stable than RNA because of the presence of: Hydrogen at 2' carbon of pentose sugar Hydroxyl group at 2' carbon of pentose sugar Uracil instead of Thymine Single-stranded structure The removal of introns and joining of exons in a defined order during transcription in eukaryotes is facilitated by a complex called: Spliceosome Ribosome Polysome Nucleosome In eukaryotic transcription, the process of 'Capping' involves the addition of an unusual nucleotide at the 5' end of hnRNA, which is: Methyl guanosine triphosphate Adenylate residues Ethyl cytosine triphosphate Methyl adenosine triphosphate In the B-DNA double helix, the stability of the helix is primarily provided by: Hydrogen bonds and stacking of base pairs Phosphodiester bonds only Glycosidic bonds only Disulfide bridges In the Lac operon, although lactose is provided in the medium, the actual molecule that binds to the repressor and inactivates it is: Allolactose Glucose Galactose Permease Spliceosomes are NOT found in cells of: Bacteria Fungi Animals Plants In prokaryotes, the termination of transcription is often facilitated by a specific protein factor known as: Rho factor Sigma factor Omega factor TFIID Protein synthesis in an animal cell occurs - On ribosomes presents in cytoplasm as well as in mitochondria On ribosomes present in the nucleolus as well as in cytoplasm Only on ribosomes attached to the nuclear envelope and endoplasmic reticulum Only on the ribosomes present in cytosol Which protein binds to the operator region of the Lac operon to prevent transcription? Repressor protein RNA polymerase Inducer Beta-galactosidase The flow of genetic information from RNA to DNA is known as: Teminism Translation Transcription Replication If the sequence of the coding strand of DNA is 5'-GATGCATGC-3' , what is the sequence of the mRNA? 5'-GAUGCAUGC-3' 3'-CUACGUACG-5' 5'-CUACGUACG-3' 3'-GAUGCAUGC-5' Which of the following is responsible for maintaining the structure of the nucleosome by binding to the linker DNA? H1 histone H2A histone H3 histone H4 histone The discovery of 'Reverse Transcriptase' by Temin and Baltimore challenged the original Central Dogma. This enzyme is also known as: RNA-dependent DNA polymerase DNA-dependent RNA polymerase DNA-dependent DNA polymerase RNA-dependent RNA polymerase Which RNA polymerase is located in the nucleolus and is responsible for the synthesis of 28S, 18S, and 5.8S rRNAs? RNA Polymerase I RNA Polymerase II RNA Polymerase III RNA Polymerase IV During translation, the formation of a peptide bond is catalyzed by: Ribozyme Reverse transcriptase DNA polymerase Lyase During the process of translation, the incoming aminoacyl-tRNA (except for the initiator tRNA) binds to which site on the ribosome? A-site P-site E-site O-site Inheritance of plastid genes (chloroplast DNA) in plants usually follows which pattern? Maternal inheritance Paternal inheritance Mendelian inheritance Biparental inheritance Which enzyme is responsible for relaxing supercoiled DNA ahead of the replication fork by cutting and rejoining the strands? DNA Gyrase DNA Ligase DNA Polymerase I Helicase Which of the following statements regarding mitochondrial membrane is not correct ? The outer membrane is permeable to all kinds of molecules The enzymes of the electron transfer chain are embedded in the outer membrane The inner membrane is highly convoluted forming a series of infoldings The outer membrane resembles a sieve In the Lac operon, the ' i ' gene codes for a protein that: Binds to the operator to inhibit transcription Binds to the promoter to initiate transcription Cleaves lactose into glucose and galactose Transports lactose into the cell Which of the following describes the largest portion of the human genome as discovered by the Human Genome Project? Repeated sequences Exons (protein-coding sequences) Regulatory sequences Introns RNA is chemically more reactive and unstable than DNA due to the presence of a free hydroxyl ( -OH ) group at which position of the ribose sugar? 2' position 3' position 5' position 1' position The backbone of the DNA double helix is formed by which type of bond between the sugar and phosphate groups? 3'-5' phosphodiester bond 2'-5' phosphodiester bond Glycosidic bond Hydrogen bond In a transcription unit, the 'terminator' is located in which direction relative to the structural gene? 3' downstream of the coding strand 5' upstream of the coding strand 3' downstream of the template strand 5' upstream of the template strand What is the function of the 'Sigma factor' ( σ ) in prokaryotic transcription? Initiation of transcription at the promoter Elongation of the RNA chain Termination of transcription Processing of the mRNA In the process of DNA replication, the enzyme 'Primase' is necessary because: DNA polymerase cannot initiate a new strand without a 3'-OH group It unwinds the DNA double helix It seals the nicks between Okazaki fragments It prevents the DNA strands from re-annealing During translation, the 'P-site' (Peptidyl site) of the ribosome is the location where: The initiator tRNA binds first The incoming aminoacyl-tRNA binds The empty tRNA exits the ribosome The mRNA binds to the small subunit What is the role of the 'Rho factor' ( ρ ) in bacterial transcription? It helps in the termination of transcription It helps in the initiation of transcription It acts as a catalyst for peptide bond formation It binds to the promoter to increase RNA Pol affinity In the Lac operon, the inducer (Lactose) binds to which of the following to initiate transcription? Repressor protein Promoter Operator Structural genes Select the wrong statement from the following. Both chloroplasts and mitochondria have an internal compartment, the thylakoid space bounded by teh thylakoid membrane Both chloroplasts and mitochondria contain DNA The chloroplasts are generally much large than mitochondria Both chloroplasts and mitochondria contain an inner and an outer membrane. While B-DNA is a right-handed helix, which of the following forms of DNA is a left-handed helix? Z-DNA A-DNA C-DNA D-DNA The actual 3D structure of tRNA, as determined by X-ray crystallography, resembles which of the following? Inverted L-shape Clover leaf Y-shape Double helix Which type of RNA is the most abundant in a cell? rRNA mRNA tRNA snRNA DNA Ligase catalyzes the formation of which type of bond to join DNA fragments? Phosphodiester bond Hydrogen bond Glycosidic bond Peptide bond In a DNA molecule, the nitrogenous base is linked to the pentose sugar via which bond? N-glycosidic linkage Phosphodiester bond Hydrogen bond Amide bond The spliceosome, a complex used in mRNA processing, is composed of which of the following? snRNA and proteins tRNA and proteins rRNA and lipids DNA and histones During DNA replication, the deoxynucleoside triphosphates (dNTPs) serve a dual purpose. What are they? Acting as substrates and providing energy for polymerization Acting as catalysts and template strands Providing structural support and acting as primers Inhibiting errors and activating ligase According to the Human Genome Project, which human chromosome has the highest number of genes? Chromosome 1 Chromosome X Chromosome 21 Chromosome Y In a DNA polynucleotide chain, the phosphodiester bond connects: The 3'-OH of one sugar to the 5'-phosphate of the next The 1'-carbon of the sugar to the nitrogenous base The 5'-OH of one sugar to the 3'-phosphate of the next The two strands via hydrogen bonds During the processing of eukaryotic hnRNA, the 'Capping' at the 5'-end involves the addition of: 7-methylguanosine Polyadenylic acid Methylated Adenine Cytidine triphosphate Which one of the following is not a constituent of cell membrane? glycolipids proline phospholipids cholesterol. The poly-A tail added to the 3'-end of eukaryotic mRNA during processing typically consists of how many adenylate residues? 200–300 10–50 500–1000 5–15 The enzyme 'Primase', which initiates DNA replication, is actually a type of: RNA Polymerase DNA Polymerase Ligase Transferase In a transcription unit, the promoter is located towards the: 5' end of the coding strand 3' end of the coding strand 5' end of the template strand 3' end of the mRNA In bacteria, which of the following RNA molecules acts as a catalyst (ribozyme) for peptide bond formation during translation? 23S rRNA 5S rRNA 16S rRNA tRNA During the process of translation, the enzyme that catalyzes the 'activation of amino acids' by attaching them to their specific tRNA is: Aminoacyl-tRNA synthetase Peptidyl transferase RNA polymerase DNA ligase In eukaryotes, which RNA molecule acts as a ribozyme during the process of translation? 28S rRNA 23S rRNA 5.8S rRNA 18S rRNA In a nucleosome, DNA is wrapped around a core of histones. How many base pairs of DNA are typically associated with one nucleosome? 200 bp 146 bp 400 bp 100 bp The 'Wobble Hypothesis', which explains why some tRNA molecules can recognize more than one codon, was proposed by: Francis Crick Marshall Nirenberg H.G. Khorana George Gamow A child is born with a characteristic 'cat-like cry', mental retardation, and facial abnormalities. This is likely due to the deletion of a part of the short arm of which chromosome? Chromosome 5 Chromosome 13 Chromosome 18 Chromosome 21 Which of the following gas ratios was used by S.L. Miller in his experiment to simulate the primitive Earth's atmosphere? CH 4 : NH 3 : H 2 in 2:1:2 ratio CH 4 : NH 3 : H 2 in 1:2:1 ratio CH 4 : NH 3 : O 2 in 2:1:2 ratio NH 3 : H 2 : H 2O in 1:1:1 ratio Which of the following is a phospholipid? Lecithin Cholesterol Oleic acid Palmitic acid Plasmodesmata are : Connection between adjacent cells Lignified cemented layers between cells Locomotory structures Membranes connecting the nucleus with plasmalemma Which type of mutation occurs when a purine is replaced by another purine or a pyrimidine is replaced by another pyrimidine? Transition Transversion Frameshift Nonsense The 'TATA box' is a conserved DNA sequence found in the promoter region of eukaryotes. It is typically located how many base pairs upstream of the transcription start site? -25 to -35 -10 only +10 -100 The experiment by Matthew Meselson and Franklin Stahl to prove semi-conservative replication of DNA used which density gradient? Cesium chloride ( CsCl ) Sucrose Potassium chloride ( KCl ) Ammonium chloride ( NH 4Cl ) In a bacterial cell, the tryptophan operon is a repressible system. What happens when tryptophan is present in high concentration? Tryptophan binds to the repressor, which then binds to the operator to stop transcription. Tryptophan binds to the RNA polymerase to enhance transcription. The repressor is inactivated, allowing transcription. Tryptophan acts as an inducer for the operon. Which of the following is the correct chronological order of the periods in the Paleozoic Era, from oldest to youngest? Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian Devonian, Cambrian, Silurian, Permian, Carboniferous Permian, Carboniferous, Devonian, Silurian, Ordovician, Cambrian Silurian, Devonian, Cambrian, Permian, Carboniferous In the structural organization of chromatin, the diameter of the 'Solenoid' fiber is approximately: 30 nm 10 nm 300 nm 700 nm In prokaryotic translation, the sequence on mRNA that helps the small ribosomal subunit (30S) identify the correct start codon is known as the: Shine-Dalgarno sequence Kozak sequence Pribnow box TATA box In the 'Cloverleaf' model of tRNA, the D-loop (Dihydroxyuridine loop) is primarily involved in: Recognition and binding of aminoacyl-tRNA synthetase Binding to the mRNA codon Binding to the large ribosomal subunit Carrying the specific amino acid Which activity of DNA Polymerase I is essential for the removal of RNA primers during DNA replication in prokaryotes? 5' to 3' exonuclease activity 3' to 5' exonuclease activity 5' to 3' polymerase activity Helicase activity Phenotypic expression where a single gene can exhibit multiple phenotypic expressions is known as: Pleiotropy Polygenic inheritance Co-dominance Incomplete dominance Cytoskeleton is made up of : Proteinaceous filaments Calcium carbonate granules Callose deposits Cellulose microfibrils The pitch of the B-DNA double helix is approximately: 3.4 nm 0.34 nm 2.0 nm 34 nm In the Lac operon, the gene ' y ' codes for which of the following proteins? Permease -galactosidase Transacetylase Repressor protein The formation of the first amino acids in S.L. Miller's experiment was significant because it supported: Chemical evolution Spontaneous generation Panspermia Biogenesis According to the Gene-Chromosome theory, what happens during Anaphase I of meiosis? Homologous chromosomes separate Sister chromatids separate Non-homologous chromosomes synapse Crossing over occurs A mutation that involves the substitution of a single base pair in DNA is known as: Point mutation Frameshift mutation Deletion Inversion Which of the following is NOT a property of the genetic code? Ambiguous Degenerate Universal Commaless In eukaryotes, the enzyme responsible for synthesizing hnRNA is: RNA polymerase II RNA polymerase I RNA polymerase III DNA polymerase In honey bees, the mechanism of sex determination is: Haplodiploidy XY type ZW type XO type The first organisms that released oxygen into the atmosphere were: Cyanobacteria Methanogens Green sulfur bacteria Chemoautotrophs Which of the following codons has a dual function, acting as both an initiator and coding for an amino acid? AUG UAA GUG UUU Pigment-containing membranous extensions in some cyanobacteria are Heterocysts Basal bodies Pneumatophores Chromatophores The specific sequence of DNA where replication is initiated is called: Origin of replication (ori) Promoter Terminator Operator In the Griffith experiment, which strain of Streptococcus pneumoniae was virulent and why? S-strain because it has a polysaccharide capsule R-strain because it lacks a capsule S-strain because it lacks a capsule R-strain because it has a polysaccharide capsule Which of the following was NOT a reason for T.H. Morgan to choose Fruit flies ( Drosophila melanogaster ) for his genetic experiments? They have a very long life cycle of about 3 months They could be grown on simple synthetic medium in the laboratory A single mating could produce a large number of progeny flies There was a clear differentiation of the sexes (male and female) The Chromosomal Theory of Inheritance, which identified chromosomes as the carriers of genetic material, was proposed by: Sutton and Boveri Mendel and Morgan Watson and Crick Avery and MacLeod Which researchers provided the crucial X-ray diffraction data that led to the discovery of the DNA double helix structure? Maurice Wilkins and Rosalind Franklin James Watson and Francis Crick Erwin Chargaff Alfred Hershey and Martha Chase In the DNA double helix, the two strands are characterized by: Antiparallel polarity with hydrogen bonds between bases Parallel polarity with phosphodiester bonds between bases Antiparallel polarity with ionic bonds between bases Parallel polarity with hydrogen bonds between bases Which chromosomal disorder is characterized by the presence of an additional copy of chromosome number 21? Down's syndrome Klinefelter's syndrome Turner's syndrome Thalassemia In a pedigree analysis, a horizontal line connecting a circle and a square symbol specifically represents: Mating Consanguineous mating Siblings Affected individuals The XO type of sex determination is typically observed in: Grasshoppers Drosophila Birds Humans Human skin color is a classic example of: Polygenic inheritance Pleiotropy Codominance Incomplete dominance A major site for synthesis of lipids is RER SER Symplast Nucleoplasm The total number of genes in the human genome as estimated by the Human Genome Project is approximately: 30,000 80,000 1,00,000 20,000 The main difference between a nucleoside and a nucleotide is the presence of: Phosphate group Nitrogenous base Pentose sugar Hydroxyl group Oparin and Haldane proposed that the first form of life could have come from pre-existing non-living organic molecules. This theory is known as: Chemical Evolution Spontaneous Generation Biogenesis Panspermia In the Lac operon, the ' a ' gene codes for which enzyme? Transacetylase Permease -galactosidase Repressor protein During which stage of Meiosis-I does the process of crossing over between homologous chromosomes occur? Pachytene Zygotene Diplotene Leptotene The experiment that proved DNA replication is semi-conservative was performed by: Meselson and Stahl Hershey and Chase Watson and Crick Taylor et al. Histones are rich in which of the following basic amino acids? Lysine and Arginine Valine and Histidine Leucine and Isoleucine Serine and Proline DNA Polymerase catalyzes the polymerization of deoxynucleotides only in which direction? 5' 3' 3' 5' Both 5' 3' and 3' 5' None of the above The universe is very old—almost 20 billion years old. How old is the Earth estimated to be? 4.5 billion years 10 billion years 2 billion years 4 million years Which property of the genetic code states that one codon codes for only one specific amino acid? Unambiguous and Specific Degenerate Universal Comma-less The Golgi complex plays a major role In trapping the light and transforming it into chemical energy In digesting proteins and carbohydrates As energy transferring organelles In post translational modification of proteins and glycosidation of lipids Failure of segregation of chromatids during cell division cycle results in the gain or loss of a chromosome(s), called: Aneuploidy Polyploidy Euploidy Haploidy In the packaging of DNA, which histone protein is not a part of the histone octamer but is associated with the 'linker DNA'? H1 H2A H2B H4 What is the 'initiation codon' that also codes for the amino acid Methionine? AUG UAA UAG UGA Which of the following is the largest known human gene, consisting of 2.4 million bases? Dystrophin Insulin TDF Hemoglobin The diameter of the B-DNA double helix is approximately: 20 Ã… 34 Ã… 3.4 Ã… 10 Ã… According to the Human Genome Project, the total percentage of the genome that codes for proteins is less than: 2% 10% 25% 50% The 'Opal' stop codon corresponds to which of the following sequences? UGA UAG UAA AUG The Human Genome Project (HGP) was officially launched in the year: 1990 1987 2003 1953 DNA is less reactive and more stable than RNA because of the: Absence of 2'-OH group in deoxyribose Presence of Thymine instead of Uracil Double-stranded nature All of the above In eukaryotes, the enzyme RNA Polymerase II is responsible for the transcription of: hnRNA rRNA (28S, 18S, 5.8S) tRNA 5S rRNA Which structures perform the function of mitochondria in bacteria ? Nucleoid Ribosomes Cell wall Mesosomes Which of the following is used as a vector for cloning genes in higher organisms (plants/animals) during Human Genome Project techniques? BAC and YAC pBR322 Lambda phage SV40 In a pedigree chart, a diamond-shaped symbol is used to represent: Sex unspecified Affected male Carrier female Consanguineous marriage A group of several ribosomes attached to a single mRNA molecule to synthesize multiple copies of the same polypeptide is known as a: Polysome Lysosome Nucleosome Phagosome During DNA fingerprinting, the DNA fragments are separated based on their size using which technique? Gel Electrophoresis Polymerase Chain Reaction Southern Blotting Centrifugation In the Z-W system of sex determination, which is found in birds, the females are: Heterogametic ( ZW ) Homogametic ( ZZ ) Heterogametic ( XO ) Homogametic ( WW ) The 'Capping' process in eukaryotic mRNA processing involves the addition of which molecule to the 5' end? Methyl guanosine triphosphate Adenylate residues Ethyl guanosine triphosphate Methyl cytosine triphosphate The inheritance of the ABO blood group system in humans is an example of both Multiple Allelism and: Co-dominance Incomplete dominance Epistasis Polygenic inheritance In DNA Fingerprinting, the term VNTR stands for: Variable Number of Tandem Repeats Very Narrow Tandem Regions Variable Nucleotide Transcript Regions Variant Nucleoside Total Replicates In a pedigree analysis, the symbol of a square connected to a circle by two horizontal lines represents: Consanguineous mating Mating between unrelated individuals Affected offspring Identical twins Which experiment effectively disproved the theory of 'Spontaneous Generation' by using swan-necked flasks? Louis Pasteur's experiment Francesco Redi's experiment Lazzaro Spallanzani's experiment August Weismann's experiment The osmotic expansion of a cell kept in water is chiefly regulated by : Mitochondria Vacuoles Plastids Ribosomes According to the Chargaff's rule, for a double-stranded DNA, which of the following is true? (A + G) / (T + C) = 1 (A + T) / (G + C) = 1 A = C G = T The enzyme 'Reverse Transcriptase' is used in the synthesis of DNA from an RNA template. This process is also known as: Teminism Translation Transduction Transformation Which of the following codons has no tRNA with a complementary anticodon under normal cellular conditions? UAA AUG GUG UUU The species of yeast used for both bread-making and beverage-making is: Saccharomyces cerevisiae Monascus purpureus Trichoderma polysporum Candida albicans During the replication of HIV in the human body, the viral RNA is converted into viral DNA by the enzyme: Reverse transcriptase DNA polymerase RNA polymerase Restriction endonuclease The term 'Baker's Yeast' refers to which microorganism used in the fermentation of bread dough? Saccharomyces cerevisiae Propionibacterium shermanii Aspergillus niger Lactobacillus acidophilus Which of the following is correctly matched for the product produced by them? Saccharomyces cerevisiae : Ethanol Acetobacter aceti : Antibiotics Methanobacterium : Lactic acid Penicillium notatum : Acetic acid Identify the molecules (A) and (B) in the following diagram of an antibody molecule. (A) Antigen binding site, (B) Heavy chain (A) Disulfide bond, (B) Light chain (A) Variable region, (B) Glycosylation site (A) Heavy chain, (B) Antigen binding site What is the function of the enzyme Reverse Transcriptase in the HIV life cycle? Copies viral RNA into viral DNA Copies viral DNA into viral RNA Translates viral RNA into proteins Integrates viral DNA into host genome The light and heavy chains of an antibody molecule are held together by: Disulfide bonds Hydrogen bonds Glycosidic bonds Phosphodiester bonds Microtubules are the constituents of :- Cilia, Flagella and Peroxisomes Spindle fibres, Centrioles and Cilia Centrioles, Spindle fibres and Chromatin Centrosome, Nucleosome and Centrioles According to widely accepted "fluid mosaic model" cell membranes are semi-fluid, where lipids and integral proteins can diffuse randomly. In recent years, this model has been modified in several respects. In this regard, which of the following statements are incorrect - Proteins can also undergo flip-flop movements in the lipid bilayer Many proteins remain completely embedded within the lipid bilayer Proteins in cell membranes can travel within the lipid bilayer Proteins can remain confined within certain domains of the membranes The main organelle involved in modification and routing of newly synthesized proteins to their destinations is - Endoplasmic Reticulum Lysosome Mitochondria Golgi apparatus A major breakthrough in the studies of cells came with the development of electron microscope. This is because- The resolution power of the electron microscope is much higher than that of the light microscope The resolving power of the electron microscope is 200-350 nm as compared to 0.1-0.2 nm for the light microscope Electron beam can pass through thick materials, whereas light microscopy requires thin sections The electron microscope is more powerful than the light microscope as it uses a beam of electrons which has wavelength much longer than that of photons There is no DNA in : Hair root An enucleated ovum Mature RBCs A mature spermatozoan Which one of the following organelle in the figure correctly matches with its function ? Rough endoplasmic reticulum, formation of glycoproteins Golgi apparatus, protein synthesis Golgi apparatus, formation of glycolipids Rough endoplasmic reticulum, protein synthesis The solid linear cytoskeletal elements having a diameter of 6 nm and made up of a single type of monomer are known as : Microtubules Microfilaments Intermediate filaments Lamins Match the following and array ll (a) Centriole & (i) Infoldings in mitochondria (b) Chlorophyll & (ii) Thylakoids (c) Cristae & (iii) Nucleic acids (d) Ribozymes & (iv) Basal body cilia or flagella array select the correct answer : (iv) (ii) (i) (iii) (i) (ii) (iv) (iii) (i) (iii) (ii) (iv) (iv) (iii) (i) (ii) Mitochondria and chloroplast are :- (a) semi-autonomous organelles (b) formed by division of pre-existing organelles and they contain DNA but lack protein synthesizing machinery Which one of the following options is correct ? Both (a) and (b) are correct (b) is true but (a) is false (a) is true but (b) is false Both (a) and (b) are false The type of ribosomes is same in: Eukaryotic cytoplasm, mitochondria and endoplasmic reticulum Cytoplasm of eukaryotic cells, their mitochondria and chloroplasts Cytoplasm of eukaryotic cells, their chloroplasts and microbodies Prokaryotes, mitochondria and chloroplasts Which of the following is an incorrect statement? Microbodies are present both in plant and animal cells The perinuclear space forms a barrier between the materials present inside the nucleus and that of the cytoplasm Nuclear pores act as passages for proteins and RNA molecules in both directions between nucleus and cytoplasm Mature sieve tube elements possess a conspicuous nucleus and usual cytoplasmic organelles Which one of the following cell organelles is enclosed by a single membrane ? (1) Mitochondria (2) Chloroplasts (3) Lysosomes (4) Nuclei Match List-I with List-II. array ll List-I & List-II (a) Cristae & (i) Primary constriction in chromosome (b) Thylakoids & (ii) Disc-shaped sacs in Golgi apparatus (c) Centromere & (iii) Infoldings in mitochondria (d) Cisternae & (iv) Flattened membranous sacs in stroma of plastids array Choose the correct answer from the options given below. a-i, b-iv, c-iii, d-ii a-iii, b-iv, c-i, d-ii a-ii, b-iii, c-iv, d-i a-iv, b-iii, c-ii, d-i Match List I with List II : array ll List I & List II A. Axoneme & I. Centriole B. Cartwheel pattern & II. Cilia and flagella C. Crista & III. Chromosome D. Satellite & IV. Mitochondria array Choose the correct answer from the options given below : A-IV, B-III, C-II, D-I A-IV, B-II, C-III, D-I A-II, B-IV, C-I, D-III A-II, B-I, C-IV, D-III Given below are two statements: Statement I: Mitochondria and chloroplasts both double membranes bound organelles. Statement II: Inner membrane of mitochondria is relatively less permeable, as compared chloroplast. In the light of the above statements, choose the mis appropriate answer from the options given below: Both Statement I and Statement II are correct. Both Statement I and Statement II are incorrect. Statement I is correct but Statement II is incorrect. Statement I is incorrect but Statement II is correct. Given below are two statements : one is labelled as Assertion (A), and the other is labelled as Reason (R). Assertion (A) : The primary function of the Golgi apparatus is to package the materials made by the endoplasmic reticulum and deliver it to intracellular targets and outside the cell. Reason (R) : Vesicles containing materials made by the endoplasmic reticulum fuse with the cis face of the Golgi apparatus, and they are modified and released from the trans face of the Golgi apparatus. In the light of the above statements, choose the correct answer from the options given below : A is false but R is true Both A and R are true and R is the correct explanation of A Both A and R are true but R is not the correct explanation of A A is true but R is false Select the correct statements regarding cell membrane in eukaryotic cell. A. Membrane of human RBCs has approximately 52% protein. B. Major phospholipids are arranged in a bilayer. C. Extensions of the plasma membrane into the cell form mesosomes. D. Tails towards the inner part of lipids are hydrophobic and thus protected from aqueous medium. E. Glycocalyx is present on the outer surface of the plasma membrane. Choose the correct answer from the options given below: C, D and E only B, C and E only A, B and D only A, C and E only Choose the correct statements regarding cell organelles and their inclusions. A. The endomembrane system includes Golgi complex, endoplasmic reticulum and mitochondria. B. Rough endoplasmic reticulum bears ribosomes on its surface. C. Both mitochondria and plastids have circular DNA. D. A network of microtubules, microfilaments and intermediate filaments present in the cytoplasm is called cytoskeleton. E. Mitochondrion is a single membrane-bound structure. Choose the correct answer from the options given below : A, B and C only C, D and E only A and B only B, C and D only What is the role of 'radial spokes' in the eukaryotic flagellum? Connecting pe