CSIR UGC NET LIFE SCIENCE PYQ WITH SOLUTION: UNIT - II (CELLULAR ORGANISATION), PART - I

1. A fixed smear of a bacteria culture is subjected to the following solutions in the order listed below and appeared red,
(a) Carbolfuchsin (heated)
(b) Acid-alcohol
(c) Methylene blue
Bacteria stained by this method can be identified as [December 2011]

1. Non-acid fast E. coli
2. Acid fast Mycobacterium sp.
3. Gram-positive E. coli
4. Gram-negative Mycobacteria

2. In contrast with plant cells, the most distinctive feature of cell division in animal cells is [December 2011]

1. control of cell cycle transition by protein kinase
2. enzyme responsible for DNA replication
3. ubiquitin-dependent pathway for protein degradation
4. pattern of chromosome movement

3. Transport of water across aquaporins is regulated by the presence of which of the following sequence of three highly conserved amino acids? [June 2011]

1. Ala-Asn-Pro.
2. Pro-Asn-Ala.
3. Asn-Pro-Ala.
4. Pro-Ala-Asn

4. Eukaryotic genomes are organized into chromosomes and can be visualized at mitosis by staining with specific dyes. Heat denaturation followed by staining with Giemsa produced alternate dark and light bands. The dark bands obtained by this process are mainly [June 2011]

1. AT -rich and gene rich regions.
2. AT -rich and gene desert regions.
3. GC-rich and gene rich regions.
4. GC-rich and gene desert regions.

5.77. ATP-driven pumps hydrolyze ATP to ADP and phosphate and use the energy released to pump ions or solutes across a membrane. There are many classes of these pumps and representatives of each are found in all prokaryotic and eukaryotic cells. Which of the following statements about these pumps is NOT correct? [December 2012]

1. P-type pumps are multipass transmembrane proteins which phosphorylate themselves during pumping and involve in ion transport.
2. F-type pumps normally use the H+ gradient across the membrane to drive the synthesis of ATP
3. V-type pumps normally use voltage gradient for transport of small molecules.>
4. ABC transporters primarily pump small molecules across cell membrane.

6. An organism that has peroxidase and superoxide dismutase but lacks catalase is most likely an [December 2012]

1. Aerotolerant anaerobe.
2. Aerotolerant aerobe.
3. Obligate anaerobe.
4. Facultative anaerobe.

7. Assuming that the histone octamer forms a cylinder 9 nm in diameter and 5 nm in height and that the human genome forms 32 million nucleosomes, what fraction (approximately)of the volume of nucleus (6 μm diameter) is occupied histone octamers? [June 2012]

1. 1/22
2. 1/11
3. 10/21
4. 10/11

8. Cystic fibrosis (CF) trans membrane conductance regulator (CFTR) protein is known to be a cAMP- dependent Cl- channel.CF patients (with mutant CFTR proteins) show reduced Clpermeability and as a result exhibit elevated Cllevel in sweat. To prove this, CFTR proteins (both wild type and mutant) are inserted in a model membrane (liposome) and Cl- transport is followed with radioactive Cl-.it is known that topology of CFTR in membrane is important for its function. Despite no proteolytic degradation of denaturation of CFTR proteins, wild type CFTR failed to transport Cl- in liposome.

1. CFTR protein gets mutated during insertion in liposomes.
2. CFTR protein loses affinity with Cl- ions.
3. CFTR protein gets wrongly inserted in liposomes.
4. CFTR protein loses channel forming property in liposomes. [June 2012]

9. When cells enter mitosis, their existing array of cytoplasmic microtubules has to be rapidly broken down and replaced with the mitotic spindle, which pulls the chromosomes into the daughter cells. The enzyme Katanin is activated during the onset of mitosis and chops microtubules into short pieces. The possible fate of the microtubule fragments created by Katanin will be [December 2013]

1. depolymerization.
2. aggregation.
3. degradation.
4. translocation.

10. Out of the list given below, which is the correct order of increasing lipid bilayer permeability? [December 2013]

1. N2 > Ethanol> H2O> Glucose> Ca+2 > RNA
2. H2O> Glucose> Ethanol> N2 > Ca+2 > RNA
3. Ca+2 > RNA > N2 > Ethanol > H2O > Glucose
4. Ethanol> RNA > Ca+2 > H2O> Glucose >N2

11. rapidly growing bacterial species such as E. coli exhibits a typical phase of growth cycle in liquid nutrient broth (Iag phase - log phase - stationary phase - death phase). If a bacterial culture has starting density of 103 cells/ml has a lag time of 10 minutes and a generation time of 10 minutes, what will the cell density be at (cells/ml) 30 minutes? [June 2013]

1.6.0 X 10^3
2. 2.0 X 10^3
3.3.0 X 10^3 4. 4.0 X 10^3

12. Phosphorylation of series as well as methylation and acetylation of Lysine in histone tails affect the stability of chromatin structure above the nucleosome level and have important consequences for gene expression. The resulting changes in charge are expected to affect the ability of the tails to interact with DNA because [June 2013]

1. DNA is negatively charged.
2. DNA-histone interaction is independent of net charge.
3. phosphorylation of serine increases DNA-histone interaction.
4. methylation and acetylation of lysine increases DNA histone interaction.

13. Which of the following statements best describe archaebacteria? [December 2014]

1. Mostly autotrophic, cell wall contains peptidoglycan, 60S ribosomes, live in extreme environment.
2. Divide by fission, not susceptible to lysozyme, live in extreme environments, mostly autotropic.
3. Not susceptible to lysozyme, contain Golgi and linear chromosomes
4. Chitinous cell wall, obligate aerobic, circular chromosomes.

14. Which of the following statements about meiosis is NOT true? [December 2014]

1. Kinetochores of sister chromatids attach to opposite poles in Meiosis I.
2. inetochores of sister chromatids attach to opposite poles in Meiosis II.
3. Chiasma is formed in Prophase I.
4. Homologous chromosomes are segregated in Meiosis I.

15. Histone acetylase and chromatin remodelling complexes are recruited to specific regions of chromatin by [June 2014]

1. gene activator proteins.
2. specific promoter sequence.
3. phosphorylation of histone acetylase.
4. dephosphorylation of chromatin remodelling complexes.

16. 125I-labelJed diaminofluorene (DAF) is a well-known photoactivable hydrophobic probe of plasma membrane integral protein. To determine the approximate length and number of hydrophobic domain in any integral membrane protein, a controlled experiment (following standard protocol) is carried out. In order to ascertain the aforesaid aspects indicate the correct combination of experimental protocols from the following choices: [June 2014]

1. Intact membrane was allowed to interact with DAF and unincorporated DAF measured
2. Intact membrane was allowed to interact with DAF, lysed and total protein precipitated with TCA and amount of radioactivity incorporated in the total proteins in the TCA precipitated fraction measured.
3. Intact membrane was allowed to interact with DAF, then membrane was solubilized with detergent, digested with proteases (limited proteolysis) run on SDS-PAGE followed by autoradiography.
4. Intact membrane was allowed to interact with DAF followed by complete proteolysis, SDS-PAGE and finally autoradiography.

17. Glycophorin having one highly hydrophobic domain is able to span a phospholipid bilayer membrane only [December 2015]

1. Once
2. Twice
3. Thrice
4. Four times

18. culture medium contains two carbon sources, one is preferred carbon source (glucose) and the second is a nonpreferred source (lactose). Which one below is correct regarding the nature of growth curve of E. coli cultured in this medium? [December 2015]

1. Growth curve will be same as when grown in presence of only glucose.
2. Growth curve will be same as when grown in presence of only lactose.
3. A lag phase will be observed between the two exponential phases.
4. Two lag phases will be observed between the two exponential phases.

19. Sting of a bee causes pain, redness and swelling. Melittin is a major peptide in bee venom. Melittin is a membrane binding peptide that is involved in activating phospholipases in the membrane. The possible target phospholipase that is activated by melittin is [June 2015]

1. Phospholipase C to generate inositol phosphates. 2. Phospholipase A2 to generate arachidonic acid.
3. Phospholipase D to generate 1', 3'- inisitol. 4. Phospholipase A1 to generate palmitic acid

20. When bacteria growing at 20°C are warmed at 370C, they are most likely to synthesize membrane lipids with more [June 2015]

1. short chain saturated fatty acids
2. short chain unsaturated fatty acids
3. long chain saturated fatty acids
4. long chain unsaturated fatty acids

21. In context to lac operon, if two bacterial strains P, and P2 with the genotypes OCI+Z- and O+I-Z+ respectively, were used to produce mero-diploid daughter strain D, which one of the following statements correctly predicts the expression of Z gene (β-galactosidase activity) in all the three strains? (O+, I+ and Z+ denote the wild type allele of the respective genes). [June 2015]

1. P1 - No expression; P2 – constitutive expression; D - Inducible expression.
2. P1 - No expression; P2 – constitutive expression; D – constitutive expression.
3. P1 - No expression; P2 – Inducible expression; D - Inducible expression.
4. P1 - Inducible expression; P2 – constitutive expression; D – Inducible expression.

22. Which one of the following combinations must be present in a steroid receptor that is located in the cytoplasm? [June 2015]

1. Nuclear export sequence (NES), leucine zipper
2. NES, zinc finger motif
3. Nuclear localization sequence (NLS), zinc finger motif
4. NLS, leucine zipper

23. Both sphingomyelin and phosphoglycerides are phospholipids. Which one of the following statements is NOT correct? [December 2016]

1. While one has a fatty acid tail attached via an ester bond, in another, the fatty acid tail is attached via an amide bond
2. The hydrophilicity of both is dependent on the phosphate group and other head groups attached to the phosphate group
3. Only one of them may contain a carbon carbon double bond (C=C).
4. Both may have choline as head group.

24. When bacteria growing at 20°C are warmed at 370C, they are most likely to synthesize membrane lipids with more [June 2015]

1. short chain saturated fatty acids
2. short chain unsaturated fatty acids
3. long chain saturated fatty acids
4. long chain unsaturated fatty acids

25. Insulin increases facilitated diffusion of glucose in muscle cells by:- [December 2016]

1. phosphorylation of glucose transporters.
2. translocation of glucose transporter containing endosomes into the cell membrane.
3. inhibition of the synthesis of mRNA for glucose transporters.
4. dephosphorylation of glucose transporters.

26. Fluorescently tagged protein was used to study protein secretion in yeast. Fluorescence was observed in: (a) the Golgi (b) the secretory vesicles (c) the rough ER. Which of the following describes best the sequence in which these events occur? [December 2017]

1. (a) --> (b) --> (c)
2. (b) --> (c) --> (a)
3. (c) --> (a)--> (b)
4. (c) --> (b) --> (a)

27. Cells in S-phase of the cell cycle were fused to cells in the following stages of cell cycle: (a) G1 phase, (b) G2 phase, (c) M phase. These cells were then grown in medium containing tritiated thymidine. Maximal amount of freshly labelled DNA is likely to be obtained in Sphase cells fused with [December 2017]

1. G1 phase cells
2. G2 phase cells
3. M phase cells
4. Both G1 and G2 phase cells

28. A membrane associated protein is composed of seven "alphahelices", with each helix containing 19 hydrophobic residues. While treating the membrane with all kinds of proteases, a major portion of this protein remains intact. Treatment with high salt (till 1.5M NaCl) and buffer with pH 5.0 failed to dissociate this protein from the membrane. Predict the most appropriate nature and orientation of this protein in the membrane. [June 2017]

1. Peripheral glycoprotein
2. Integral protein with seven membrane spanning regions
3. Peripheral protein with both N and C- terminals remain exposed to outer surface of the cell membrane
4. Peripheral protein with both N and C- terminal remain exposed to cytosolic surface of the cell membrane

29. Which one of the following proteins is most likely to be found in the intermembrane space of mitochondria? A protein containing [December 2018]

1. an N-terminal matrix targeting sequence followed by hydrophobic stop-transfer anchor sequence.
2. an N-terminal matrix targeting sequence followed by a cleavable hydrophobic sequence that blocks complete translocation.
3. a protein with multiple internal sequences that are recognized by Tim 22 complex
4. a protein with an outer membrane localization sequence followed by a matrix targeting signal

30. Irrespective of the chromosomal configuration, a single X-chromosome remains active in all diploid human somatic cell lines, Which one of the following mechanisms best accounts for the above phenomenon? [June 2019]

1. A maternally inherited X-chromosome is developmentally programmed to remain active by avoiding DNA methylation.
2. Chromosome specific expression and binding of rox1 to one of the X-chromosomes protects it from Xist mediated silencing.
3. The T-six gene produces just enough of the Xist antisense RNA to block one Xic locus.
4. A cell produces just enough of the blocking factor to block one Xic locus.