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1. Which of the following best describes the hyperchromicity of DNA?
A. The shift in UV absorbance to longer wavelength upon denaturation
B. The shift in UV absorbance upon hydrolysis
C. The increase in absorbance at 260nm upon annealing
D. The increase in absorbance at 260nm upon denaturation
E. The increase in absorbance at 260nm upon renaturation
2. The virus that causes acquired immune deficiency syndrome (AIDS) parasitizes
A. Cytotoxic T cells
B. B cells
C. The membranes of lymph nodes
D. Helper T cells
3. Each human cell has 6x109 nucleotide pairs the number of nucleosomes will be
4. Which of the following organelles has DNA in animal cells?
A. Ribosome and mitochondria
B. Chloroplast and nucleus
C. Mitochondria and nucleus
D. Chloroplast and ribosome
E. Mitochondria, chloroplast and nucleus
5. Histones are rich in lysine and argine because
A. DNA is negatively charged
B. DNA has no charge
C. DNA is positively charged
D. DNA is polar molecule
E. None of the above
6. The mode of action of antibiotic penicillin is
A. Inhibits transcription
B. Antibiotic is exclude by membrane
C. It deactivates membrane transport
D. It inhibit glycolase moiety of cell wall enzyme
E. Antibiotic is not allowed to enter the cell
7. Reverse transcriptase is a
A. DNA dependent ant RNA polymerase
B.RNA dependent DNA polymerase
C. DNA dependent DNA polymerase
D. Both A and B
E. Both B and C
8. Endocytic vesicles are usually coated by
9. Site where HMP shunts can occur include
D. lactating mammary gland
10. The 5’cap of RNA is required for the
A. Transport of RNA only
B. Stability and transport of RNA
C. Methylation of RNA
D. Stability of RNA only
E.All of the above
11. Globular proteins when treated with organic solvent get denatured. The main interaction which is affected on treatment with chloroform is
A. Hydrogen bonds
B. Covalent bonds
C. Ionic interactions
D. Hydrophobic interactions
E. Disulphide bonds
12. Which of the following molecules is involved in Ca2+ dependent cell-cell adhesion?
13. The most probable place where life would have originated?
A. In oceans
B. Deep hydrothermal vents
C. Outer space
D. Barren rocks
E. Fresh water
14. A biodiversity hotspot is a
A. Region that has higher temperature, so biodiversity is lower
B. Human –created island that harbours a small organismal population
C. Region rich in endemic species
D. Region of high biodiversity
E. Nitrogen limited plant community
15. In India, brown antlered deer (sangai) is found only in the floating landmasses of
a. Wular lake
b. Dal lake
c. Lok Tak lake
d. Sasthamkotta lake
16. Which of the following is a characteristic of an early seral community?
a. Narrow niche specialization
b. High species diversity
c. Open mineral cycling
d. Low community production
17. A much greater proportion of energy fixed by autotrophs is transferred to the herbivore level in the open ocean ecosystem than in a forest ecosystem because
a. Aquatic autotrophs are small
b. Aquatic herbivores are more efficient feeders
c. Terrestrial autotrophs are less efficient feeders
d. Terrestrial autotrophs have more indigestible tissues
18. Which of the following is not a characteristic of phylum Chordate?
a. Pharyngeal slits
b. Amniotic egg
c. Postanal tail
19. “ Imperfect fungi ” is a group represented by fungal species which have
a. Simple mycelia
b. Unknown phylogenetic relationship
c. No known mechanism of sexual reproduction
d. Lost its survival mechanism against harsh environments
20. AIDS is caused by
b) Blood cancer
c) Human T-cell leukemia virus
e) None of these
Answers with explanation
Reason: Absorbance of DNA is mainly due to the presence of nitrogenous bases. Upon denaturation, Nitrogenous bases will be exposed and thus absorbance increases.
Reason: HIV virus depletes the Helper T cell population that are primarily responsible for cell mediated immunity.
Reason: Each nucleosome consists of 200 nucleotide base pairs i.e. 6x109/200=3x107
Reason: In animal cells DNA is found in two organelles Nucleus and mitochondria
Reason: Histones are rich in basic proteins (lysine and Arginine) as DNA is negatively charged.
Reason: Inhibits formation of the bacterial cell wall by blocking cross linking of the cell wall structure.
Reason: reverse transcriptase in retrovirus is an RNA dependent DNA polymerase enzyme when viral RNA serves as a template for the synthesis of DNA inside the host. This DNA strand serves as a template for the synthesis of ds DNA (DNA dependent DNA polymerase activity)
Reason: Endocytic vesicles are usually coated by Clathrin
Reason: 5’cap protects mRNA against ribonuclease degradation, functions in the initiation of protein synthesis and transport of RNA
Reason: The hydrophobic interaction is the most important interaction responsible for proper folding of a protein that makes the protein functional
Reason: Cadherin is the molecules involved in Ca2+ dependent cell-cell adhesion.
Reason: Present scientific evidence suggests that deep hydrothermal vents the most probable place where life would have originated.
Reason: Region rich in endemic species are called biodiversity hotspots.
Lok Tak lake largest fresh water lake in Eastern India
Narrow niche specialization
Terrestrial autotrophs have more indigestible tissues
19. C No known mechanism of sexual reproduction
20. c) Human T-cell leukemia virus
- AIDS(Acquired Immunodeficiency Syndrome) caused by a retrovirus HIV(Human Immunodeficiency Virus),belongs to lentivirus family.
- It is a set of symptoms and infections resulting from the damage to the human immune system by the virus, that depletes the number of T-lymphocytes(CD4 T cells or helper T-cells).
- The greatest hurdle in controlling HIV attack and T4 cells damage is that HIV changes its genetic constitution so quickly that its identification becomes almost impossible. This phenomenon is known as 'antigenic drift'.