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1. When an unpolarised light beam is incident from the air onto glass \((n= 1.5)\) at the polarising angle, then:

1.	reflected beam is polarised \(100\) percent.
2.	reflected and refracted beams are partially polarised.
3.	the reason for (1) is that almost all the light is reflected.
4.	all of the above.

2. Monochromatic light waves (wavelength - \(\lambda\)) enter an optical system, and when these waves exit: the upper half of the entering wavefront \(W,\) turns into \(W_1,\) while the lower half turns into \(W_2.\) The two wavefronts \(W_1,W_2\) make a small angle \(\phi\) between them. The fringe width on a screen placed symmetrically between them is:

1.	\(\dfrac{\lambda}{\phi}\)	2.	\(\dfrac{2\lambda}{\phi}\)
3.	\(\dfrac{\lambda}{2\phi}\)	4.	\(2\lambda\phi\)

3.

4. A glass slab of refractive index \(1.5\) is introduced between the object and a concave mirror of a focal length of \(20~\text{cm}\) as shown in the figure. What should be the thickness of the slab so that the final image is formed over the object?
                 
1. \(10~\text{cm}\)
2. \(12.5~\text{cm}\)
3. \(15~\text{cm}\)
4. \(30~\text{cm}\)

5. A hydrogen atom in the ground state absorbs an ultraviolet photon of wavelength \(25\) nm. Ignore any momentum associated with the photon. The ejected electron has an energy of nearly:
(Take \(hc = 1240\) eV-nm)
1. \(10\) eV 
2. \(25\) eV
3. \(35\) eV
4. \(50\) eV

6. Which of the following is true about a glycosidic linkage?
1. It contains a carbonyl bond
2. It contains an ether bond
3. It contains an ester bond
4. It contains an amide bond

7. Find out the major product \((\text{X})\):

1.
2.
3.
4.

8. In Carius method of estimation of halogen, \(0.45 \mathrm{~g}\) of an organic compound gave \(0.36 \mathrm{~g}\) of \(\mathrm{AgBr} \text {. }\)Find out the percentage of bromine in the compound:
(Given: Molar masses: \(\mathrm{AgBr}=188 \mathrm{~g} \mathrm{~mol}^{-1} ; \mathrm{Br}=80 \mathrm{~g} \mathrm{~mol}^{-1}\))
1. \(34.04 \%\)
2. \(40.04 \%\)
3. \(36.03 \%\)
4. \(38.04 \%\)

9. The major product P of the following reaction is:

1.		2.
3.		4.

10. Select the correct order of basicity for the following compounds:

1. (iv) > (iii) > (ii) > (i)
2. (ii) > (i) > (iv) > (iii)
3. (i) > (ii) > (iv) > (iii)
4. (iii) > (ii) > (i) > (iv)

11. How many of the following statements are correct?

I.	An organism with a high intrinsic rate of natural increase (r) has the ability to multiply rapidly under optimal environmental conditions.
II.	Verhulst-Pearl logistic growth is described by the equation dN/dt = rN(K-N)/K, where K represents the carrying capacity of the environment.
III.	Predation acts as a conduit for energy transfer across trophic levels and helps maintain species diversity by reducing intense competition among prey species.
IV.	In brood parasitism, the parasitic bird lays eggs with different color and size patterns compared to the host's eggs to ensure better survival of its offspring.
V.	Mycorrhizae represent a mutualistic association where the fungus absorbs nutrients from soil and provides them to the plant, while the plant provides energy in the form of food to the fungus.

1. Two
2. Three
3. Four
4. Five
 

12. How many of the following statements are correct?

I.	Interferons are a type of antibody secreted by virus-infected cells that protect non-infected cells from further viral infection.
II.	Active immunity is slow and takes time to develop its full effect, while passive immunity is fast-acting but short-lived, as seen in colostrum providing antibodies to newborns.
III.	The life cycle of Plasmodium involves sexual reproduction in the human host and asexual reproduction in the female Anopheles mosquito.
IV.	Cancerous cells are characterized by contact inhibition property and undergo controlled cell division regulated by normal growth factors.
V.	Morphine is extracted from the latex of the poppy plant Papaver somniferum and acts as a depressant, slowing down body functions.

1. One
2. Two
3. Three
4. Four

13. How many of the following statements are correct?

I.	Primary productivity is defined as the amount of biomass produced per unit area over a time period by plants during photosynthesis, and gross primary productivity (GPP) minus respiratory losses (R) gives net primary productivity (NPP).
II.	In a terrestrial ecosystem, detritus food chain begins with dead organic matter and is made up of decomposers which are mainly bacteria and fungi, and this detritus food chain may be connected with grazing food chain at some trophic levels.
III.	The pyramid of energy is always upright and can never be inverted because energy transfer follows the second law of thermodynamics with only 10% energy being transferred to each successive trophic level.
IV.	Phosphorus cycle is a sedimentary cycle where the main reservoir is rock, and unlike nitrogen and carbon cycles, the phosphorus cycle does not have any atmospheric component.
V.	Secondary productivity is defined as the rate of formation of new organic matter by consumers and decomposers, and it is always higher than primary productivity in any given ecosystem.

1. One
2. Two
3. Three
4. Four

14. Evaluate the following two statements:

Statement I:	HIV has a very high rate of mutation during replication because its reverse transcriptase enzyme lacks proofreading ability, and this high mutation rate is the primary reason why HIV-infected individuals do not develop effective immune responses despite having a functional immune system.
Statement II:	The decrease in T-helper lymphocyte count in AIDS patients leads to immunodeficiency because these cells activate both cell-mediated and humoral immune responses, and their depletion prevents the body from mounting coordinated immune defence against pathogens.

Which of the following is correct?

1.	Statement I is correct, Statement II is correct
2.	Statement I is correct, Statement II is incorrect
3.	Statement I is incorrect, Statement II is correct
4.	Both statements are incorrect

15. Bt brinjal, genetically modified to express a toxin from Bacillus thuringiensis targeting the fruit and shoot borer, was developed to reduce pesticide use and increase yield. In India, its commercial release sparked intense debate. Proponents highlighted reduced insecticide sprays and higher farm income, while opponents raised concerns about potential cross-pollination with wild brinjal relatives, long-term soil health impacts, and corporate control over seeds.
The controversy surrounding Bt brinjal’s release in India primarily revolves around which fundamental conflict in agricultural biotechnology?

1.	The immediate benefit of decreased pesticide use versus the potential long-term ecological and health consequences.
2.	The promise of higher yields and farmer profits versus the risk of reduced genetic diversity in cultivated brinjal varieties.
3.	The need for food security through advanced technology versus the preservation of traditional farming practices and crop lineages.
4.	The advantages of insect-resistant crops versus the ethical concerns regarding patent control and seed sovereignty.

16. Bacterial cells are made "competent" by treating them with divalent cations (Ca²⁺) followed by heat shock to enable plasmid DNA uptake.
What is the primary molecular mechanism enabling DNA uptake?

1.	Divalent cations permanently damage the cell wall creating pores for DNA diffusion, while heat shock denatures membrane proteins blocking DNA entry.
2.	Divalent cations cause DNA aggregation into condensed structures for easier penetration, while heat shock triggers bacterial SOS response increasing membrane permeability
3.	Divalent cations activate membrane transport proteins that actively pump DNA across using ATP, while heat shock increases membrane fluidity.
4.	Divalent cations neutralise negative charges on both cell membrane and DNA backbone reducing electrostatic repulsion, while heat shock creates transient membrane pores.

17. Evaluate the following two statements:

Statement I:	RNA interference involves silencing of specific mRNA molecules using complementary double-stranded RNA sequences, and this mechanism was first discovered in plants as a defence against viral infections, later found to be a natural gene regulation mechanism in eukaryotes.
Statement II:	The technique of RNA interference has been successfully used to develop transgenic plants resistant to nematode infections by introducing genes that produce dsRNA complementary to nematode genes, causing silencing of essential nematode genes when the parasite feeds on the plant.

Which of the following is correct?

1.	Statement I is correct, Statement II is correct
2.	Statement I is correct, Statement II is incorrect
3.	Statement I is incorrect, Statement II is correct
4.	Both statements are incorrect

18. A researcher uses EcoRI to cut both a plasmid vector and a foreign DNA fragment, then ligates them together.
Why is using the same restriction enzyme for both vector and insert DNA essential for recombinant DNA formation?

1.	It ensures both DNAs are cut at the same rate, preventing over-digestion of one molecule while the other remains uncut, which would make ligation impossible.
2.	It produces complementary sticky ends on both DNAs, enabling base pairing between overhangs that positions fragments for DNA ligase to seal phosphodiester bonds.
3.	It creates blunt ends with matching 5'-phosphate and 3'-hydroxyl groups, allowing direct end-to-end joining without requiring complementary sequences.
4.	It ensures both DNAs have identical palindromic sequences flanking cut sites, which DNA ligase recognises to bind both molecules simultaneously during ligation.

 

19. A pond ecosystem shows:

• GPP = 12,000 kcal/m²/year
• Respiratory losses by producers (R) = 7,000 kcal/m²/year
• Energy to primary consumers = 500 kcal/m²/year

Which statement MOST accurately interprets this data?

1.	NPP is 5,000 kcal/m²/year; the 10% energy transfer to consumers indicates a healthy ecosystem, with the remaining 4,500 kcal/m²/year lost as heat during herbivore metabolism.
2.	NPP is 5,000 kcal/m²/year; only 500 kcal/m²/year reaches consumers, indicating 4,500 kcal/m²/year of plant biomass is not consumed and enters the detritus food chain.
3.	High respiratory losses (58% of GPP) suggest stressed conditions, while low transfer to consumers (4.2% of GPP) indicates inefficient herbivory or competitive exclusion.
4.	Primary consumers utilise 10% of GPP directly; the remaining 90% is either respired by plants or lost as heat, consistent with the second law of thermodynamics.

 

20. How many of the following statements are correct?

I.	Methanogens like Methanobacterium are found in the aerobic sludge during sewage treatment and produce methane from the organic matter.
II.	Cyclosporin A, produced by the fungus Trichoderma polysporum, is used as an immunosuppressive agent in organ transplant patients.
III.	Lactobacillus converts milk into curd by producing lactic acid during fermentation, which coagulates and partially digests the milk proteins.
IV.	The flocs formed during secondary sewage treatment consist of masses of bacteria associated with fungal filaments to form mesh-like structures.
V.	Rhizobium forms symbiotic association with roots of leguminous plants and fixes atmospheric nitrogen, while Azospirillum and Azotobacter are free-living nitrogen-fixing bacteria.

1. One
2. Two
3. Three
4. Four