141.

The most important property of any microscope is its power of resolution, which is numerically equivalent to D, the minimum distance between two distinguishable objects. D depends on three parameters namely, the angular aperture, α, the refractive index, N, and wavelength, λ,of the incident light. Below are given few possible options to increase the resolution of the microscope.

A. Decrease the value of λ or increase either N or α to improve resolution.

B. Moving the objective lens closer to the specimen will decrease sin α and improve the resolution.

C. Using a medium with high refraction index between the specimen and the objective lens to improve the resolution.

D. Increase the wavelength of the incident light to improve the resolution.

Which of the following combination of above statements is correct?

• A and C

• B and C

• A and D

• C and D

In an animal experiment,

(i) Electrical stimulation of an area in the brain (A) increased a function (F) which was prevented by systemic injection of adrenergic antagonistic, prazosin.

(ii) Injection of carbachol (cholinergic agonist) into A also increased function F which was, however, not prevented by systemic injection of adrenergic antagonistic, prazosin.

The results are likely to be due to stimulation of

• Nonadrenergic and cholinoceptive neurons

• Cholinergic and non-adrenoceptive neurons

• Adrenergic terminals in ‘A’

• Both neurons and fibres passing through A  

T-cell proliferation in vivo is to be analyzed. The cells are labeled with CFSE (a fluroscent probe) and injected in CD86-deficient mice and BALB/ c mice along with the required antigens. Three days later, the cells are recovered and analyzed by flow cytometry. Which one of the following is logically correct?

In the following statement taken from a research paper, what does p in the parenthesis stand for?

“The mean temperature of this region now is significantly higher than the one 50 years ago (p < 0.05, t – test)”.

• Ratio of the mean temperatures of the two time periods tested.

• Probability of the error of rejecting a true null hypothesis.

• Probability of the error of accepting a false null hypotheis.

• Probability of the t-test being effective in detecting significant differences in the mean annual temperatures of the two time periods.   

Which of the following behavioural changes are expected in a rat when its nucleus accumbens is experimentally ablated?

• Aggressive behaviour increases

• Explaoratory behaviour decreases

• Nest-building activity increases

• Level of parental care drops