Question

Which of the following statements is/are true?
A. The resolution power of unaided human eye is 100 micrometre.
B. The highest resolution is obtained with the light of shortest wavelength.
C. Dark field microscope is most useful for viewing the living cells.
D. Chromatography is the method of separation of molecular components of the cells present in cytosol.
E. ln gel filtration chromatography, molecules can be separated in picogram to nanogram quantities.

• A. A, C and D only
• B. B and D only
• C. C and E only
• D. C, D and E only
• E. A, B and D only

Answer 1

Answer: (E)

Resolving power is the ability to distinguish two close objects as distinct. Its value is calculated by Abbe equation; resolving power = 0.61 (wavelength of light used)/ NA; where NA is numerical aperture. NA is the light collecting ability of the lens. It is multiple of refractive index of medium and sine of angle subtended by optical axis and outer ray covered by objective. Resolution power of unaided human eye works out to be 100 micro meter or 0.1 mm. As per formula, lower the wavelength of light higher will be the resolution.
Chromatography is the technique of separating molecular components of a mixture or colloid by using the principle of partition coefficient due to which molecules move at different rates through a stationary phase and get separated. A certain amount of material is required for separation. The gel filtration technique is not sensitive enough to separate pico and nano gram quantities.
Dark field microscopy is usually used to study surface features of microorganisms and cell organelles.