Tag: microscope

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Multiple choice botany cell and cellular organization cell theory microscope cell and its discovery

Fluorescent screen or photographic plate is used for observation in

  1. Electron microscope.

  2. Fluorescent microscope.

  3. Ultraviolet microscope.

  4. All of the above.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In electron, fluorescent, and ultraviolet microscopes, the light or radiation used is often invisible to the human eye, requiring a fluorescent screen or photographic plate for detection.

Multiple choice botany cell and cellular organization cell theory microscope cell and its discovery

In which of the following microscopes direct observation is not possible?

  1. Compound microscope

  2. Dark field microscope

  3. Phase contrast microscope

  4. Ultraviolet microscope
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Ultraviolet light is invisible to the human eye, so direct observation through an eyepiece is not possible; the image must be captured on a photographic plate or digital sensor.

Multiple choice botany cell and cellular organization cell theory microscope cell and its discovery

Fluorescent microscope employs

  1. UV rays

  2. Visible light

  3. Beam of electrons

  4. Both A and B.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Fluorescence microscopy relies on the excitation of fluorophores using high-energy light, typically UV or blue light, to emit visible light. Therefore, it utilizes both UV rays for excitation and visible light for the resulting emission.

Multiple choice botany cell and cellular organization cell theory microscope cell and its discovery

Lenses used in ultraviolet microscope are

  1. Glass lenses.

  2. Quartz fluorite.

  3. Lithium fluoride.

  4. Both B and C.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Standard glass lenses absorb ultraviolet light, making them unsuitable for UV microscopy. Quartz and fluorite are transparent to UV radiation, so lenses made from these materials are used instead.

Multiple choice botany cell and cellular organization cell theory microscope cell and its discovery

Stop disc is meant for

  1. Blocking light.

  2. Stopping objective in pressing slide.

  3. Altering light rays.

  4. Splitting light rays.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A stop disc (or dark-field stop) is placed in the condenser to block the central light rays, allowing only oblique rays to strike the specimen. This creates the dark-field effect where the specimen appears bright against a dark background.

Multiple choice botany cell and cellular organization cell theory microscope cell and its discovery

Stop disc is used in which microscope?

  1. Compound light microscope

  2. Differential interference contrast microscope

  3. Dark field microscope

  4. Phase contrast microscope
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A stop is an opaque object that blocks the central light when placed underneath the stage condenser. This also causes light to scatter in all azimuths, resulting in a cone of light that allows for dark field observation.

So C is correct option. 

Multiple choice botany cell and cellular organization cell theory microscope cell and its discovery

Detailed structure of biological molecules can be known with the help of _____________.

  1. Atomic force microscope.

  2. Scanning probe microscope.

  3. Scanning tunneling microscope.

  4. All of the above.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Atomic force microscopy (AFM) is a type of scanning probe microscopy capable of imaging surfaces at the atomic level, providing detailed topographical information about biological molecules.

Multiple choice botany cell and cellular organization cell theory microscope cell and its discovery

A living cell can be best studied by the means of______________.

  1. Dark field microscope.

  2. Electron microscope.

  3. Phase-contrast microscope.

  4. Compound microscope.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Phase Contrast Microscope was developed by Zernike. The microscope has a phase plate and an annular diaphragm. They bring about changes in light rays passing through the specimen producing differences in light intensity. Denser parts alter path of light more than the thinner parts. This produces varying contrast for different regions. Hence, staining is not required and the difference between denser and lighter parts of the specimen is revealed by the phase difference. The microscope is useful in the study of small living organisms, living cells, constituents of living cells, effect of various factors over living structures, and study of various cellular events like behaviour of chromosomes during mitosis and meiosis, spindle formation, cytokinesis, pinocytosis, phagocytosis, cyclosis, glandular secretions, spermatogenesis, oogenesis etc.

So C is the correct option. 

Multiple choice botany cell and cellular organization cell theory microscope cell and its discovery

Fluorescent microscope uses _______________.

  1. UV radiations.

  2. Complementary filters.

  3. Annular diaphragm.

  4. Both A and B.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Fluorescence microscopes use UV or blue light to excite samples and require specific filters (like excitation and emission filters) to isolate the wavelengths of light, which are often referred to as complementary filters.