1. where do the secondary electrons in a scanning electron microwcope come from?
ID: 163736 • Letter: 1
Question
1. where do the secondary electrons in a scanning electron microwcope come from?
A)Electrons from the specimen
B) Electron collector
C) Electron magnetic Fields
D) Electron Gun
2. when its anion has color, a salt dissolves in water as?
A) Basic Dye
B) special stain
C) acidix dye
D) a neutral dye
Use similiaritus or differences to choose how many of the siz kingdoms habe the cellular characteristics described in the next three questions? (note: you nay use any answers (A-D) more than an once if applicable)
A) applies to only one.
B) applies to two kingdoms
C) Applies to four of the six
D) none (does not apple to any)
3. the same kingdom has both unicellular organisms (choose from A-D above from above)
4. both animal and plant cell platforms can be found in this kingdom (choose A to D from abobe)
5. the same kindom includes both prokaryotic and eukaryokic organisms (choose A to D from above)
True or false Read the statement and choose below
6. Reduced aperture size of an objective lens improves resolution.
7. the cell theory states that all cells have cytoplasm.
8. regardless of its final color, the cation of a dye comes from a baze.
9. illumination with a longer wavelength reveals more details.
10. the final image produces by an electron microscope has no color and its always blacm.
11. Protista have prokaryotic cells.
12. A build in fluorescent screen, for viewing the final image, is presenf in a transmission electron microscope, but is absent from a fluorescence microscope
13. Eubacteria are eukaryokic organisms
14. Chromosome is the?
A) genetic material of the cell
B) pigment that makes blood cells red
C) ion that gives color to a dye
D) organelle that carries out photosynthesis
15. every cell has
A) cell wall
B) organelle
C) nucleus
D) plasma membrane
16. the net effect of refraction is to
A) block light and make background dark
B) change the direction of light
C) absorb light
D) cauze transmitted light travel straight
Explanation / Answer
1.A)Electrons from the specimen
The electrons produced by the electron gun are guided and focused by the magnetic lenses on the specimen.the focused beam of electrons is then scanned across the surface in a raster fashion.This scanning is achieved by moving the electron beam across the specimen surface by using deflection/scanning coils.The number of secondary electrons produced by the specimen at each scanned point are plotted to give a two dimensional image.In principle,any of the signals generated at the specimen surface can be detected.Most electron microscopes have the detectors for the secondary electrons and the backscattered electrons.As backscattered electrons come from a significant depth within the sample,they do not provide much information about the specimen topology.
2.C) acidic dye.The color of the salt is the characteristic of the cation or anion.Basic dyes are water-soluble cationic dyes.Acidic dye salts are anionic.
3.b)Two KINGDOMS HAVING UNICELLULAR ORGANISMS
4.a) both animal and plant cell platforms can be found in this kingdom-protists
5. a)the same kindom includes both prokaryotic and eukaryokic organisms-monera
6.false
For resolution to occur,at least the direct beam and the first-order diffracted beam must be collected by the objective.If the lens aperture is too small,only the direct beam is collected and the resolution is lost.
7.true
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