Question

4-17 Microscopes have come a long way since their invention centuries ago. Nevertheless, ask your instructor why many colleges tend to hold onto their older scopes rather than purchase new instruments (beyond the issue of cost). Clue: It's all about the glass! 4-18 Complete the summary table comparing the features and functions of the compound and dissecting microscopes. Attribute/Characteristic: Compound Microscope Dissecting Microscope Binocular function Magnifying power of eyepiece

Answer 1

Ans 17: Many people tend to stick to older microscopes rather than purchasing a newer one because older microscopes are very robust and durable also the optics with which they are supplied are also very premium in nature. Newer microscopes, although they have advance technologies such as cameras and all but they lack that unique vintage charm that the older microscopes had. The quality of older microscopes are much better and superior than than of newer microscopes and remains durable for a very long period of time. Because of cost cutting reasons newer microscopes are made up of cheap and plastic materials which make it wobbly and a bad user experience. The lenses that were used on the older microscopes are something to cherish. The objective, eyepiece, condenser lenses provides much more better magnification and resolution hence detailed observation of the specimen than the microscopes of newer age. In older days lenses were made with extreme precision and care which resulted in long lasting and better quality of the lenses. Today such good quality lenses are difficult to find.

Ans 18:

CHARACTERISTIC	COMPOUND MICROSCOPE	DISSECTING MICROSCOPE
BINOCULAR FUNCTION	Yes (newer models)	Yes
MAGNIFYING POWER OF EYE PIECE	10X	10X
RANGE OF OBJECTIVE POWER	10X, 40X and 100X	7X (some models have 10X)
TOTAL MAGNIFICATION POWER	1000X	70X
FINE FOCUS CAPABLE	Yes	No
INVERTED IMAGE	Yes	No
CONDENSED/IRIS PRESENT	Yes	No
SIZE OF WORKING DISTANCE	4 mm	150 mm
TYPES OF ILLUMINATION AVAILABLE	Source of light is present below specimen and light passes through the specimen.	Source of light is present above the specimen. Specimen is viewed by the reflected light.
APPROPRIATE APPLICATIONS	Study cells, microorganisms like bacteria, yeast, fungus etc	Study and Dissection of large specimen, micro-surgeries etc.

Ans 15: Animal cells, since they lack cell wall, they are required to be maintained in isotonic conditions that is the solute concentration of the external medium must be similar to that of the solute concentration of the cell cytoplasm so that there is no net movement of water in and out of the cell through semipermeable membrane.