1. Simple optical microscope. One lens.
Disadvantage: Only Van Leeuwenhoek made them, and he's dead.
Advantage: Worked pretty well. With them, Van Leeuwenhoek discovered protozoa and bacteria.
2. Compound optical microscope. Has both an ocular and objective lens.
Disadvantage: limited resolution. Can resolve bacteria, but not smaller things like viruses.
Advantage: can be used with live specimens (using phase contrast or polarized or other special illumination).
3. Binocular dissecting microscope (optic). Has a pair of ocular and objective lenses, and supposedly presents a "3D" view of the specimen to the viewer (I was never able to see in 3D using these darn things).
Disadvantage: Limited magnification
Advantage: Can be used to perform surgery on small but not microscopic specimens, such as fruit flies. Is used in "microsurgery" in hospitals too.
Hope this helps buddy!
Answer:
Chitin.
Explanation:
The structure that is not a component of wall of sponges is Chitin. Their body comprise of calcareous or siliceous spicules or protein spongin fibres. Choanocytes are the distinctive cells located in the interior body walls of sponges. Sponges are similar to other animals in many characteristics such as they are multicellular, heterotrophic, lack cell walls and produce sperm cells in order to produce offspring sexually and also different from animals due to lack of tissues and organs.
Maintain homeostasis - eg. blood sugar control by insulin and glucagon.<span>
HOP THIS HELP GOOD LUCK:)</span>
I believe the correct term to fill in the blank would be pain. <span>Phantom limb sensations and other experiences of amputees show that the brain can produce pain in the absence of normal sensory input. Hope this answers the question. Have a nice day.</span>
