BIOD 171/Microbiology Lab 2 Exam Portage Learning ( A+ GRADED 100% VERIFIED)

BIOD 171/Microbiology Lab 2 Exam Portage Learning ( A+ GRADED 100% VERIFIED) brightfield microscopy - answerobjects are dark and the field is light; can be used to observe unstained microorganisms phase-contrast microscopy - answersmall differences in the refractive properties of the objects and the aqueous environment are transformed into corresponding variations of brightness diffracted - answerin phase-contrast microscopy the ring of light passes through the object causing light rays to diffract (bend) Brownian movement - answernot true motility of microbe; movement is caused by the molecules in the liquid striking an object and causing the object to shake or bounce wet-mount technique - answer1. suspend infusions by stirring them carefully. 2. use Pasteur pipette to transfer small drop or use inocculating loop 3. handle coverslip carefully by edges and place on drop 4. view slide on low (10x), adjust iris, concentrate on larger moving organisms. bacteria is visible as tiny dots 5. examine on high dry (40x) increase light and focus 6. record observations hanging-drop procedure - answer1. obtain clean handing drop (depression) slide 2. pick up small amount of petroleum jelly 3. pick up coverslip and carefully touch jelly with an edge of coverslip to get a small rim of jelly 4. place the coverslip on papertowel, jelly side up 5. add loopful of infusion to coverslip 6. place depression slide (well-side down) over drop and quickly invert 7. examine under low power, reduce light with iris and focus 8. switch to high-dry and record observations 9. do not use oil immersion phase-contrast microscopy - answer1. make a w