18. rnai is a technique that silences genes by targeting them and degrading their mrna. how can this technique be used in scientific laboratories? a. rnai is observed in nature, but it can't be used in laboratories. b. rnai allows scientists to turn off one gene specifically to study its effect. c. rnai has been used in laboratories to make bacteria more susceptible to antibiotics, but has limited application in eukaryotic cells. d. rnai is a powerful tool for degrading mrna, but because it doesn't degrade other types of rna, its use is limited.

Which of the following best describes the relationship between glucose and complex molecules such as hormones?

Astudent from one of the research labs is having trouble preparing a slide for examination and photographing. the bacterial slide that he has brought to you was prepared using a commercially purchased stain. he has asked for your in determining what he is doing wrong so that he can change the lab protocols and continue on with his project. after examining the slide under oil immersion, you determine that no bacteria are present even though the student is able to show you the culture he used to make that slide that has visible growth in the liquid medium. which of the following statements does not explain the fact that there are no bacteria present on the student’s slide? by not allowing a glass slide to completely air dry before heat fixation, the flame will cause the surrounding water to boil and this will damage the bacterial cell. overheating during the fixation step boiled the water within the bacterial cells and resulted in the cells bursting. insufficient heating of the slide did not drive out the thin layer of water and this resulted in minimal bonding between the bacteria and the glass slide. rinsing with alcohol during the washing step stripped the bacteria off the glass slide. rinsing with alcohol during the washing step stripped the bacteria off the glass slide.

Will ! a cell containing a 3% sucrose solution is placed into a beaker containing a 7% sucrose solution. assume the cell’s membrane is permeable to water, but not permeable to the sucrose. where will the water diffuse? explain.