Petri dishes are inverted during incubation to prevent condensation from falling into the microbes, thereby contaminating samples. Condensation in Petri dishes causes bacterial samples to spread and potentially mix with each other. Warm incubators tend to attract more condensation, so the dishes are inverted. Inversion allows water to drip down onto the lid, away from the agar, rather than onto bacteria.Know More
Inversion also prevents contamination of other bacteria in the samples, in case Petri dishes were not thoroughly cleaned or other microbes happened to contaminate samples. Petri dishes can be stored up to three months in cold storage before use in an incubator.
Inverted Petri dishes also minimize the evaporation of water used to grow the samples sealed in the containers. Dishes are sealed with tape so that lids do not fall off when the inversion occurs, and the tape can be written on for labeling purposes. The apparatus can also be stacked for easy storage in an incubator.
Petri dishes were invented in 1887 by German physician Julius Petri. He improved upon the design of his mentor, Dr. Robert Koch, by inventing a small plate that has a slightly larger plate that fits over it to create smaller samples for bacterial growth. The plate allowed samples in growth media to be more easily observed under a microscope without cross-contamination from other samples. Previously, glass plates were kept under a bell jar.Learn more about Biology
A Petri dish is a shallow dish that is used to culture microorganisms. By mixing different ingredients, such as blood, salts, amino acids or bacteria, together with an agar (or medium), scientists are able to observe reactions and watch microorganisms grow and develop.Full Answer >
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An inverted or retroverted cervix typically occurs when a woman has a tilted uterus in which the angle of the uterus is abnormal. According to Women's Health Magazine, about 30 percent of women have a tilted uterus, and therefore have an inverted cervix. According to HealthTap, this condition rarely causes complications with pregnancy.Full Answer >
The inverted bob, also called a graduated bob, is a hair style that is shorter in the back and longer in the front. Inverted bobs have layers in the back to create a stacked look.Full Answer >