Question

What is a petri dish and how do scientists use them?

Answer 1

Hint: A petri dish is a circular dish made of glass or plastic and with a loose-fitting cover, used in culturing cells. In cell and microbiological techniques, Petri dishes are one of the most common equipment in laboratories.

Complete answer:
Petri dish is a shallow cylindrical, round glass that is used in laboratories to culture different microorganisms and cells. Petri plate was invented by a German bacteriologist named Julius Richard Petri.
Petri dishes are used to support the growth of microorganisms and it is the best choice for a culture medium plate.

The dish is used to culture cells by providing storage space and preventing them from getting contaminated.
Petri dishes are transparent, so it is easy to observe the growth stages of microorganisms clearly.
The size of the Petri dish enables it to be kept under the microscope directly for observation without the need to transfer it onto a microscopic plate.

Petri dish is also used in schools and colleges for activities like the observation of seed germination.
Before using a Petri dish in the laboratory it should be sterilized well.

To observe the growth of bacteria, first the dish is filled with agar medium (prepared with the help of red algae).
Petri dishes are stored in the refrigerator in an upside-down position.
To make culture plates, remove the petri dishes from the refrigerator and use them once they are back at room temperature.
A sample of bacteria or any other microorganism is taken and slowly poured on the agar medium or a cotton swab is used to apply the bacteria on the agar medium in a zigzag manner.
Then the Petri dish is covered with a lid and stored at appropriate temperature for a few days and the sample of bacteria are allowed to grow. After one or two days, the bacterial sample will be ready for further research.

Note: Agar medium contains nutrients, blood, salt, indicators, antibiotics, etc. that help in the growth of microorganisms. A sample of bacteria or any other microorganism is taken and slowly poured on the agar medium or a cotton swab is used to apply the bacteria on the agar medium in a zigzag manner.