The following is a brief explanation of some ways of calculating dilutions that are common in biological science and often used at quansys biosciences. Most questions you will be asked to answer about serial dilutions are of two types. It is a common practice to determine bacterial counts for both liquid and solid specimenssuspensions of e. A site dedicated to learning about microbiology in the laboratory. This calculator is intended for laboratory scale applications although it can also be used for bigger scale applications as well. Dilutions are useful in science when making solutions or growing an acceptable number of bacterial colonies to count.
Molarity and serial dilutions teacher handout module overview one of the most important skills in science is to calculate dilutions. For this ph worksheet, students experiment with dilutions of acidic solutions to test for the ph using cabbage as an indicator. This lesson plan introduces the concept of serial dilutions in microbiology. How to perform serial dilutions in microbiology youtube. Serial dilution and food microbiology flashcards quizlet. Terms in this set 17 what device do we use for the direct count method. Simple dilution dilution factor method based on ratios a simple dilution is one in which a unit volume of a liquid material of interest is combined with an appropriate volume of a solvent liquid to achieve the desired concentration.
Each dilution will reduce the concentration of bacteria by a specific. A series of five dilutions is made of this first dilution by diluting it 110, rediluting 110, and then three times more, each resulting solution then being a 110 dilution of the previous one in the series. Bacterial dilutions and a foolproof way to figure them out look at the dilution scheme below. Note that serial dilution is a special case of series of dilutions.
Serial dilutions are often used in microbiology, biotechnology, and in chemistry classes, to name just a few. How to work microbiology dilution problems sciencing. Example problems and activities encourage students to apply the concepts learned in the video to practical scenarios. Dilution techniques and pipetting biology libretexts.
Dilutions are used many times during the semester in the microbiology lab, for a variety of purposes. Free gamified quizzes on every subject that students play in class and at home. This quiz and attached worksheet will help gauge your understanding of the properties of serial dilution. When a sample diluted 1100 is added to a sample diluted 1. Dilutions worksheet 1 if i add 25 ml of water to 125 ml of a 0. Serial dilutions are used extensively in biochemistry and microbiology. Find serial dilution lesson plans and teaching resources. Dilutions worksheet w 329 everett community college. I made this for my as biology students who dont take chemistry and needed some practice with serial dilutions before jumping straight into a full practical. Serial dilutions are commonly used in microbiology where the solution being diluted contains bacterial colonies. A set of serial dilutions is made, a sample of each is placed into a liquefied agar medium, and the medium poured into a petri dish. In the lab, correct dilutions of solutions are critical to performing accurate science.
Since the enumeration of microorganisms involves the use of extremely small dilutions and extremely large numbers of cells, scientific notation is routinely used in calculations. In microbiology, dilutions are usually reported as exponents. Dilutions worksheet w 329 everett community college student support services program 1 if 45 ml of water are added to 250 ml of a 0. The best way to fully grasp serial dilutions is to. Colonies grow within the agar, as well as on top of the agar. For example, when you are making orange juice from a frozen concentrate, you mix 1 can of concentrate with 3 cans of water. Dilution is the process of making a solution weaker or less concentrated. This manual, which explains the basic techniques necessary to carry out microbiology experiments safely and effectively, is intended as a guide for teachers and technicians. This is called a dilution series or a serial dilution.
Choose from 97 different sets of dilution microbiology flashcards on quizlet. There are three formulas used to work microbiology dilution problems. Microbiology is a popular option for practical work in schools. A serial dilution is a series of sequential dilutions used to reduce a dense culture of cells to a more usable concentration. A serial dilution is the dilution of a sample, in 10fold dilutions. Dilutions part 3 of 4 calculating colony forming unitsml. Answers serial dilutions practice worksheet biol 307. Serial dilution protocol pdf it is a method of diluting a stock solution where concentration decreases by the same quantity in each successive step. The first type gives you the number of bacterial colonies found on a plate and asks for the number of bacteria per ml in the original culture. This general microbiology practical lecture explains the serial dilution techniques in pour plate method to isolate bacteria. We could also have said the dilution factor was 110, or the dilution factor was 0. In microbiology, serial dilutions log dilutions are used to decrease a bacterial concentration to a required concentration for a specific test method, or to a concentration which is easier to count when plated to an agar plate.
The resulting serial dilution series has a dilution factor of approximately 1. We worked through the first example together on the board and the students did the dilution using coloured water. Topics you will need to know in order to pass the quiz. Serial dilution practice problem set the following problem sets test your ability to calculate dilution factors and concentration s dilution factor calculation.
Serial dilution, pour plates, and enumeration of bacteria introduction. When youre thinking about dilution, it helps to simplify your actions into dilution factors. Although invisible to the unaided eye, microbes play many important and beneficial roles in nature as well as within the human body. Serial dilution practice problem set science primer. The buffer is typically water, but it also can be other liquids, depending on the solution in test tube a. Pltw, mi unit 1 serial dilution practice quiz quizizz. A serial dilution is a dilution where a series of dilutions are conducted, each one may be onetenth as concentrated as the previous. When doing very high dilutions like 110,000 or 11,000,000, it is more accurate to do the dilution in a series of smaller dilutions rather than in one giant dilution. Since a great deal of experimental lab work in biology involves solutions, the ability to work with and manipulate them is very important. When we said the diluted coffee was 110th as strong as the original that was a dilution factor. Serial dilution worksheet bio152 paramedical microbiology 1. Lab math solutions, dilutions, concentrations and molarity. Start studying serial dilution and food microbiology.
A solution of lower concentration is made by diluting a calculated volume of a solution of higher concentration with solvent most commonly water up to a specified volume the volume of. Colonies grow within the agar, as well as on top of the agar and below the agar between the agar and the lower dish. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Pipetting and serial dilutions lab flashcards quizlet. Remember, there are many ways to make 110 and 1100 dilutions. This procedure is repeated until the desired concentration is reached. Karla fjeld demonstrates how to perform serial dilutions using microbiologics lyophilized qc microorganism pellets. Choose from 500 different sets of dilutions flashcards on quizlet.
The agar solidifies, with the bacterial cells locked inside of the agar. Dilutions worksheet awesome science teacher resources. A serial dilution is a series of sequential dilutions used to reduce a dense culture of cells to a more usable concentration tubes containing your diluting liquid in exact quantities a tube. There are many ways of expressing concentrations and dilution. Therefore, it is important that each person understand how to use the pipette, how to read the pipette accurately, and how to determine what dilution was produced. Colonies grow within the agar, as well as on top of the agar and below the agar b etween the agar and the lower dish. Answers serial dilutions practice worksheet biol 307 studocu. A very quick lesson on how to do the math for serial and simple dilutions.
Dilution worksheet and problems biology libretexts. The microbiology society, in association with the microbiology in schools advisory committee misac. Viable plate count and loop dilution microbiology lab. Serial dilutions are the culmination of a number of diluted tubes used in order to get smaller dilutions. Serial dilution worksheet bio152 paramedical micro. Use the following example of a series of dilutions and plating to answer the problems below. Determine the concentration or dilution factor for the flasks and plates. Dilution and concentration theory dilution and concentration theory sounds ominous but you use dilutions and concentrations fairly frequently outside of your scientific life. So, by calculating the total dilution over the entire series, it is possible to know how many bacteria you started with. You need to know the above equation, how to use it, and how to express dilutions as exponents.
Fill test tube a with 10 ml of the solution and fill test tube b with 9 ml of a buffer to dilute the original solution. Laboratory exercises in microbiology mclaughlin and petersen i. A series of five dilutions is made of this first dilution by diluting it 110, rediluting 110, and then three times more, each resulting solution then. In a serial dilution, the final total dilution is a product of each individual dilution in the series. Lesson objective after completing this lesson, you should be able to. Enumeration of microorganisms is especially important in dairy microbiology, food microbiology, and water microbiology. In this lab you will investigate several techniques for working with solutions. The dilution factor is the total number of unit volumes in which your material will be.
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