Question

questions 2 and 3 please with work

1.1 point) In the image above, the final dilution is 1: 100,000,000 (10^8) 10 ml 100 90 m 9.0 ml 19 2. (1 point) in the image above, the final dilution is 1: 3. (1 point) What are two reasons serial dilution is a useful technique for counting populations of bacteria? Original

Answer 1

As per request only questions 2 & 3 are answered.

2) We know that, dilution factor = Volume of stock solution taken/ Final volume

At first 1 mL of stock solution is transferred from flask to the first tube which contains 9 mL of diluent.

So, the final volume of first tube = (1 + 9) mL = 10 mL

So, individual dilution factor of first tube = 1/10

Next, 1 mL of solution is transfer from first tube to the second tube which contains 9 mL of diluent.

So, the final volume of second tube = (1 + 9) mL = 10 mL

So, individual dilution factor of second tube = 1/10

But overall this is second dilution.

So, total dilution factor (TDF) of second tube = 1/10 x 1/10 = 1/100

Similarly, all tube will have individual dilution factor of 1/10.

So, final dilution factor of last tube (Total dilution factor of last tube) = 1/10 (For first tube) x 1/10 (For second tube) x 1/10 (For third tube) x 1/10 (For fourth tube) x 1/10 (For last tube) = 1/100,000 (10⁵)

So, answer will be 100,000 (1: 100,000).

3) Advantages of serial dilution-

• Since, dilution fold is same in each step, it is easier to make without unnecessary complication.
• We can easily find cell concentration of a particular tube or original culture from the colonies cultured from a serial dilution tube.