Question 20 – Practical skills assessed in a written examination - Questions

An agricultural scientist wanted to estimate the total number of viable fungal spores (Fusarium oxysporum) in a 60 cm³ soil suspension. They carried out the following two serial dilutions:

0.5 cm³ of the original suspension was mixed with 14.5 cm³ of sterile distilled water to make Solution B.
2 cm³ of Solution B was mixed with 8 cm³ of sterile distilled water to make Solution C.

The scientist transferred 0.15 cm³ of Solution C onto a growth medium plate. After incubation, 42 distinct fungal colonies grew on the plate.

Calculate the estimated number of fungal spores in the original 60 cm³ soil suspension.

Express your answer in standard form to three significant figures. Show your working.

An agricultural scientist wanted to estimate the total number of viable fungal spores (Fusarium oxysporum) in a 60 cm³ soil suspension. They carried out the following two serial dilutions:

0.5 cm³ of the original suspension was mixed with 14.5 cm³ of sterile distilled water to make Solution B.
2 cm³ of Solution B was mixed with 8 cm³ of sterile distilled water to make Solution C.

The scientist transferred 0.15 cm³ of Solution C onto a growth medium plate. After incubation, 42 distinct fungal colonies grew on the plate.

Calculate the estimated number of fungal spores in the original 60 cm³ soil suspension.

Express your answer in standard form to three significant figures. Show your working.

Practical skills assessed in a written examination

Question 18

Practical skills assessed in a written examination

Question 18

Practical skills assessed in a written examination

Question 18

Practical skills assessed in a written examination Questions

Practical skills assessed in a written examination

Question 18

Practical skills assessed in a written examination Questions