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You have a pure culture of a given bacterium, and you want to determine its CFU, so you perform the following steps: Take 1 mL from the pure culture and add it to 9 mL of sterile saline in test tube 1; mix. Take 0.1 mL from test tube 1 and add it to 9.9 mL of sterile saline in test tube 2; mix. Take 0.1 mL from test tube 2 and add it to 9.9 mL of sterile saline in test tube 3; mix. Take 0.1 mL from test tube 3 and add it to the surface of a solid medium in a plate using the spread-plate method. Repeat step 4 using a second plate to obtain a duplicate. Incubate for 24 hours. After incubation, you count 178 colonies on one plate and 165 colonies on the other. What is the calculated CFU of the original pure culture?

Consider the following image showing the electron transport chain complexes that can be found in Escherichia coli.    Knowing that ATPase needs approximately 3.3 H+ to make 1 ATP molecule, how many more ATP molecules per NADH will be produced by E. coli when oxygen is used as the final electron acceptor compared to nitrate.

Bacteria can have positive, neutral, or negative effects on humans and other macroorganisms. Which of the following would be a negative association?  

Which of the groups listed below are prokaryotes that tend to be found in more extreme environments and are therefore commonly known as extremophiles?

Consider the following chemical reaction:  C6H12O6 + 6O2 → 6CO2 + 6H2O  ΔG’ = -686 kcal/mol Which of the following statements is correct?

Arrange Koch’s postulates in the correct order.

5.2 Waarom gebruik die digter die Engelse rekenaarterm as titel van die gedig? (1)

Imagine a cell membrane that is permeable to Cl- The membrane potential is initially – 55 mV. The equilibrium potential for chloride is -60 mV. There is a higher concentration of Cl- ions outside than inside the cell.

In a  resting membrane , what is the state of various channels in the membrane?

Of the choices provided, what the 2nd step in the sequence of events that occur when you spin in a chair?