Stationary phase describes which phase of the growth curve t

Stationary phase describes which phase of the growth curve to the right? a. A b. B c. C d. D e. all of the above Generation time is: a. equal to the growth rate b. the time it takes for a cell population to double in size c. the time it takes for a population to enter stationary phase d. the time it takes for a population to enter exponential growth phase Bacteria use siderophores to transport: a. glucose b. protons c. iron d. the transported substrate depends upon the structure of the siderophore The _____ oxidizes NADH to produce proton motive force. a. Pentose phosphate pathway b. Glycolysis pathway c. B-oxidation pathway d. Electron transport chain Radiation kills bacteria by the same mechanism that _____ kills bacteria. a. heat b. acidity c. pressure d. dessication

Solution

Answer:

1. Stationary phase describes which phase of the growth curve to the right?

Answer c(C)

Explanation: Phase A in the graph represents the lag phase where little to no cell division occurs and cells are metabolically very active. Phase B in the graph is log or exponential growth phase and in this phase cells divide and grow exponentially. Next phase C is stationary phase where the growth rate slows down and is balanced out by death rate. Phase D in graph is the dearth phase where the cell population steadily declines from toxic buildup or starvation.

2. Generation time is

Answer b – the time it takes for a cell population to double in size.

3. Bacteria uses siderophores to transport

Answer: c – iron

Explanation: Microorganisms like bacteria acquire iron by producing Siderophores which are low molecular weight iron chelating molecules. Siderophore forms complex with free iron and transport it in the cell.

4. The ___________ oxidize NADH to produce proton motive force

Answer: d - Electron transport chain

Explanation: The NADH formed during the process of glycolysis, beta oxidation and Tricarboxylic acid cycle gets oxidized during Electron transport chain to produce proton motive force.

(The proton gradient generated by NADH oxidation is called proton motive force).

5. Radiation kills bacteria by the same mechanism that _____________ kills bacteria.

Answer a – heat

Explanation: Microwave energy gets absorbed by cell molecules causing them to vibrate fast and produce heat (thermal effects)