Problem 4 Growth rate in a batch culture of the freshwater diatom, Cyclotella me

Question

Problem 4 Growth rate in a batch culture of the freshwater diatom, Cyclotella meneghiniana, is studied under silicate-limiting conditions, unbuffered freshwater medium containing 25 ?? silicate is inoculated with cells. Samples are taken over a period of 4 days for measurement of cell concentrations. The results are shown below: a. Does this culture exhibit exponential growth? b. What is the value of umax? c. Is there a lag phase? Time Cell Concentration cells/1) 4.41E+05 5.53E+05 1.31E+06 3.00E+06 4.82E+06 1.12E+07 1.67E+07 2.57E+07 0 0.5 1.5 4

Explanation / Answer

First of all,

Cycostella meneghiniana ::- A freshwater diatoms having enclosure of silicon called frustle. For diatoms, silicon presence is unique feature.

Exponential growth::-formation of many and many cells in presence of plenty of sources like food,space,sanitation etc.

But in part A)

Above given culture is batch type and is with limited sources like 25 micromolar Silicon. So in batch culture only food,space is given once. So no exponential growth will be there. This will show S shaped growth curve.

C). Yes, Lag phase will be there because lag phase involves all enzymes and DNA replication and other preparation needed for cell division and it must be happened first then number of cells devides and growth occurs. So lag phase is necessary

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