growth curve Flashcards
How many phases are in the growth curve of bacteria?
5 phases
Name all five phases in the growth curve
lag phase (A), log phase (B), stationary phase (C), decline phase (D), survival phase (E)
Name and explain the first phase in the growth curve
lag phase (A): Bacterial numbers remain constant. They are adapting to the new environment.
What may the bacteria be doing in the first phase (lag phase)
They may be producing new enzymes to digest the nutrients on which they grow.
Name and explain the second phase in the growth curve
log phase (B): The bacterial numbers increase rapidly. They are reproducing at their maximum rate. The number of bacteria is doubling in every new generation. This is a result of ideal conditions.
What are the two names for the second phase?
The log phase and the exponential phase
Name and explain the third phase in the growth curve
stationary phase (C):
There is no increase in bacterial numbers.
The production of new bacteria is compensated for by the death of equal numbers of bacteria.
In phase C, what factors cause the rate of growth to slow down.
lack of food, lack of space, lack of moisture, lack of oxygen, the build-up of toxic waste products
Name and explain the fourth phase in the growth curve
Decline/death phase (D):
The number of bacteria falls rapidly.
Bacteria numbers fall when the death rate is greater than the rate of reproduction.
In phase D, what causes the slow rate of reproduction?
The slow rate of reproduction is caused by the same factors that caused the stationary phase.
Name and explain the fifth phase in the growth curve
Survival phase (E): A small number of bacteria survive by remaining dormant as spores. Spores can survive for a long time by remaining dormant until conditions are suitable again.
How do spores survive in the survival phase?
Spores can survive for a long time by remaining dormant until conditions are suitable again.
