Stages of the population growth graph
- Created by: Sophia Dowden
- Created on: 29-05-16 15:47
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- Stages of the population growth graph
- Lag Phase
- 1. Small number reproducing because time needed to:
- Activate genes
- Synthesis of enzymes for the medium they are in
- Remember that , if organisms are in an complex growth medium e.g. xylose or sucrose rather, glucose
- Cells are growing in size before reproducing
- Proteins are made e.g. photosynth. e.g. enzymes.
- 1. Small number reproducing because time needed to:
- Log Phase
- Maximum growth rate
- Growth is exponential i.e. numbers double i constant time periods/every generation
- There are no limiting factors e.g. there is plenty of oxygen/nutrients and waste products aren't poisoning them yet.
- Stationary phase
- Growth rate /production is slow
- Limiting factors are in operation (nutrients/oxygen low or competition for them is very high/waste products of metabolism/toxins/extreme pH killing some cells.
- Number of new cells = number of dying cells
- Birth rate = death rate
- Carrying capacity
- Decline phase
- Death of cells exceeds production of new cells
- Waste products/toxin are rapidly killing cells
- Become overcrowded and starved of nutrients/oxygen.
- Occurs when all resources have been used up. e.g.nutrients - toxins
- Building up/space limited/ disease due to overcrowding
- Lag Phase
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