6.4.8: Population growth in a closed culture.

Question 1

How would you dilute a solution by a factor of 10?

Answer 1

• 1cm3 broth

- 9cm3 water

Question 2

Lag phase:

Answer 2

• Population doesn’t grow quickly because population is small and organisms are adjusting to the new environment.
• Taking up water
• Cell growth
• Switching on genes
• Synthesis of proteins e.g.enzymes

Question 3

Log phase:

Answer 3

• Organisms have adjusted and have the enzymes they need to survive.
• Each individual has enough nutrients and space.
• Rapid growth and reproduction.
• Population doubles each generation.

Question 4

Stationary phase:

Answer 4

• The increased number of organisms use up nutrients.
• Waste products build up e.g.CO2 and metabolites
• Rate of population growth decreases and death rate increases until…
• population growth=death rate.

Question 5

Death (decline) phase:

Answer 5

• Nutrients run out
• Concentration of waste products may become lethal.
• More individuals die than are produced.
• Population begins to fall.
• All organisms eventually die.