Chapter 4: Microbial Growth - Influence of Environmental Factors (oxygen, pH, Osmotic pressure) Flashcards
1
Q
Is oxygen a requirement for growth in all microorganisms?
A
- no
- only required by some organisms
- can be extremely toxic to others
2
Q
Name the different types of bacteria based on their oxygen consumption requirements (5)
A
- obligate aerobes
- Facultative anaerobes
- obligate anaerobes
- Microaerophiles
- aerotolerant anaerobes
3
Q
What are obligate aerobes? (2)
A
- require oxygen for respiration
- for energy generation
4
Q
What are facultative anaerobes?
A
- can use oxygen for respiration but can also grow in its absence
5
Q
What are obligate anaerobes?
A
- cannot use oxygen and are killed by it
6
Q
What are microaerophiles?
A
- require oxygen in low amounts, but killed by high concentrations
7
Q
What are aerotolerant anaerobes?
A
- cannot use oxygen but are not killed by it
8
Q
What is pH?
A
- measurement of acidity or alkalinity
9
Q
What pH do most bacteria grow?
A
- pH 6.5-7.5
10
Q
What are two classifications of bacteria based on pH?
A
- acidophiles
- alkaliphiles
11
Q
What are acidophiles?
A
- bacteria that grow at very low pH
12
Q
What are alkaliphiles?
A
- bacteria that grow at high pH
13
Q
What is osmotic pressure?
A
- the movement of solvent molecules across a semi-permeable barrier
14
Q
How is water moving through the cytoplasmic membrane an example of osmotic pressure?
A
- water will move from areas of high concentration to areas of low concentration
15
Q
What is a hypertonic solution, and where will water move if the cell is placed in a hypertonic solution? (3)
A
- high solute concentration (ex. salt or sugar)
- water flows out of the cell
- cell dries up - plasmolysis
