L39 Microbial growth and behaviour (Winogradsky column)
Description
1.Describe the different energy and carbon sources used by
microorganisms.
2.Describe the growth characteristics of prokaryotes in a
‘closed’ batch culture system.
3.Outline some examples of microbial behaviour.
Choose the incorrect statement about trophic nourishment.
Answer
Chemoheterotrophs can get their energy and carbon from the same organic compound.
A phototroph uses light as en energy source, and can be oxygenic or anoxygenic.
A chemotroph uses chemical energy as an energy source.
Autotrophs can make complex carbons from CO2.
Anoxygenic phototrophs oxidise molecules like H2S and do not produce oxygen.
Oxygenic phototrophs reduce H2O and produce oxygen.
Question 2
Question
Choose the correct statements about cyanobacteria.
Answer
They use light as an energy source.
They oxidise water for electrons.
They use complex carbons for a carbon source.
They carry out oxygenic photosynthesis.
They reduce water for electrons.
Question 3
Question
Choose the incorrect statement about green and purple cyanobacteria.
Answer
They are photoautotrophs.
They oxidise H2S to S for an electron source.
They use CO2 for an energy source.
Question 4
Question
Choose the correct statement about colourless sulfur bacteria(Beggiatoa).
Answer
They sit below green and purple sulfur bacteria in the Winogradsky column.
They are chemoheterotrophs.
They oxidise H2S to SO4.
They use complex organic carbons for a carbon source.
Question 5
Question
Sulfate reducing bacteria are chemoheterotrophs that essentially reverse the processes that colourless sulfur bacteria carry out.
Answer
True
False
Question 6
Question
Organisms which carry out fermentation are [blank_start]chemoheterotrophs[blank_end]. Their energy source, carbon source, and electron donor, are always [blank_start]complex carbons[blank_end] (organic molecules) and sometimes are even the same molecule. An example of [blank_start]a fermenting chemoheterotroph[blank_end] are cellulose degrading bacteria, which break pyruvate down into [blank_start]acetate[blank_end] and simultaneously degrade cellulose into [blank_start]lactate[blank_end]. Other examples include clostridium and [blank_start]rumen[blank_end] bacteria.
Answer
chemoheterotrophs
chemoautotrophs
complex carbons
fermenting chemoheterotrophs
fermenting chemoautotrophs
acetate
acetic acid
lactate
lactose
rumen
colourless sulfur
Question 7
Question
Microbial growth in a [blank_start]closed batch[blank_end] culture system is not like nature, in that it is a 'Feast and [blank_start]Famine[blank_end]' situation controlled by the examiner. There are four stages which characterise the growth [blank_start]curve[blank_end] for bacteria in this system.
Firstly, there is a [blank_start]lag phase[blank_end]. It is shown as little to no change in the population size. The lag period [blank_start]differs depending[blank_end] on how much the inoculum must evolve and adjust before it is suited to the environment/has the proper [blank_start]biosynthetic reactions[blank_end] taking place.
The next phase is the [blank_start]exponential phase[blank_end]. During this phase there are [blank_start]no limited resources[blank_end] or competition and so the bacterial population can [blank_start]double[blank_end] in size every generation via binary fission, displaying exponential population growth.
The next phase is the [blank_start]stationary phase[blank_end]. This appears to be a stable population size, but does not indicate static activity. Instead, it reflects the cryptic growth of the organisms. Cryptic growth is the state of [blank_start]dynamic[blank_end] equilibrium where organisms survive by feeding from the lysed, dead bodies of deceased organisms.
Finally, there will be a [blank_start]death phase[blank_end] where the population size decreases until it is at a stable end point.
Answer
closed batch
open batch
Famine
curve
lag phase
exponential phase
stationary phase
death phase
depends
biosynthetic reactions
double
no limited resources
limited resources
dynamic
Question 8
Question
What might cause a persistent bacterial infection?
Answer
Microbes which are able to degrade antibiotics.
Microbes not all being in the same stage of a life cycle, and the non-dividing organisms not being targeted by antibiotics.
Microbes which can repopulate faster than a patient can be medicated.
Question 9
Question
To be antibiotic resistant a microbe must carry the genes which confer resistance.
Answer
True
False
Question 10
Question
Choose the incorrect statement about microbial behaviour.
Answer
Some bacteria are very large e.g. thiomargarita.
Some bacteria have organelles e.g. Anammox bacteria
Myxobacteria display social behaviour.
None of these are incorrect.
Question 11
Question
Which statement best describe the 'sliding' behaviour displayed by myxobacteria.
Answer
It is a form of social motility wherein each bacteria pulls with pili and secretes slime like a propellent.
It is the microbial version of hunting like a wolf pack.
It is swarm feeding cooperatively by sharing enzymes and attacking targets as a group.
Question 12
Question
When a food source is exhausted, myxobacteria form 3D structures of endospores. What are these referred to as?