part 5 Flashcards
How would you distinguish bacterial colonies from fungi?
Bacterial colonies are shiny or smooth whereas fungi look like cotton wool with fluffy hyphae.
Why would serial dilutions be used in microbiology?
To determine the population size and growth rate of a population of microorganisms.
Describe how you’d make a serial dilution that has a dilution factor of 10.
Use 1cm3 of broth and 9cm3 of distilled water.
What can be done with a dilution series after making it?
Place 1 drop of each dilution onto a sterile agar plate. Allow colonies to form. Count the number of colonies on the plate which is easiest to count. Then multiply by the dilution factor.
Describe the difference between primary and secondary metabolites.
Primary metabolites are produced during the normal activities of the microorganism during the log phase whereas secondary metabolites are produced during the stationary phase.
Is batch culture carried out in a closed fermenter, with nothing added or removed?
Yes, batch culture is carried out in a closed fermenter, with nothing added or removed.
Is batch culture characterized by microorganisms being left for a set period of time?
Yes, batch culture microorganisms are left for a set period of time.
Is continuous culture carried out in an open fermenter, with nutrients added and products removed?
Yes, continuous culture is carried out in an open fermenter, with nutrients added and products removed.
What is an advantage of batch culture over continuous culture?
The fermenter can be used for different reactions with each separate use.
What is a disadvantage of batch culture over continuous culture?
There is lots of idle time between use therefore higher costs.
What is a disadvantage of continuous culture over batch culture?
Higher risk of contamination due to constant additions and adjustments.
How is penicillin produced - batch culture or continuous culture?
Batch (fermentation).
How are bioreactors cooled?
Using a water jacket.
Why is it necessary to cool bioreactors?
Reactions are exothermic - heat generated can denature enzymes.
Which gas is added to aerobic fermenters?
Oxygen.
Describe and explain the condition of all reactants added to a fermenter.
Sterile - to avoid contamination of the product / to avoid competition from other microorganisms for reactants.
How are substrates and organisms mixed in a fermenter?
Motor with stirrers / mixing blades (impellers).
How is the pH monitored in a fermenter?
Using an electronic pH probe.
Why is it necessary to monitor and adjust the pH in bioreactors?
Enzyme activity (and therefore growth) is affected by extremes of pH.
How are fermenters sterilised?
With superheated steam.
Define immobilised enzyme.
An enzyme that is held in place and not free to diffuse through the solution.
Give 1 / 2 / 3 advantages of using immobilised enzymes.
Extraction costs are lower as enzymes do not mix with the product / the enzymes can be easily reused / a continuous process is made easier as there are no cells requiring nutrients and releasing waste products / the enzymes are protected from extreme conditions so don’t get easily denatured.
Give 1 / 2 disadvantages of using immobilised enzymes.
Setting up the immobilised enzymes is more expensive / immobilised enzymes are less active so the reaction is slower.
Name the method described: enzyme molecules are bound to a supporting surface by hydrophobic interactions and ionic links.
Adsorption.
Name the method described: enzyme molecules are separated from the reaction mixture by a partially permeable membrane.
Membrane separation.
Name the method described: enzyme molecules are bonded to a supporting surface by strong covalent bonds.
Covalent bonding.
Name the method described: enzyme molecules are trapped in a matrix that does not allow free movement.
Entrapment.
What materials can be used as a supporting surface when using adsorption as a technique to immobilise enzymes?
Unreactive material - eg. Clay, porous carbon, glass beads, resins.
Give one disadvantage of using adsorption as a method of immobilising enzymes.
Active site may be distorted so enzyme activity may reduce / enzymes can become detached and leak into reaction mixture so need separating or replacing.
Give one disadvantage of using covalent bonding as a method of immobilising enzymes.
Can be expensive / can distort the active site.
Give one disadvantage of using entrapment as a method of immobilising enzymes.
Substrate needs to diffuse in to the matrix / product needs to diffuse out so only suitable for processes where substrate and product are small.
Why is it an advantage to convert glucose to fructose?
Used to produce high fructose corn syrup - much sweeter than sucrose.
What is the role of lactase?
Converts lactose to glucose and galactose to produce lactose-free milk.
Define the term ‘abiotic factor’.
Any non-living factor e.g. sunlight.
Define the term ‘biotic factor’.
Any living factor e.g. predators.
Give 3 examples of abiotic factors.
Temperature, light, pH, water, humidity, oxygen availability, edaphic(soil) factors.
Give 3 examples of biotic factors.
Competition, food, territory, breeding partners, predators.
Describe the importance of soil for plants.
Soil provides minerals for growth, water for photosynthesis, anchorage for roots.
Explain how particle size affects the air content and permeability of soils.
Small particles - few air spaces, retains water and floods easily eg. clay. Large particles - lots of air spaces, does not retain water eg. sand.
Define the term ecosystem.
Made up of all the living organisms that interact with one another in a defined area and also the physical factors present in that region eg. rock pool.
Define the term producer.
Producer - makes its’ own food, usually by photosynthesis to produce biomass (includes algae and plankton).
Define the term carnivore.
Eats only other animals.
Define the term herbivore.
Eats only plants.
Define the term omnivore.
Eats both plants and animals.
Define the term primary consumer.
Eats producers, usually a herbivore.
Define the term secondary consumer.
Eats primary consumers, usually an omnivore.
Define the term tertiary consumer.
Eats a secondary consumer.
Define the term trophic level.
Trophic level - position or stage that something occupies in a food chain.
Define the term biomass.
The mass of living material present in a particular place or in particular organisms.
How do you find the dry mass of an organism?
Organism has to be killed and put in an oven to evaporate the water.
How do you calculate the net production of biomass made by a primary producer?
Net production = gross production – respiratory losses.
A group of scientists measured the gross production of a grassland area as 60gm-2yr-1. If respiration loss was 20gm-2yr-1, calculate the net production of this area of grassland.
60-20 = 40gm-2yr-1.
Why can’t plants use all of the sunlight that hits them?
Some parts of a plant do not photosynthesize, some light passes through, some is the wrong wavelength.
Why isn’t all energy transferred to the next trophic level?
Some parts of an organism are not digested, some parts are not eaten eg. bones, some is used up for energy for movement/ respiration (respiratory losses).
Approximately what % of energy is passed to the next trophic level?
0.1.
How do you calculate % efficiency of energy transfer?
Net productivity of energy transfer of trophic level / next productivity of previous trophic level x 100.
What is the role of a herbicide?
Kills weeds that compete with crops - reduces competition.
What is the role of a fungicide?
Kills fungal infections that damage crops.
What is the role of an insecticide?
Kills insect pests that damage and eat crops.
What is the role of fertiliser?
A chemical that provides crops with the minerals required for growth.
Why is intensive farming beneficial?
Controls living conditions for organisms so that more energy is put into growing e.g. animals are kept warm and move around less.
Define the term ecosystem.
Self contained unit in ecology made up of biotic and abiotic factors.
Define the term community.
All the populations of different species living and interacting with each other in a particular area.
What is meant by ‘nitrogen fixation’?
When nitrogen gas is converted to nitrogen containing compounds.
Give examples of two types of bacteria that are involved in nitrogen fixation.
Azotobacter and Rhizobium.
Explain why Rhizobium bacteria can be described as mutualistic.
Rhizobium live in root nodules in peas and beans and they get carbohydrates from the plant, the plant gets amino acids from the bacteria.
What is meant by ammonification?
Production of ammonia from organic compounds e.g. urea, proteins and nucleic acids.
Describe the process of nitrification.
Ammonium ions –> nitrite ions –> nitrate ions.
Give the role of nitrosomonas bacteria in the nitrogen cycle.
Ammonium ions –> nitrite ions.
Give the role of nitrobacter bacteria in the nitrogen cycle.
Nitrite ions –> nitrate ions.
What is denitrification and how does it occur?
When soil nitrates are converted to nitrogen gas. Occurs when soil becomes waterlogged, short of oxygen and carried out by anaerobic bacteria - means that less nitrogen compounds are available to plants.
List 3 processes that return carbon dioxide to the atmosphere.
Respiration, decomposition and combustion.
Name a process that removes carbon dioxide from the atmosphere.
Photosynthesis.
Give reasons for the levels of carbon dioxide increasing over the past 100 years.
Combustion of fossil fuels, deforestation.
Define the term global warming.
The increase in average temperature over the last century.
Give 3 consequences of global warming.
Changes in temperature, precipitation, failure of crops, timings of the seasons may change, melting ice caps, flooding of low lying land, increasing extreme weather, alter niches available - loss of species we don’t know.
Give reasons for the levels of methane increasing.
Increased extraction of fossil fuels, increased decaying waste in landfill, more cattle producing methane, frozen stores are thawing.
Define the term succession.
The process of ecosystem change over time.
State features of a pioneer species.
Produce large quantities of easy to disperse seeds/spores, rapid germination of seeds, ability to photosynthesize, ability to fix nitrogen, withstand extreme conditions.
Define the term deflected succession.
A community that remains stable only because human activity prevents succession from running its course.
Where does primary succession occur?
On land that has been newly formed.
What is meant by the term ‘climax community’?
When the soil is rich enough to support large trees the climax community is formed (may not be large trees if in the Arctic for example).
When does secondary succession occur?
On land that has been cleared but where soil remains.
Give the calculation for estimating population size using ‘capture, mark, release and recapture’.
Population size = (number in first sample x number in second sample) / number in second sample previously marked.
Define the term abundance.
The number of individuals of one species in a particular area.
Define the term distribution.
Where a particular species is within the area you are investigating.
How could you ensure that your sampling method is random?
Use a random number generator for coordinates.
What is a transect?
A transect is a line across an area of land.
Name 2 types of quadrat.
Frame quadrat and point quadrat.
How could you capture fish?
Use a net.
How could you capture insects?
Use a sweepnet.
How could you capture butterflies?
Make a pitfall trap.
Name 2 pieces of apparatus needed for calculating percentage cover of plant species.
Frame quadrat and measuring tape (transect) (could have species index).
How can distribution of organisms be measured?
Using line or belt transect - non-random, systematic sampling.
Should measuring distribution be random or non-random?
Non-random.
Give the equation to calculate the estimated plant abundance within an area of 1m2.
(number of individual in sample) ÷ (area of sample in m2).
What method is used to find the animal abundance in an area?
Capture-mark-release-recapture technique.
Name an assumption you make when you use the mark-release-recapture method.
Marking the organism does not impact its survival / no migration / organisms randomly distribute after first release.
What is the term to describe the maximum population size that an ecosystem can maintain?
Carrying capacity.
Why can’t populations reach an infinite size?
Limiting factors - Resources are limited.
True or false: exponential growth always takes place in real ecosystems.
False.
State the term for non-living factors.
Abiotic factors.
What will happen to the population size when abiotic conditions are favourable?
Increase.
What is a limiting factor?
A factor in a habitat limits the further growth of a population.
Are limiting factors abiotic or biotic?
Both abiotic and biotic.
What is happening at the lag phase of a population’s growth?
Individuals are acclimating to a habitat, low reproduction rate.
What is happening at the log phase of a population’s growth?
Plenty of resources available in good conditions, population increasing rapidly.
What is happening at the stationary phase of population growth?
Rate of reproduction equals mortality, stable population size.
What are the names given to the different stages of a population growth curve?
Lag, log (or exponential), stationary.
What does it mean by ‘density independent factors’?
They act irrespective of the size of the population.
Suggest an example of a density independent factor.
Weather or climate.
Give 3 examples of limiting factors that are density dependent to birds.
Availability of food, water, light, oxygen, nesting sites.
Name the type of competition between individuals of different species.
Interspecific.
Name the type of competition between individuals of the same species.
Intraspecific.
In interspecific competition, what biotic factors could be involved?
Food source, habitat.
Fill in the gaps: There is a limited supply of resources in ecosystems. Species have …..?…. that allow them to gain resources faster than other species are more likely to survive and therefore ….?….
Adaptations / reproduce.
What is a predator?
Animals that hunt other animals for food.
What are prey?
Animals that are hunted by other animals (predators) for food.
What is the relationship between the numbers of a predator and a prey?
When the predator population increases more prey are eaten and the numbers of prey fall. When the prey population decreases there is less food for predator and so their numbers fall.
What mechanism controls the predator and prey populations?
Negative feedback.
Define Preservation.
Keeping a species or habitat as they are now, minimising any human impact.
Define Conservation.
An active management process of a species, habitat or ecosystem involving human intervention.
Which strategy focuses on improving biodiversity, preservation or conservation?
Conservation strategies.
What is biodiversity?
The range and number of different living species in an ecosystem.
How is the human population threatening biodiversity?
Over-exploitation of wild populations for food/ disruption and fragmentation of habitats/ introduction of new species to an ecosystem outcompeting native species.
What is an important factor of a successful conservation strategy?
Effective education and liaison with the local community.
Give 2 examples of the strategies that could be used for conservation?
Providing extra food raising the carrying capacity / restricting dispersal of individuals using fencing / vaccination of animals against disease / controlling predators or poachers / preserving habitats by preventing pollution / moving individuals to enlarge populations.
What ethics are involved in a conservation strategy?
All species have value and humans have an ethical responsibility to look after them.
What economic or social reasons might influence the conservation of a species or habitat?
A valuable food source or potential food source / potential drug sources or potential biological control agent.
What are two examples of strategies that could be used for conservation?
Providing extra food or raising the carrying capacity.
Other examples include restricting dispersal using fencing, vaccinating animals against disease, controlling predators or poachers, preserving habitats by preventing pollution, and moving individuals to enlarge populations.
What economic or social reasons might influence the conservation of a species or habitat?
A valuable food source or potential food source, potential drug sources, or potential biological control agents for pests.
What is cutting down trees in a way that lets them grow back known as?
Coppicing.
What happens to grassland without management?
It would quickly turn into shrubs and then woodland by succession.
What does sustainable management mean?
Management of an ecosystem to provide resources in a sustainable way, avoiding depletion of natural resources.
Why have humans had to use more intensive methods of agriculture?
Due to increasing population.
What problems has the increasing world population caused to ecosystems?
More intensive land use and disruption or destruction of ecosystems, reducing biodiversity.
How does coppicing provide sustainable timber production?
Woodland is divided into sections, with only one section harvested each year in rotation.
What is pollarding of trees?
Branches of a tree are cut back to a point higher up the mainstem from the ground.
What is the difference between coppicing and pollarding?
Coppicing cuts branches at ground level while pollarding cuts them above ground level.
Why is rotational coppicing good for biodiversity?
Different areas of the woodland will be at different stages of development, providing a variety of habitats.
Why is large scale clear felling of woodland not good for biodiversity?
Habitats are destroyed on a large scale and the soil is left susceptible to erosion.
What land management problems could result from clear felling a large forest?
Erosion of the soil and reduction of soil mineral content.
Why is there an optimal distance for planting trees in woodland?
Too close results in too much competition for light, producing tall and thin trees, leading to poor quality timber.
What are the principles of modern sustainable forestry?
Replace any tree that’s harvested, maintain the ecological function of a forest, and ensure local people benefit from the forest.
What is selective cutting or harvesting in forests?
Removing the largest or most valuable trees.
How is selective cutting good for biodiversity?
Only a few trees are removed, which leaves the habitat broadly unaffected.
How do foresters manage the trees in sustainable woodland to maximize yields?
Control pests and diseases, only plant tree species that will grow well, and position trees the optimum distance apart.
Name two ways of managing fish stocks.
Fishing quotas and mesh sizes.
What are the principles of fish sustainability proposed by the Marine Stewardship Council?
Fish at a level that ensures continuing fish stocks, maintain diversity of ecosystem, and follow local and national regulations.
To allow sustainability of fish populations, what must happen if there is overfishing?
The fish population must be allowed to build back up.
What would be the optimum strategy for managing fish populations?
Maintain the fish population at the carrying capacity for that environment, while fishing continues to harvest fish in excess of that capacity.
How can human activities affect populations of plants and animals?
Habitat destruction, competition for natural resources, hunting, and pollution.
What protection areas have humans set up to protect plant and animal species around the world?
Setting up national parks and reserves, green belt land, world heritage sites, marine protected areas, and areas of outstanding natural beauty.
Why has the human population on the Galapagos Islands increased?
Increased demand for marine products and increased tourism.
How has more building development and increased use of land for agriculture affected the Galapagos Islands?
Destruction and fragmentation of habitats.
Why has it been difficult to foster a culture of conservation and education on the Galapagos Islands?
Because most residents were not born on the islands.
What are large areas of coastal zones designated as ‘No Take’ zones?
No extraction of any resources is allowed, leaving communities undisturbed.
What are financial incentives given to farmers in national parks?
To reduce chemical use, safeguard hedges, and care for natural habitats.
How do they manage cliffs, rock, and scree habitats in the Lake District?
Seasonal restrictions on walkers during nesting, education of visitors, and good maintenance of paths.
