B6 Flashcards
How can yeast respire?
Aerobically and anaerobically
What does anaerobic mean?
Without oxygen
What does yeast produce when it respires anaerobically?
Ethanol, carbon dioxide and energy
What is It called when yeast respired anaerobically?
Fermentation
What is the equation for fermentation?
glucose —> ethanol + carbon dioxide (+ energy)
What is ethanol?
A type of alcohol
What is the fermentation process used for?
Making beer and wine
What does aerobic mean?
With oxygen
Yeast can respire aerobically and anaerobically, which one produces more energy?
Aerobically
What is the word equation for the aerobic respiration of yeast?
glucose + oxygen —> carbon dioxide + water (+energy)
What is different about the aerobic respiration of yeast to the aerobic respiration of plants and animals?
Nothing
Which way does yeast prefer to respire and why is this?
Aerobically, because it produces more energy
When does fermentation take place?
In the absence of oxygen
What happens when yeast respires quickly?
It reproduces faster
What is the reproduction of yeast controlled by?
Temperature
Availability of food
pH
How quickly waste products are able to be removed
How is the reproduction rate of yeast affected by temperature?
It reproduces faster at warmer temperatures.
The growth rate doubles for every 10 degrees C rise in temperature until the optimum is reached.
If it is too hot the yeast enzymes are denatured and it dies.
How does the amount of food affect the reproduction of yeast?
The more food (glucose) there is, the faster the yeast reproduces.
How do toxic waste products affect the reproduction of yeast?
A build up to toxic waste products (e.g. ethanol) slows down reproduction.
How does the pH level affect the reproduction of yeast?
It works at an optimum. Too high or too low of a pH will slow down reproduction.
How does the presence of oxygen affect the reproduction of yeast? And what effect does this have on it?
It speeds it up. Meaning it is able to respire aerobically, giving it more energy for reproduction.
How can you measure the rate at which yeast is reproducing?
Measuring how much glucose it breaks down.
The faster the yeast reproduces, the more glucose will be broken down.
Why do food-processing factories use yeast?
They need it to break down the sugar in the water that they have produced.
They cant release it into the atmosphere because bacteria will feed on it and reproduce quickly using all the oxygen in the water, causing fish to die. So they use yeast to treat the contaminated water before it is released.
What is the first part of beer brewing?
Beer is made from barley
The barley grains are allowed to germinate for a few days
The starch in the grains is broken down into sugar by enzymes.
The grains are dried in a kiln, this process is called malted
The malted grain is mashed up and water is added to produce a sugary solution with lots of bits in it
This is then sieved to remove the bits
Hops are added to the mixture to give the beer its bitter flavour
What is the first part of wine being made?
The grapes are mashed and water is added
What is germination?
When a seed starts to grow into a new plant
How are alcoholic drinks made after their independent first stage?
Yeast is added and the mixture is incubated (kept warm)
The yeast ferments the sugar into alcohol
The beer and wine produced is drawn off through a tap
Sometimes chemicals called clarifying agents are added to remove particles and make it clearer
The beer is then pasteurised
Wine isn’t pasteurised
The beer is casked and the wine is bottled ready for sale.
What is pasteurisation? (in terms of beer)
Where beer is heated to kill any yeast left in the beer and completely stop fermentation.
How can you increase alcohol concentration?
By distillation
What is produced when cane sugar is fermented and then distilled?
Rum
How do you distil a liquid?
The fermentation products are heated to 78 degrees C (the temperature at which the alcohol, but not the water boils and turns into vapour) The alcohol vapour rises and travels through a cooled tube which causes it to condense back into liquid alcohol and run down the tube into a collecting vessel
Why cant do distil things at home?
Because it is a commercial process that can only be done on licenced premises
What is biomass?
Living or recently-dead organic material. e.g. plant matter.
It’s also a store of energy.
What can energy stored in biomass be transferred to?
More useful forms:
Fast growing trees can be burnt, releasing heat
Biomass can be fermented by yeast and bacteria to create products such as biogas, which can be used as fuel.
Why is it better to burn fast growing trees?
Because fast growing trees can be replaced quickly and easily, much quicker and easier than slow growing trees
What is biogas mainly made of?
Methane
What are the gas percentages of biogas?
70% methane (CH4)
30% carbon dioxide (CO2)
And traces of hydrogen, nitrogen and hydrogen sulphide
Give a property of biogas with more than 50% methane in it
It burns easily
Give a property of biogas with around 10% methane
It can be explosive
What is biogas made by?
Bacteria in a digester. The bacteria’s respiration produces methane
How can biogas be used as fuel?
It can be burned to power a turbine, which can be used to generate electricity.
Can be burned to heat water and produce steam to heat central heating systems.
It can be used as a fuel for cars and buses.
Why is biogas useful in remote areas?
Because you can use it to produce electricity in the remote areas which have no mains supply.
How is biogas made?
By anaerobic fermentation of waste material.
It is made from plant waste and animal poo in a simple fermenter called a digester.
What is used to make biogas on a large scale?
Sludge waste
What do the several different types of bacteria do when producing biogas?
Some decompose the organic matter and produce waste, then another type decompose that waste, and so on until you get biomass.
What is the optimum conditions for biogas digesters?
30-40 degrees C, any cooler and the bacteria don’t produce biogas as fast, any hotter and the bacteria will be killed.
The conditions in the digester also need to be anaerobic
What does a simple biogas generator need to have?
An outlet for the digested material to be removed through
An outlet so that the biogas can be piped to where it is needed
What method does large-scale biogas production use?
A continuous flow method
Organic waste is continuously fed into the digester, and the biogas and solid digested material are continuously removed at a steady rate
What are the advantages of biofuel?
They can be produced in a sustainable way
The crops used to make biofuels are replaced quickly
The plants used will photosynthesise - reducing CO2 in the atmosphere
It is a cleaner fuel because it doesn’t produce particulates which can cause lung cancer
Why advantages of biofuels are only true in certain conditions and which conditions are these?
Biofuels are only carbon neutral if they are burnt at the same rate that the new biomass is being produced
Burning biogas can only balance the release of CO2 in the atmosphere if the area they are being burned in is clear from any other vegetation
What are the disadvantages of burning biofuel?
It is more dilute than fossil fuels
Large areas of land are cleared of vegetation to create space to produce biofuels. This increases greenhouse gas levels and can have a bad effect on the ecosystem.
What effects can biofuels have on the ecosystem?
Habitat loss - as plants are cleared, the habitats of many plant and animal species are destroyed
Extinction of species - the loss of habitats and a change of food availability might mean that some species might die out in the area
What can ethanol be burned as and why is it a better alternative?
Fuel, because it is a cleaner fuel and produces fewer pollutants than petrol or diesel
What is ‘gasohol’?
A mixture of 10% ethanol and 90% petrol
What are the advantages of using gasohol?
It means less crude oil is being burned
The growth of crops for ethanol production means that CO2 is being absorbed from the atmosphere
It is great for places that grow a lot of sugar cane and not a lot of oil
What do sandy soils contain and what does this mean?
They have large sand particles and large pores, this means that they have a high air content and are very permeable
What do clay soils contain and what does this mean?
They are mostly made up of tiny particles, packed tightly together, they have very small pores - clay soils have a low air content and low permeability. They tend to retain more water because the water molecules cling to the small particles
What do loam soils contain and what do their properties depend on?`
A mixture of sand and clay particles, their properties depend on the relative amounts of the different types of particles.
What do most soils contain?
Humus
What is humus?
Decomposed, dead organic matter. It helps to support soil life
How can you measure the water and humus content in soil?
Take the mass of a small sample of soil
Heat the sample to 105 degrees C until it reaches a constant mass - this will boil off all the water in the soil
Take the mass of the soil sample again - the different between the first and the second reading is the mass of the water in the soil
Heat the soil sample to 550 degrees C for two hours - this will burn all the humus from the soil sample
Take the mass of the soil sample for the third time. The difference between the second and the third reading is equal to the mass of humus in the original soil sample
How can you measure the air content in soil?
Loosely pack a sample of soil into a beaker of test tube and measure the volume of soil
Fill a pipette with a known value of water and gradually add it to the beaker, letting it seep down into the soil sample
Continue doing this until the water comes up to the top of the soil sample
To find out how much water you added, subtract the volume of water left in the pipette from the volume you started with
As the water has replaces the air in the soil, the volume of water added is the same as the volume of air that was in the sample to begin with
What does measuring the air, water and humus content of soil help you to do?
Work out the structure of the soil
Name three herbivores that live in the soil
Slugs, snails and wire worms
Name three carnivores that live in the soil
Centipedes, ground beetles, spiders
Name three detritivores that live in the soil
Earth worms, millipedes, springtails
What do plants need soil for?
Anchorage, supply of minerals, water
Which three types of living things are found in the soil?
Herbivores, carnivores, detritivores
What types of organisms live in the soil?
Microscopic protozoans, fungi, nematode worms and bacteria
What does soil need in order to support life?
Water and oxygen
How does the presence of humus help to support life in soil?
- As organic material is slowly being broken down by decomposers, minerals and nutrients are released into the soil. These compounds can then being used by other organisms
- Humus also increases the air content of the soil, making more oxygen available to the organisms that live there
Why are earthworms good for soil structure and soil fertility?
They bury leaves and other organic material in the soil, where bacteria and fungi can decompose them
Their burrows allow air to enter the soil and water to drain through it
They mix up the soil layers, distributing the nutrients more equally
Soil in earthworm poo is less acidic than the soil they eat, this can neutralise soil acidity
What is aeration?
When worms burrows allow air to enter the soil
Give some advantages of living in water
There's a plentiful supply of water Less variation in temperature Holds support for plant and animals that have no skeletal system No danger of dehydration Waste disposal is easier
What are the disadvantages of living in water?
Water is more resistant to movement so things living in it have to use more energy to move about
They have to be able to control the amount of water in their bodies
What would happen if an animal couldn’t control the amount of water in it’s body?
If an animal lives in salty water then the water molecules would leave it’s cells by osmosis causing them to shrivel and die
If an animal lives in freshwater its cells would contain a higher solute concentration then the surrounding water. If the animal wasn’t able to regulate water then water molecules would enter its cells by osmosis, causing them to swell and burst
How do amoebas regulate their water content?
They have things called contractile vacuoles which collects the water that diffuses by osmosis. The vacuole then moves to the cell membrane and contracts to empty the water outside the cell
What are plankton?
Microscopic organisms that live in fresh and salt water
What are the two types of plankton?
Phytoplankton - these are microscopic plants
Zooplankton - These are microscopic animals
Which plankton feeds on which plankton?
Zooplankton feeds on phytoplankton
Which plankton are the main producers in aquatic food webs and where are they important?
They are the main producers in aquatic food webs, so they are important in both freshwater and salt-water ecosystems
What is photosynthesis affected by?
temperature
light intensity
availability of mineraLS
Give some examples of how photosynthesis varies in the sea
winter months in deep water - low as less light intensity and low temperature - mineral however is high so light and temperature limit the photosynthesis
summer near surface - light intensity and temperature high but mineral concentration lower so mineral limits it
When do phytoplankton populations usually increase?
between late spring and early summer
because of longer sunnier days
What is the increase in phytoplankton population called?
an algal bloom
What does an algal bloom do to the water?
makes it go murky and green
Why does the phytoplankton population increase?
more light available for photosynthesis - energy created used for growth
temperatures increase
population of zooplankton increase because theres more phytoplankton to eat
What are most ocean food webs?
grazing food webs
what is a grazing food web?
means they begin with a living producer
What are the producers often in ocean food webs?
Phytoplankton
but in deep water no light so its bacterial producers that rely on sulphur from sea vents instead of sunlight
marine snow - dead decomposing material that has slowly fallen from the surface (happens in deep sea webs)
Name two causes of water pollution
fertilisers and sewerage
industrial chemicals and pesticides
Describe how fertilisers and sewerage cause water pollution
eutrophication - add extra nutrients, algae bloom, algae die and decay, bacteria feed using up oxygen in water, animals unable to respire so die
What are indicator species?
animals which are particularly sensitive to the level of oxygen or pH of the water
Give some examples of clean water indicator species
stonefly nymph
mayfly nymph
Give some examples of low pollution level indicator species
freshwater shrimp
caddis fly larvae
give some examples of high pollution level indicator species
bloodworm
water louse
Give some examples of very high pollution level indicator species
rat-tailed maggots
sludgeworm
Give an example of some chemicals which have caused water pollution
DDT
PCBs
How do industrial chemicals and pesticides cause water pollution?
if polluted organisms at bottom of food chain take them up , theyre then passed on and the concentration of the chemical increased as it is passed on so organisms at the top of the food chain accumulate a huge dose and may die
Whats used in biological washing powder?
enzymes
How are these stains taken out of clothes?
Carbohydrate
Lipid (fats)
Protein
Amylases break into simple sugars
Lipases break into fatty acids and glycerol
Proteases break into amino acids
all the things they break them into are soluble in water so easily washed out of clothes
When and do biological washing powders work best and why?
moderate wash temperatures
enzymes denatured at high temperatures
(some new powders contain enzymes resistant to heat)
Why do biological washing powders not work well in alkaline or acidic waters?
enzymes denatured
How is diabetes diagnosed?
by presence of sugar in urine
used to be tested using benedicts solution
-when heated it changes colour from blue to orange if theres sugar
now use reagent strips
-contain enzymes which change colour if sugar present
Give three examples where enzymes are used in the food industry
Low-calorie food
Cheese
Juice extraction
How do enzymes help in low calorie food?
sucrase breaks down sucrose (sugar) into glucose and fructose which are sweeter so you get same level of sweetness using less sugar
How do enzymes help in cheese?
rennet clots milk in first stage of cheese production
How do enzymes help in juice extraction?
pectinase breaks down pectin in fruit causing the cells to release their juice
What is an advantage of using immobilised enzymes?
don’t contaminate the product
one sin alginate beads can be used in continuous flow processing
enzymes still active so still speed up reactions
How are enzymes immobilised?
encapsulate them in alginate beads - formed by mixing the enzyme with alginate then dropping into calcium chloride solution
What makes people lactose intolerant?
lack the enzyme lactase which breaks lactose into glucose and galactose
How is lactose free milk made?
uses immobilised lactase to break the lactose into glucose and galactose
continued flow processing
Describe continuous flow processing
Substrate solution run through column of immobilised enzyme
Enzymes convert substrate into the products but only products emerge as enzymes stay trapped in the column
Describe reagent strips
measure blood glucose concentration
contain immobilised enzymes
enzymes make it change colour depending on the glucose concentration
What does genetic engineering do?
alters the genetic code of an organism
gene of desirable characteristic is removed from one and inserted into another
Why are we able to transfer genes from one organism to another?
because the genetic code is universal
What is a genetically modified organism called?
a transgenic organism
What are the five main steps in genetic engineering?
identify the gene you want
remove gene
cut open DNA of organism putting gene into
Insert gene into DNA
Host can now be cloned to make more with desirable characteristics
What is the cutting and inserting of DNA in genetic engineering done with?
Enzymes
Describe an example of genetic engineering
bacteria making human insulin
gene identified
remove from human cell by cutting it out of DNA with restriction enzymes (leaves the DNA with ‘sticky ends’)
Loop of bacterial DNA called plasmid is prepared - restriction enzymes cut it open leaving it with ‘sticky ends’
Insulin gene inserted into plasmid - sticky ends allow it to ligase (enzyme) to join the DNA strands together -plasmid then taken up by the bacteria
bacteria then cultured by cloning
What is the plasmid that carries the human insulin gene known as?
a vector - organism which carries a gene into another organism
What is DNA fingerprinting?
a way of comparing two DNA samples to see if they are identical or similar
What is DNA fingerprinting used in?
forensic science
paternity tests
What are some ideas about DNA fingerprinting?
everyones DNA should be stored on a database so criminals found quickly
worry its an invasion of privacy
false positives can occur if errors are made in the procedure or the data is misinterpreted
Describe DNA fingerprinting
DNA extracted from cells
restriction enzymes cut DNA into fragments -cut at every place where they recognise a particular order of bases
DNA bits separated out by electrophoresis
DNA tagged with radioactive probe and placed on photographic film which goes dark where radioactive showing the positions of the DNA fragments
What happens in electrophoresis?
DNA fragments suspended in gel and electrical current passed through - DNA negatively charged so moves towards positive anode - small bits travel faster so get further
