1
Q
What is the typical size of a bacterial cell?
A
A few microns (thousandths of a mm)
2
Q
What may a bacterial cell have? (6) What are their functions?
A
- flagellum (for movement)
- cell wall (to maintain shape and prevent it from bursting)
- bacterial DNA (to control the cell’s activities and replication of the cell)
- cell membrane (controls the movement of molecules in and out of the cell)
- cytoplasm (a jelly-like substance where most of he reactions within the cell occur)
- capsule (protection against antibiotics)
3
Q
What are the four main shapes of bacteria?
A
- Spiral
- Spherical
- Rod
- Curved rods
4
Q
Describe how bacteria reproduce by splitting in to 2?
A
Bacteria can reproduce very quickly. Bacteria divide in to 2 different cells and reproduce asexually. This process is known as binary fission.
5
Q
How can bacteria:
- can survive on an enormous range of energy sources
- van exploit a very wide range of habitats
A
Because some bacteria can consume organic nutrient and other can make their own.
6
Q
3 unusual places where bacteria can survive
A
- Human
- Hot springs
- Peat bogs
7
Q
Describe aseptic techniques for culturing bacteria on an agar plate
A
- Make sure you don’t contaminate the plate
- Keep it free of microbe or sterile
8
Q
What kingdom does yeast belong in?
A
Fungus
9
Q
How yeast growth increases for every 10’c rise in temperature?
A
- It doubles until the optimum temperature is reached
10
Q
Comparison of viruses with bacteria and fungi
A
- Viruses are much more smaller in comparison to bacteria and fungi
11
Q
Describe the structure of a virus
A
- a protein coat
- surrounding a strand of genetic material
12
Q
Limitations of viruses
A
- Can only reproduce in other living cells
- Can only attack specific cells
- May attack plant, bacterial or animal cells
13
Q
Explain how viruses reproduce
A
- attaches itself to a host cell
- injects its genetic material in to host cell
- using the cell to make components of new viruses
- causing the host cell to split open releasing new virus
14
Q
Describe methods of how bacteria can enter the body
A
- nose (airborne diseases)
- mouth (contaminated food or water)
- skin (insect bites, cuts, infected needles)
- reproductive organs (contact)
15
Q
How does yeast reproduce?
A
Yeast cells reproduce in an asexual manner by a process called budding. The nucleus divides first, then a bulge forms on the side of the parent cell, which will develop into a new cell. (Binary fusion)
16
Q
The optimum growth rate of yeast can be controlled in:
A
- availability of food
- temperature
- pH
- amount of waste products
17
Q
What does bacteria cause?
A
- Cholera
- Food poisoning
18
Q
What does virus cause?
A
- Chicken pox
- Influenza
19
Q
What does fungus cause?
A
- athlete’s foot
20
Q
Prevention of entry of microbes
A
- Skin (physical barrier, blood clots, washing)
- Stomach (acid kills bacteria)
- Respiratory system (cilia and mucus)
- Reproductive system (acidic urine kills many microbes)
21
Q
Ways which allow the entry of microbes
A
- Contaminated food
- Contaminate water
- Contact
- Airborne diseases
22
Q
How does a natural disaster increase transmission of disease?
A
- Broken sewage pipes
- Damaged water supplies
- Electricity supply cut off, hence food isn’t refrigerated
- Health services become over stretched, lack of supplies
- Many homeless, diseases can be easily transmitted
23
Q
Define disease
A
Disease is a state in which the body is not healthy
24
Q
What are the four stages of infectious diseases
A
- entry in to body
- rapid growth; the incubation period
- production of many toxin
- appearance of symptoms
25
Describe the germ theory (Louis Pasteur)
- Proved that decay was caused by micro-organisms
- He went on to explain microbes entering the body cause illness
- He later proposed that if we were to stop microbes entering the body, we would stop illness developing.
26
Describe the development of antiseptics. (Joseph Lister)
Antiseptics are solutions which kill microbes. Lister would spray his medical equipment with carbolic acid. This killed many microbes and reduced the number of postoperative infections.
27
Describe the discovery of Penicillin. (Alexander Fleming)
- He discovered that a mould called penicillin produced chemicals which killed bacteria.
- The fungus grew on one of his agar plates of bacteria. It caused an area where bacteria didn't grow because the antibiotic would kill the bacteria, preventing the formation of bacteria.
28
How are viruses impacted by antibiotics?
- Viruses remain unaffected by antibiotics.
| - This is because viruses do not feed and do not have a cell structure to damage.
29
How do strains of bacteria become resistant to antibiotics?
- A mutation occurs in some bacteria which gives them resistance to the antibiotics
- Treatment by the antibiotic kills the bacteria without such a mutation
- The bacteria with the resistance survive
- The surviving bacteria reproduce, passing the resistance gene on
- Eventually the whole population becomes resistant
30
How can the formation of resistant strain be avoided?
- Only prescribing antibiotics when required
| - Completing the entire course
31
Place where bacteria is used
- Yoghurt making
- Cheese production
- Vinegar production
- Silage production
- Composting
32
Describe the process of making yoghurt
- Sterilisation of equipment
- Pasteurisation of milk
- Incubation of culture
- Sampling
- Addition of flavours, colouring and packaging
33
Purpose of Lactobacillus
- Breakdown of lactose in milk
| - Production of lactic acid
34
What is fermentation?
Fermentation is the production of alcohol, beer and wine, by the breakdown of sugars by yeast in the absence of oxygen
35
Describe what is meant by pasteurisation and why it has to be done in the case of bottled beers
The product is heated and cooled quickly to kill any remaining microbes to give it a longer shelf life.
36
Word equation for fermentation
Glucose(sugar) ----> Ethanol (alcohol) + carbon dioxide
37
Some products can further be treated to increase the alcohol concentration to produce spirits.
T/F
True
38
Describe the main stages of brewing beer or wine
- Extracting sugar from source material
- Adding yeast, keeping it warm
- Preventing entry of any oxygen or other microorganisms
- Extracting the wine and beer (clarifying by a filtration process to purify)
- Pasteurising/Packaging
39
Explain how plants produce biomass
Photosynthesis produces the biomass within the plants, and this biomass can be directly or indirectly be used as biofuel.
40
Give examples of fuels from biomass
- Alcohol
- Wood
- Biogas
41
Describe different methods of transferring energy from biomass fuels
- burning fast growing trees
| - fermenting biomass using bacteria or yeast
42
Advantages of using biofuels
- alternative source to fossil fuels
- no increase in greenhouse gas levels
- no particulates produced
43
Disadvantages of biofuel
- causes habitat loss because a lot of land is required to grow enough trees
- habitat loss can lead to species extinction
- data shows that some biofuels transfer less energy than other fuel types
44
Explain why the burning of biofuels doesn't cause a net increase in greenhouse gases levels
- the plants take in carbon dioxide to grow and release it when burnt
45
Biogas (mainly methane) is an important energy resource in certain remote parts of the world lacking a mains electricity supply or mains sewage system.
T/F
True
46
Rotting of organic material such as dead plants and animal waste:
- occurs in marshes, septic tanks and animal digestive systems
- produces a mixture of gases, including methane
- is caused by the action of bacteria
T/F
True
47
What is used to produce biogas on a large scale?
Digester
48
Explain why methane being released from landfill site is dangerous
It can burn or explode preventing use of the site for many years
49
Alcohol:
- can be used as a biofuel by mixing with with petrol
- can be made from yeast
T/F
True
50
What does biogas contain?
- Mainly Methane
- some carbon dioxide
- traces of hydrogen, nitrogen and hydrogen sulfide
51
How is biogas produced on a larger scale?
- Wet plant waste or animal manure is constantly added
- The gas produced is removed
- Gas production is the fastest at 32-35'C as the fermenting bacteria grow the fastest at such a temperature
- The remaining solids can be removed and can sometimes be used as fertilisers
52
Uses of biogas
- Burning to generate electricity
- Burning to generate hot water and steam for heating systems
- Used as a fuel for vehicles
53
Biogas containing more than 50% methane can be burnt in a controlled way but a lower percentage of about 10% is explosive
True/False
True
54
Biogas and Natural gas energy released comparison
Biogas releases less energy because it contains less methane
55
What is the mixture of petrol and alcohol called? What is it used for?
- Gasohol
| - Is used for car in countries such as Brazil
56
Why does temperature affect the production of biogas?
Because the fermenting bacteria grow best at 32'C - 35'C, hence gas production is quicker then
57
Describe the main components of soil
- Different sized mineral particles
- Dead material
- Living organisms
- Air
- Water
58
Describe a typical food chain
- Includes a herbivore such as slugs, snails and wire worms
- Includes a detritivore such as earthworm, millipede and springtails
- Include a carnivore such as centipedes, spiders and ground beetles
59
What is the role of bacteria and fungi?
They are decomposers, which increase the surface area of the dead material in order to increase the surface area, thus increasing the rate at which the material decays at.
60
Why is soil important for the majority of plants?
Plants rely on soil for water, minerals and to anchor themselves
61
Describe the difference between a sandy soil and a clay soil in terms of particle sizes
The particle size of the particles in the sandy soil are much larger (approximately 0.05-2mm) whereas the particle size of particle in the clay soil are much smaller (less than 0.002mm)
62
What does loam contain?
Mixture of clay and sand
63
What is the dead material called that is largely decomposed in the soil?
Humus
64
Describe the simple tests for different soil constituents?
- Moisture: weigh,bake, and reweigh sample
- Humus: weigh,burn, and reweigh sample
- Air: weight the sample and measure its volume
65
Explain how particle size affects the air content and permeability of soils.
If the particles are small: - few air spaces
- often full of water, reducing oxygen levels
If the particles are large: - plenty of oxygen in the many air spaces
- water will drain away
66
Explain the importance of humus in the soil
- Decomposition to release minerals
| - Increasing this air content
67
Explain why neutralising acidic soils and mixing up soil layers is important
It allows more plants to be grown, hence increasing crop yield
68
Explain why earthworms are important to the soil's structure and fertility
- burying organic material for decomposition by bacteria and fungi
- aerating and draining soil
- mixing up soil layers
- neutralising acidic soil
69
Charles Darwin recognised the importance of earthworms in improving the structure and fertility of the soil
True
70
What are microscopic plants and microscopic animals known as?
- Phytoplankton
| - Zooplankton
71
Role of phytoplankton in the food web
Phytoplankton are producers in aquatic food chains because they are able to photosynthesise
72
Planktons:
- have limited movement and so rely on water currents
- show seasonal variations in numbers due to variation in light, temperature and minerals
True
73
What can affect the numbers and variety of aquatic microorganisms? (2)
- Pollution
| - Acid rain
74
List pollutants in water (6)
```
Oil
PCBs
Sewage
Fertilisers
Pesticides
Detergents
```
75
Explain the advantages of living in water. (3)
- No problem with water shortage and dehydration
- Less variation in temperature
- Easy disposal of waste products
76
Explain the disadvantages of living in water. (2)
- Regulating water content
| - Resistance to water
77
Explain the problems of water balance caused by osmosis
In fresh water, the fish must urinate often to remove the excess water from the body.
Sea water is salty, the fish in this must have the same concentration of salt within their body. If not, they can actively get rid of the salt from the water they drink.
78
Describe the action of the contractile vacuoles in microscopic animals such as amoeba
- Microscopic animals such as amoeba have a cell structure called the contractile vacuole
- The excess water goes in to this cell structure
- The vacuole moves to the cell surface
- Fuses with it
- And releases in to the water
79
List which factors affect photosynthesis which vary at differ t depths and different seasons in the water
- Light intensity
- Temperature
- Minerals
80
What do food webs deep in the ocean rely on?
- Marine snow (dead food falling from above)
| - Bacteria, deep in the ocean, acting as producers
81
Explain how sewage and fertilisers run-off can cause eutrophication
- Rapid growth of algae, covering the surface of the water source
- Resulting in death and decay of plant as they can photosynthesise
- Bacteria using up oxygen
- Causing death of animals as they can't respire
82
Describe which species are used as indicators for pH levels and oxygen levels
- pH changes in water can be indicated by a reduced number of amphibians in polluted streams and bogs
- Oxygen levels are indicated by rat-tailed maggots
83
Explain the accumulative, long term effect of PCBs and DDT on animals such as whales
Killer whales are one of the most contaminated species on earth, this is because they are top of the food chains as they are top carnivores in their food web. Chemicals such as PCBs and DDT are easily able to build up. PCBs are known to suppress the immune system, which impacts the population of the species.
84
Describe everyday uses of enzymes
- Biological washing powders and stain removers
- Cheese production and juice extraction
- The preparation of medical products such as reagent sticks
- Altering flavours of food products
85
Why do enzymes not work at high temperature?
They are denatured
86
Describe how diabetic patients can test their urine for the presence of glucose
Either:
- Benedict's test
- Reagent strip sticks
87
How can enzymes be immobilised?
- In gel beads
| - On reagent sticks
88
Immobilised enzymes on reagent sticks can be used to measure glucose levels in the blood
T/F
True
89
Describe the enzymes in biological washing powder
Amylase - to digest carbohydrate starch
Lipase - to digest fat and remove fatty stains
Protease - to digest protein and remove protein stains
90
Describe how sucrose can be broken down by the use of a enzyme called sucrase(invertase)
The enzyme digests sucrose in to glucose and fructose. When sucrose is broken down, it is much more sweeter, making it useful in the food industry
91
Explain how foods are sweetened using invertase
- Invertase converts sucrose into glucose and fructose
- these sugars are sweeter than the sucrose
- foods can therefore be sweeter without adding so much sugar ( low calorie food)
92
Describe how enzymes can be immobilised in gel beads
- Mixing the enzyme with alginate
| - Dropping the mixture into calcium chloride solution
93
Explain the advantages of immobilising enzymes
- The mixture not becoming contaminated with the enzymes
| - Immobilising enzyme in alginate beads can be used in continuous flowing process
94
Explain the condition of lactose intolerance
- They cannot produce the enzyme lactose
- So bacteria in the gut ferment lactose
- Fermentation cause diarrhoea and wind
95
Explain the principles behind the production of lactose-free milk for people with lactose intolerance
- Immobilised lactase converting lactose in milk into glucose and galactose
- These simple sugars can then be absorbed
96
Define genetic engineering
- Altering the genetic code of an organism by inserting genes
97
Describe the process of genetic engineering
- Removing a gene from one organism
- Inserting it in to another organism
- The gene works in the new organism
98
Bacteria can be genetically engineered to produce useful human proteins such as:
- Insulin
| - Human growth hormone
99
Main stages of genetic engineering
- Identification of desired gene in one organism
- Removal of gene from DNA
- Cutting open the DNA in another organism
- Inserting the new gene in to the DNA
- Gene works in transgenic organism
- Transgenic organism can be cloned to produce identical copies
100
The new organism produced by genetic engineering is called
Transgenic organism
101
Describe how bacteria can be used in genetic engineering to produce human insulin
- The gene for producing human insulin is cut from the human DNA
- A loop of bacterial DNA is cut open
- The insulin gene is inserted in to the loop
- The loop is inserted in to the bacterium
- The bacteria is then able to produce insulin
- Transgenic bacteria are cultured by cloning
- Large quantities of insulin are harvested
102
Bacteria have loops of DNA called plasmids in their cytoplasm
True
103
Explain how they can be used as vectors
Because plasmids can be used as vectors in genetic engineering
104
Assaying techniques can be used to check that the new gene has been correctly transferred
True
105
Describe the stages in the production of DNA fingerprint
- Extraction of DNA from sample
- fragmentation of DNA using restriction enzyme
- separation using electrophoresis
- visualising pattern using radioactive probe
Biology
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