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42 Cards in this Set
- Front
- Back
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How are bacterial cells different from animal cells? (5) |
Smaller and simpler. Have a cell wall to retain shape and stop them from bursting. Have a strand of DNA in the cytoplasm. Sometimes have a flagellum (tail). Can consume large amounts of organic nutrients from the surroundings and/or make them themselves, meaning that they can survive in almost any habitat. |
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How do bacterial cells reproduce? (3) |
Asexually. Very quickly. Reproduce faster when warm. |
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How do you culture bacteria? (2) |
Place it on an agar plate (Petri dish) using a wire inoculation loop. Use aseptic techniques to ensure that no other bacteria ends up in the agar plate. |
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How is yoghurt made? (3) |
Milk is pasturised to kill off unwanted bacteria. A starter culture of lactobacillus bacteria is added. It is incubated in a fermenter where the bacteria break down the lactose sugar in the milk into lactic acid, which causes the milk to clot and solidify into yoghurt. |
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What are viruses like? (3) |
They aren't cells, usually only a protein coat around genetic material. Can only reproduce around living cells so must infect other organisms to multiply. Plant, animal and bacterial cells can all be infected however each virus can only infect a specific type. |
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How does a virus reproduce? (3) |
It attaches itself to a specific host cell and injects its genetic material into the cell. This then causes the host cell to make the components of new viruses. This eventually causes the cell to split open which releases the new viruses. |
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How can diseases be transmitted? (4) |
Food - food poisoning. Water - cholera. Airborne Droplets - influenza (flu). Contact - athletes foot. |
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What is the incident of diseases? |
The amount of new cases that occur in a population in a certain time. |
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What are the four stages of an infectious disease? (4) |
Microorganism enters the body. Replicates rapidly. Produces toxins which damage cells and tissues. The toxins causes symptoms of infection (your immune system can also cause symptoms). |
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What is the incubation period? |
The time of exposure to the microorganism to the development of symptoms. |
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How do antiseptics help stop disease? |
They are used outside the body to prevent infection by cleaning wounds and surfaces. |
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How do antibiotics help stop disease? |
They are used inside the body to kill the bacteria of an already infected person. They are usually taken as a pill or ingested. |
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How must we be careful with antibiotics? |
They should only be prescribed when its really necessary and you should finish the full course. |
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What did Louis Pasteur come up with? |
The common understanding at the time was that diseases appear out of nowhere; he argued that microbes in the air cause disease. |
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What experiments did Louis Pasteur do? |
He heated broth in 2 flasks, one with a S-shaped neck and one with a straight neck. As the microbes settled in the curve that broth didnt go off, however the one with a straight neck did. |
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What did Joseph Lister do? |
A lot of people were dying of infections in hospital and, knowing of Louis Pasteur's work, he started using the antiseptic carbolic acid to clean and dress surgery wounds which prevented septis and eventually caught on with other doctors. |
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What did Alexander Fleming do? |
He was cleaning agar plates and saw that no bacteria grew around some mould that developed, concluding that the mould produced something that killed the bacteria (penicillin). |
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What is the word equation for yeast respiring anaerobically? |
Glucose --> ethanol + carbon dioxide (+energy) |
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What is the symbol equation for yeast respiring anaerobically? |
C6H12O6 --> 2C2H5OH + 2CO2 (+energy) |
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What is the word equation for yeast respiring aerobically? |
Glucose + oxygen --> carbon dioxide + water (+energy) |
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What affects the rate of reproduction of yeast? (5) |
Temperature. Glucose levels. pH. Oxygen levels. |
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How can we measure how fast yeast is reproducing? |
By measuring the amount of glucose it breaks down. |
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How can factories get rid of sugary water? |
Put yeast in it as it breaks down the glucose as it respires. |
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What are the properties of sandy soils? |
Large particles so high air content and very permeable. |
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What are the properties of clay soils? |
Small particles so low air content and low permeability. |
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What are the properties of loam soils? |
Mixture of sandy and clay soils. |
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What is humus? |
Dead, decomposed organic matter. In most soils and helps to support soil life. |
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How can you measure the water and humus levels of soil? |
Measure mass. Heat to 105'C to boil off water. Remeasure to get mass of water. Heat to 550'C to burn off humus. Remeasure to get mass of humus. |
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How does humus help support soil life? (2) |
Organic material is decompsed into different compounds (humus) that can then be used by other organisms. It also increases oxygen content and therefore increases the oxygen availability for organisms. |
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How do earthworms help soil? |
They bury leaves in the soil. Aerate and irrigate the soil. Mix it up, evenly distributing the nutrients. Their waste is less acidic than the soil which helps neutralise it. |
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How do amoebas regulate their water content? |
They have a contractile vacuole that collects the excess water in the cell, take it to the cell membrane then contract to release it. |
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What are the two types of plankton? |
Phytoplankton - Microscopic plants. Zooplankton - Microscopic animals that feed on phytoplankton. |
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Why do algal blooms happen? |
The summer days mean there are longer days and sunnier days, resulting in more light and higher temperatures so the phytoplankton thrive. |
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Where do deep sea food webs get their energy from? |
Sulfur air vents. Dead organisms that have fallen from the surface. |
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What are the 3 main enzymes and their products? |
Amylase: Carbohydrates --> Sugars Lipase: Fats --> Fatty acids and Glycerol Protease: Protein --> Amino acids |
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How does Benedict's solution help detect diabetes? |
When urine is mixed with the solution and heated it changes colour. Uses chemicals, not enzymes. |
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What does sucrase do? |
Breaks down sucrose into glucose and fructose which are much sweeter. |
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How can enzymes be immobilised? |
By mixing the enzyme with alginate (gel) and dropping them in a calcium chloride solution. |
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What are the advantages of immobilised enzymes? (2) |
Can be filtered out so don't contaminate the product. Can be used in continuous flow processing. |
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How can milk be made lactose free using continuous flow processing? |
Flow the milk through a column of immobilised enzymes. |
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How can bacteria be engineered to produce insulin? (6) |
Identify the gene that produces insulin. Remove it using restriction enzymes, which leave it with sticky ends. Cut a space in a plasmid of the other cell using restriction enzymes, leaving it with sticky ends. Insert the gene into the plasmid and connect the sticky ends using the ligase enzyme. The plasmid is taken up by the bacteria. Ensure that the bacteria contains the new gene using assaying techniques. |
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How does DNA fingerprinting work? |
DNA is extracted from the sample. Restriction enzymes cut the DNA up, where they cut them up depends on your DNA. Electrophoresis is used as the fragments are suspended in a gel and are charged, and the smaller the DNA segments are the further they move. The DNA is tagged using a radioactive probe (they bound to the DNA fragments) and then can be viewed by being placed on a photographic film. |
