B6 : Beyond the microscope
Qu / Biofuels / Ans / Biofuels1 / Name 2 biofuels / 1 / Biogas and Gasahol
2 / What is the main gas in biogas? / 2 / Methane
3 / What is the second most abundant gas in biogas? / 3 / Carbon dioxide
4 / What gases are found in biogas in extremely small amounts? / 4 / Hydrogen, Nitrogen and Hydrogen sulfide
H5 / Why are high temperatures (above 45 degrees Celcius) in biogas fermenters a problem? / H5 / High temperatures denature the enzymes in the methane producing bacteria.
H6 / What type of acids do bacteria produce in biogas fermenters? / H6 / Fatty acids from lipids and amino acids from proteins.
H7 / What kind of conditions do the methane producing bacteria need? / H7 / Anaerobic
8 / What type of fermentation is where substances are continually added and products continually removed? / 8 / Continuous
9 / What is the biofuel in gasohol? / 9 / Ethanol
10 / Waste agricultural material contains starch and cellulose. How can this waste be treated to produce sugars? / 10 / Use of cellulase to digest cellulose and amylase to digest starch.
11 / Biofuels are sometimes referred to as “carbon neutral”. Explain this. / 11 / Carbon dioxide is removed from the atmosphere during photosynthesis and the carbon dioxide is put back into the atmosphere during the combustion of the biofuel.
H12 / What are the advantages of using biofuels? / H12 / Fossil fuels are running out.
Biofuels are sustainable.
Biofuels do not increase the levels of carbon dioxide in the atmosphere, so do not contribute to the Greenhouse Effect.
No particulates are produced during combustion.
H13 / What are the disadvantages of using biogas? / H13 / Biogas is a mixture of gases and contains less energy than natural gas.
Qu / Life in soil / Ans / Life in soil
1 / How do earthworms improve the fertility of the soil? / 1 / 1. Burrowing aerates the soil and improves drainage.
2. Eating and burrowing mixes the layers in the soil.
3. Taking organic material from the surface and burying it allows bacteria and fungi in the soil to decompose it.
4. Adding chalk as it eats the soil helps to neutralise acidic soil.
2 / What does soil contain? / 2 / 1. Particles from broken up rocks
2. Living plants and animals
3. Humus (decayed remains of dead plants and animals)
4. Air
5. Water
H3 / Why is sand added to waterlogged soil? / H3 / It creates air spaces to allow water to drain through
4 / What are earthworms and millipedes called that feed on dead organic matter called? / 4 / Detritivores
H5 / What type of plant contains nitrogen fixing bacteria in their root nodules? / H5 / Legumes e.g. peas and clover
H6 / What type of bacteria convert nitrates in the soil into nitrogen gas? / H6 / Denitrifying bacteria
H7 / What type of bacteria convert nitrogen gas into nitrates? / H7 / Nitrogen Fixing Bacteria
H8 / What type of bacteria converts ammonium into nitrates? / H8 / Nitrifying bacteria
H9 / What type of microbes cause decomposition of dead material into ammonia? / H9 / Saprophytes
H10 / What is the process of turning ammonium into nitrates called and what conditions does it need? / H10 / Nitrification and it needs aerobic conditions.
H11 / What process is the turning of nitrogen gas into nitrates and what conditions does it need? / H11 / Nitrogen fixation and it needs anaerobic conditions.
H12 / What nitrogen containing substance is made in the liver from excess amino acids and is removed by the kidney? / H12 / Urea
H13 / What type of relationship do legumes and nitrogen fixing bacteria have with each other? / H13 / Mutualistic
H14 / What conditions does denitrification need? / H14 / Anaerobic
H15 / Why are waterlogged conditions bad for plant growth? / H15 / 1. It creates anaerobic conditions that encourages denitrification and discourages nitrification.
2. It stops aerobic respiration in the root tissue, so less ATP is made, so less active transport of mineral ions into the roots occurs
H16 / Give the name of a nitrogen fixing bacteria that lives in root nodules of legumes. / H16 / Rhizobium
H17 / Give the name of nitrogen fixing bacteria that live free in the soil. / H17 / Azotobacter
Clostridium
H18 / Give 2 names of nitrifying bacteria / H18 / Nitrosomonas
Nitrobacter
H19 / Which ions do plants take nitrogen from the soil? / H19 / Nitrates
Qu / Microscopic Life in water / Ans / Microscopic Life in water
1 / What is the advantage of living in water? / 1 / 1. Organisms do not dry out.
2. Water is thermally stable due to the high specific heat capacity, so it does not heat up easily.
3. Organisms can grow large as the water will support their weight.
4. Excreted waste does not build up to a high concentration as the large volume of water dilutes it.
2 / What are microscopic photosynthetic organisms called that live in the sea? / 2 / Phytoplankton.
3 / What are the microscopic animals in the sea called that feed on the phytoplankton / 3 / Zooplankton
H4 / What structure does amoeba use to remove the water that has entered by osmosis? / H4 / Contractile vacuole
H5 / How do salmon respond to being in fresh water? / H5 / 1. The gills actively transport salt from the water into its body.
2. Produce large volumes of dilute urine.
H6 / How do salmon respond to being in salt water? / H6 / 1. Salmon drinks sea water secrete salt back into the sea.
2. Produce very concentrated urine.
7 / What can pollute water? / 7 / 1. Organic matter such as sewage.
2. Oil.
3. PCBs.
4. Nitrates from fertilisers.
5. Pesticides.
6. Detergents
8 / What can be used to indicate how polluted water is? / 8 / Indicator species. Caddis fly larvae can only survive in clean water with high levels of oxygen.
9 / What is it called why excess nitrates wash into fresh water and cause algal blooms, eventually leading to the reduction in oxygen levels in the water? / 9 / Eutrophication
H10 / What is it called where substances such as DDT or PCBs increase in concentration as they pass along the food chain? / H10 / Bioaccumulation
Qu / Enzymes in Action / Ans / Enzymes in Action
1 / What enzymes can be found in biological washing powders? / 1 / Amylases (that digest starch), proteases ( that digest proteins) and lipases ( that digest fats or oils)
2 / Why does pH affect the activity of biological washing powders? / 2 / Extremes of pH denature the enzymes
3 / What are fats digested into by lipases? / 3 / Fatty acids and glycerol.
4 / What are proteins digested into? / 4 / Amino acids
5 / What is starch digested into / 5 / Maltose
H6 / What does sucrase digest sucrose into? / H6 / Glucose and fructose
H7 / Why is it an advantage to use glucose and fructose in some foods rather than sucrose? / H7 / Glucose and fructose are much sweeter, so less needs to be added to get the same sweetness.
8 / What are the advantages of immobilised enzymes? / 8 / 1. It keeps the product enzyme free.
2. The enzymes are not lost, so can be used again.
3. They can be used for continuous processes.
9 / What are the disadvantages of immobilised enzymes? / 9 / 1. The shape of the enzyme may change during the immobilising process.
2. The enzyme has less kinetic energy, so a slightly lower rate of reaction.
3. It is expensive to initially immobilise the enzyme.
H10 / What does lactase do? / H10 / It digests lactose into glucose and galactose
H11 / What are people called who cannot produce lactase and get diarrhoea and wind after drinking milk? / H11 / Lactose intolerant
H12 / How can immobilised lactase be used to help lactose intolerant people and animals? / H12 / Milk is passed over the immobilised lactase and the lactose in the milk is digested to glucose and galactose, so there is no lactose for bacteria to ferment and make gas.
Qu / Genetic Engineering / Ans / Genetic Engineering
1 / Genetic engineering changes the genetic code of an organism. It involves putting a new gene in the organism’s existing DNA. What is the term to describe the altered organism? / 1 / Transgenic
H2 / What type of enzymes is used to cut pieces of DNA at specific points? / H2 / Restriction enzyme
H3 / What type of enzymes is used to join pieces of DNA together? / H3 / DNA ligase
4 / What term describes the plasmid that carries the useful gene into another organism? / 4 / Vector
Qu / Understanding Bacteria / Ans / Understanding Bacteria
1 / What features do bacterial cells NOT have? / 1 / 1. A nucleus.
2. Mitochondria
3. Chloroplasts
2 / What features do bacterial cells have? / 2 / 1. Cell wall made from murein
2. Plasmids
3. Cell Membranes
3 / What is the process called where bacteria reproduce asexually by splitting in two? / 3 / Binary Fission
H4 / A few bacteria can photosynthesise, but most absorb readymade food molecules such as sugars or amino acids. Some can use chemicals to make organic molecules. Give two examples of these chemicals. / H4 / Ammonia
Hydrogen sulfide
5 / When making yoghurt why is the milk used pasteurised and the equipment sterilised? / 5 / So that any pathogenic or unwanted microorganisms do not grow.
6 / Why is the milk cooled before the culture of bacteria is added? / 6 / To prevent the enzymes in the bacteria becoming denatured.
7 / What are the procedures called that are taken to minimise contamination with unwanted bacteria? / 7 / Aseptic technique
Qu / Harmful Microorganisms / Ans / Harmful Microorganisms
1 / What are disease causing microbes called? / 1 / Pathogens
2 / Who carried out experiments to prove that microbes in the air cause decay of food and not just the air? / 2 / Louis Pasteur
3 / Who developed antiseptics that prevent wounds becoming infected? / 3 / Joseph Lister
4 / Who discovered antibiotics? / 4 / Alexander Flemming
Qu / Microorganisms factories for the future / Ans / Microorganisms factories for the future
1 / What is the method of asexual reproduction called that yeast use? / 1 / Budding
2 / Why do high temperatures and extremes of pH kill yeast cells? / 2 / The enzymes in the yeast become denatured.
H3 / What is the balanced symbol equation for anaerobic respiration in yeast cells? / H3
H4 / How can alcohol tolerant yeast be produced? / H4 / Genetic engineering
5 / How is beer preserved? / 5 / Pasteurisation
6 / What is malting? / 6 / Starch being turned into maltose a sugar during the brewing process.
7 / Why do wines only have a concentration of alcohol around 13%? / 7 / The alcohol the yeast makes eventually kills or poisons it.
8 / How can alcohol drinks be produced that have a concentration much higher than 13% / 8 / Distillation