B6 Beyond the microscope (B6.5 - B6.8)

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  • Created by: GraceLong
  • Created on: 14-05-16 16:39
How do particles in sandy soil compare to particles in clay soil?
Sandy soil particles are larger, therefore there is higher air content and higher permeability
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What does loam soil contain?
A mixture of sand and clay and large amounts of partly decomposed animal and plant waste (humus)
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Describe the simple experiment on soil samples to compare content
Humus content found by burning over bunsen burner; air content found by see how much water needed to fill spaces; water content found by heating soil and evaporating water
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Will soil hold more or less water and air if it has a higher humus content?
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What do many organisms living in soil depend onto survive?
Water for chemical reactions and oxygen for respiration
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Why is humus (partly decomposed animal and plant waste) important to living organisms?
It releases minerals and increases the air content of the soil
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What do earthworms do in soil to improve structure and fertility?
Bury organic matter for decomposition by bacteria and fungi; aerate and drain the soil; mix up soil layers; neutralise acid soil
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How does draining and aerating soil help some organisms?
Organisms respire aerobically
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Why is neutralising soil important?
Some plants will not grow if pH too low
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Who was the first person to understand the importance of earthworms?
Charles Darwin
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What are the advantages of living in water?
No risk of dehydration; temperature varies less than air; water provides support; waste products easily disposed of
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What are the disadvantages of living in water?
Water content of body needs to stay constant which might be difficult to control in water; water is denser than air so harder to move
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Explain what might happen to organisms in freshwater and salt water.
In fresh water, organisms might take in too much water by osomosis; in salt water organisms might loose too much water by osomosis
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Describe how a contractile vacuole controls excess water
The vacuole stores the excess water and then fuses with the cell membrane and empties the water to the outside
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What are phytoplankton and zooplankton?
Phytoplankton are small aquatic plants; zooplankton are small aquatic animals
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Why do the number of phytoplankton and zooplankton vary in different seasons?
Different factors affect the rate of photosynthesis, e.g. less light in winter; lower temperatures in winter; minerals used up towards the end of summer
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What are the three main food sources that are relied on by food webs?
Green plants; marine snow; bacteria
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Why can some chemicals like PCBs and DDT kill animals at the top of the food chain?
They are toxic and do not break down quickly so become concentrated higher up the food chain - they then affect animals with long lifespans eg whales
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What are enzymes used for in washing powders (give specific examples)?
Amylase digests carbohydrates; lipase digests fats. protease digests proteins
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Why do biological washing powders wok best at moderate temperatures?
It is the optimum temperature for them to work
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What happens to the products after digestion with washing powder?
They are soluble so wash out easily of the clothes
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Which enzyme breaks down sucrose?
Sucrase (invertase)
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What happens to sucrase once it is broken down by the enzyme?
Glucose and fructrose are made which are much sweeter - food industries can use much less of it, lowering costs and energy
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How can enzymes be immobilised in gel beads?
Mixing enzymes with alginate and dropping the mixture into calcium chloride solution
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Why are immobilised enzymes useful?
The mixture does not become contaminated with enzymes and they can be used in a continuous flow process
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What makes people lactose intolerant?
They cannot produce the enzyme lactase meaning bacteria in the gut ferment lactose producing diarrhoea and wind
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How can milk be treated for people who are lactose intolerant?
Immobilised lactase is used to convert lactose in milk to glucose and galactose which can then be absorbed from the milk with no side effects
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Why can lactose intolerant people eat yogurt?
Because the bacteria have converted lactose in milk to lactic acid
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Genetic engineering involves transferring genes from one organism to another. What is the name of the organism that receives the new genes?
Transgenic organism
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Describe the main stages of genetic engineering.
Identifying and removing desired gene from one organism and cutting open the DNA in another organism. The new genes are then inserted into the DNA and the genes are checked to make sure they work
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Why does the process of genetic engineering work?
Because the genetic code is universal and genes from one organism will produce the same proteins needed
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What do restriction enzymes do?
They cut open DNA and leave some unpaired bases on the cut ends (sticky ends)
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What do ligase enzymes do?
They join DNA strands because the 'sticky ends' join to complementary pairs
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Describe the stages of genetically engineering bacteria to produce human insulin
Genes are cut from human DNA and one end of bacteria DNA cut. The insulin genes are inserted into the bacteria loop and the loop is inserted back into the bacteria. Copies are then made of the bacteria by cloning
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What are the loops of DNA called in the process of making human insulin?
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Describe the assaying technique
Scientists add a gene to make bacteria resistant to antibiotics and then the bacteria are flooded with antibiotics by being grown on agar containing the antibiotic. Scientists then choose the bacteria that survive
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What can DNA 'fingerprinting' be used for?
Identify individuals e.g. committing crimes, assessing likelihood of developing disease
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What are the main stages of DNA 'fingerprinting'?
Extracting DNA from sample and cutting up DNA using restriction enzymes. The fragments are then separated using electrophoresis and made visible by using a radioactive probe
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Other cards in this set

Card 2


What does loam soil contain?


A mixture of sand and clay and large amounts of partly decomposed animal and plant waste (humus)

Card 3


Describe the simple experiment on soil samples to compare content


Preview of the front of card 3

Card 4


Will soil hold more or less water and air if it has a higher humus content?


Preview of the front of card 4

Card 5


What do many organisms living in soil depend onto survive?


Preview of the front of card 5
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