Biology Rhythms, Plant Defences and Growing Microorganisms

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  • Created by: Libby
  • Created on: 07-03-13 19:04
How do plants defend themselves from attack?
Plants produce chemicals which can deter pests or kill pathogens.
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Why do plants expend energy producing defences?
Pests and pathogens can destroy leaves which reduces photosynthesis efficiency. By producing defences they can minimize this damage and ultimately gain more energy than they would lose through damage to their leaves.
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What are 3 plant defence chemicals and their uses in medicine?
Quinine (found in the anchona tree) can treat malaria. Aspirin (found in the willow tree) is a painkiller. Digoxin (found in the foxglove) is used for treating heart disorders.
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Explain fully why a farmer may invest money in pesticides for his crops.
Pests can destroy crops and make them grow less efficiently by damaging their leaves. Pesticides will destroy the pests and pathogens which can ruin plants, increasing the yield. A larger yield will give more profit, cancelling out the original cost.
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What is photoperiodicity?
Photoperiodicity is a response to changes in day length.
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Give an example of photoperiodicity.
.Some examples of photoperiodicity include germination in spring, stopping growth in winter and flowering at a particular time of the year.
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What is a circacidian rhythm?
A circacidian rhythm is a pattern of behaviour which changes of a 24 hour period, controlled by the biological clock.
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What is the biological clock?
The biological clock uses external factors such as day and night to match the circacidian rhythms in animals to changes in the environment
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Describe the results of Louis Pasteur's experiments.
Louis Pasteur proved that after microorganisms in a substance have been killed by a method such as heating, they will not suddenly reappear unless they come into contact with a contaminated substance, such as air.
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What do aseptic techniques do?
Aseptic techniques involve destroying microorganisms to sterilize a substance and then prevent it from coming into contact with unsterile substances.
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What are the uses of aseptic techniques?
Aseptic techniques are used to prevent food from spoiling and to sterilize surgical equipment to prevent infections.
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Describe the growth of bacteria.
The numbers of bacteria doubles roughly every 20 minutes, causing exponential growth. This will continue until it is limited by a factor such as the nutrient supply.
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How do temperatures impact on the growth of bacteria?
At low temperatures, bacteria do not multiply and high temperatures kill bacteria. At temperatures around 20-30 degrees celsius, bacteria multiply very quickly.
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Other cards in this set

Card 2

Front

Why do plants expend energy producing defences?

Back

Pests and pathogens can destroy leaves which reduces photosynthesis efficiency. By producing defences they can minimize this damage and ultimately gain more energy than they would lose through damage to their leaves.

Card 3

Front

What are 3 plant defence chemicals and their uses in medicine?

Back

Preview of the front of card 3

Card 4

Front

Explain fully why a farmer may invest money in pesticides for his crops.

Back

Preview of the front of card 4

Card 5

Front

What is photoperiodicity?

Back

Preview of the front of card 5
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