The advantages and disadvantages of the biological control method of pest management?

Andrew Wilson The advantages and disadvantages of the biological control method of pest management The biological control method of pest management does not use chemicals. Biological control uses various organisms that are either predators or parasites to the pest. A pest is an organism which causes damage to people and their crops, however this is an economical definition, as opposed to a biological one. Something is considered to be a pest when it reduces productivity by 5-10%. Plants require certain mineral ions in order to grow well, however there is a limited amount of these in soil. Therefore if weeds are growing in a wheat crop, they will take some of the mineral ions that would go to the wheat plants. Interspecific competition is the competition between organisms of different species for the resources that they require, and intraspecific competition is the competition between organisms of the same species. Weeds also compete with crops for water and light as opposed to just mineral ions. Pests reduce the yield of plants in various ways. They can have a direct effect by damaging the leaves of the plant. Aphids feed by inserting their mouthparts into plant cells, this often results in leaves curling up and becoming distorted. Considering the leaves of a plant are the places where the majority of the photosynthesis takes place, it follows that a plant with stunted

  • Word count: 651
  • Level: AS and A Level
  • Subject: Science
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Investigation of Microorganisms

Introduction For my AVCE Science coursework I will be doing an investigation into organisms; however I will be describing 2 of them in specific detail. The organisms that I will be investigation are: Barley Yeast Hen Farming I will be investigating in further detail of the barley and yeast. I have chosen to investigate the barley and yeast organisms because as part of my course I visited a brewery manufacturing company. I collected a lot of information on these two. While I was there I understood how barley is used towards the organisations success. Plan I will research the different types of organisms and compare them as well as research the to chosen organism and look at them in depth to get a better understanding. To increase my knowledge and give me a better understanding I will visit a brewing shop, preferably Carlsberg. I will gather information on how the brewing process is done. I will use relevant data collected from different websites and use the correct terminology, which I think is correct. Outlines of Barley It grows faster in cold conditions, it is an major food around the world, it is also used to feed animals such as horses, cattle etc. It mixed with other grains such as rice. A particular strain of barley found in China, it is effective in breaking down animal fats in the body. This was considered to be the poorer person's food source in the early

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  • Level: AS and A Level
  • Subject: Science
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Transgenic organisms; scientific breakthrough or historical disaster

Transgenic organisms; scientific breakthrough or historical disaster In this report I will be showing how transgenic organism are introduced into animals and plants and the modern day issues of these process. A transgenic organism contains stable integrated recombinant DNA. This is achieved by inserting a new piece of deoxyribonucleic acid (DNA) on every chromosome in each cell. To achieve this would take large amount of time, so new DNA strand is inserted when the organism is only one cell. Though the process of mitosis the single cell will replicate its self identically and every cell in the organism will now contain this new DNA strand. This whole process is called recombinant DNA technology DNA contains thousands of different genes, which are made up of nucleotides. Each gene corresponds to different characteristics and hereditary information. The DNA strand is usually extracted from other organism and the new gene inserted is called transgene. This additions of a new DNA strand will allow organisms either, animals or plants to have properties of other organisms have. Here is a diagram a strand of DNA containing a gene, The purpose of this process is to produce modified crops and animals, which have enhanced genital information, to improve yield and productivity. The ethical issues of transgenic organisms are very equal. As the advantages of this process is it

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  • Level: AS and A Level
  • Subject: Science
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Investigating the Resistance Of A Light Bulb As The Voltage Is Increased.

Investigating the Resistance Of A Light Bulb As The Voltage Is Increased. Plan Resistance is the confrontation of electrons flowing through an electrical component. The resistance slows down the flow through the component, due to the friction created. The current in a circuit gets smaller the bigger the resistance is. To work out resistance you can use this formula: Ohm's Law - R= V (Resistance = Voltage/ Current) I To measure the resistance in a circuit you would need to find out what the voltage and the current is in the circuit. To find the voltage of a light bulb in a series circuit and hence the voltage of the circuit you would need to use a voltmeter, which would be connected in parallel with the light bulb to find the voltage across the bulb. (See diagram below). Then you would need to find the current in the series circuit by placing an ammeter in the circuit, which would give you the current of the circuit as well as the bulb current. (See diagram below.) To find the resistance of the circuit, you would then divide the voltage by the current. For this experiment I will be using a series circuit rather than a parallel circuit. This is because I only need to test the resistance of one light bulb rather than testing three or four light bulbs in a parallel circuit. This way the lamp will be more efficient. Safety To make sure that the test is safe, I would

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  • Level: AS and A Level
  • Subject: Science
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Measuring The Constant g; The Acceleration Due To Gravity

AS Physics Investigation - Measuring The Constant 'g'; The Acceleration Due To Gravity Contents Abstract - Page 1 Introduction - Page 2 Equipment Listing - Pages 2-3 Preliminary Investigation - Pages 3-4 Final Methods - Pages 4-5 Results Tables & Statistical Analysis - Pages 5-7 Conclusions To Data - Page 7 Evaluation Of Experiment - Page 8 Abstract The gravitational field strength , also referred to as the 'acceleration due to gravity' (symbol 'g') is a crucial fundamental constant which affects the motion of all objects from within earth's gravitational field. For this investigation, I chose to measure this using suitable methods obtained from research into the calculation of 'g', and ultimately I had successfully done so to a substantial degree of accuracy, making it a success overall. The two main techniques which I used to measure this are as follows: ) Dropping a preferably large and dense object from various heights, and timing how long it takes to fall to the ground. The displacement 's' and time 't' are related to 'g' by this formula: s = 1/2gt( Which rearranges to: g = 2s/t( 2) This method involved timing the swings of a pendulum , with a solid mass suspended by a string of a given length. The period of a pendulum (the time for one back and forth oscillation) is given by: P = 2?v(L/g) Where 'L' is the length of the string. In order for me to

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  • Level: AS and A Level
  • Subject: Science
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Induction motors

Induction motors Induction motors use electromagnetic induction to rotate a shaft or rotor and create mechanical energy from electric energy. With minimal design alterations an electric motor like this also has the ability to create electricity from mechanical energy, although these motors are referred to as generators. Electromagnetic induction is the production of an electrical potential difference (or Voltage) across a conductor situated in a changing magnetic field. Faradays Law states that electromotive force (EMF) produced along a closed path is proportional to the rate of change of the magnetic flux through any surface bounded by that path. In practice, this means that an electrical current will flow in any closed conductor, when the magnetic flux through a surface bounded by the conductor changes. This applies whether the field itself changes in strength or the conductor is moved through it. (http://www.absoluteastronomy.com/encyclopedia/e/el/electromagnetic_induction.htm) This rule governs the design of all induction motors, generators, transformers and most electrical devices. The most basic Induction motor is the Squirrel cage motor. Squirrel cage motors are the most common industrial AC motor, when running off a constant AC supply they are simply constant speed devices. They acquired there name from the rotors used which resemble a squirrel running cage. This

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  • Level: AS and A Level
  • Subject: Science
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In the production of photochemical smog, there are primary and secondary sources that contribute to its production.

In the production of photochemical smog, there are primary and secondary sources that contribute to its production. Primary sources are injected directly into the atmosphere, whereas secondary sources are formed in the atmosphere through chemical and photochemical reactions. As the graph shows, motor vehicles (the red and pink columns) contribute largely to most of the primary pollutants. The main pollutants though are Carbon Monoxide and oxides of nitrogen (Nox). Motor vehicles also contribute largely to the secondary pollutant Nitrogen Dioxide. During the combustion of coal, primary pollutants are formed. Oxides of Nitrogen and Sulphur are formed because is there is both nitrogen and sulphur in coal - initially from the decomposed organisms. This becomes oxidised by burning. Oxides of Nitrogen are also created because there is such a high temperature of combustion, atmospheric nitrogen and oxygen form what is called thermal NOx (1). Photochemical smog is a condition that develops when primary pollutants interact under the influence of sunlight (2) to produce secondary pollutants. Several reactions lead to the production of the constituents of photochemical smog, taking place in the troposphere. Ozone is present in all levels of the atmosphere, even in unpolluted air. In unpolluted air, Nitrous Oxide reacts with the ozone, producing Nitrous Dioxide and Oxygen: 03 + NO

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  • Level: AS and A Level
  • Subject: Science
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The Effect of Substrate Concentration on the Rate of Reaction

The Effect of Substrate Concentration on the Rate of Reaction Aim: The aim is to look at how the rate of reaction in yeast catalase is affected by a particular substrate concentration. The substrate that is used in this experiment is hydrogen peroxide on the yeast catalase, which will bring faster and more precise results. Enzymes only work with substrates that fit their active site, called the lock and key mechanism. This is where the substrate fits into the enzyme in the same way that a key fits into a lock. During the process, a substrate is fitted into an active site of an enzyme. Not all substrates fit in, only particular ones, hence, the 'lock and key'. When they are together, the enzyme - substrate complex is made into a product. This is when the bonds in the substrate are weakened. The products are left from the enzyme, leaving the enzyme unchanged after the reaction. The reaction is a catabolic reaction, which means the yeast catalase breaks down the hydrogen peroxide into water and oxygen gas. H2O2 H2O + O2 Apparatus Used: . Stop watch. 2. Measuring Scale. 3. Stand with clamps. 4. Gas syringe. 5. Measuring cylinder. 6. Clonical flask. 7. 1.5 grams of yeast catalase. 8. 4 cm³ of hydrogen peroxide of various concentrations. Method: . 1.5 grams of yeast catalase has to be measured. 2. The

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  • Level: AS and A Level
  • Subject: Science
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Investigating the factors affecting the size of current flowing through a length of resistivity putty.

04/02/97 ????? GCSE PHYSICS SC1 INVESTIGATION 996/7 INVESTIGATING THE FACTORS AFFECTING THE SIZE OF CURRENT FLOWING THROUGH A LENGTH OF RESISTIVITY PUTTY. CANDIDATE NUMBER 6247 CENTRE NUMBER 15131 PLANNING AIMS The main aim of this investigation will be to investigate the factors that have an effect on the size of the current passing through a length of resistivity putty. I will also try to explain my results using a number of models formulae and theories including Ohm's law, the formula for resistivity and a water model. VARIABLES Below is a list of the variables which are likely to have a major effect on the size of the current passing through a length of resistivity, putty: . The length of putty used. 2. The cross-sectional area of the putty. (Including the amount of contact between the plates and the putty). 3. The temperature of the putty. 4. The voltage across the putty. 5. The resistance of the wires etc. and the contact resistance between the plates and the putty. Other factors, for example the density of the carbon inside the putty, or the pressure at which the experiment is carried out, may also have an effect on the size of the current, however these factors would either be difficult to control in a school physics laboratory or are not likely to have a significant effect compared to the inaccuracies of the experiment. The two

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  • Level: AS and A Level
  • Subject: Science
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Current rating of fuses and MCB's.

CURRENT RATING OF FUSES AND MCBS Name of Instructor: Miss. B.S.K. Subasinghe Name : Perera K.N.S. Index No : 020287 Field : ENTC Date of Per. : 10/12/2003 Date of Sub.: 19/12/2003 CALCULATIONS: For the fuse For MCB From graphs drawn, Fusing current for 5A fuse = Tripping current for 2A MCB = RESULTS Fusing Factor Tripping Factor DISCUSSION: Fuses and Miniature Circuit Breakers (MCBs) are used to protect electrical equipment and for the safety of the users. The conditions that require circuit protection are direct shorts, excessive current and excessive heat. When one or more of these conditions occur the above protective devices (connected in series with the supply) are able to disconnect the circuit thus preventing the danger. Fuses Circuit symbol: This provides protection by melting due to the heat produced because of ohmic resistance, when a higher than a rated current flows through it. There are three main types of fuses, Re-wirable fuses These have a thin wire that is held on a ceramic holder. The wire is designed to burn when a high current passes. An advantage is the reusability but it is vulnerable to mishandling where incorrect fusing elements can be fitted by inexperienced people, putting users in danger. Other Problems with this type are the oxidization (causes the cross section of the wire to reduce

  • Word count: 1356
  • Level: AS and A Level
  • Subject: Science
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