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  • Level: GCSE
  • Subject: Science
  • Essay length: 1182 words

An investigation in to how Light intensity effects plant biodiversity.

Extracts from this essay...

Introduction

An investigation in to how Light intensity effects plant biodiversity. Abstract An investigation as to the effects of light intensity on plant biodiversity. My hypothesis stated that as light intensity increases, so does plant biodiversity. I investigated this through a practical case study of Hounslow Heath, using quadrats and a light meter to measure light intensity. The investigation proved my hypothesis to be correct. Hypothesis As light intensity increases, so does plant biodiversity Variables: * CO2 in atmosphere * O2 in atmosphere * Salinity of soil * Soil moisture * pH level of soil * Nutrient content of soil * Interspecific competition * Temperature * Humidity * Light intensity CO2 Carboxylation reactions occur in the light independent part of photosynthesis in order to produce organic compounds. Carbon dioxide is therefore essential to a plant. Atmospheric air contains carbon dioxide at a partial pressure of approximately 0.04 kPa and it if for this reason that carbon dioxide is often a limiting factor. However a partial pressures of >1.0kPa, CO2 can potentially damage plants. O2 O2 is required for plant respiration; it is a very similar reaction to that of photosynthesis, however respiration uses O2 and C6H12O6 to produce CO2 and H2O.

Middle

The macronutrients are only needed in small amounts. These are iron, boron, copper, manganese, chlorine and zinc. Nutrients are essential for plant growth. A plant will grow at its optimum rate until they run out of a nutrient growth then becomes limited. Nutrient deficiency is often shown through discolouration or deformity. Interspecific Competition: This is competition between different species of plant. There is a limit to the availability of essential resources. When these resources are limited, competition increases. High competition will result in a lower growth rate and a decreased ability to reproduce. Competition also reduced population growing too much and acts as a natural form of environmental resistance. Temperature: In order for metabolic reactions to occur, a certain temperature must be maintained. Too cold a temperature however will often lead to plants freezing and dying, too high a temperature will lead to plants becoming easily dehydrated. Background Information Hounslow Heath The heath in Hounslow overlies the Taplow river terrace, deposited by the great river Thames approximately 20,000 years ago. It has formed on a flat gravel drift. This drift means that the soil is slightly acidic and well drained; this is the basis of what makes 'Heathland'.

Conclusion

a carrier molecule, react with the electrons from the water molecules. This reaction changes NADP from an oxidised state (NADP+) to a reduced state (NADPH). This process requires a great deal of energy, gained from light energy being trapped by chlorophyll. The light-independent reactions; In these reactions the ATP and NADPH produces are used to reduce CO2. A three-carbon compound, glyceraldehyde 3-phosphate is produced. Lights effect on chlorophyll When light is at the wavelength absorbed by chlorophyll, the rate of photosynthesis is at its optimum. Light absorbed by a chlorophyll molecule is directly absorbed by electrons. These electrons 'excited' and move to an energy level known as photoexcitation. When electrons have absorbed enough energy, they leave their chlorophyll molecule, positively charged, and move out. This process is photoionisation. Within whole chloroplasts each chlorophyll molecule has both an electron acceptor and an electron donor, all three components make up a photosystem. When photoionisation occurs, the acceptor takes up the energised electrons, and the electron donor, donates a pair of electrons, thus making the chlorophyll molecule stable once more. The electrons now within the electron acceptor are carried through an electron transfer system, back and forth, through the thylakoid membrane. It is this process here that generates sufficient energy for ATP to be synthesised from ADP and a phosphate.

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