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Photoynthesis - Coggle Diagram
Photoynthesis
Acid Rain
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Happens when:
- When any type of fuel is burnt, so lots of different chemicals are produced.
- When the smoke that comes from a fire or the fumes that come out of a car exhaust don't just contain the sooty grey particles that you can see - they also contain lots of invisible gases that can be even more harmful to our environment.
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How acidic is acid rain?
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When the air is more polluted with nitrogen oxides and sulphur dioxide the acidity can increase to a pH value of 4.
The effects of Acid Rain
The rain falls and it can have a serious effect on soil, trees, buildings and water.
Forests
- Acid rain can cause trees to grow more slowly or even to die.
- There are some types of soil that can help to neutralise the acid, they have what is called a "buffering capacity".
- Other soils are already slightly acidic and these are particularly susceptible to the effects of acid rain.
Effect in trees:
- It can dissolve and wash away the nutrients and minerals in the soil which help the trees to grow.
- It can cause the release of harmful substances such as aluminium into the soil.
- It can also wear away the waxy protective coating of leaves, damaging them and preventing them from being able to photosynthesise properly.
They weaken the trees which means they can be more easily attacked by diseases and insects or injures by bad weather.
Lakes and Rivers
- Acid rain runs off the land and ends up in streams, lakes and marshes - the rain also falls directly on these areas.
- As the acidity of a lake increases, the water becomes clearer and the numbers of fish and other water animals decline.
- The acidity of the water can cause deformity in young fish and can prevent eggs from hatching properly.
- The acidity of the water also causes toxic substances like aluminium to be released into the water from the soil, harming fish and other aquatic animals.
- If a species of fish disappears, the animals which feed on it will gradually disappear too.
- If the extinct fish used to feed on a particular species of large insect, that insect population will start to grow, this in turn will affect the smaller insects or plankton on which the larger insect feeds.
Buldings
- Acid rain can help to make natural process even quicker.
- Statues, buildings, vehicles, pipes and cables can all suffer.
- The worst affected are things made from limestone or sandstone as these types of rock are particularly susceptible and can be affected by air pollution in gaseous form as well as by acid rain.
What can be done?
Reduce emissions:
- Burning fossil fuels is still one of the cheapest ways to produce electricity so people are now researching new ways to burn fuel which don't produce so much pollution.
- Governments need to spend more money on pollution control even if it does mean an increase in the price of electricity.
- Sulphur can also be 'washed' out of smoke by spraying a mixture of water and powdered limestone into the smokestack.
- Cars are now fitted with catalytic converters which remove three dangerous chemicals from exhaust gases.
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Conserving Resources
- Greater subsidies of public transport by the government to encourage people to use public transport rather than always travelling by car.
- Every individual can make an effort to save energy by switching off lights when they are not being used and using energy-saving appliances - when less electricity is being used, pollution from power plants decreases.
- Walking, cycling and sharing cars all reduce the pollution from vehicles
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The structure of a leaf
Inside the leaves, energy from sunlight is captured by chlorophyll and used to combine carbon dioxide and water together to form sugar and oxygen.
Upper epidermis
- Especially on the upper surface of the leaf.
- It is covered with a layer of wax, called the cuticle.
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Mesophyll
Palisade mesophyll
Made up of tall, rectangular cells.
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Photosynthesis in a leaf
Photosynthesis happens inside the mesophyll cells, especially the palisade mesophyll cells.
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Chloroplasts need water, carbon dioxide and sunlight.
Supplies
Carbon dioxide supply
There is a concentration gradient for carbon dioxide, resulting in the net diffusion of carbon dioxide into the leaf.
Carbon dioxide molecules diffuse through the stomata, through the air spaces between the spongy cells, through the cell walls, cell membranes and cytoplasm of the spongy and palisade cells, and finally into their chloroplasts.
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Water supply
Plants get their water from the soil.
Taken up by root hairs and moves across the root into the xylem vessels.
It flows up through the vessels, which carry it up through the center of the root, into the stem, and finally into the leaves.
Once inside the leaf, the water moves out of the xylem vessel through tiny holes in their walls.
Some of the water goes into the chloroplasts in the mesophyll layer.
Sunlight supply
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The palisade cells are nearer to the top of the leaf that the spongy cells, so it is the palisade cells that get the most sunlight, and where most photosynthesis happens.
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