AQA GCSE Geography Latest Update 100% Pass

AQA GCSE Geography Latest Update 100% Pass Describe how nutrients are cycled in a land-based ecosystem. When dead material is decomposed, nutrients are released into the soil.The nutrients are then taken up from the soil by plants. The plants may be eaten by consumers. When the plants or consumers die, the nutrients are returned to the soil. This transfer of nutrients is called nutrient cycling Describe the global distribution of tropical rainforests - Along the equator between the Tropic of Cancer and the Tropic o Capricorn - Asia, Africa, South America - Amazon is the largest area of tropical rainforest Outline one reason why the concentration of carbon dioxide in the atmosphere has changed over time. There has been an increase in thermal power stations that burn fossil fuels which releases gases including carbon dioxide which build up in the atmosphere. Describe the distribution of hot deserts. - Most of the world's hot deserts lie between 15° and 35° north and south of the equator (1) - Several deserts are found on the western side of continents, for example, the deserts of South America and southern Africa (1) - The largest desert (the Sahara) stretches across northern Africa into the Middle East (1) - Some hot deserts extend much closer to the equator, for instance, the Atacama desert on the western side of South America (1). Describe and explain the features of the vegetation in a tropical rainforest [6 marks] - Due to the high rainfall, leaves often have drip tips which allow the water to be channelled to the end and fall so the leaf does not break. Leaf stems are also flexible to allow leaves to move with the sun. - Some plants such as lianas climb up trees to reach sunlight for photosynthesis due to the thick foliage and canopy layer not allowing enough sunlight - Buttress roots support the trees as they grow incredibly tall (over 50m) as there is great competition for sunlight. Outline one possible environmental impact of deforestation When trees are felled, more carbon dioxide remains in the air. Also, fire is often used in clearing rainforests, which means that the carbon stored in the wood returns to the atmosphere leading to a rise in global warming. Suggest one way that international co-operation can help make tropical rainforests more sustainable. - Countries can be relieved of some of their debt, known as debt for nature schemes (1) in return for retaining their rainforest areas (2) - International organisations such as the Forest Stewardship Council (FSC) promote sustainable forestry (1) by guaranteeing that timber products are sourced from sustainable managed forests (2). How does a cold environment provide opportunities for development? 1) Mineral Extraction: 1/5 of state wealth comes from gold 2) Fishing: Adds $6 billion to the state economy every year. Employs 1/10 of Alaskans 3) Energy: more that 50 HEP plants provide 1/5 of Alaskan electricity 4) Tourism: 2 million people visit Alaska every year How does a cold environment provide challenges for development? 1) Extreme Temperature: Temperature can fall to 40 degrees 2) Inaccessibility: Very few surfaced roads and even paved roads are covered in permafrost so transportation costs are very high 3) Provision of buildings and infrastructure - Hear from buildings can cause the active layer below to heat up which can cause subsidence. Give two reasons why the biomass changes between each level in the food chain. Loss of energy through movement Loss of energy through excretion Give one effect of deforestation on the soils of the rainforest. They become less fertile and the lose nutrients as the rainwater may cause leaching. What are the impacts of deforestation? [Basic] 1) Economic development 2) Soil Erosion 3) Contribution to climate change 4) River pollution 5) Loss of biodiversity 6) Decline of indigenous tribes Economic Development [Impact of deforestation] - Development of land for mining, framing and energy will lead to job creation: 2008 $7 billion from cattle. - Companies will pay tax to the government which can be used to improve public services. - Minerals such as gold are very valuable BUT can cause fish poisoning in the Amazon river Soil Erosion [Impact of deforestation] When part of the forest cover is cleared, the thin topsoil is quickly removed by heavy rainfall. Once the top soil has been removed, there is little hope of anything growing again Land becomes bare and unusable Climate Change [Impact of deforestation] - Global Warming: When trees are felled, more carbon dioxide remains in the air. Also, fire is often used in clearing rainforests, which means that the carbon stored in the wood returns to the atmosphere. - Local: Deforestation disrupts the water cycle. With the felling of trees, evapotranspiration is reducing so there is less moisture in the atmosphere. The local climate becomes drier. Once the recycling of water is reduced, the local climate becomes warmer. This is bad for farming. River Pollution [Impacts of deforestation] Gold mining not only causes deforestation but the mercury used to separate the gold from the ground is allowed to enter the rivers. Fish are poisoned as well as people living in nearby towns. Loss of Biodiversity [Impacts of deforestation] Biodiversity will be reduced and individual species will become endangered or extinct. Every year 50,000 species of animals and insects are lost every year. Medicinal cures can be lost through this destruction. Decline of indigenous tribes [Impacts of deforestation] There are now only around 240 tribes left compared with over 330 in 1900. Many have been forced out due to the construction of roads, logging, and the creation of ranches and the opening of mines. Describe the characteristics of a small scale UK ecosystem. - High biodiversity - Deciduous woodland - Large number of native tree species eg. Oak, elm, ash - Lower shrub layer of holly and hazel overlying a field layer of field grasses, brambles, bracken and fern. - 700 species of fungi, which are important decomposers Impacts of human change on a small-scale UK ecosystem - Agricultural fertilizers can lead to eutrophication: nitrates increase growth of algae, which will deplete oxygen and fish may die. - Ponds may be drained to use for farming. Aquatic plants will die, as will fish and other pond life. Woods cut down, destroying habitats for birds and affecting the nutrient cycle - Hedgerows removed to increase the size of fields. Habitat will be destroyed, altering the plant/animal balance Give reasons for the biodiversity in tropical rainforests - Perfect climatic conditions all year round for plant life support huge numbers of species. - Large numbers of plant species provide food for a similarly large number of animal species. - Stratification (layers) of the rainforest produces different ecological niches. Different species evolve to meet the different needs of these niches. - Tropical rainforests are ancient - plants and animals have been evolving there for hundreds of thousands of years. Describe the pattern of changing rates of deforestation. - Between 2000 and 2010 there is to be a greater number of countries which have experienced an increase in the rates of deforestation compared to the countries which have experienced a decrease in the rate of deforestation. - 9 countries experienced increased deforestation, whereas only seven have seen a decrease in deforestation. - However, in some of the countries with large expanses of rainforest there has been a significant decrease. For example, Brazil has experienced a 21% drop in deforestation in the 10 year period. - Overall though, even the countries that have seen a decrease in deforestation are still experiencing some deforestation. Describe the value of tropical rainforests to the environment 1) Rainforests are important sources of freshwater. About 20% of the worlds freshwater comes from the Amazon Basin 2) Tropical rainforests contain 50% of the world's plants and animals, including thousands of different species - many yet to be discovered, which may produce cures for illnesses in the future. 3) Rainforests are known as the 'lungs of the world' as they contribute 28% of the world's oxygen. 4) Rainforests absorb carbon dioxide from the atmosphere, acting as a 'carbon sink'. This helps to offset global warming. Describe the value of tropical rainforests for people - Medicines: 1/4 of all natural medicines have been found in TRFs - Cash Crops: Wild coffee that resists disease has a higher yield than traditional Arabica beans traditionally used by growers in the rest of Brazil - Raw Materials: Rainforests can be logged to produce timber such as hardwoods. What are the causes of deforestation? [Basic] 1) Subsistence Farming 2) Commercial Farming 3) Logging 4) Road building 5) Mineral Extraction 6) Energy Development 7) Settlement and population growth Subsistence farming [Causes of deforestation] Slash and burn involves the use of fire to clear the land. The burning creates valuable nutrients that help plants to grow. 2/5 of tropical deforestation is caused by subsistence activities These fires, however, can grow out of control destroying large areas of forest Commercial farming [Causes of deforestation] - Cattle: This accounts for 80% of tropical rainforest destruction in Brazil. However, the land cannot be used for long. - Crops= The forest is being cleared to make way for vast plantations, where crops such as bananas, palm oil, pineapple, sugar cane, tea and coffee are grown. - The amount of forest cleared for soy beans has doubled between 1990 and 2010 Logging [Causes of deforestation] 3% of all deforestation in Brazil. Timber companies are interested in mahogany and teak and sell them to other countries to make furniture (selective logging). Road Building [Causes of deforestation] The Trans-Amazonian highway began construction in 1972 and is 4000 km long. It has played a major part in opening up remote areas of the Amazon. However it destroys large swathes of rainforest Mineral extraction [Cause of deforestation] In 1999, there were 10, 0000 hectares of land being used for gold mining. Today, the area is over 50,000 hectares. The rainforest suffers badly from this. Energy development [Causes of deforestation] An unlimited supply of water and ideal river conditions have encourage dams to be built to generate hydroelectric power. This involves flooding large areas of rainforest. Settlement and Population Growth [Causes of deforestation] As population increases rainforests are used for construction materials or building plots. Give examples of interdependent relationships in an ecosystem - Photosynthesis - sunshine, carbon dioxide (abiotic) are used by plants to create sugars/food (biotic) - Rain is stored in the soil (abiotic) and taken up by plants (biotic) - Rocks are weathered releasing minerals into the soil (biotic), which are taken up by plants (biotic) - Plants and animals die and are decomposed by bacteria (biotic), adding organic matter to the soil (abiotic)