Mr. Lajos Papp The British International School, Budapest 2014/2015

The organism in the environment

Understand the terms population, community, habitat and ecosystem.

Population A group of living organisms belonging to the same species that can interbreed and live in the same place at the same time.

Community A group of populations occupying a particular area and interact with each other and their environment.

Habitat Place where a living organism or a population normally lives or occurs.

Ecosystem A community with its environment.

Quadrats can be used to estimate the population size of an organism in two different areas. Sunny and shaded areas to find population sizes.

Quadrats can be used to sample the distribution of organisms in their habitats. Use a quadrat and a rope to determine the distribution of a living organism, for example, up a rocky shore.

Feeding relationships

Explain the names given to different trophic levels to include producers, primary, secondary and tertiary consumers, and decomposers.

Food chain: a linear consequence of links starting from a species that eats no other species in the chain and ends at a species that is eaten by no other species in the chain.

Trophic level: the position that an organism occupies in a food chain.

Producer An organism that produces complex organic compounds from simple molecules using an external source of energy.

Primary consumer A primary consumer obtains its energy from producers. Therefore e. g. a rabbit is a primary consumer because it eats grass and other plants.

Secondary consumer The secondary consumers are carnivores and feed on other animals (primary consumers) in a food chain.

Tertiary consumer An animal that feeds on secondary consumers in a food chain.

Decomposer Decomposers break down dead organisms into nutrients; thus, making organic nutrients accessible in the ecosystem (nutrients are recycled). They include moulds, worms, bacteria and fungi.

Understand the concepts of food chains, food webs, pyramids of number, pyramids of biomass and pyramids of energy transfer.

Produce a poster of a food web. You could use images from magazines / Internet to illustrate the poster.

Understand the transfer of substances and of energy along a food chain. Explain why only about 10% of energy is transferred from one trophic level to the next.

Light is the initial energy source for almost all communities. Only a small proportion of the incoming energy (1-2%) enters the ecosystem.

Producers convert light energy into the chemical energy of sugars and other organic compounds. This energy trapped by the producers eventually leaves them in one of three ways:

1. release energy by cell respiration for use in the producer then loss as heat; 2. energy passes to a primary consumer when it eats the producer; 3. death of the producer so the energy passes to decomposers when they digest the producer.

The energy that passes to decomposers is eventually released by cell respiration and lost as heat. In most communities all the light energy that was trapped by producers is ultimately lost as heat after flowing through the food chain.

Cycles within ecosystems

Describe the stages in the carbon cycle, including respiration, photosynthesis, decomposition and combustion.

Processes Photosynthesis by terrestrial plants and aquatic algae in which atmospheric carbon dioxide is removed and fixed as organic compounds such as carbohydrate, lipid and protein.

Respiration by all organisms in which they metabolize (break down) organic molecules releasing carbon dioxide.

Decomposition organic substances are broken down into simpler forms of matter. The process is essential for recycling the finite matter.

Combustion the burning (reaction with oxygen) of fossil fuels and burning of biomass.

Human influences on the environment

Understand the biological consequences of pollution of air by sulfur dioxide and by carbon monoxide. carbon monoxide – takes the place of O 2 in haemoglobin, causing oxygen starvation sulfur dioxide – causes acid rain

- sulfur dioxide → acid rain lowers pH (increases acidity) of lakes/ponds and leaches aluminium out of the soil causing: - the fishes' gills to be damaged eventually killing them, this is fixed by adding calcium hydroxide

- destroys the top of the trees and the aluminium damages tree roots = dead tree, important nutrients leached away - poses health hazards for humans (asthma sufferers) - fewer crops can be grown on an acidic field (fixed by adding lime)

Understand that water vapour, carbon dioxide, nitrous oxide, methane and CFCs are greenhouse gases.

Understand how human activities contribute to greenhouse gases. water vapour: natural processes.

carbon dioxide: burning of fossil fuels.

nitrous oxide: Agriculture: the use of nitrogen fertilisers, and animal waste handling can all stimulate naturally occurring bacteria to produce more nitrous oxide. Industrial sources: the production of nylon, and the burning of fossil fuel in internal combustion engines.

methane: is a primary component of natural gas, and thus during the production, processing, storage, transmission, and distribution of natural gas, a significant amount of methane is lost into the atmosphere.

Farming also acts to increase atmospheric methane through ruminant farm animals, such as sheep or cows.

Rice agriculture has become one of the most powerful anthropogenic (human) sources of methane. With warm weather and water-logged soil, rice paddies act like wetlands, but are generated by humans for the purpose of food production.

Due to the large collections of organic matter and availability of anaerobic conditions, landfills are one of the largest sources of atmospheric methane. Even after a landfill is closed, the mass amount of decaying matter continues to emit methane for years.

CFCs: aerosols and refrigerators.

Understand how an increase in greenhouse gases results in an enhanced greenhouse effect and this may lead to global warming and its consequences.

1. an increase in the frequency of heat waves; 2. a reduction in the surface area and thickness of glaciers; 3. the melting of icebergs; 4. loss of mass of polar ice sheets in the Antarctic and Greenland;

5. increased average ocean levels; 6. disrupted water cycle, which may lead to heavy rainfall (flooding) or prolonged droughts; 7. changes in vegetation (flowering dates, harvest times, etc.); 8. migrations of animal species (e.g. insects).

Understand that eutrophication can result from leached minerals from fertiliser.

Eutrophication: when water plants receive too many nutrients. Plants need minerals such as nitrates and phosphates. They absorb these from the soil. In general, the more they have, the better they can grow. It works like this:

1) Fertilisers put in soil by farmers 2) Fertilisers with nitrates / detergents with phosphates leach into rivers and lakes after rain 3) Water plants grow more than usual

4.1) they block sunlight and kill plants underneath 4.2) they die and sink to bottom 5) Bacteria/fungi decompose remains using the O 2 and decreasing the O 2 concentration 6) Fish and other creatures die from oxygen starvation

Understand the effects of deforestation, including leaching, soil erosion, disturbance of the water cycle and of the balance in atmospheric oxygen and carbon dioxide.

leaching, soil erosion: the presence of vegetation provides a protective cover over the soil. Vegetation helps to maintain the soil fertility. When it rains, nutrients enter the soil. Plant roots absorb the dissolved nutrients from the soil.

When leaves fall, small organisms such as worms and insects break down the leaves as they decompose and this returns the nutrients to the soil. Hence, the fertility of the soil is maintained. However, with the clearance of the forest, there is a loss of a protective cover for the soil.

With deforestation, there will be a higher rate surface runoff and this results in a higher rate of soil erosion and soil leaching. In soil erosion, the topsoil is being removed or washed away by the higher surface runoff.

Soil leaching, a process by which nutrients are washed deeper into the soil, causes the top soil to become increasing infertile over time, This, through soil erosion and soil leaching, the soil in the deforested area gradually loses its fertility.

disturbance of the water cycle: trees draw ground water up through their roots and release it into the atmosphere by transpiration. As forest trees removed the amount of water that can be held in an area decreases.

the balance in atmospheric oxygen and carbon dioxide: photosynthesis (carbon dioxide uptake and oxygen release).