Section 9 - Ecosystems and Material Cycles Flashcards
Ecosystems and interactions between organisms, investigating ecosystems, human impacts on biodiversity, conservation and biodiversity, the carbon cycle, the water cycle, the nitrogen cycle
What is an ecosystem?
A community of organisms along with all the non-living (abiotic) conditions
What is meant by the term āinterdependenceā?
The way that each species in a community depends on other species for things such as food, shelter etc.
What is the difference between a population and a community?
A population includes all the organisms of one species in a habitat, whereas a community includes all the organisms of different species in a habitat.
What is biodiversity?
The variety of living organisms in an ecosystem.
What is a non-indigenous species?
A species that doesnāt naturally occur in an area.
How can eutrophication cause the plants at the bottom of a lake to die?
Eutrophication is an excess of nutrients in the water. It can cause algae in the lake to grow fast and block out the light. Plants in the bottom of the lake wonāt be able to photosynthesise due to the lack of light, so theyāll start to die.
How is carbon transferred between organisms in an ecosystem?
Compounds containing carbon are passed up the food chain when animals eat plants and other animals, and when microorganisms break down dead organisms.
Describe the role of respiration in the carbon cycle.
When organisms respire, carbon is returned to the atmosphere as carbon dioxide.
Explain how microorganisms are involved in cycling materials through an ecosystem.
Microorganisms break down dead organisms and the waste products of living organisms, returning elements to the soil or air. Microorganisms also respire, which returns carbon dioxide to the atmosphere.
Why is it important that carbon is being constantly recycled in an ecosystem?
Thereās only a fixed amount of carbon in the world, so it must be constantly recycled for there to be enough carbon available to the organisms in an ecosystem. This is vital because carbon is an important element in the materials that living things are made from.
Describe how water from the land, sea and plants forms clouds.
Energy from the Sun makes water evaporate from the land and sea, turning it into water vapour. Water also evaporates from plants, which is known as transpiration. Warm air rises, so the warm water vapor is carried upwards, where it condenses to form clouds.
Explain how reverse osmosis can remove salt from salty water.
Salt water is first treated to remove solids, before being fed at a very high pressure into a vessel containing a partially permeable membrane. The pressure causes the water molecules to move from a higher salt concentration to a lower salt concentration. As the water is forced through the membrane, the salts are left behind, removing them from the water.
What is nitrogen fixation?
The process of turning nitrogen gas (Nā) from the air into nitrogen-containing ions in the soil which plants can use.
What type of bacteria turn ammonia into nitrates?
Nitrifying bacteria (they turn ammonia into nitrites and then into nitrates)
Denitrifying bacteria thrive in waterlogged, poorly drained soils. Suggest why a farmer might want to ensure that his fields are well drained.
Denitrifying bacteria turn nitrates back into Nā gas. This means that there is less nitrogen in the soil that plants can use. A farmer might therefore want to ensure his fields are well drained so that denitrifying bacteria donāt grow well. This would mean that the soil is more likely to have enough nitrogen to allow the farmerās crops to grow well and the farmer might not need to use as much fertiliser.
