Energy and ecosystems - Yr 2 Flashcards
Biomass
The total mass of living material in a specific area at a given time. Usually measured in gm-2. Fresh mass is quite easy to assess, but varies depending on the water content. Measuring dry mass overcomes this problem but the organism must be killed, it is usually only a small sample and may not be representative.
Calorimetry
The chemical energy store in a dry mass can be estimated using this technique. When a sample of dry material is weighed and then burnt in pure oxygen within a sealed container (bomb). The bomb is surrounded by a water bath and the heat of combustion causes a temperature rise. This can be used to work out the energy released from the mass of burnt biomass.
Producer
Photosynthetic organism that manufacture organic substances using light energy, water, carbon dioxide and mineral ions.
Consumer
An organism that obtains its energy by feeding on (consuming) other organisms. Primary consumers eat producers. Secondary consumers eat primary consumers. Tertiary consumers eat secondary consumers.
Extracellular digestion
When saprobionts release enzymes externally which break down large biological molecules into smaller ones which are then absorbed by digestion or active transport.
Trophic level
Each stage in a food chain
GPP
Gross primary production which is the total quantity of the chemical energy store in plant biomass, in a given time. Plants use 20-50% of this energy in respiration.
NPP
Gross primary production – respiratory losses. The chemical energy store which is left when these losses to respiration have been taken into account. This is available for plant growth and reproduction and available to other trophic levels in the ecosystem (such as consumers and decomposers).
Respiratory losses
Taken away from GPP to calculate NPP.
Food chain
Describes a feeding relationship in which the producers are eaten by primary consumers, which are eaten by secondary consumers, which are then eaten by tertiary consumers. These could then be eaten by quarternary consumers. Each stage is referred to a trophic level.
Food web
How food chains link together in a habitat to form a food web.
Pyramid of Number
A pyramid drawn with bar lengths proportional to the numbers of organisms present
Pyramid of Biomass
A pyramid drawn with bar lengths proportional to the mass of plants/animals
Pyramid of Energy
A pyramid drawn with bar lengths proportional to the energy stored in organisms
Productivity
The rate of generation of biomass in an ecosystem. Usually measured in units of mass per area put unit time (gm-2y-1). Farming practices try to improve this by increasing yields by increasing the efficiency of energy transfer along the food chains which produce our food.
Intensive farming
A type of farming which uses processes, such as using confined spaces to restrict movement, keeping the environment warm and excluding predators, to try and make energy conversion more efficient by ensuring that as much energy from respiration as possible goes into growth rather than other activities or other organisms.
Percentage Efficiency
Can be calculated by dividing the energy available after the transfer by energy available before the transfer x 100.
Energy Transfer
(Energy available after the transfer / energy available before the transfer) x 100
Biological Control
Controlling pests by introducing predators
Selective Breeding
Breeding of organisms by human selection of parents for certain characteristics
Ecosystem
All the living and non-living components of a particular area.
Saprobiontic microorganism
Also known as saprophyte – an organism that obtains its food from the dead or decaying remains (detritus) of other organisms.
Detritrivores
Organisms that help saprophytes do their job. They feed on pieces of dead and decaying material and finely break it up increasing its surface area.
Decomposer
Any organism which breaks down organic matter. Include saprophytes and detritivores.
Nitrogen cycle
Four main stages: ammonification, nitrification, nitrogen fixation and denitrification. This is because all living organisms require a source of nitrogen from which to manufacture proteins, nucleic acids and other nitrogen-containing compounds.
Nitrogen fixation
Conversion of nitrogen gas into nitrogen-containing compounds. Carried out by free-living nitrogen fixing bacteria and mutualistic nitrogen-fixing bacteria which live in nodules on the roots of plants such as peas and beans. It can also be carried out industrially and occurs naturally when lightning passes through the atmosphere.
Nitrogen fixing bacteria
Carry out the process of nitrogen fixation. Can be free-living or mutualistic bacteria.
Ammonification
Production of ammonia from organic nitrogen-containing compounds e.g. urea and proteins. Saprobiontic microorganisms feed on faeces and dead organisms materials, releasing ammonia which then forms ammonium ions in the soil.
Nitrification
Carried out by free-living nitrifying bacteria. Some convert ammonia into nitrites and some convert nitrites into nitrates using oxidation reactions which release energy. Good drainage and ploughing prevents air spaces from being filled with water and allows nitrification to continue.
Denitrification
Carried out by anaerobic denitrifying bacteria which convert of soil nitrates into nitrogen gas.
Phosphorus cycle
Enables the cycling of phosphorous which is an important biological element as it is a component of ATP, phospholipids and nucleic acids. There is no gaseous phase in the phosphorous cycle.
Phosphate
PO43- ions are how phosphorous exists mostly in the form of sedimentary rock deposits.
Weathering
How rocks are worn away - how phosphate ions in wastes and remains e.g. guano, bones and shells and in rocks are released into oceans, lakes and soils as dissolved phosphate ions.
Mycorrhizae
Mutualistic association between certain types of fungi and the vast majority of plants. The fungi act like extensions of the plant’s root system and increase the surface area for absorption of water and minerals. The fungi receives organic compounds such as sugars and amino acids from the plant. The mycorrhiza act like a sponge and so holds water and minerals in the neighbourhood of the roots, enabling the plant to better resist drought and take up inorganic ions more readily. They improve the uptake of relatively scarce ions such as phosphate ions.
Guano
The excrement of seabirds and bats.
Symbiotic
When two species live in close proximity. Mutualistic is a type of symbiotic relationship where the relationship is mutually beneficial for two organisms.
Fertiliser
Using these replenishes mineral ions, especially nitrates. They are necessary to improve productivity because in agriculture crops are harvested and mineral ions are not returned to the soil by decomposition by microorganisms, like would normally happen. They increase productivity because they provide minerals such as nitrogen for plants to build proteins, ATP and DNA nucleotides.
Inorganic
Type of fertiliser which are mined from rocks and deposits and then converted into different forms and blended together to give the appropriate balance of minerals for a particular crop. Contain nitrogen, phosphorous and potassium.
Organic
Type of fertiliser which consist of the dead and decaying remains of plants and animals as well as animal wastes such as manure, slurry and bone meal.
Leaching
Process by which nutrients are washed from the soil into watercourses. Rainwater will dissolve any soluble nutrients, such as nitrate ions and carry them deep into the soil, eventually beyond the reach of plant roots.
Eutrophication
Consequence of an increase in nutrient concentrations in watercourses that leads to an algal bloom, leading to light being the limiting factor for the growth of plants and algae at lower depths, leading to saprobiontic bacteria creating an increased demand for oxygen. This leads to aerobic organisms dying and anaerobic organisms populations rising. It leads to a decrease in biodiversity.
Greenhouse Gases
Gases such as methane and CO2 which trap more heat energy, raising the Earth
