exam cards 132 Flashcards

Question

what are Autotrophs

Answer 1

Autotrophs are the primary producers in trophic levels. Most plants are photoautotrophs. They harness solar energy to form biomass from simple inorganic sources.

Answer 2

Heterotrophs are reliant upon other organisms for energy (consumers).

Answer 3

150 million Km from Earth 8.3 minutes to reach Earth

Answer 4

400-500 nm (blue) 600-700 nm (red)

Answer 5

Tropical rainforest 13% grassland 25% woodland 16-18% farm crops 15-26%

Answer 6

At enhanced CO2 levels, for example in a commercial greenhouse, the rate of photosynthesis increases for a given amount of light compared with normal ambient (atmospheric) CO2 concentrations.

Answer 7

Chloroplasts are situated throughout the interior of the leaf. The first products of photosynthesis are molecules with 3 carbon atoms - hence the name C3. C3 photosynthesis is relatively inefficient because the the concentration of CO2 in the chloroplasts is relatively low. A significant proportion of the CO2 fixed is released back to the atmosphere in a process called photorespiration.

Answer 8

C4 plants first became abundant on Earth 7 million years ago, during the late Miocene, when extensive grasslands developed. They evolved as a result of falling global atmospheric CO2 levels and increasing aridity C4 plants are more efficient in their use of CO2

Answer 9

N primarily stored in living and dead organic matter is converted to the ammonia or ammonium salts through decomposition in the upper soil layer.

Answer 10

N in the form of ammonium salts can be absorbed onto the surfaces of clay particles in the soil. Chemoautotrophic bacteria oxidise:

Answer 11

Anaerobic waterlogged soils -up to 15% N lost through denitrification. Nitrate reduced by heterotrophic bacteria to give N2or N2O gases.

Answer 12

Nitrate is very soluble in water -lost from the soil system by leaching. Flows in the hydrological system to the ocean. Supplies bacteria with oxygen for respiration. These examples above could all occur naturally in the wild Anthropogenic influences Up to 25% global nitrogen fixation - chemical industry - fertilizers 450 million tonnes of nitrogen fertilizer per year, mostly in the form of anhydrous ammonia, ammonium nitrate, and urea. The application of nitrogen fertilizers to crops has caused increased rates of denitrification and leaching of nitrate. In lakes, the added N can lead to eutrophication (excess primary production).

Answer 13

Main industrial procedure for the production ofammonia (NH3). Developed by German chemists Fritz Haber & Carl Bosch (in the first half of the 20th century). Converts atmospheric nitrogen (N2) to ammonia (NH3) by a reaction with hydrogen (H2) using a metal catalyst under high temperatures and pressures

Answer 14

- Cyanobacteria(‘blue-green algae’) floating on the surface. - Cyano-bacteria are N-fixers but also need P inputs. - Outcompete other algae when N is in short supply.

Answer 15

- S is an essential nutrient for all living organisms - S is generally found in the abiotic environment (found in rocks) - Fluxes between abiotic and biotic components - The sulphate anion (SO4^2-) - weathering and oxidation of rocks, present in both soil and soil water, absorbed by plants roots and incorporated into sulphur, Containing proteins and vitamins. In this form sulphur is passed along food chains to animals.

Answer 16

- Acid rain became a major international concern in the 1970's - Acid rain rarely directly kills trees but stunts growth through soil degradation. Eventually the trees are likely to die from nutrient deprivation and exposure to the released toxins - Acid rain accelerates natural weathering processes

Answer 17

P is essential to life being involved in energy transfer (via ATP) and in the passage of genetic information in the deoxyribonucleic acid (DNA) of cells. P is one of the scarcest recycled elements that often limits the productivity of biological systems (e.g. NPP). Naturally present in environment - crystalline rocks e.g. apatite (Ca5(PO4)3OH). Released through chemical and microbiological weathering. Only very small atmospheric phase (dust) - P availability depends mainly upon soil pH - Acidic: relatively insoluble compounds, variscite - AI(OH)2H2PO4 - Alkaline: insoluble compounds, hydroxyapatite - Ca10(PO4)6(OH)2 - Neutral: Soil contains minerals that are rich in P. Minerals slowly break down over time (weathering) and release P to the soil solution for plant uptake

Answer 18

Soil - is top layer of the earth, composed of mineral particles, organic matter, water and air, often discriminated by soil horizons Soil Horizon - is a layer parallel to the soil surface whose physical, chemical and biological properties differs from layers above and beneath Soil Profile - is vertical display of soil horizons Soil begins where geological areas end Soil Pedon - is 3D unit that represents the entire soil body, it is the smallest volume of soil showing characteristics properties of a particular soil Pedosphere - outermost layer of the earth Pedology - study of soil - soil science

Answer 19

fine earth: clay <0.002, slit 0.002 - 0.05, fine sand 0.05 - 0.2, course sand 0.2 - 2mm, course fragments: gravel 2mm - 20 mm, stones >20mm

Answer 20

Kaolinite 1:1 non-expanding Illite (mica) 2:1 non-expanding firm bonds potassium ions Montmorillonite 2:1 expanding, weak bonds Vermiculite 2:1 expanding, weak bonds water molecules Chlorite 2:1 non-expanding, firm bonds

Answer 21

- volume change caused by wetting/drying – swelling and shrinking - Colloidal properties – clays carry an electric charge – important for soil physical and chemical reactions - Organic and inorganic cations and anions are adsorbed on clay surfaces because of the permanent negative charge - Clays act as a binding agent for other soil particles and help forming soil aggregates

Answer 22

- Fine textured soils (contain more clay) have much larger surface areas, smaller pores, can hold water for longer, often get waterlogged. - Coarse textured soils (contain more sand) have smaller surface areas, larger pores, water easily drains out so sandy soils dry out quickly.

Answer 23

Soil Organic Matter (SOM) – dead and living matter consists of debris of green plants and animal residues colonized by soil organisms, SOM consist of 58 % carbon

Answer 24

O - surface organic layer A - topsoil mineral layer with high organic matter content E - lighter in colour, eluvial layer, i.e. washed out of clays/organic matter B - subsoil, illuvial layer (deposition from above) C - parent material

Answer 25

Cambisol Podzol histosol Glaysol ferrasol Andosol

Answer 26

Tropical (a), Arid (b), Temperate (c), Cold (d), Polar (e)

Answer 27

Parent material – material from which soil is formed. - Consolidated bedrock or loose deposits (e.g. river sediment, glacial till, volcanic ash) - Mode of transportation – affects soil horizons development - Chemical and physical composition

Answer 28

- Leaching (Cambisol) - Gleying (Gleysol) - Podzolization (podzol)

Answer 29

Washing of the soil with rainfall (pH 5.5), weak acid dissolves minerals and carry away basic cations like Ca, Mg, K, Na and replaces by H or Al ions. - lowering pH with depth.

Answer 30

Extreme leaching at the surface layer (acid organic layer) and translocation of sesquioxdes (Fe, Al) into the subsoil.

Answer 31

- Process in waterlogged soils - O2 is very low, iron is reduced from oxidised stated (Fe3+) to reduced (Fe2+), soluble in water. - Removal of Fe leaves soil a grey or bluish colour - Orange/red mottling appears when soil layer exposed to O2 (oxidation of remaining iron).

Answer 32

Nitrogen, oxygen 99.03% Carbon dioxide, aragon 0.97% Hydrogen, methane and others 0.003%

Answer 33

troposphere, stratosphere, mesosphere, thermosphere, and exosphere

Answer 34

H2O 10days N2 14 million yr O2 6000 yr CO2 5 to 200 yr

Answer 35

Absolute humidity = mass of water vapour/volume of air (kg/m^3) Saturated humidity = maximum absolute humidity, deceases with temperature Relative Humidity = Absolute humidity / Saturated Humidity

Answer 36

Polar cell, Ferrel Cell, Hadley Cell

Answer 37

intertropical Convergence Zone these zones create area of high and low pressure making it, hot spot for storms and hurricanes

Answer 38

The circulation of water from the sea, through the atmosphere to the land, and thence, with numerous delays and at various speeds, either back to the sea by overland and underground routes or back to the atmosphere through evapotranspiration without reaching the sea

Answer 39

- The GLOBAL cycle is a CLOSED system with no gains/losses of water; outputs of any part directly affect the rest of the system It is the delays, speeds and routes – and how they vary over the Earth’s surface spatially and temporally (i.e. through time) in response to weather and climate, climatic change and Man’s actions Precipitation = evaporation Eo + EL = Po + PL A closed system, 97.2 % currently in the oceans (but c. 4 % lower at Last Glacial Max) Only 2.8 % on land (but > 7 % at the Last Glacial Max) Most land water is ice and groundwater Ice volumes were 3x higher at the Last Glacial maximum than now

Answer 40

- The GLOBAL and BASIN hydrological cycles are physical, sequential and dynamic systems - Systems comprise sub-systems, each with their inputs, throughputs, storages, outputs - and transfer processes The BASIN hydrological cycle is an OPEN system with gains and losses to the system through time; outputs (evapotranspiration and river flow ) do not control inputs (precipitation).

Answer 41

- Catchment (drainage basin) – area of land in which water flowing across the surface drains into a particular stream or river; unit of study hydrology