EES- Sem 2.pdf

An ecos yste m is mad e up of both living (bioti c facto rs) and non- living (abio tic facto rs) BF: peng uins, bears , wolv  es, foxes AF: rocks , soil, snow , air,...

An ecos yste m is mad e up of both living (bioti c facto rs) and non- living (abio tic facto rs) BF: peng uins, bears , wolv  es, foxes AF: rocks , soil, snow , air, temp eratu re Loss heat at each stage ; ecolo gical pyra mid And so, the prod ucers  on our plane t prod uce food, make energ y usabl e Energ y com es from the sun or che mical s All plant s do  phot osynt hesis and so they take energ y from the sun and into the energ y of the bond s of food Som e Che mosy nthet  ic bact eria can do the same thing with che mical s like hydro gen sulfid e Once they have mad e the energ y usabl e, they  can respi rate, and so can all the cons umer s that sit abov e or belo w them on the troph ic level Can meas ure the amo unt of energ y that is conv erted throu gh prod uctivi ty in one of two ways , gross prim ary prod uctivi ty or net prim  ary prod uctivi ty Gros s is the overa ll amo unt of energ y conv erted Net is how muc h the plant h\get s after it  uses some of the energ y for respi ratio n Effici ency- how muc h energ y make s it to the next level Biom ass- how muc h  living mate rial do we have Energ etics is the study of how energ y gets from the sun to organ ism 1st step is Phot  osynt hesis - we take carb on dioxi de in the air, water , and energ y and sunli ght and conv ert into oxyge n and gluco se Turn the  arro w arou nd and now we have the equa tion for cellul ar respi ratio n Che mosy nthes is is a biolo gical proc ess by whic h organ isms conv ert che mical energ y into the carb ohydr ates and gluco se the organ ism need s for food. Che mosy  nthet ic organ isms typic ally exist in ecos yste ms that are abse nt of sunli ght. 99% move throu gh it, boun ce off it and the  plant does not get it GPP is 1%, respi ratio n (60% ), Net (40% ) Net prod uctivi ty move s depe nding on the seas on 30/07/2024  Energy cannot be created or destroyed; it may be transformed from one form into another, but the total amount of energy in an isolated system never changes. The combination of energy and matter make up the universe: o Matter is substance, and energy is the mover of substance. - K.E. = ½(mass x speed2)- an object has due to its motion - Chemical – energy stored in the bonds  of chemical compounds - Electrical – is the power an atom’s charged particles must cause an action or move an object, movement of electrons from one atom to another - Light- a kind of kinetic energy with the ability to make types of light visible to human eyes - Thermal- the energy contained within a system is responsible for its temperature, heat - Gravitational potential energy- the energy an object has due to its position above  Earth, energy due to its height Geothermal energy from radioactive isotopes And Rotational energy from the spinning of the Earth are internal sources of energy Sun is major external source driving systems like our weather and climate Sun warms the surface and atmosphere in varying amounts, causes convection Convection- produces winds and influences ocean currents Infrared radiation, radiating out from the warmed surface of the Earth, gets trapped by greenhouse gases and further affects the energy flow  Sun major source for plants, algae and cyanobacteria Use sun light to produce organic matter from carbon dioxide and water Release this food energy using chemical reactions like combustion and respiration Eating from producers is a way to get energy without continual input of energy To generate electricity heat from burning fossil fuels is used to power turbines that rotate magnets, which in turn, create magnetic field changes relative to a wire causing electrons to be induced to flow in the wire Electricity for city depends on being able to power the flow of electrons  Also be induced to flow by direct interaction with light particles, (solar cell) Wind, water, geothermal, biofuel Plate Tectonics Earth’s density gives us clues about its internal structure. density = mass/volume Estimates of Earth’s mass and volume give a whole Earth density of ~5.5 g/cm3 Rocks at the surface have a density of 2.7-3.0 g/cm3 Earth’s shape gives us clues to the internal structure. If density increased uniformly with depth, Earth would flatten into a disk.  If the interior was a liquid, it would be affected by tidal forces. Earthquake waves pass through the Earth. ○ Wave velocity increases with depth. ○ Depth increases pressure, thus density ○ Velocity changes give depth of layer changes. The core has a solid inner core and fluid outer core. Inge Lehmann discovered the core had two distinct layers in 1936 by examining earthquake data, and calculating from the size of P  and S wave shadow zones. The core is rich in iron; approximately 80%. Geologists deduce this by examining: ○ Composition of the crust ○ Composition of asteroids ○ Mass of the Earth ○ Earth’s magnetism The core is the source of radiogenic heat within the Earth, estimated at 47 TW. The mantle is divided into sections (based  upon seismology data): upper mantle (7-35 km to 410 km) lithospheric mantle (to 100km depth) asthenosphere (to 660km depth) transition zone (410 to 660 km) lower mantle or mesosphere (660 to 2,891 km) The composition is thought to be largely ultra-mafic silicate rock, similar to peridotite. The mantle transports heat from the core to the surface via convection. Thus, the mantle is plastic (viscoelastic solid); neither solid nor liquid.  Lithosphere – The brittle portion of Earth’s interior. Behaves as a non-flowing, rigid material. The material that moves as tectonic plates. Made of 2 components: crust and upper mantle. Asthenosphere – The ductile portion of Earth’s interior. Shallower under oceanic lithosphere. Deeper under continental lithosphere. Flows as a soft ductile solid.  Contains a small percentage of melt (< 2%) Brittle-ductile transition Defined by a significant change in rock physical properties (viscosity) Also defined as the depth below which earthquakes do not occur. Capable of transporting earthquake waves Incapable of generating earthquakes The outermost “skin” of Earth with variable thickness. Thickest under mountain ranges (70 km). Thinnest under mid-ocean ridges (3 km).  The Mohorovičić (MOH-hə- ROH-vih- chitch;)discontinuity or “Moho” is the lower boundary. Separates the crust from the upper mantle. Discovered in 1909 by Andrija Mohorovičić. Marked by a change in the velocity of seismic P waves. Crustal density controls surface position. Continental crust Less dense; “floats higher.” Oceanic crust More dense: “floats lower.” 98.5% of the crust is comprised of just 8 elements. Oxygen is (by far!) the most abundant element in the crust Geologists in the late 1800s learned that many stratigraphic successions on different continents had similar rock types, ages, fossils and depositional settings. Henri Becquerel (French physicist) in 1896 discovered radioactivity. Radioactivity provides a source of heat for the Earth. This allows for the Earth to be much older as it would not have cooled to its present state in only a few tens of millions of years. Alfred Wegener (German meteorologist, astronomer and geophysicist) in 1912 was the first to publish a comprehensive theory of Continental Drift (and the first to use that name).  However, he did not propose a mechanism. “the Mid-Atlantic Ridge... zone in which the floor of the Atlantic, as it keeps spreading, is continuously tearing open and making space for fresh, relatively fluid and hot sima [rising] from depth” (Wegener, 1912) Wegener’s evidence: continental fit, distribution of fossils, ancient climates, and truncated geologic features. Harry Hess (American Rear  Admiral and geophysicist) in 1959 informally proposed that new ocean floor is formed at the rift of mid-ocean ridges. The ocean floor, and the rock beneath it, are produced by magma that rises from deeper levels. Hess suggested that the ocean floor moved laterally away from the ridge and plunged into an oceanic trench along the continental margin. This explained: Relatively little sediment accumulation on the ocean floor. Seafloor fossils being no older than 180 my. The movement of continents.  Evidence for plate tectonics includes: age of oceanic crust symmetrical magnetic anomalies parallel to mid- ocean ridges (paleomagnetism) zones of large earthquakes active volcanoes at some ocean margins fossil distribution (e.g. the restriction of certain mammal groups to Australia) In plate tectonics, Earth’s outermost layer, or lithosphere— made up of the crust and upper mantle—is broken into large rocky plates. These plates lie on top of a partially molten layer of rock called the asthenosphere. A divergent boundary occurs when two tectonic plates move away from each other. Along these boundaries, earthquakes are common and magma (molten rock) rises from the Earth’s mantle to the surface, solidifying to create new oceanic crust. The Mid- Atlantic Ridge is an example of divergent plate boundaries. When two plates come together, it is known as a convergent boundary. The impact of the colliding plates can cause the edges of one or both plates to buckle up into a mountain ranges or one of the plates may bend down into a deep seafloor trench. Two plates sliding past each other forms a transform plate boundary. One of the most famous transform plate boundaries occurs at the San Andreas fault zone, which extends underwater Ocean- continent convergent Plate of oceanic crust collides with plate of continental crust. Oceanic crust is subducted (goes under) continental plate Ocean-Ocean Convergent Two oceanic crust plates collide. Older, denser plate usually subducts, forming a deep depression called a trench. Seafloor spreading occurs at divergent plate boundaries. As tectonic plates slowly move away from each other, heat from the mantle's convection currents makes the crust more plastic and less dense. The less-dense material rises, often forming a mountain or elevated area of the seafloor. When the Earth's magnetic field reverses, a new stripe, with the new polarity, begins. Such magnetic patterns led to recognition of the occurrence of sea-floor spreading, and they remain some of the strongest evidence for the theory of plate tectonics. Palaeomagnetism is the study of the Earth's magnetic field preserved in rocks. The discovery that some minerals, at the time of their formation, can become magnetized parallel to the Earth's magnetic field Convection is the movement of particles through a substance, transporting their heat energy from hotter areas to cooler areas. The increase of temperature at the center of the Sun due to gravitational contraction eventually triggers nuclear fusion, which converts some of the mass into energy. ★ Atomic nuclei repel each other due to like charges. ★ At low speeds, this prevents collision. ★ Very high speed is needed to overcome the repulsive electromagnetic force between the protons to get them very close to each other. ★ Temperature is a measurement of the average kinetic energy (speed) of the particles. ★ The core of the Sun has a temperature of 15 million degrees kelvin. ★ High density is necessary so that the probability of fusion is high. ★ High density is achieved by immense pressure; the core of the Sun reaches 150g/cm3. ★ Once the protons are close to each other, the strong nuclear force can bind them together to make a new and heavier element. If the rate of fusion increases, then: ◻ thermal pressure increases causing the star to expand. ◻ star expands to a new point where gravity would  balance the thermal pressure. ◻ the expansion would reduce compression of the core ◻ the temperature in the core would drop ◻ the nuclear fusion rate would subsequently slow down ◻ the thermal pressure would then drop ◻ the star would shrink ◻ the temperature would rise again and the nuclear fusion rate would increase stability would be re- established between the nuclear reaction rates and the gravity compression ◻ Force equilibrium- A force is a vector quantity which means that it has both a  magnitude (size) and a direction associated with it. If the size and direction of the forces acting on an object are exactly balanced, then there is no net force acting on the object and the object is said to be in equilibrium. ◻ Hydrostatic equilibrium - balance between: ◻ thermal pressure from the hot core pushing outwards ◻ gravity squeezes the star collapse to the very center ◻ Nuclear fusion rate is very sensitive to temperature. ◻ A slight increase/decrease in T causes fusion rate to increase/decrease by a large amount. Balance between pressure, heat from fusion, and  gravity determines Sun’s size. Photons produced in core of the Sun take about a million years to move to the surface. Slow migration because they scatter off the dense gas particles Move about only a centimetre between collisions. In each collision, they transfer some of their energy to the gas particles. As they reach the photosphere, gamma rays have become visible photons. Originates with the thermonuclear fusion reactions occurring in the sun Represents the entire electromagnetic radiation (visible light, infrared, ultraviolet, x-rays, and radio waves). Photosynthesis is Anabolic – it builds up molecules Photosynthesis is Endergonic – it requires energy Photosynthesis requires Carbon dioxide (CO2) Energy Water (H2O) Chlorophyll Essential for the light dependent reaction Absorbs light (photons) and transforms that to chemical energy blue – 420nm Red – 660nm green wavelength is reflected Found in thylakoid membranes of chloroplasts. Plants are autotrophs – they make own food. Important locations in photosynthesis Mesophyll cells-is everything between the upper epidermis and lower epidermis. Photosynthesis occurs in cells with chloroplasts. Stomata- (guard cells on either side) allow carbon dioxide to enter into the leaf and allow oxygen to leave the leaf Photosynthesis occurs in two parts: Light-dependent reaction Water is oxidised, releasing O2 and H+ Light-independent reaction CO2 and H+ are combined to form glucose - C6H12O6 Water is produced as a byproduct So, why do leaves change colour during autumn? In addition to chlorophyll, there are other pigments present. During autumn, chlorophyll greatly reduced – reveals other pigments. PS. Carotenoids are pigments that are either red or yellow which explains why leaves are red/orange/yellow/brown in autumn! Primary production refers to all or any part of the energy fixed by plants possessing chlorophyll. The total amount of solar energy converted (fixed) into chemical energy by green plants (by the process of photosynthesis) is called 'Gross Primary Production' (GPP). Primary production is the foundation of all metabolic processes in an ecosystem, and the distribution of production has a key part in determining the structure of an ecosystem. Gross primary productivity (GPP): is gained through photosynthesis in primary producers. Net primary productivity (NPP): is the gain by producers in energy or biomass per unit area per unit time remaining after allowing for respiratory losses. (Available for consumers in ecosystem) Wegener used fossil evidence to support his continental drift hypothesis. The fossils of these organisms are found on lands that are now far apart. Grooves and rock deposits left by ancient glaciers are found today on different continents very close to the equator. Plate tectonics support continental drift by confirming that the continents were all connected at one point in Earth's history while explaining why and how they could drift apart. Oceanic crust is denser than continental crust. Oceanic plates are denser basaltic rocks than the less dense granitic rocks in the continental crust. Due to their higher density, oceanic plates will sink under continental plates. Conduction is the process by which heat is transferred from the hotter end to the colder end of an object. The object's ability to conduct heat is known as its thermal conductivity and is denoted k. Radiation is energy that moves from one place to another in a form that can be described as waves or particles. The energy from the Sun - both heat and light energy - originates from a nuclear fusion process that is occurring inside the core of the Sun. The specific type of fusion that b occurs inside of the Sun is known as proton-proton fusion. In the core of the Sun hydrogen is being converted into helium. This is called nuclear fusion. It takes four hydrogen atoms to fuse into each helium atom. UV intensity tends to be highest during the summer months. The sun's rays are strongest at the equator where the sun is most directly overhead and where UV rays must travel the shortest distance through the atmosphere.