Bio 20 - Chapter 2: Cycles of Matter PDF

BIO 20: Chapter 2 Cycles of Matter Key Questions What are the processes of the hydrological cycle? What special properties about water make it so important? What are the processes of the carbon-oxygen cycle? What are examples of slow and rapid cycling of carbon?...

BIO 20: Chapter 2 Cycles of Matter Key Questions What are the processes of the hydrological cycle? What special properties about water make it so important? What are the processes of the carbon-oxygen cycle? What are examples of slow and rapid cycling of carbon? What is a carbon sink? What is acid rain? What are the processes of the nitrogen cycle? What is the importance of nitrogen fixing bacteria in agriculture? What are the processes of the phosphorus cycle? (short term and long term) What happens if there is too much phosphorus in an ecosystem? What are stromatolites? Why is it important to maintain balance of energy and matter in the biosphere?  Section 2.1 The Role of Water in Cycles of Matter Water in the Biosphere Because Earth is a closed system, matter must cycle within it The water that we see in surface water sources may have come from snow and ice, from oceans, or it may have been a product of cellular respiration  Water in the Biosphere Water in our atmosphere acts as a greenhouse gas, trapping heat and warming the Earth The transfer of heat throughout our biosphere is also mostly due to water’s ability to absorb large amounts of heat energy The Hydrologic Cycle The Universal Solvent Water is a polar molecule When an ionic compound is placed in water, it pulls apart the ions and makes it dissolve  As well, there is attraction formed between nearby water molecules as a hydrogen bond forms This allows water molecules to surround compounds while dissolving them Hydrogen Bonding and Water’s Phases Because water molecules have relatively strong hydrogen bonds between them, it requires a large amount of energy to break these bonds so that the molecules can move freely This means that water will have very high heats of fusion and vaporization It also means that water has high melting and boiling points when compared to similar hydrogen compounds  These hydrogen bonds and the forces of repulsion between the oxygen atoms contributes to the open spacing seen in the crystal structure of ice  Because ice is less dense than water, lakes always freeze from the top down This prevents most lakes and ponds from freezing solid http:// As well, it contributes to www.islandnet.com the cycling of oxygen and nutrients during the spring and fall in bodies  The hydrogen bonds in water produce cohesion between molecules, which gives water its surface tension Adhesion also occurs between water molecules and molecules of other substances (such as glass) The force of adhesion is responsible for the capillary action that occurs in the xylem of plants  Water and Heat The hydrogen bonds between water molecules means that water has a high specific heat capacity As a result, water stores huge amounts of heat energy Large bodies of water will moderate temperatures because of this At the level of the individual organism, the high specific heat capacity of water prevents body temperatures from changing too quickly 14 Water and Organisms Organisms gain water from their environment through eating, drinking, absorption, and cellular respiration Organisms lose water through breathing,  Water as a Resource When ecosystems lack water, the producers that use it during photosynthesis quickly disappear Therefore, droughts in areas can be devastating to ecosystems If global temperatures rise, then droughts will become more common in areas such as Alberta, which will greatly affect our economy  Water Quality Not all freshwater is suitable for use In many areas, the water is contaminated with toxic chemicals or pathogens Even if the pathogens can be killed by chemical treatment or boiling, some toxins are extremely difficult to remove from polluted water  Water and Ecosystems Changes in the amount of water available in an ecosystem will affect the growth of producers Research carried out in the rainforest shows that trees exposed to drought conditions will extend their roots deeper than normal in search of  As well, the rate of growth of the trees decreased, and some of the largest trees died This could contribute further to climate change as less CO2 would be absorbed from the atmosphere The lack of growth in trees and other producers due to drought will also affect other chemical cycles in our biosphere  Section 2.2 Biogeochemical Cycles The Necessity of Cycles Again, because there is a limited amount of matter in our ecosystem, chemicals must be recycled constantly The main biogeochemical cycles are the oxygen, carbon, nitrogen, sulfur, and phosphorus The Carbon and Oxygen Cycles The Carbon and Oxygen Cycle Carbon and oxygen are closely related in our ecosystem As a result, they can often be illustrated in the same cycle Carbon-Oxygen Cycle http://  Atmospheric CO2 Photosynthesis Combustion Respiration Organic Carbon Fossil Decomposition Fuel  Slow vs. Rapid Cycling of Carbon Organisms are involved in the rapid cycling of carbon through photosynthesis and cellular respiration However, some larger producers (like large trees) also store carbon for long periods of time in their tissues, and the carbon is not recycled until the tree dies and is broken down by Carbon Sinks A carbon sink is a storehouse of carbon in the biosphere The largest stores of carbon in the biosphere are Earth’s oceans The water in the ocean contains billions of tonnes of dissolved carbon dioxide Other carbon sinks include forests, limestone rock (calcium carbonate) and petroleum deposits Acid Deposition The combustion of fossil fuels that contains sulfur releases sulfur oxides into the atmosphere Sulfur dioxide reacts with oxygen and water vapour in the atmosphere to form sulfuric acid and sulfurous acid When this acid condenses, it falls as acid precipitation The acid can change soil and water pH,  Acid Deposition The soil in Alberta is naturally alkaline. If acid rain is acidic, and alkaline soil is basic, what type of chemical reaction will occur that reduces the impact of acid deposition? – Neutralization reaction Nitrogen Cycle  The Nitrogen Cycle Nitrogen is required by organisms to form the amino acids that form proteins and to make up the structure of DNA However, the nitrogen gas in our atmosphere cannot be used for this purpose The nitrogen gas must therefore be converted into other forms Nitrogen Cycle Processes in the Nitrogen Cycle Nitrogen fixation is the conversion of atmospheric nitrogen into ammonium (NH4+) This is carried out by nitrogen-fixing bacteria found in nodules attached to the roots of legumes…or by lightning. Ammonification also produces ammonium as bacteria break down Nitrogen Cycle The Three Sisters Legumes are used to restore nitrogen levels in soils. This agricultural method has been practiced for 35  Nitrification turns ammonium into usable nitrites and nitrates During denitrification, bacteria complete the cycle by breaking down nitrogen compounds and releasing nitrogen gas back into the atmosphere Denitrification typically occurs in anaerobic environments Nitrogen Cycle https://www.you https://www.youtube.com/watch?v=vZ9b5c8 tube.com/watch BOT4&t=126s ?v=K5EOZenS SB8 39 The Phosphorus Cycle The Phosphorus Cycle Phosphorus is required for cellular materials such as DNA, phospholipids, and ATP Phosphorus does not cycle in the atmosphere, but is found in soil and water Large amounts of phosphorus are Phosphorus Cycle  Long-term Cycle Most common form: a part of rocks Properties: soluble - dissolve in water Phosphates dissolve in water— erosion carries them from land to streams and rivers and then finally to the oceans Oceans → sediments may be pushed upward and once again form land through geological Short-term Cycle Phosphates in water also enter the food chain through producers Plants are eaten by animals Decomposition of dead organisms → soluble phosphates are absorbed by plants and used during photosynthesis  Overabundance of Phosphorus Because most of the world’s phosphorus is locked in rocks and sediments, the growth of plants is limited However, adding excess phosphorus can cause uncontrolled growth of algae and plant life, which reduces available oxygen in aquatic ecosystems Energy and Matter Transfer Remember that energy is involved in each step of these cycles As well, water is also a necessary component of these cycles, so the biogeochemical cycles are all linked together through energy and water 2.3 – The Balance of Matter and Energy Exchange  CONDENSATION PRECIPITATION EVAPORATION SNOWMELT PERCOLATION GROUNDWATER  Interactions MOISTURE As well, moisture plays a significant role in the productivity of an Productivity rates are ecosystem often expressed as energy or biomass SU BIOMASS N The amount of sunlight an area receives often determines its Balance in the Biosphere Inside our own bodies, we maintain homeostasis To do this, we must use energy In 1979, James Lovelock proposed the Gaia Hypothesis, which is homeostasis on a global level In essence, this hypothesis suggests that the Earth is self-regulating The Gaia Hypothesis and Living Things Life itself plays a large role in the balance we see in our biosphere The composition of our atmosphere, for instance, would be very different if living things had not modified it through cellular respiration and photosynthesis As well, some of the sediments that make up our geological features come from biological sources  Stromatolites are formations of sedimentary rocks that are composed partly of the cellular debris of organisms Early stromatolite layers show that there was large amounts of oxygen trapped in iron oxides Later layers indicate that this oxygen was no longer being trapped – it had moved out of the oceans and into the Stromatolites  Replicating Earth’s Biosphere Scientists have tried to replicate the biosphere on a small scale However, these http:// www.mistershape.com experiments were not very successful because our biosphere is extremely complex http:// https://www.theguardian.com/fil m/2020/jul/13/spaceship-earth-ar izona-biosphere-2-lockdown 59 Future Projects NASA programs such as ALS (Advanced Life Support) are being studied to see how plants may be grown in a space colony for food and oxygen Such programs also look for ways to recover usable resources from waste  The Haughton-Mars Project In the Canadian Arctic, NASA sponsors a research station that is intended to simulate the conditions of Mars’ surface The purpose of such research is to study what factors need to be in place for sustainable manned missions to other planets Human Interference Humans have significant ability to change our surroundings However, sometimes these changes cause a disruption in the flow of matter and energy, which interrupts the delicate natural balance of ecosystems Therefore, much work is being done into looking for ways to reduce our environmental impact Preserving Natural Balance The development of alternative energy sources is one possible method of reducing the impact we have on our planet As well, we may need to reconsider how we use land and resources to prevent damage to the ecosystems around us THE END