Chapter 3 Matter, Energy & Life

Transcription

1 Chapter 3 Matter, Energy & Life 1

2 Outline Elements of Life Organic Compounds and Cells Energy Laws of Thermodynamics Photosynthesis/Respiration Ecosystems Food Chains Ecological Pyramids Material Cycles 2

3 Elements of Life MATTER - everything that has mass and takes up space Solid - Liquid - Gas = 3 states of matter CONSERVATION OF MATTER: The idea that matter cannot be created nor destroyed but is simply transformed from one form to another The atoms in your body may have been in a dinosaur or a tree! 3

4 Elements ELEMENTS - substances that cannot be broken down into simpler forms by ordinary chemical reactions All matter consists of elements. 118 elements, but just four (oxygen, carbon, hydrogen and nitrogen) make up 96% of the mass of living organisms. 4

5 Elements of Life All elements are composed of atoms. ATOMS - smallest particles exhibiting characteristics of the element Atoms are composed of: PROTONS (positively charged +) NEUTRONS (neutrally charged) ELECTRONS (negatively charged -) Protons &neutrons are in the nucleus Electrons orbit the nucleus. 5

6 Elements of Life ATOMIC NUMBER: Number of protons ATOMIC MASS: Number of protons and neutrons in an atom. Average of all isotope masses 6

7 Elements of Life ISOTOPE - forms of an element differing in atomic mass due to the fact that isotopes have different numbers of neutrons 7

8 Radioactive Isotopes Unstable isotopes release energy and/or particles: Alpha, Beta or Gamma rays Decay ends as a stable form or another element 8

9 MOLECULE: two or more atoms joined together COMPOUND: a substance composed of 2 or more different kinds of atoms Molecules & Compounds 9

10 Ionic Chemical Bonds CHEMICAL BOND - chemical energy holding atoms together to form molecules IONIC BOND - Atoms with opposite charges (ions) form a bond. One atom loses one or more electrons, the other atom gains one or more electrons 10

11 Ionic Chemical Bonds IONS - atoms that contain more or fewer electrons than protons and therefore have a positive or negative charge ANIONS (-) have a negative charge. CATIONS (+) have a positive charge. 11

12 Covalent Chemical Bonds COVALENT - atoms share electrons 12

13 WATER IS DIFFERENT! COVALENT BONDS IN WATER In water the oxygen attracts the electrons more strongly than the hydrogen atoms do, so the hydrogen atoms have a slight positive charge and the oxygen has a slight negative charge. 13

14 WATER IS DIFFERENT! Water molecules are attracted to each other due to the Polar Covalent bonds of other water molecules Universal Solvent due to its polar nature, water is capable of dissolving most molecules Cohesion the attraction between water molecules Surface Tension the resistance of surface molecules to be broken Adhesion - water molecules bonding to another surface 14

15 WATER IS DIFFERENT! High Heat of Vaporization - requires a lot of energy to turn liquid water into a vapor/gas High Specific Heat water must absorb a lot of heat energy for the temperature to rise & it holds onto this heat energy for a long period of time Water EXPANDS when it freezes this makes ice less dense than liquid water allowing it to float Water has a ph of 7 it is NEUTRAL in solution the molecules break apart into (OH-) Hydroxyl Ions and (H+) Hydrogen Ions 15

16 Oxidation and Reduction OXIDATION - When an atom gives up one or more electrons, it is oxidized. REDUCTION - When an atom gains one or more electrons, it is reduced. Oxidation and reduction are important parts of how organisms gain energy from food. Endothermic: breaking bonds absorbs energy Exothermic: forming bonds releases energy Activation Energy: the energy needed to initiate a chemical reaction (ie: friction to light a match) 16

17 Acids, and Bases ACID a substance that releases hydrogen ions when put into water. Acids are Hydrogen (H+) donors ie: sulfuric, hydrochloric, acetic, carbonic BASE a substance that releases hydroxide ions (OH-) in water Bases easily bond with hydrogen ions producing water and a neutral ph ie: sodium hydroxide, calcium hydroxide ammonium hydroxide, 17

18 ph Scale ph scale: is logarithmic; each step is 10X 0 to 6.9 is acidic 7 is neutral 7.1 to 14 is basic ie: a substance with a ph of 4 is x More acidic than a substance with a ph of 6 18

19 ENVIRONMENTAL BUFFERS BUFFER: a substance that accepts or releases hydrogen ions buffers help to neutralize a solution ie: adding lime (calcium carbonate) to a lawn will decrease effects of acid rain ie: a lake affected by acid rain may be buffered by surrounding soils or alkaline bedrock of limestone or igneous type rocks. (Granite & shale are acidic and would be detrimental to a lake affected by acid rain.) 19

20 Organic Compounds Organic Compounds - Material making up biomolecules, which in turn make up living things. All organic compounds contain carbon. Four major categories of organic compounds:

21 LIPIDS - CHO Lipids Fatty acids, oils, steroids, waxes, some hormones store energy produce cell membrane do not easily dissolve in water (non-polar) Hydrocarbon family (petroleum, methane) 21

22 Carbohydrates CARBOHYDRATES - CHO Monosaccharides: simple sugars (glucose, sucrose, lactose) Polysaccharides: starch & cellulose Store energy Used in cellular structure 22

23 Proteins PROTEINS CHON (S) - Composed of chains of amino acids 20 types of amino acids - Folded into 3D shapes & perform countless functions in cells and organisms antibodies, enzymes, cell shape, hormones, transport other substances, muscle contractions, etc. 23

24 NUCLEOTIDES / NUCLEIC ACIDS - CHONP Nucleotides are monomers that combine to create nucleic acids - Made of a sugar, a phosphate group and a nitrogen containing base - Form long chains of RNA and DNA - 4 types of DNA Nucleotides adenine guanine cytosine thymine (uracil in RNA) - DNA extraction is very useful in taxonomy, agriculture (GMO s), medical genetics, etc. 24

25 ORGANISM FUNCTIONING Cells - minute parts of a living organism which carry out processes of life Surrounded by lipid & protein membrane controlling flow of materials in and out of the cell Cells are composed of organelles that perform cell functions. Prokaryotes bacteria Archea single-celled extremophiles Eukaryotes protists, fungi, plants animals 25

26 ORGANISM FUNCTIONING Enzymes - Molecular catalysts that regulate chemical reactions. Enzymes are usually proteins. Metabolism the total of all enzymatic reactions performed by an organism 26

27 ENERGY ENERGY the ability to do work KINETIC - energy in moving objects POTENTIAL - stored energy CHEMICAL potential energy stored in food or fossil fuels NUCLEAR nuclear atomic particles give way to radioactive decay GRAVITATIONAL due to height. Becomes kinetic energy when the object falls MAGNETIC forces between magnetic materials (poles & distance) 27

28 ENERGY MEASURING ENERGY Units of heat Calorie - amount of energy needed to heat 1 gram of H 2 O 1 o C Units of work Joule - work done to accelerate 1kg at one meter per second per second (m/s/s) 1 calorie = J ENERGY vs POWER Energy is the ability to do work Power is the rate at which work is done Energy = power x time Power = energy time 28

29 HEAT ENERGY HEAT - Energy that can be transferred between objects of different temperature. When a substance absorbs heat, the motion of its molecules increases and it may change state (e.g. a solid to a liquid to a gas). When a substance releases heat, the motion of its molecules decreases and it may change state (e.g. a gas to a liquid to a solid). Remember... Evaporation and condensation help distribute heat around the globe. (Convection Currents) Heat storage in lakes & oceans moderates climate and helps maintain different biomes 29

30 USEFUL ENERGY Forms of energy that can be used for work is considered useful and HIGH-QUALITY. Diffuse forms of energy that can not be used for work are considered LOW-QUALITY. Which of the following have useful energy? Atlantic Ocean a piece of coal a warm brick a flame a flowing stream a rock rolling downhill 30

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32 HEAT - can be transferred between objects by convection, conduction and radiation. 32

33 THERMODYNAMICS: The study of Energy FIRST LAW OF THERMODYNAMICS - a.k.a. Law of Conservation of Energy Energy is neither created nor destroyed. The amount of energy in the universe is constant. SECOND LAW OF THERMODYNAMICS - With each successive energy transfer, less energy is available to perform work. - ENTROPY (disorder) increases as energy is used to do work. 33

34 ENTROPY is a thermodynamic quantity representing the amount of energy in a system that is no longer available for doing mechanical work. As energy is used in doing work, some energy is lost from the system. Lost as Heat, Friction, Sound, etc. Video: EXAMPLES: 34

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36 Energy for Life Energy must be continually supplied by the sun to keep biological processes running. As energy flows through the various biological processes, it becomes dissipated, diffuse, unable to be used. Ultimately, most organisms depend on the sun for the energy needed to carry out life processes. Exception: 36

37 Energy from the Sun Solar energy is essential for 2 reasons: Warmth - Most organisms can exist only in a relatively narrow temperature range. If too cold - If too hot - Photosynthesis in plants - Radiant energy is transformed into useful, high-quality chemical energy in the bonds of organic molecules. Almost all life on Earth depends on photosynthesis. 37

38 Energy From the Sun PHOTONS Massless packets of electromagnetic radiation that travel at the speed of light. Long wave energy (radio waves) are low energy Short wave energy (x-rays) are high energy Of all insolation reaching the earth s surface: 10% is ultraviolet 45% is visible light 45% is infrared Most energy is absorbed by the land &/or water, or reflected back into space. Only 1-2% of the sunlight falling on plants is captured for photosynthesis. 38

39 Electromagnetic Spectrum 39

40 Photosynthesis Occurs in chloroplasts within plant cells 6H CO 2 + solar = C 6 H 12 O 6 + 6O 2 energy Water and carbon dioxide in the presence of sunlight and chlorophyll (the green pigment in chloroplasts) yield glucose and oxygen. Glucose serves as primary fuel for all metabolic processes. Energy in its chemical bonds can be used to make other biomolecules (lipids,proteins) or it can drive movement, transport, etc. 40

41 CHEMOSYNTHESIS Ancient organisms called ARCHAEA get their energy from inorganic compounds such as H 2 and S found in vents in the sea floor or from hot springs. ARCHAEA represent one-third of all the biomass on the planet. Those living in ocean sediments create enormous quantities of methane. Fortunately, bacteria which consume methane also exist. 41

42 Cellular Respiration Photosynthesis captures energy, while cellular respiration releases energy. They are opposite processes!! C 6 H 12 O 6 + 6O 2 = 6H 2 O + 6CO 2 + energy (AEROBIC respiration provides more energy than ANAEROBIC respiration) This is how animals get all their energy. The reason that you need to breathe is to supply this pathway with oxygen. 42

43 Energy Exchange in Ecosystems 43

44 From Species to Ecosystems Species - all organisms of the same kind that are genetically similar enough to breed in nature and produce live, fertile offspring Population - all members of a species living in a given area at the same time Biological Community - all of the populations of organisms living & interacting in a particular area a.k.a. BIOTIC FACTORS BIOMASS - the total mass of all living matter in a specific area 44

45 From Species to Ecosystems Ecosystem a biological community and its physical environment The physical environment includes ABIOTIC (non-living) FACTORS such as climate, water, minerals, soil, energy, etc. It is difficult to define the boundaries of an ecosystem. Most ecosystems are open in that they exchange materials and organisms with other ecosystems. BIOSPHERE all ecosystems on earth. From deepest ocean trench to highest mountain peaks. (20 km thick layer around earth) 45

46 ECOSYSTEM PRODUCTIVITY PRODUCTIVITY - the amount of biomass produced in a given area in a given period of time. PRIMARY PRODUCTIVITY synthesis of organic matter (biomass) by plants using solar energy during photosynthesis. SECONDARY PRODUCTIVITY - manufacture of biomass by organisms that eat plants. 46

47 ECOSYSTEM PRODUCTIVITY GROSS PRIMARY PRODUCTIVITY (GPP) measure of the total amount of solar energy captured by producers during photosynthesis. NET PRIMARY PRODUCTIVITY (NPP) - measure of the total energy captured minus the energy respired by producers. 47

48 GPP VS NPP NPP = GPP Respiration MEASURING GPP Total CO 2 taken up during photosynthesis = CO 2 taken up in light + CO 2 produced in dark This figure is expressed as Kg C / m 2 / day (year) 48

49 CALCULATING NPP A forest in N. America has a GPP of 2.5 kg C / m 2 / year This same forest loses 1.5 kg C / m 2 / year due to respiration. Calculate the NPP in terms of % of GPP 49

50 NPP for Ecosystems NPP is highest where temp is high, large amounts of water and sunlight are present 50

51 Identify 3 food chains in the picture below. Each chain must have at least 3 organisms 51

52 Food Chains and Food Webs Food Chain sequence of consumption from producer to consumers Food Web multiple food chains, shows complex relationships. Trophic level - An organism s feeding status in a food web. 52

53 TROPHIC LEVELS - Producers PRODUCERS AUTOTROPHS All plants, Some protists ALGAE Chemosynthetic Archaea Some bacteria These organisms produce glucose through photosynthesis or chemosynthesis and are the base of the food chains. 53

54 TROPHIC LEVELS - Consumers CONSUMERS HETEROTROPHS All animals Some protists PROTOZOA Herbivores eat only plants Carnivores eat only animals - wolves Omnivores eat both plants & animals Bears, fox, raccoons 54

55 TROPHIC LEVELS Consumers Some animals feed on dead organic matter SCAVENGERS eat carcasses DETRITIVORES eat debris (waste/decaying matter) breaking it down into smaller pieces called DETRITUS 55

56 TROPHIC LEVELS - Decomposers DECOMPOSERS SAPROTROPHS - most BACTERIA - All FUNGI (mushrooms, mold) Decomposers break down detritus into elements and smaller molecules to be recycled back into ecosystems through matter cycles. THIS IS AN EXTREMELY IMPORTANT ROLE 56

57 PROCESS OF DECOMPOSITION 57

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59 Ecological Pyramids Due to the Second Law of Thermodynamics, energy is lost at each level of the pyramid. Energy is lost as heat during metabolism. Some energy is lost due to inefficient predation. 10% Rule (Energy / Biomass) 100 kg of clover yields 10 kg of rabbit which yields 1 kg of fox which yields 0.01 kg of eagle 59

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61 Energy Pyramid When organisms at various trophic levels are arranged diagrammatically, they form a pyramid with many more producers than consumers. 61

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63 Remember - 90% of energy is lost at each step 63

64 INVERTED FOOD PYRAMIDS INVERTED FOOD PYRAMIDS NEVER REPRESENT ENERGY!!! Inverted pyramids exist under a few conditions: In this example, a single tree can support hundreds or thousands of insects which in turn can support a few carnivorous birds such as woodpeckers. Draw a fourth level representing a hawk which may prey on the woodpecker. 64

65 INVERTED FOOD PYRAMIDS Inverted pyramids exist under a few conditions: In this example, a field of grass can support a few rabbits which in turn support thousands of parasites both internal and external. 65

66 INVERTED FOOD PYRAMIDS Inverted pyramids exist under a few conditions: Aquatic ecosystems are often inverted at the primary consumer level. Phytoplankton reproduce quickly and have short lives so there are never as many as the next level. In contrast, grasses have longer lives and are rarely consumed in their entirety. Thus, are a broader base for terrestrial food pyramids. 66

67 BIOGEOCHEMICAL CYCLES Matter is conserved as it cycles over and over through ecosystems. 1. HYDROLOGIC CYCLE 2. CARBON CYCLE 3. NITROGEN CYCLE 4. PHOSPHORUS CYCLE 5. SULFUR CYCLE SOURCE releases more of a compound than it absorbs SINK stores more of a compound than it releases 67

68 Hydrologic Cycle 68

69 HYDROLOGIC CYCLE Path of water through the environment 1. Solar energy evaporates water from surface supplies and land. 2. Water is released by plants via TRANSPIRATION 3. Winds distributes water vapor around the globe. 4. Water vapor condenses over land surfaces, producing precipitation. 5. Water runs off, percolates into sediment or is taken up by plants 69

70 Carbon Cycle 70

71 Carbon Cycle Begins with intake of CO 2 during photosynthesis. Carbon atoms are incorporated into sugar which is eventually released by cellular respiration either in the plant or in organisms that consumed it. Sometimes the carbon is not recycled for a long time. Coal and oil are the remains of organisms that lived millions of years ago. The carbon in these is released when we burn them. Some carbon is also locked in calcium carbonate (shells, limestone). 71

72 Carbon Cycle The parts of the cycle that remove and store carbon dioxide from the atmosphere (vegetation) are called carbon sinks. The parts of the cycle that release carbon dioxide are called carbon sources. Burning of fuels generates huge quantities of carbon dioxide that cannot be taken up fast enough by the carbon sinks. This excess carbon dioxide contributes to global warming. 72

73 Nitrogen Cycle 73

74 Nitrogen Cycle Nitrogen is needed to make proteins and nucleic acids such as DNA. Plants take up inorganic nitrogen from the environment and build protein molecules which are later eaten by consumers. Nitrogen-fixing bacteria change nitrogen to a more useful form by combining it with hydrogen to make ammonia. Other bacteria convert ammonia to nitrites and then nitrates, which can be taken up by plants to make proteins. - Members of the bean family (legumes) have nitrogen-fixing bacteria living in their root tissue. 74

75 Nitrogen Cycle Nitrogen re-enters the environment: - By death of organisms - Animal excrement and urinary wastes Nitrogen re-enters atmosphere when denitrifying bacteria break down nitrates into N 2 and nitrous oxide (N 2 O) gases. - Humans have profoundly altered the nitrogen cycle via use of synthetic fertilizers, nitrogenfixing crops, and fossil fuels. 75

76 Phosphorus Cycle 76

77 Phosphorus Cycle Phosphorus is needed to make DNA, & ATP (the energy currency of the cell) and other important biomolecules. Phosphorus compounds are leached from rocks and minerals and usually transported in aqueous form. Taken in and incorporated by producers - Passed on to consumers Returned to environment by decomposition Cycle takes a long time as deep ocean sediments are significant sinks 77

78 Sulfur Cycle 78

79 Sulfur Cycle Most sulfur is tied up in underground rocks and minerals. Inorganic sulfur is released into air by weathering and volcanic eruptions. Cycle is complicated by large number of oxidation states the element can assume. Human activities release large amounts of sulfur, primarily by burning fossil fuels. - Important determinant in acid rain 79