Ecosystems: What Are They and How Do They Work? Chapter 3

Concepts  What is ecology?  What keeps us and other organisms alive?  What are the major components of an ecosystem?  What happens to energy in an ecosystem  How do scientists study ecosystems?

Core Case Study: Tropical Rain Forests Are Disappearing Page 50  Cover about 2% of the earth’s land surface  Contain about 50% of the world’s known plant and animal species  Disruption will have three major harmful effects Reduce biodiversity Accelerate global warming Change regional weather patterns

3-1 What Is Ecology? 1) Cells: basic unit of life page 51 2) Species: set of individuals that can mate and produce fertile offspring 3) There are estimated between million species (some ranges between mill) 4) Only 1.8 have been identified 5) About ½ of animal and plant species live in rain forests

6) Insects make up most of the known species pg 54 7) Species are described on 8) Ecology: study of how organisms interact with their environment 9) levels: a) Population: members of a species within an area b) Community: all populations within an area c) Ecosystem: all living and non-living things within an area d) Biosphere: everywhere life can exist

10) Genetic diversity: differences within individuals in a species 11) Habitat: where a population normally lives

You need to draw and label the following pictures

Fig. 3-2, p. 55

Fig. 3-17, p. 66

Fig. 3-18, p. 68

Fig. 3-19, p. 69

Fig. 3-21, p. 71

Fig. 3-22, p. 72

3-2 What Keeps Us and Other Organisms Alive? 1) 4 components of the life support system a) atmosphere: gases around the earth 1. troposphere: air we breathe (N-785, O-21% & greenhouse gases) 2. Stratosphere: upper layer contains ozone b) Hydrosphere: all the water on or near the surface c) Geosphere: the earth layers d) Biosphere: parts where life exists 2) Biome: terrestrial part of biosphere, named for vegetation

3) Aquatic life zone: water parts of the biosphere 4) Factors that sustain life: a) One-way flow of high-quality energy: As energy flows through organisms, it is released as heat b) Cycling of matter and nutrients: matter exists in a fixed amount and must be recycled c) Gravity: allows the planet to hold the atmosphere and enables movement of chemicals

5) What happens to solar energy? a) Most is absorbed or reflected back into space b) ozone absorbs 95% of UV c) 1% generates winds d) 0.1 % is used in PSN e) also lights and warms air and surface f) Greenhouse effect: some of the heat is trapped by the gases in the atmosphere, which keeps the planet warm

3-3 What Are the Major Components of an Ecosystem? 1) Abiotic VS Biotic Fig. 3-6, p. 57

2) Range of tolerance: the range where organisms can survive

3) Limiting factors: more important factors that regulate the population growth 4) Limiting factor principle: too much or too little of a abiotic factor can limit the growth of a population 5) Major factors: landwater Precipitationdissolved oxygen soil nutrientssalinity Temperature

6) Trophic levels (feeding level) a) producers or autotroph b) Consumer or heterotroph 7) Types of consumers herbivores carnivores omnivores decomposers (bacteria and fungi) detritivores (animals)

Fig. 3-10, p. 60

8) Photosynthesis: 6 CO H 2 O + solar energy  C 6 H 12 O O 2 9) chemosynthesis: makes nutrients form chemicals 10) Respiration: a) all organisms must produce energy from food b) Aerobic respiration: most common uses oxygen C 6 H 12 O O 2  6 CO H 2 O + ATP c) Anaerobic respiration (fermentation): does not use oxygen and produces methane, acetic acid, hydrogen sulfide and ethyl alcohol

11) Energy Flow and Nutrient cycles Fig. 3-11, p. 60

3-4 What Happens to Energy in an Ecosystem? 1) Food Chain: shows the energy flow through a series of organisms Fig. 3-12, p. 62

Fig. 3-11, p. 60 2) Food web: shows the complex flow of energy

3) Useable energy decreases with each link a) Biomass: the dry weight of organic matter, stores chemical energy b) Ecological efficiency: percentage of usable energy transferred to the next level (10% typical) c) Pyramid of energy flow: graph formed by showing the amount of energy at each level d) This explains why there are fewer top predators and you can feed more people with plant material than animal.

Fig. 3-14, p. 63

4) Production of plant matter a) Gross Primary Productivity (GPP): rate solar energy is converted into chemical energy as biomass b) Net Primary Productivity (NPP): GPP – what is used by the organism c) Different ecosystems produce energy at different rates

Fig. 3-16, p. 64

3-5 What Happens to Matter in an Ecosystem? 1) Biochemical cycle (nutrient cycle): movement of elements & compounds moving through air, water, soil, rock & organisms 2) Reservoir: area where nutrients accumulate 3) Be sure to read through the cycles 4) Read Water’s unique properties page 67

Science Focus: Water’s Unique Properties  Properties of water due to hydrogen bonds between water molecules: Exists as a liquid over a large range of temperature Changes temperature slowly High boiling point: 100˚C Adhesion and cohesion Expands as it freezes Solvent Filters out harmful UV

3-6 How Do Scientists Study Ecosystems? 1) Field research: actually getting in the field and observing nature directly 2) Laboratory research: Modeling ecosystems under laboratory conditions 3) Models: mathematical models & computer simulations 4) Models are limited by the data and assumptions used in developing it