General Biology 1 Fall 2024 Ecosystem Part 2 PDF

General Biology 1 Fall 2024 Ecosystem – part 2 Prof : Dr. Vincent Gagnon Book Raven, Biology, 13th edition  Book Study guide: Topic References (13th E...

General Biology 1 Fall 2024 Ecosystem – part 2 Prof : Dr. Vincent Gagnon Book Raven, Biology, 13th edition  Book Study guide: Topic References (13th Ed) Define the components of an ecosystem and describe the flow of Section 56.1, page 1265. material and energy within an ecosystem. Section 56.2, page 1271, Figure 56.10 Section 56.1 Carbon, pages 1265-1266, Figure 56.1 Draw and label diagrams of the following biogeochemical cycles: Water, pages 1266-1267, Figure 56.2 Water, carbon, nitrogen, and phosphorous. Nitrogen, pages 1267-1268, Figure 56.4 Phosphorous, pages 1269, Figure 56.5 Draw and/or interpret food chains and webs Section 56.2, Figures 56.8, 56.9, 56.10 Identify the different types of organisms within the ecosystem: Autotrophs, heterotrophs, producers, consumers, herbivores, Section 56.2, pages 1271-1272 carnivores, saprophytes, detritivores, etc. Identify the different trophic levels within an ecosystem. Differentiate Section 56.2, pages 1271-1273, between primary and secondary productivity. Figure 56.8 Interpret ecological pyramids. Pages 1275-1276, Fig 56.13  Ecosystem World matter and energy Contrary to matter, energy is never recycled. Instead, radiant energy from the Sun that reaches the Earth makes a one-way pass through our planet's ecosystems before being converted to heat and radiated back into space. First Law of Thermodynamics: Energy can be neither created nor destroyed, but only change form. For example, energy can be: Light Chemical-bond Motion Heat Organisms cannot convert heat to any of the other forms of energy, thus if an organism convert some chemical-bond or light to heat, this energy is lost.  Ecosystem Second Law of Thermodynamics: Whenever organisms use energy under the form of light or chemical-bond, some of this energy is converted to heat (entropy). Earth functions as an open system for energy, thus part of the thermal energy is radiated back to space. However, since the industrial revolution, Humans have produce a large quantity of greenhouse gases (CO2, CH4, etc.), which is threatening this thermal equilibrium between the sun input of energy and CH4 the amount that is radiated CO2 back to space. Thus changing the climate.  Ecosystem Energy flow through the trophic levels of the ecosystems Almost all living organisms on Earth use the energy of the sun in a direct and indirect way.  Ecosystem Energy flow through the trophic levels of the ecosystems Almost all living organisms on Earth use the energy of the sun in a direct and indirect way. Autotrophs: “Self-feeders” synthesize the organic compounds of their bodies from inorganic precursors.  Ecosystem Energy flow through the trophic levels of the ecosystems Almost all living organisms on Earth use the energy of the sun in a direct and indirect way. Autotrophs: “Self-feeders” synthesize the organic compounds of their bodies from inorganic precursors. 1) Photoautotrophs: Organisms that can make their own energy using sun light and CO2 (carbon fixation) via photosynthesis (ex.: plants, algae, cyanobacteria).  Ecosystem Energy flow through the trophic levels of the ecosystems Almost all living organisms on Earth use the energy of the sun in a direct and indirect way. Autotrophs: “Self-feeders” synthesize the organic compounds of their bodies from inorganic precursors. 1) Photoautotrophs: Organisms that can make their own energy using sun light and CO2 (carbon fixation) via photosynthesis (ex.: plants, algae, cyanobacteria). 2) Chemoautotroph: Create their own energy and biological materials from inorganic chemicals (rare). Example: prokaryote that use hydrogen sulfide available in deep water vent.  Ecosystem 1) Photoautotrophs: Anabolism Catabolism  Ecosystem Energy flow through the trophic levels of the ecosystems Heterotrophs: Organism that cannot produce their own food using inorganic compound (carbon fixation) and therefore derives their energy by breaking the chemical bond of organic matter, from plants and/or animals.  Ecosystem Energy flow through the trophic levels of the ecosystems Heterotrophs: Example of aerobic respiration. Catabolism  Ecosystem Producers and Consumers Trophic levels: level at which an organism “feeds”. Consumers Producer Tertiary Consumers Secondary Consumers Primary Consumers  Ecosystem Producers and Consumers Trophic levels: level at which an organism “feeds”. Primary producers: all the autotrophs in the system. Consumers: heterotrophs Herbivores: first consumer level. Primary carnivores: eat herbivores. Heterotrophs Secondary carnivores: eat primary carnivores or herbivores. Detritivores: eat decaying matter. Decomposers: microbes / fungi that break up dead matter.  Ecosystem Producers and Consumers Trophic levels: level at which an organism “feeds”. Trophic level 4 Secondary carnivores Trophic Consumers Primary level 3 carnivores Trophic level 2 Trophic Primary level 1 producers  Ecosystem Producers and Consumers Trophic levels: level at which an organism “feeds”. Heat Secondary carnivores Primary carnivores Heat Heat Primary producers  Ecosystem Food chains Organized by trophic level, it’s a useful, but simplistic way of following matter and energy in a ecosystem.  Ecosystem Food web In reality the matter and energy resemble more a food web, where multiple food chains are interconnected. For example an animal, like you, can eat both some primary producer (lettuce) and some herbivore (chicken). You are considered as an omnivore.  Ecosystem Food Chain  Ecosystem Food web Food Chain  Ecosystem Productivity It’s the rate at which the organisms in the trophic level collectively synthesize new organic matter (biomass). Gross Primary productivity (GPP): productivity of the primary producers (biomass). Respiration: primary producers break down organic compounds to make ATP. Net primary productivity (NPP): It’s the GPP less the respiration of the primary producers. Plants have chloroplasts and mitochondria.  Ecosystem Productivity Secondary productivity: The productivity of a heterotroph trophic level is termed secondary productivity. For instance, the rate at which new organic matter is made by means of individual growth and reproduction in all the herbivores in an ecosystem is the secondary productivity of the herbivore trophic level. Each heterotroph trophic level has its own secondary productivity. Secondary Productivity: biomass of heterotrophs Primary Productivity: biomass of autotrophs and heat  Ecosystem How trophic level process energy Only 1% of incoming solar energy is captured by producers (1% per year). Primary producers store this energy in chemical bond. Some of this chemical energy is use during the primary producer respiration. Some of the energy release by the chemical bonds is lost to heat. Heterotrophs have only chemical-bond energy left in primary producers.  Ecosystem How trophic level process energy From the initial amount of sun energy capture by the producer (pants), only a small amount goes into the biomass of the herbivore (grasshopper). The rest of chemical-bond energy of the plants is lost through the animal respiration and heat, in addition part of the matter is lost through undigested food (feces). Secondary Productivity: Primary Productivity: biomass of heterotrophs So only 17% biomass of autotrophs of the initial sun energy is left in the biomass of the grasshopper for the bird to use. and heat  Ecosystem How trophic level process energy Ecologists figure as a rule of thumb that the amount of chemical-bond energy available to a trophic level over time is about 10% of that available to the preceding level over the same period of time. Number of trophic levels is limited by energy availability Limits on top carnivores: exponential decline of energy left (chemical energy) Smelt limits the lengths of trophic chains and the numbers of top carnivores an ecosystem can support. Only about 1/1000 of the energy captured by photosynthesis passes all the way through to secondary carnivores.  Ecosystem How trophic level process energy  Ecosystem Ecological pyramids illustrate the relationship of trophic levels Imagine that the trophic levels of an ecosystem are represented as boxes stacked on top of each other. Imagine also that the width of each box is proportional to the productivity of the trophic level it represents. The stack of boxes will always have the shape of a pyramid; each box is narrower than the one under it because of the inviolable rules of energy flow. A diagram of this sort is called a pyramid of energy flow or pyramid of productivity.  Ecosystem Ecological pyramids illustrate the relationship of trophic levels Imagine that the trophic levels of an ecosystem are represented as boxes stacked on top of each other. Imagine also that the width of each box is proportional to the productivity of the trophic level it represents. The stack of boxes will always have the shape of a pyramid; each box is narrower than the one under it because of the inviolable rules of energy flow. A diagram of this sort is called a pyramid of energy flow or pyramid of productivity. You can do the same with biomass and number of organisms.  Ecosystem Ecological pyramids illustrate the relationship of trophic levels Inverted pyramids of biomass The pyramid of biomass may be "inverted". For example, in aquatic system where algae (phytoplankton) is the primary producers and copepods is the primary consumer (herbivore), the pyramid can be inverted. This can be explained by the fact that phytoplankton reproduce very quickly, but have much shorter individual lives. In other words, even though the productivity of the algae is much higher than that of the copepods, the biomass at any point in time of the copepods is greater than that of the algae