A1 - How Energy Enters the Biosphere (Updated 2024) PDF

A1 - How Energy Enters the Biosphere I can… Apply the laws of thermodynamics to explain the flow of energy through the biosphere Explain how photosynthetic/chemosynthetic and cellular respiratory activities are balanced in different environments Link the roles of producers and...

A1 - How Energy Enters the Biosphere I can… Apply the laws of thermodynamics to explain the flow of energy through the biosphere Explain how photosynthetic/chemosynthetic and cellular respiratory activities are balanced in different environments Link the roles of producers and consumers to energy flow in the biosphere Discuss and provide examples of energy flow through trophic levels Pre-Assessment 1. What is the biosphere? 2. How might matter/energy cycle through the biosphere? 3. What impacts might humans have on the biosphere? Pre-Assessment On the diagram, identify… 1. Two biotic and abiotic factors. 2. A producer, consumer, and decomposer. 3. 2 different food chains, each with at least 3 organisms. The Biosphere Biosphere: The narrow zone around Earth that harbours life Earth has three basic structural zones where living organisms are found: 1. Lithosphere (land) 2. Hydrosphere (water) 3. Atmosphere (air) Laws of Thermodynamics First Law of Thermodynamics Energy can’t be created or destroyed, can only be converted from 1 form to another/transferred from one object to another Radiant energy is converted to chemical energy stored in the bonds of carbohydrate molecules Second Law of Thermodynamics No process of energy conversion is 100% efficient With each conversion, there is less energy available to do useful work Energy Flow All organisms need energy to live According to the first law of thermodynamics, energy cannot be created or destroyed So where does this energy come from? And where does it go? Albedo 100% of the Earth’s energy comes from the Sun However, not all of the sun’s energy reaches the Earth’s surface - most of it gets reflected! Albedo: Amount of energy reflected by clouds, water, and land 30% is reflected from clouds and the atmosphere 19% is absorbed by gases (H2O and CO2) 51% of sun’s energy reaches surface ○ Only 1-2% of the energy that reaches the ground is used to drive photosynthesis We know that energy cannot be created or destroyed. It can, however, be converted into different forms. Solar energy that does reach the earth is converted into various forms of usable energy by living things. The path of energy flow through our biosphere: ENERGY TRANSFORMATION #1 ENERGY TRANSFORMATION #2 = PHOTOSYNTHESIS = CELL RESPIRATION Photosynthesis Photosynthesis is the process by which producers (plants, algae, and some bacteria) convert radiant energy from the sun into chemical potential energy Chemical energy is stored in the bonds glucose, or sugar, which may then be used to fuel cellular activities Because producers use the sun’s energy to create their own food, they are also referred to as “autotrophs” Glucose Photosynthesis Radiant energy is converted into chemical energy. Cellular Respiration In cellular respiration, consumers convert the chemical energy stored in the bonds of glucose into ATP ○ ATP: Serves as our body’s main fuel source Producers also use cellular respiration to break down the glucose they produce ATP is “burned” to transform it into usable forms of energy, such as thermal (to keep us warm) and kinetic (to move) Because consumers obtain their energy from other organisms, they are also referred to as heterotrophs Cellular Respiration Chemical energy converted into kinetic and heat energy. Cellular Respiration and Photosynthesis Energy is required by all living things All organisms use cellular respiration to obtain energy from chemical compounds Photosynthesis is carried out by producers - plants, algae, and some bacteria  SINCE PHOTOSYNTHESIS & CELL RESP ARE COMPLIMENTARY, O2 & CO2 ARE BALANCED & MAINTAINED IN ANY ECOSYSTEM. Fermentation Fermentation: In anaerobic environments, some heterotrophs (usually bacteria) are able to perform cellular respiration without oxygen In regular aerobic respiration, glucose is broken down into a molecule called pyruvate, which is used to generate large amounts of ATP Fermentation When oxygen is not present, pyruvate is still created, but very little ATP is produced. Instead, the absence of O2 causes pyruvate to be broken down into different by-products, depending on the species of anaerobic bacteria This is how we get foods such as wine, yogurt, and bread Chemosynthesis Chemosynthesis: The process by which non-photosynthetic organisms convert inorganic chemicals to organic compounds without solar energy Organisms capture energy from hydrogen sulfide (H 2S) and produce sulfuric acid (H2SO4) as a byproduct “Chemo” means chemicals, “synthesis” means putting together Organisms that live in areas without light can’t perform photosynthesis 6 CO2 + 6 H2O + 3 H2S → C6H12O6 + H2SO4 Chemosynthesis Occurs near deep-sea vents in oceans Specialized bacteria split hydrogen sulfide molecules that come out from vents ○ The energy obtained from breaking chemical bonds creates energy-storing compounds Other types of bacteria that carry out chemosynthesis have been found in other environments ○ Ex. Nitrifying bacteria have been found in soil Producers and Consumers Producers: Organisms that are able to use Sun’s energy to produce food for themselves ○ Known as autotrophs (self-feeders) Consumer: Organisms that consume other consumers or autotrophs ○ Known as heterotrophs (other feeders) Consumers Consumers can’t capture the Sun’s energy directly - must feed on producers as source of energy Are classified into different groups, depending on how they obtain food Characterization of Consumers 1. Primary Consumers Organisms that eat plants (autotrophs/herbivores) Ex. Some insects, grazing mammals, mammals that eat fruit and seeds, some species of birds and fish 2. Secondary Consumers Organisms that mainly eat herbivores or primary consumers (can be omnivores or carnivores) Ex. Spiders, frogs, insect-eating birds 3. Tertiary Consumers Organisms that mainly eat other carnivores (true carnivores) Ex. Lions, wolves, polar bears, eagles 4. Decomposers Organisms that absorb leftover or waste matter Ex. Fungi, bacteria, some insects Trophic Levels Trophic levels: Categorize living things by how it gains energy The first trophic level contains autotrophs, and each higher level contains heterotrophs The first trophic level provides all the chemical energy required to fuel the other trophic levels (producers) All remaining trophic levels consist of consumers Decomposers may feed at any of the trophic levels Decomposers Decomposers play an important role in ecosystems ○ Ex. Bacteria, fungi, insects Obtain energy-rich molecules by eating or absorbing leftover/waste matter Without them, nutrients trapped in bodies of dead organisms wouldn’t be released ○ Return organic and inorganic matter to soil, air, H2O for use by producers Energy Transfer As energy is transferred from producers to consumers along the trophic levels, some of that energy is lost… This idea is described by the second law of thermodynamics, which states that with each conversion of energy, there is less energy available to do useful work Because no process is 100% efficient, each time a cell uses energy to perform a function, a portion of that energy is lost as unusable heat What implication does this have for food chains? Energy Transfer This means that less and less energy is available to higher trophic levels Organisms at the top of the food chain must consume far more than organisms at the bottom of the food chain to obtain enough energy This also means that the length of any given food chain has limits, as there is a finite amount of energy available Food Webs Food webs are more commonly used to represent energy transfer within an ecosystem as opposed to linear food chains They are a more accurate reflection of an ecosystem, as they allow us to show how some organisms feed at multiple trophic levels Arrows always point in the direction of energy flow Rule of 10 Energy is lost as it is passed along food chain (approx. 90%) Rule of 10: Less than 10% of energy that is present at one level is passed on to the next Will limit the number of trophic levels (levels in food chain) in an ecosystem at 4 or 5 Rule of 10 (Example) According to the rule of 10, the grass in the food chain shown above receives 10,000 kJ of energy from the sun Only 10 kJ of energy is available to the eagle at the end of the food chain Of that 10 kJ, only 1 kJ of energy is actually converted into useful energy by the eagle Taking into consideration the Rule of 10, does it make more sense to maintain a mostly vegetarian diet, or one that consists mostly of meat?