Energy and Matter Exchange in the Biosphere

Energy and Matter Exchange in the Biosphere

Energy and Matter Exchange in the Biosphere Unit 1 Pictures from space show the Earth is a single

unit, a large system, which we seek to understand and maintain. The cycling of matter and the flow of energy on Earth.

It can be said that the earth is in a state of dynamic equilibrium (equilibrium - all acting influences are balanced resulting in a stable condition / dynamic fluctuating) Some recent research indicates that the earth's dynamic equilibrium may be in danger of being

upset. The Biosphere Structural zones of the earth 1. lithosphere - land (10 km) 2. hydrosphere - water 3. atmosphere - air (900 km)

Living organisms are present in all three zones (biosphere) Solar energy and global temperatures 99% of Earth's energy comes from the Sun

Atmosphere traps surface heat radiation and reflects it back to earth Angle at which the sun strikes the earth helps to determine the temperature as does the number of daylight hours Tilt of the earth helps to generate the

seasons we experience How Energy Enters the Biosphere Energy enters the biosphere by photosynthesis. (For some organisms, energy enters their part of the biosphere through the process of chemosynthesis.)

Energy Transfer Photosynthesis: conversion of solar energy into chemical energy (Example: Carbohydrates) Cellular Respiration: break down of energy-rich molecules to produce useable energy Use this energy for growth, repair, movement and reproduction

Feeding Levels Trophic level - locates the position or level of organism during its energy seeking activities Plants are at the first trophic level Heterotrophs that feed on plants are at the second level etc.

Producers: Organisms able to use the Suns energy to produce food Also known as autotrophs Consumers:

Organisms that must eat others to obtain their energy Also known as heterotrophs Suns Energy The sun is the source of all energy for producers 51% of the Suns rays reach the Earths surface and are absorbed

Of the 51% of the Suns energy that reaches the Earth only about 1-2% is converted into chemical energy by photosynthesis. But producers generate about 150 billion to 200 billion tonnes of organic matter/year. This is how life is supported on Earth Albedo Effect

Amount of sunlight reflected from a material Higher albedo = less energy absorbed; temperature drops correspondingly Dust, water vapour, snow and other atmospheric conditions all increase the albedo Deep Ocean Energy

Solar Energy does not reach the depths of the ocean but producers are still able to live at the bottom of the Ocean Bacteria live on organisms and capture the energy stored in chemical bonds This is known as chemosynthesis

Consumers Directly or indirectly depend on producers to meet their energy needs Types of consumers: Primary Consumers: eat plants and other producers (herbivores) Secondary Consumers: eat other animals

(carnivores) Tertiary Consumers: eat secondary consumers Decomposers: eat or absorb waste material or dead organisms Scavengers: Eat dead organic matter

Trophic Levels Food Chains and Food Webs Food Chain- A model shows the linear pathways through which food is transferred through trophic levels

Food Web: a model of food (energy) transfer in an ecosystem that shows the connections among food chains 2 basic types of food chains: 1.Grazer- start with producers

and end with top carnivore 2. Detritus - start with dead organisms and return their remains back to the ecosystem According to the laws of thermodynamics,

energy cannot be created or destroyed, only transformed from one form to another. Ecologist often assume that 10% of the energy at one trophic level is transferred to the next trophic level (very inefficient) The Earth is a closed system to matter but an

open system in terms of energy Ecological Pyramids Designed to show the

relationship between numbers, energy & trophic levels of an ecosystem

Pyramid of Numbers Count the number of organisms at each trophic level Volume of each level = the number of organisms Easiest to make but least efficient in

accurate representation Pyramid of Biomass Biomass total dry mass of all the living material in an ecosystem Measure of stored energy in living tissues

Second best representation but it is very hard to make Pyramids of Energy Measures the amount of energy available at each trophic level Few individuals are supported at the top

because they require so much energy This is the best one to use but is the hardest to make Available energy always decreases as one moves up the trophic levels Energy Transfer

Efficiency = useful energy output x 100 total energy input The inefficiency of energy transfer from one trophic level to another typically limits the number of trophic levels to about 5

This inefficiency also means that fewer organisms can be supported at each trophic level Biomagnification Increasing concentration of a substance in the tissues of organisms at higher trophic levels

Causes top predators to suffer more harm from toxin than those in lower levels Water

Water is constantly recycled in the hydrologic cycle Product of Cellular Respiration EXTREMELY IMPORTANT to all life on Earth Properties of Water Universal solvent High boiling and melting points

Special adhesive and cohesive properties High heat capacity The Role of Water in Cycles of Matter The amount of water in the biosphere is finite. Water exists in the environment as a solid, a liquid,

and a gas. It is recycled through the hydrological cycle. Water dissolves a wide range of substances. Hydrogen bonding and polarity play key roles in determining the properties and uses of water, such as its

ability to dissolve and transport materials. Water as a Universal Solvent Many different substances are able to dissolve in water Water can carry these different compounds to various places as it moves through the hydrologic

cycle Example: Water in the soil has dissolved nitrogen and phosphorous in it Polar Molecules Water is made up of 2 hydrogen atoms bonded to 1 oxygen atom

When they are bonded together the hydrogen atoms have a slightly positive charge and the oxygen has a slightly negative charge This is known as a polar molecule Hydrogen Bonds The reason water is able to stay in liquid form from 0C- 100C

One hydrogen bond is very weak but MANY hydrogen bonds together are very strong This strength is why it takes so much energy to change water from a liquid to a gas Hydrogen Bonds Hydrogen bonds also affect the density of water

When water freezes it expands because the hydrogen bonds hold it in crystal form making it less dense than liquid water As water melts this crystal structure breaks down; the molecules are closer together and the water becomes more dense Most dense at 4C

Hydrogen Bonds Hydrogen bonds also cause cohesion- the attraction of water molecules to each other This attraction causes surface tension which allows insects to walk on water Hydrogen bonds also add to adhesion- the

attraction of water molecules to molecules of other substances Heat Storage Water has a very high specific heat capacity compared to other

substances Requires a large amount of energy to cause small changes in temperature Water is essential for humans and ecosystems. Drought and poor water

quality can affect water availability and impact humans and the environment. The Role of Water in Cycles of Matter The hydrologic cycle plays a central role in nutrient cycles (biogeochemical cycles). This flow chart demonstrates only some of the interactions

between these cycles. precipitation legumes (nitrogen fixation by bacteria)

plants use nitrate as a nitrogen source photosynthesis

carbon and oxygen cycles sulfur and phosphorus used by plants

acid deposition (sulfur cycle) weathering and erosion release sulfur and

phosphorus trapped in rocks Biogeochemical Cycles In biogeochemical cycles substances are temporarily stored in nutrient reservoirs such as organisms, soil, air and water

Substances can cycle through these nutrient reservoirs quickly or slowly Rapid cycling- substances move between nutrient reservoirs quickly Slow cycling- substances move between nutrient reservoirs slowly (fossils)

Carbon and oxygen are found in living organisms and in the land, atmosphere, and water. Carbon and Oxygen Cycles Plants take in more carbon in the form of carbon dioxide every year than plants and animals make

Most of the carbon release back into the atmosphere is from forest fires and the breakdown of organic material by decomposers Plants, animals and decomposers play a very important role in the rapid cycling of carbon Slow Cycling of Carbon

Much of the carbon in the environment is held in living organisms Trees are known as carbon sink as they store large amounts of carbon that they only release once they die and

are decomposed Some organic matter is not decomposed once the organism dies It will settle and become fossils

Fossils hold onto carbon for thousands or millions of years until they are burned as fuel and release their carbon stores Human Activity and Carbon Cycle

Human activity has greatly influenced the cycle of carbon We mine fossil fuels and burn them to heat our homes or run our vehicles This returns mass amounts of carbon to the atmosphere much quicker than normally would happen We are also decreasing the amount of carbon dioxide being taken back up be clearing forests and other vegetation

Oxygen Cycle The oxygen cycle is closely linked to the carbon cycle Oxygen is also cycled by means of cellular

respiration and photosynthesis Nitrogen is also found throughout the biosphere. The Nitrogen Cycle

Nitrogen gas makes up 78.1% of the Earths atmosphere Nitrogen is an ESSENTIAL part of proteins found in organisms and the make up of DNA Nitrogen is not easy for organisms to access as most cannot use atmospheric nitrogen Atmospheric nitrogen only reacts under limited conditions To be useful to plants nitrogen must be in the NO3- form (nitrate ion)

Nitrogen Fixation Nitrogen Fixation- the changing of atmospheric nitrogen into NO3 This can be done 2 ways: Lightning- causes nitrogen to react with oxygen to make NO3

Some bacteria found in the roots of legumes (peas, clover) can convert nitrogen gas into ammonium Ammonification- when decomposers break down organic matter and make ammonia Denitrification- some bacteria will convert nitrite or

nitrate back into nitrogen gas and give it off to the atmosphere Denitrification occurs in environments with very little oxygen Sulfur Sulfur also cycles through the atmosphere,

living organisms, land, and water. Sulfur All organisms require sulfur as it is an important part of proteins and vitamins Plants and algae use sulfur in the form of sulfate

Sulfur Bacteria are an essential part of the sulfur cycle Use sulfur- containing compounds in photosynthesis or cellular respiration Sulfate reducers- convert sulfate to sulfide Sulfur oxidizers- convert sulfide to elemental sulfur and sulfate

Acid Deposition Some sulfur is taken out of rapid cycling as it becomes part of rocks Fossil fuels (oil, coal, natural gas) contain sulfur

Sulfur is also found in rocks and is released by weathering Acid rain- when sulfur dioxide reacts with oxygen and water vapor to form sulfurous acid and sulfuric acid These acids return to earth as rain, snow, or sleet If there are large amounts of acid rain these can damage

vegetation, acidify lakes, leach nutrients from the soil and damage buildings Phosphorus is found in living organisms, land, and water, but it does not cycle through the atmosphere.

Phosphorous Cycle Phosphorous is an essential nutrient fir DNA and ATP and a major component of bones and teeth Is available in very limited quantities Phosphorous does not cycle through the atmosphere Found in soil and water and rocks

Animals obtain phosphorous through eating grain, meat and drinking milk Plants can only use phosphorous in its phosphate form as it dissolves in water Algal Bloom- overgrowth of algae caused by excess phosphorous in lakes Algal blooms are detrimental to aquatic environments

as the decomposers breaking down the organic matter use up all the oxygen One side of this lake is bright green due to an algal bloom

caused by excess phosphorus. Nutrient run-off can cause algal blooms and dead zones.

Excess nutrients in Lake Erie have resulted in algal blooms, which have created a dead zone in the lake.

Carbon, oxygen, sulfur, nitrogen, and phosphorus are all recycled through biotic and abiotic processes. They are stored in nutrient reservoirs and cycle through these reservoirs at different rates. Because biogeochemical cycles are interrelated, disruptions in one cycle can affect another.

Biotic and abiotic processes maintain the balance of matter and energy exchange in the biosphere. Composition of Earths Atmosphere and Oceans Productivity is the rate at which an ecosystems

producers capture and store energy over time. It is influenced by factors such as sunlight and nutrient availability. Natural processes and human activities can affect the transfer of energy and the cycling of matter through the biosphere.

Wetlands can clean polluted water and provide other ecosystem services. Chapter 2 Review What properties of water make it an excellent solvent?

How do biogeochemical cycles interrelate with the hydrologic cycle? What is productivity? What can affect productivity? What causes algal blooms and why are they harmful to ecosystems?

Chapter 2 Concept Organizer The composition of the atmosphere of ancient Earth was different from its composition today.

Water transports nutrients and other chemicals through the biosphere. Earth is a closed system; therefore, all

matter in the biosphere is recycled. Natural processes and human activities remove matter from long-term storage.

Relatively rapid biogeochemical cycles transfer matter between organisms and soil, air, and

water. Ecosystem productivity is limited by available energy

nutrients water Energy and matter exchange in the biosphere is in a state of

dynamic balance. Photosynthesis and cellular respiration account for the balance of

oxygen and carbon dioxide gases in the atmosphere. Human activities can alter the

composition of Earths atmosphere with both short-term and long-term consequences. Chapter 2 Summary

The amount of water in the biosphere is limited. It is re-used through the hydrologic cycle. Water can dissolve a wide array of substances due to hydrogen bonding and polarity. Water is essential to humans and ecosystems. Carbon, oxygen, sulfur, and nitrogen cycle through the atmosphere, land, living organisms and water. Phosphorus is rarely found in the atmosphere. Cycling of these nutrients through biotic and abiotic

processes makes them continuously available. They can also be stored in reservoirs for varying lengths of time. Chapter 2 Summary Natural processes and human activities can affect the transfer of energy and the cycling of matter through the biosphere. An

imbalance in one cycle can affect another cycle. For example, excess phosphorus and nitrogen can run off into aquatic ecosystems, where it can cause algal blooms.

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