We All Belong to the Biosphere
Biosphere is Process
Life on Earth is dynamic and everchanging as its members live and die, as the winds and waters circulate life-materials around the globe. The planet itself is filled with processes, all of which affect living organisms.
The Processes of the Biosphere are so enormous and complex that we can grasp them more easily as six kinds of processes:
| Photosynthesis: How Life Feeds |
Photosynthesis is the process of making food, on which all life depends. "Photo" means "light"; "synthesis" means "putting together," so the word means "putting together with light." It all begins with energy. Earth continuously receives two enormous kinds of energy from the sun: Light and Heat (infra-red).
Photosynthesis is life's greatest invention. It began in the ocean. Tiny early bacteria anddiscovered that by using this new process, they could feed themselves instead of having to eat other bacteria.
The food it learned to make is called a carbohydrate, or simple sugar. It uses light for energy plus water plus carbon dioxide. This is the way it's written in chemistry:
12H2O + 12CO2 ---------->>>>>C6H10O5 + O2
That is, water (H2O) plus carbon dioxide (CO2) combined in a chloroplast in the presence of light results in f sugar (C12H22O11) plus oxygen (O2). The oxygen is a by-product, or leftover. Or waste. This 'waste' oxygen, generated by countless billions of photosynthetic bacteria and archaea for millions of years, created the oxygen atmosphere that allows animals to breathe.
This description of photosynthesis is vastly simplified. In truth, it is much more complex. There are dozens of steps or stages in the process, and more subtle chemical changes than are shown above. Mineral nutrients dissolved in water are also necessary. A little of the light energy is used to create proteins and fatty acids in different kinds of photosynthesis.
Plant cells, like other eucaryotes (protists and animals), evolved through symbiosis, that is, two or more organisms combining to make a new kind of cell. They combined by engulfing (swallowing) each other. We know this because chloroplasts and mitochondria have their own bacteria-style DNA, which is quite different from the DNA in the cell nucleus. Animal cells contain two kinds of DNA: nuclear DNA (which contains the genetic heritage of the species) and mitochondrial DNA (mitochondria are the "power generators" in every cell). Plant cells contain three kinds of DNA, the same two that animals have, plus chloroplast DNA. Plant cells, in other words, are the result of two symbiosis events, one to contain mitochondria, and one to contain chloroplasts.
Plant leaves 
get carbon dioxide from the air by opening tiny pores called stoma. This one is on a corn leaf. The two yellow cells are the guard cells that open and close the hole. Keeping the stoma open requires plentiful water available for transpiration. If stomas close, no carbon dioxide enters and photosynthesis stops.
Here is the basic sequence of plant photosynthesis:
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The plant "inhales" carbon dioxide through its leaves. |
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The plant "soaks up" sunlight through its leaves. |
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The plant pulls in water and dissolved mineral nutrients through its roots and mcorrhizal fungi partner. |
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With its sap, the plant circulates carbon dioxide and water and dissolved minerals to every cell |
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Each cell then produces food, using carbon dioxide and water
plus sunlight. Photosynthesis produces oxygen as a by-product or leftover. |
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A little of the leftover oxygen is used by the plant for respiration (energy-making); most of the oxygen is released into the air. |
| Floating Continents: Tectonic Plates |
Life has created some of Earth's outer crust, the limestones. Only in the twentieth century did science verify that Earth's crust is in constant movement.
The continents float around on the surface of the earth in super-slow-motion. They float on "rafts" of rock called tectonic plates (white lines on the picture below). There are about fifteen major plates, and many small plates. All the land on earth floats, but not on water. It floats on the Mantle of semi-liquid rock just beneath Earth's crust. The mantle is an 1,800 mile deep sphere beneath the crust. It is solid in its center, but soft on its upper boundary. Like a thick liquid, the upper mantle has convection currents--which make the plates move. When the mantle oozes out of a plate boundary, or out of a volcano, we call it lava.
plate boundaries in white
Earth's crust beneath the land is different from the crust beneath the ocean. The continental crust is thicker but lighter than the ocean crust, on the average 20-40 miles thick, and as a result it floats higher in the outer mantle than the oceanic basins. The oceanic crust consists of a number of igneous rocks among which is basalt--a hard black rock, also nickel, magnesium, and iron. The oceanic crust is much thinner than the continental crust (between 2 and 5 miles thick)--thinner, but heavier, which means it settles deeper into the semi-liquid outer mantle than the continents do.
About 225 million years ago (mya)--during the Jurassic Period, the plates were clustered together forming a connected land mass supercontinent we call "Pangea." By 200 mya Pangea had split into Gondwanaland and Laurasia. By 135 mya things begin to look familiar. India is floating north; Antarctica is floating south. By 65 mya, Australia has broken off Antarctica and is floating northeast.
The continental plates are still creeping apart--in the middle of the Atlantic Ocean at the plate boundary, the plates are moving apart, and new crust is being formed.
Today, if we look at the shapes of the various continents on a map or a globe, we can see how the shapes appear to fit together like puzzle pieces.
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Life Helps Make Earth's Crust
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When we find fossil ferns in the rock we call coal, we discover again how lively a planet this is. We also discover that life doesn't just live here--it helps build the earth.We have a habit of thinking of Earth as inert and dead--just rock. But that habit of thinking can get in the way of understanding how Earth works. In fact, much of the Earth we know has been created by living organisms.
Beginning about 340 million years ago, and continuing for 60 million years, land life on earth found its way onto barren land and colonized it. Plants formed great swampy forests of tree ferns, conifers, and horsetails. Insects rapidly developed many forms, and amphibians became large creatures that looked somewhat like alligators.
The plants that formed these vast forests grew using sunlight, just as plants do now. As plants in these forests died, lots of them were covered by water and became, over a long time, beds of peat. Over a long time, these peat beds were covered with mud and sediments. The weight of these materials on top of the peat squeezed the water out of the peat. Later pressure and heat slowly, slowly transformed the peat into coal. This process has been going on ever since. The "younger" coal beds we discover today are poor-quality coal for burning. The oldest coal is the best coal.
Life creates other parts of the earth's crust, too. In the oceans, for billions of years, shell-building algae and zooplankton have been living and dying and falling to the ocean floor, where their shells eventually became limestone, chalk, and other kinds of rocks. 
Some of them transformed into natural gas and petroleum--life created the oil and gas we all depend on.
Sea life, in the form of ancient iron-concentrating bacteria, has also created the deposits of iron that we mine. Fossil shark teeth are frequently found in iron mines.
Other bacteria concentrated aluminum from seawater and created the bauxite deposits we mine now for beverage cans and airplane skins.
Life created all the petroleum, all the coal, and all the natural gas there is.There are many other examples.
The point is that Earth's crust is partly the result of life. So Life doesn't just use Earth as a stage where it plays out its dramas. Life creates some of the stage.
Earth spent hundreds of millions of years putting sunlight energy into the bank in earth's crust. All the oil, coal, and natural gas that exists comes from organisms that transformed solar energy into their bodies. This vast bank of stored energy in the earth's crust is now quickly being withdrawn by our civilization.
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Rock Cycle: The Marriage of Water and Rock |
Everything in the Biosphere is part of one system, so Rock Cycles could be discussed under Circles as well as under Biosphere. The Water Cycle and the Rock Cycle are closely interlinked, as if they were partners in a long marriage. Everything really is connected to everything else.
The creation and movement of rock around the earth is the rock cycle. It is a very slow process that happens over millions and millions of years.
People have been finding fossils of ocean creatures high up in the mountains for hundreds of years. How they got there was once a great mystery of science. Now we know that some of the land on each continent was once the ocean floor.
This mountain was under water once. It still is,
but now it's under snow and ice.
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a fossil trilobite in limestone
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The Rock Cycle is coupled with the Water Cycle. Every time water touches rock, it tries to dissolve it, and it does dissolve a tiny bit. The dissolved mineral from the rock becomes part of the water and travels with the water through the ground or down the rivers.
Water is the most powerful solvent there is. Given enough time, water can dissolve almost anything. Water dissolves iron, water dissolves stone. Water dissolves mountains!
Water begins the Rock Cycle. Soil bacteria help water to dissolve rock particles in soils.
Every river on earth contains dissolved rock. Rivers also contain rock particles in suspension. These minerals are washed into the ocean, where they become part of the bodies of a multitude of living organisms. Without the dissolved rock brought by rivers to the ocean, most ocean life would die.
Weathering: What Else Wears On Rock? |
The Rock Cycle is so slow that human eyes cannot see it. Glaciers are one slow power working on the rock of mountains. The glaciers are rivers of ice that do flow, but only a few feet a year. They grind over bedrock and break it up into boulders, then pebbles. What we ordinarily call gravel was left behind by melting glaciers. Rivers running out from beneath glaciers are sometimes "milky" with mineral content .
Glacier at its starting point,
carving rock and carrying rock. |
Glacier at its end, 'calving'
icebergs into the ocean
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The Winds work on rock too. Wind has a lot to do with turning rocks into sand, which is simply very small pebbles called grains. Wind can grind rock right down to dust. Sometimes when wind is wearing rock, it creates beautiful sculptures, such as these:
Hoodoo at Arches Nat. Park
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Pinnacles at Arches Nat. Park
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Temperature Changes work on and wear down the hardest rocks. When rock gets cold it shrinks a little. When rock gets warm, it expands a little. When this seesaw expansion and contraction goes on for a few hundred years, or a few thousand, or million, the rock gets tired and breaks.
Water gets into the action here, too. Rock often has small cracks in it. Water seeps into the cracks, and when it freezes, it expands, which eventually can break the rock apart.
Another power working on rock is life. Living systems such as lichens slowly dissolve rock by using chemicals they create.
Wind action, temperature change, and rainfall, all working together is called Weathering.
Water as rain and snow and ice (glaciers) travels down watersheds, percolates through soil, dissolves a little sand, comes to the bedrock, dissolves a little rock, carries it all along as an invisible part of the water, and flows into a river. Rivers are full of dissolved rock. Rivers carry this dissolved rock into the world-ocean. (They also carry rock particles, or sediment, but that's a different process.)
Question: So, why isn't the ocean filled up with rock?
Easy Answer: Because the rock is dissolved.
Try a Mind-Experiment: Imagine dissolving table salt or sugar into a glass of water. Say you tried to dissolve a half-cup of salt or sugar in one glass of water. Stir like crazy. From your own experience, you know that a lot of the salt would just fall to the bottom of the glass and refuse to dissolve. You have just reminded yourself that water can hold only a limited amount of dissolved salt or sugar. Water can only hold a certain amount of dissolved minerals.
Ever since land lifted up out of the world ocean and the first continents were born, water has been dissolving the land and rivers have been carrying it back into the ocean. Remember, this has been going on for over three billion years--that is, three thousand million-year-periods.
Two questions:
1. So what really does happen to all that dissolved rock?
2. Why haven't the continents just dissolved and disappeared?
Answer 1. The Marriage of Life and Rock. Living organisms take the minerals out of solution and make room for more dissolved rock. The particles of rock that are carried in suspension are pulled to the seafloor by gravity. Tiny floating plankton organisms called diatoms (a kind of algae) and foraminifera, dinoflagellates, and radiolarians (kinds of protozoa) make beautiful microscopic shells, called tests,out of the dissolved calcium and silica and carbon they take out of ocean water.
diatom test |
foramiferan test |
diatom test |
radiolarian test
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a foramiferan test |
a dinoflagellate test |
They live in their shells, and when they die, they drift down to the ocean floor in a slow steady rain of tiny shells. Billions of tons of these shells accumulate on the ocean floor every year. These sediments get squeezed together by the immense weight of all that water above them, and slowly, slowly, ever-so-slowly turn into rock again. So what began as rock on land eventually ends up as rock on the ocean floor.
A little of the dissolved rock does just 'fall out' (precipitate) of the water onto the ocean floor, but most of it is processed by life. This life process is called carbon burial. If life did not take so much carbon out of the cycle for eons, carbon dioxide might increase in the air and overwarm Earth--the greenhouse effect. Explore further: Balance
Plankton drifters such as diatoms aren't the only life forms taking minerals out of the water. Bacteria take a lot of minerals out, too. Bacteria can concentrate different minerals inside their tiny bodies. Some bacteria specialize in dissolved metals, such as iron. Very long ago certain early bacteria concentrated iron in their bodies and died and accumulated on the ocean floor and eventually created most of the iron ore deposits that we mine today. Bacteria that concentrated aluminum in their cells created the bauxite (aluminum ore) deposits that we mine today.
Question 2. Why haven't the continents just dissolved and disappeared?
The short answer is that the continents are always being renewed. Rock circulates from the ocean depths back onto land.
Earth is covered with plates of floating crust rock. They 'float' on magma, which is semi-liquid rock beneath the crust. Some of the rock created on the ocean floor ever-so-slowly sinks down under the plates at their edges and melts into the magma. This is called subduction. Here is a diagram of a deepwater ocean plate (oceanic lithosphere) sinking into the mantle where it collides with the continent of South America (continental lithosphere.
You already know one way the melted seafloor rock can get back onto the continents. Right. Volcanoes. Lava is magma raised to the surface of the continents.
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Typical volcano cone |
Volcano erupting underwater. The steam and smoke show the violent collision of lava and seawater. Many islands have been born this way. |
Continents are renewed through a process called Uplift. Remember now that these crustal rock processes are extremely slow--to us. When tectonic plates collide, sometimes one sinks below the other. Other times they 'rub' against each other and cause earthquakes. But fairly often in the history of Earth, both colliding plates push upward. Example: When the Indian sub-continent (modern India plus) broke free from Gondwanaland (see above) long ago, it floated north until it collided with the Asian plate. That collision pushed the edges of both plates upward and created the Himalaya Mountains. Remember that the rock cycle begins again on "new" mountains. Glaciers and rivers and wind begin to carve them away and carry their particles and dissolved minerals back to the ocean, where they were before--perhaps several times before. It is very hard to imagine the enormous stretches of Deep Time that the Rock Cycle takes to complete a cycle.
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The Marriage of Wind and Water:
Atmosphere and Ocean Currents |
Water and Wind work together in this lively biosphere. As we saw when we looked at the rock cycle, the water cycle and the winds work together to dissolve the continents' rock and carry life-materials to the ocean. The sun's infra-red (heat) radiation powers the water cycle and powers the worldwide winds. That solar heating in turn drives the ocean currents; the winds play a vital role in mixing waters of differing temperatures. The ocean currents have a huge impact on human lives. If it were not for the warm ocean Gulf Current that crosses the Atlantic, Europe would be so cold it would be almost uninhabitable.
Recently, we have been able to observe earthwide winds from weather satellites in orbit above us.
When we observe the winds by watching clouds, we are watching water vapor circulate around the earth.
Meteorologists translate the satellite information into weather maps like this, below.
Part of North America's weather one day
There is also an earthwide system for observing the ocean. Part of that is done by satellite, part is done by "drifters", large free-floating buoys which radio their locations and the water temperature back to ocean scientists. There were 778 drifters operating when this map was made in 1997. Several countries cooperate in the drifter research.
Each red dot represents a drifter's location.
By looking at the height of waves, oceanographers also study the combination of wind and water that mixes waters of different temperatures.
Wave height and direction worldwide
From all these sources of information, oceanographers chart the vast currents that circulate ocean waters around the globe.
Worldwide ocean currents for two days
One of the most crucial outcomes of the marriage of wind and water is Upwelling.
Upwelling is the uplift of water all along continental shelves. This means that cold, nutrient-rich water comes to the surface of the ocean for up to 200 miles out from land. Upwelling is the result of coriolis winds. These are winds created by the Earth's daily rotation. The coriolis winds push the surface waters away from the coasts. This pulls colder water up and mixes more nutrients into the water there, and eventually into most of the ocean. These nutrients support the whole oceanic food chain, beginning with floating planktron.
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| Animal/Plant Gas Exchange |
Our planet is lively in many ways. Everything on Earth is part of one system, so Gas Exchange could be discussed under Cycles, Interliving, or under Balance. Everything really is connected to everything else.
Every living organism must exchange gases to stay alive. We each take in a gas (breathing) we need from the atmosphere, use it to make food or transform food, and release the leftover part of the gas, which the living cells have chemically changed into a different gas.
Animals take in oxygen gas, transfer it to their blood, and carry it to every cell, where it is used to transform food into energy, where carbon dioxide gas is created as a by-product or leftover. This is called respiration. This carbon dioxide is released into the air.
Plants and algae breathe in carbon dioxide and carry it to every green cell, where it is used to transform sunlight into food. This is called photosynthesis. In this process, oxygen gas is created as a by-product or leftover, and is released into the air.
Plants must have carbon dioxide to live. Animals must have oxygen to live. Both plants and animals give each other their by-products. We all live on leftovers. The diagram below show the circle of gas exchange between photosynthetic life and animal life.
Gas Exchange is a system of Giving and Receiving
Plants give oxygen to animals (including you), and animals give carbon dioxide to plants.
Gas Exchange is also a system of Receiving.
Plants receive carbon dioxide from animals, and animals receive oxygen from plants.
So Gas Exchange is really a Gift Exchange, a life and death Gift Exchange. We can't live without each other.
Some Details of Gas Exchange for Animals
Not only flowering land plants give off oxygen. All the billions of green algae in the oceans do as well--and all the cyanobacteria in lichens of the forest, and in the cryptobiotic crusts of deserts. All photosynthesis creates free oxygen as a by-product.
Every life has to breathe, or respire. This is a chemical process within cells Here are the basic steps of respiration:
Plant cells respire in roughly similar fashion, but by using a little of the oxygen in the sap that it liberates during photosynthesis.
