Extreme Biology

by Lauren (AP Biology)

Evolution is arguably the most central theme in biology because it ties all other major themes together. Evolution is defined as a change in alleles in a population over time. In each level of life, there is proof of evolution on a population through natural selection on individuals. Darwin, credited as the founder of evolutionary theory, made four main points in his book that described how it works:

1. Each species produces more offspring than can survive.
2. These offspring must compete with each other for limited resources required to survive.
3. Organisms in all populations vary in alleles and are different.
4. The individuals with the most favorable traits or variations are the most likely to survive and therefore produce more offspring.

Molecular
Genes are the units that help code for proteins within an organism. Evolution has seen the selection of specific genes that code for specific proteins over less desirable genes. For instance, the gene that codes for blindness in the blind cavefish is chosen over the gene for eyesight. The reason for this is that one of the two genes involved in senses of the fish must be traded for the others. In easier terms, the eyesight of the fish must be sacrificed so that the jaw and taste buds can develop. In this case, the pleitrophy gene that controls this development is slightly inhibited by another gene. The only reason the inhibiting gene is selected is because while it inhibits eyesight, the fish can rely on its other sensory organs, which proves to be successful.

Cellular

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On a cellular level, eukaryotic cells are complex in comparison to prokaryotic cells. According to the endosymbiotic theory, the evolution of organelles originated from a prokaryotic cell that joined with separate prokaryotic cells. The organelles in the cell proved to be exceptionally helpful, such as the mitochondria, which supplied it with energy. The earliest mitochondrion is believed to have begun as a very primitive bacterium. With a source of internal energy, the eukaryotic cell was more favorable and through natural selection, became more frequent.

Organismal

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The kidneys are responsible for filtering the wastes of the blood and reabsorbing nutrients during the process. Some animals have evolved to have excretory systems to compliment the environment that they live in. For instance, in dry and arid environments, many animals have an extra complex collecting duct, where the most water is reabsorbed during excretion, to maximize the amount of water conserved. Those organisms that have the systems to do this can survive longer and are favorable to the environment because of their success in retaining water, which is a necessity in their environment.

Population

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One of the easiest examples to observe since it reproduces so quickly, bacteria helps explain genetic drift in populations. If you were to put a culture of bacteria in a nutrient rich environment, they would reproduce. But if you added an antibiotic into the environment that killed most of the bacteria, only the bacteria that had alleles that made them resistant to the antibiotic would survive. Since the bacteria that died did not have a high fitness, they were not able to continue contributing their genes to the pool. Only the surviving bacteria will be able to pass on their genes, which include resistance. This, in time, will lead to a whole generation of antibiotic resistant bacteria that has evolved from the original population to one made of resistant genes.

Community

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The predators and prey evolve together, the prey trying to stay one step ahead of the predator, and the predator trying to catch up. In the case of wolves and rabbits, wolves evolve mechanisms to help them survive by obtaining food such as speed, stealth, camouflage, and excellent sensory senses. Likewise, the prey, rabbits, develop similar mechanisms to aid in avoidance and escape of a predator. Any trait such as long legs to run or hop faster will enable the prey to escape its predator, and pass its genes to its offspring. Those that are eaten obviously were not fit to their environment and their genes, which did not help them, will not be passed on.

Biosphere

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The globe is made up of many different climates and geographic features, each factors of a specific biome. With in a biome, an ecosystem of organisms exists which specifically suit that particular biome. Producers within the biome have evolved features that give them high evolutionary fitness. The consumers that feed off of these producers are also well suited to their biome, as discussed in population. With the combination of all of the organisms well suited to their environment in one biome, there is an ecosystem that is specifically designed to survive there. If you were to take a kangaroo and place it in the arctic, the kangaroo would not be able to find the resources it needs to survive. The food that it lives off of, the habitat it is used to and the mates it needs to reproduce are not there. That is why each biome is made up of biotic and abiotic factors that specially suit the surrounding ecosystem.

by Stevie (AP Biology) 

Ha! I Don’t Need You!… Or Do I?

How does life exist on our planet without everything else? Is it possible for any living thing to survive without using the energy from or bi-products of another organism? This raises an even more extreme question- can any organism survive completely by itself, without any other matter at all? Of course not! Any and every living organism on this planet needs not only extra matter, but also other organisms to survive! This dependence that every living thing has on other organisms and other a-biotic factors in their habitats, or even the biosphere, is referred to as the “Interdependency of Nature.” The interdependency of nature exists on all different levels life in the biosphere! Let’s take a closer look at this concept in the following examples:

Molecular 

On a molecular level, every living thing depends on several key elements to survive. Some of these include oxygen, hydrogen, carbon, and nitrogen. All four elements make up numerous molecules and compounds that make up an organisms body or complex! (Of course there are others, but these are the main four). One simple, yet vitally essential, of these molecules is water.

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All organisms, no matter what species, have to meet a required amount of this substance of they will become desiccated, or dried up, and die. However, organisms must re-circulate water right? If there was only so much water on earth, all of it would have been used up a long time ago and we would never have even existed! All organisms, in many ways depend on water for survival. Many organisms actually break up the elements on water (hydrogen and oxygen) to use for their own ends, mostly in basic cell functions. But if so, won’t they just need more water to replace what they’ve already broken down to use? No! All organisms recycle water! In some way, all organisms resynthesize the hydrogen and oxygen molecules and return the water to nature to be used by other organisms! So we see here that even at the smallest level of existence all parts of nature depend on one another, living and Abiotic!

Cellular

When dealing with individual cells, there are millions upon billions of ways that all things in nature are interdependent upon one another. Take, for example, a nerve cell and the action potential of a nerve cell needed to send a message to another part of the body.What occurs in a nerve to send a message is really quite fascinating! First, a stimulus is picked up on by the dendrites of the cell. The stimulus causes a truly amazing reaction to occur in the cell! First, sodium ions rush into the cell through protein channels on the axon membrane, creating a positive charge inside the cell and a negative charge outside the cell called depolarization. Then, potassium ions rush out of the cell through protein channels on the axon membrane, thus creating a positive charge outside the cell again and a negative charge inside the cell (as it was at its resting potential). This process is called an action potential! The action potential then codes for the synaptic terminals at the end of the axon to expel molecules called neurotransmitters that continue the message throughout the body. This example serves to show that without the sodium and potassium ions, the nerve cell could not function to carry the message on to other parts of the body and the brain would never receive those signals! Thus, it shows us that without the sodium and potassium ions the nervous system could not properly function and meaning that we are dependent on sodium and potassium to survive! In turn, someday our bodies will decease and we can give back that when our bodies decompose, or even through the simple act of sweating!

Another example of the way cells are dependent on matter in nature is in the process of cellular respiration. Cellular respiration is the process by which cells break down glucose and oxygen into ATP (the cells main source of energy), water, and carbon dioxide using the mitochondrion organelles in the cell.

This proves that, like all consumers in the biosphere, we need outside sources to get our energy. Here we use the glucose that we get from consuming food by turning it into a compound called pyruvate and progressing through the three stages of cell respiration to come up with the end result of ATP. Our cells use the energy stored in ATP to perform almost all the cellular functions we need to have carried out in our bodies for them to function correctly. Once again, we depend on other things in nature obtain that energy we need to carry out the essential processes of life and survive! In turn, other organisms in nature, like decomposers, depend on all organisms to give back when they die and use the dead organisms as food for them to create ATP and carry out their own cell functions!

Organismal 

In the bodies of all colemate animals there are organs and organ systems in which those organs function. Not only do the organs within the organ systems depend on one another, but the organ systems themselves depend on one another! Take, for example, the circulation and respiratory systems in humans.

In a healthy human cardio-respiratory system, blood carries oxygen from the lungs to the rest of the body and excretes carbon dioxide from the rest of the body through the lungs. In basic terms, what occurs is the heart pumps blood into blood vessels in the lungs for gas exchange to occur. As you breathe in, you take a lot of oxygen into your lungs. As blood flows through, carbon dioxide on red blood cells is diffused through the membranes of the alveoli (shown above) and oxygen is diffused back across to attach to empty red blood cells and be carried to the rest of the body. Here, the heart is depending on the lungs to get rid of the carbon dioxide and replace it with oxygen and the lungs are inversely depending on the heart to displace and transport the oxygen that they have taken in and supply carbon dioxide for them to expel from the body! Both systems depend on one another to carry out their specific functions.

Population 

In a population members of the same species must depend on one another to reproduce to continue the population of their species. Take giraffes for example.

Each giraffe is an individual in a population that needs to look out for itself and even compete with other members of the same population to survive on the available resources (that is, if the resources should become scarce.) However, one of the two main purposes of life in biological terms is to survive and reproduce! Now, many organisms can reproduce through asexual methods without need of a mate or even another member of the population. But for those who cannot, they must have a member of the opposite sex in the population to mate with and produce fertile offspring and continue the survival of their own species. Hence these giraffes depend upon one another to mate and produce an offspring that will, in good faith, someday survive to reach maturity and find a mate of its own and do the same!

Community 

In a community several different species share the same general environment and must therefore compete with one another for resources. One resource that a species needs is in almost constant need of is food! And though Mother Nature is sometimes cruel, many species do indeed consume members of other species for food and, there-in, energy. Take for example the Great White Shark and the sea-lion.

Great White sharks live in virtually all oceans of the world, and spend a liberal amount of time near islands where their prey, sea lions, lives. The sharks of course consume the sea lions and depend upon them for the rich energy they provide. However, believe it or not, but the sea lions (as a population) benefit from this relationship as well. An ecosystem can only support so many members of a population until the population has reached its carrying capacity. Once this is reached, the ecosystem no longer has the resources to support the numbers of the members of the population, and therefore those not best fit to survive will die off and let those that are live on and reproduce to pass those best-fit traits on to their offspring. Well, in many cases, the sharks will have the same effect! The sharks will wait and pick a target that seems slower, weaker, or most vulnerable to take as prey. So they are also picking out those best fit to survive in the population and encouraging the shift towards higher percentages of those genes in the population from generation. Here we do see that the sharks depend on sea lions for food and energy, but the sea lions as a population depend on the sharks to enforce natural selection and encourage the evolution of the species!

Biosphere 

In the same way that different populations are dependent on one another in a community, so are all communities and the ecosystems they reside in. In the biosphere, all living things exist and carry out the functions that they need to survive. In any ecosystem and even the whole biosphere, plants and algae perform photosynthesis and all the leftover oxygen that they do not use for respiration is put back into the air or water. Well, who else uses that oxygen but consumers? They breathe (or filter) oxygen out of the air or water to use in respiration. The consumers, in turn, produce carbon dioxide as a bi-product of respiration that the plants can use to make their own food in photosynthesis! Here we see again dependency once more! But how does this apply to the biosphere? The neat about oxygen is that it is, in most forms, a gas and can therefore move very quickly and over great distances before it is ever used! An algae in the Gulf of Mexico could be supplying oxygen to a kangaroo in Australia, and a penguin in Antarctica could be providing carbon dioxide for a tree Central Park! Clearly we can see here that all aspects and parts of nature really do depend on one another, whether living or not!

Is there anything in nature that doesn’t depend on some other aspect of nature?  Should abiotic factors be observed as part of nature? Why or why not?  What other examples can you think of?

by Melody

Regulation is a very important theme in biology.  It is present in everything around us, and without it the world would be in chaos.  The world and things around us are constantly changing.  It is regulation that keeps things in balance through positive and negative feedback.  Homeostasis is the process in which things are regulated so they are kept in balance. Like I said, regulation is a part of everything from the cell to a population.

Molecular
On the molecular level (think carbohydrates and proteins etc.) an important example of regulation is the lac-operon.  It may have a funny name but the lac-operon serves a very vital purpose in regulating your digestive system every time you eat or drink a dairy product (which contain lactose).  The lac-operon is a gene that codes for the making of lactase (an enzyme that breaks down lactose).  Whenever you drink milk your digestive system is filled with lactose. The presence of the lactose “turns on” the lac-operon and causes it to make lactase. However, it is energy expensive. Therefore, the lac-operon only makes the lactase when it is needed (when you eat a dairy product).  This is an example of gene regulation. This website goes into more detail about the lac-operon.

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Cellular
The cell also needs to be regulated.  A prime example of this is the cell membrane, which is a barrier between the cytoplasm and the extracellular space.  The cell membrane is semi-permeable (meaning it only lets certain things in, and keeps other things out). It is made up of a lipid bi-layer and proteins are imbedded within it that can transport certain things in and out of the cell and are important in cell communication. It is important because it takes waste out of the cell and stops bad invaders from coming in.

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Organismal
Regulation is also important on an organismal level. An example would be osmoregulation (or the regulation of water).  Water and solute concentrations need to be maintained in an organism. The regulation is dependent on the environment the organism lives in. So, a fish, and other marine animals, are hypoosmotic to their environment.  This means that they have a lower water concentration than where they live.  Therefore, they regulate by drinking constantly, rarely urinating and secreting a lot of salt.  The opposite is true for land animals.  Land dwellers are hyperosmotic to their environment so they need to be constantly drinking. A message is sent to your brain that tells you that you are thirsty when you start to lose too much water.  Another way land animals osmoregulate is by using metabolic water.

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Another organismal example is the way the pancreas regulates blood sugar levels.  The pancreas releases two hormones that are important to blood sugar regulation; they are insulin and glucagon.  When the amount of glucose in your blood rises (which would happen when you eat a lot of candy or carbohydrates) insulin is released.  Insulin stimulates cells in your body to start absorbing and using glucose. Glucagon has the opposite effect.  It is released when blood sugar levels are too low.  It causes cells to release glucose into the blood stream. However glucagon also acts as a control for when your body releases too much insulin.  So the blood sugar concentration is regulated and kept at levels that are healthy for the organism.

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Population
In an environment, different species fall into different niches (or level of an ecosystem).  However, there is only room for one species in each niche.  This is because of a limited amount of resources such as food.  Each environment has a carrying capacity (or a limit on how many organisms can survive in it).  This carrying capacity serves as a regulator because it stops the population from growing too big.  The organisms often compete for the resources and whoever wins gets them. If there are no resources left the organisms cannot survive to reproduce and they will die out.

(Campbell, Neil A., and Jane B. Reece. AP Edition Biology. 7th ed. San Francisco: Pearson Education Inc., 2005. 1145.)

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Community
Regulation also occurs between different species in a community.  This is shown in the predator-prey relationship.  When there is a large amount of prey it is regulated when the predators feed on the prey.  This stops many organisms from overpopulating and using too many resources in the environment.

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Biosphere
Lastly, humans, on a biosphere level, also often control Regulation. An example of this would be hunting.  When a deer population gets too big the government controls the amount of deer that can be hunted so that the populations do not get too big.  This affects humans, the deer and the plants (among many other organisms) that in turn effects our biosphere. Regulation is key in the way our world works as a whole, because without it there would not be a normal level of harmony.

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by Kelsey (AP Biology)

Unity and Diversity is one of the major themes of biology. It explains that even though every living this is unified, there is still so much diversity in the world. It also explains how individuals can be unified, but still diverse, such as a human and a moss.

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Molecular
Every living thing has DNA, deoxyribonucleic acid, which is made up of nucleic acids. Every single strand of DNA no matter what only contains four nucleic acids; adenine, guanine, cytosine, and thymine. Adenine will always pair with thymine, and cytosine will always pair with guanine. This is how every living organism is unified molecularly. However, each strand of DNA has a completely different sequence of these nucleic acids. Different sequences of these nucleic acids will read differently and code for different types of genes. This is how each organism is so vastly different (source).

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Cellular
Every single living is made up of one or more cells. If something has cells, it is considered a living thing. Living organisms are unified because they all have cells. Diversity among these cells is determined by which part of the DNA strand in the cell is read off. This causes cells to be very specific; each one has a specific job or responsibility. An example of this is the diversity found between animal and plant cells. Plant cells have chloroplast to carry out photosynthesis, and a cell wall to contain the chloroplast. Obviously, animals do not perform photosynthesis; therefore their cells lack chloroplast and a cell wall, making them very different from a plant cell (source).

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Organism
Every single organism in the Domain Eukarya has a nucleus and membrane bound organelles. These are called eukaryotic cells; every eukaryote is unified this way. They are diverse because of the different classifications under the Domain. Each organism is separated into different Kingdoms. For example, mosses and humans are both in the Domain Eukarya, they both have eukaryotic cells; however, mosses are in Kingdom Planate, they produce food through photosynthesis, and humans are in Kingdom Animalia, they are heterotrophs (source).

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Every organism in the genus Sistrurus is a pit viper. These are rattlesnakes. They belong to the class pit vipers, which basically mean that they are venomous. They all have a rattler at the end of their tails, and they all give live birth rather than laying eggs. Every species of rattlesnakes share the same diet of rodents and small animals. They are all extremely similar because they are all part of the same genus. However, each species is so diverse that if they interbred, they could not make fertile offspring. There are over fifty different species of rattlesnakes, and each one is vastly different even though they all are in the same genus and share very similar characteristics. For example, the Sidewinder rattlesnake is only 18 inches long. It lives in the desert and only secrets small quantities of venom, while the Eastern Diamondback rattlesnake can kill six human adults with one secretion of venom, and is normally 5 feet long (source).

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Population
A population is defined as organisms of the same species living in the same general area. For example, a bunch of white- bellied spider monkeys living in the same forest. They are all unified because they are the same species and they all live in the same area, but obviously not every single monkey is going to be exactly alike. Their characteristics will differ. Some might have longer hair than others, some might be louder or more playful, some are going to be bigger and some will be smaller. This relates back to molecular unity and diversity. The majority of these monkeys’ entire DNA is the same, but it that little bit that makes them so diverse (source).

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Community
A community is an interaction of organisms of different species sharing an environment. In most communities, relationships called symbiotic relationships are present. This is when two organisms that are different species both benefit from the relationship they’re in. In every symbiotic relationship, the individuals gain something and have to give something. It varies depending on the organism and what each individual needs. Different relationships gain different things, sometimes the organism will gain food and sometime, they will gain a clean body. A bee and a flowering plant have a symbiotic relationship. The bee gains food as it is in the flower, pollen is rubbed on its body, and the flower gains help reproducing and fertilizing. Completely different from that is a cleaner shrimp cleaning a zebra moray eel. The shrimp receives food off of the eel’s body and the eel stays clean and healthy. Each symbiotic is the same, “I’ll scratch your back, you scratch mine,” however each relationship is very different depending on the organisms and what they need (source).

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Biosphere
Every single ecosystem is unified in some way. They all contain the same things, living organisms, and non-living biotic factors. They all interact and every part of the world has ecosystems. The diversity of the ecosystems depends on where they are located, their climate, and what types of factors resonate inside of them. For example, in desert ecosystems, vegetation is scarce because water is scarce. It contains many living organisms, such as cacti, insects, and snakes. It also contains rocks and sand, which are abiotic factors. A rain forest ecosystem is going to be very different because it receives a high amount of precipitation. It also contains insects and snakes, just different species. There are many abiotic factors such as rocks and dirt. They contain a lot of the same families of animals, but they are different because of the climate and location of the ecosystem (source).

by Jackie (AP Biology)

Form fits function is a very important theme in Biology. It can unify many different parts of life and yet also uniquely make them different. There are many different examples of how form fits function that you can see all throughout life. When you look at organisms, rarely will they ever have a structure that will hurt their ability to survive. Every structure in an organism’s body was created for a purpose, a function. Their specific forms and structures of their physical appearance, or their internal appearance go hand in hand with their specific function, to help them to be able to survive in their environment.
 
Molecular

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The molecular structure of proteins is very key into what the function of the protein actually is. Proteins are polymers of amino acids joined together by peptide bonds. There are 20 different amino acids that make up essentially all proteins on earth. Each of these amino acids has a specific design composed of a central carbon atom, hydrogen, a carboxyl group, an amino group, and a side chain or “R” group. The “R” group is what the most important part of the structure for the function. The side chain of the amino acid is very specific and is what distinguishes one amino acid from another. All amino acid structures are the same except for the “R” group. Therefore, whatever the “R” group is, will dictate the specific function of that protein. This causes the variation between all the amino acids, and what their specific purpose is.

Also on the structure of proteins, one or more polypeptide chains twist and form into a 3 dimensional shape to form a protein. The unique shape of the protein determines its function. For instance, structural proteins such as collagen and keratin are fibrous and stringy and on the other hand, some proteins are folded and compact like hemoglobin. As you can see in this picture, the protein (in this picture it is GFP) is slightly coiled and rounded.

Cellular

The Cellular importance in form fits function can be seen in the structure of a cell. Plant and animal cells contain many organelles that are necessary for the cell to perform necessary functions. For example, the structure of the Endoplasmic Reticulum (ER) goes hand in hand with what its specific function is. The endoplasmic reticulum structure has many membranous tubules and flattened sacs surrounding the nucleus that connects with the nuclear membrane and runs throughout the cytoplasm. The rigid outside of the ER allows for a greater surface area. This surface area is used primarily for protein and lipid synthesis and storage in the cell. It also provides a pathway for molecule transport inside the cell. The rough ER has many ribosomes attached to it. This allows for the ribosome’s to make proteins to be exported out of the cell. In contrast the smooth ER does not contain these ribosomes, and don’t make protein but instead makes lipids, hormones, and steroids. The membrane of the endoplasmic reticulum is folded, which is what allows for the greater surface area.

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Another part of the cell is the Cytoskeleton. The cytoskeleton is important part that holds the cell together and enables it to keep its shape. The structure of the cytoskeleton is essential to how it supports and creates the shape and mobility to cells. There are three very important fibers when it comes to this structure. Microtubules are made from tubulin. Any biology student will recognize microtubules in being in the most important part of the separation of cells during cell division. There is also are in cilia (in the picture) and flagella, which help in the movement of particles. The second part is the microfilaments which are made from actin, and are important in the contraction of your muscles. Last, intermediate filaments are made from keratins (protein) and function for the shape and position of organelles in the cell. Without these three important fibers, the cytoskeleton would not be able to provide a structure for the cells.

Organismal

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Obviously human organ systems are essential to our survival. Being able to understand the structure of these organ systems can explain how the organ systems work. For example, one of the most important systems in your body is the circulatory system, which is based out of the heart. The structure of the heart contains four chambers that circulates blood by rhythmic contraction.  The heart pumps oxygenated blood from the left ventricle out to the aorta and there it goes through arteries to feed the organs, muscles, and tissues of the body. The veins (vena cava system) then returns deoxygenated blood from the body to the lungs for oxygen. The blood then enters the heart in the right atrium through to the right ventricle, and flows back to the lungs for oxygen. Now, the blood has completed one cycle through the whole entire body.

Obviously, this is essential to our life and it is important that the structure of our heart can perform these functions. A lot of pressure is put onto the left ventricle to pump the blood, so its structure must be able to withstand it.  The structure of the left ventricle is important and helpful in the way that it is the thickest AND the most muscular part of the heart.  This makes sense functionally because the left ventricle is the portion of the heart that needs to pump the blood into the aorta and to the rest of the body. This is structurally designed to fit its function. The right ventricle is smaller and less muscular because it only pumps blood a short distance to the lungs for some more oxygen, so it makes sense that its structure fits its function as well. 

Population

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The population aspect of the theme Form fits Function deals with the interaction between organisms of the same species.  Communication between species in an environment can happen in many ways, but one crucial way is by visual communication. The main goal for an organism is to be able to survive and reproduce. In order to sexually reproduce, the organism needs a mate. The way they do this is fascinating. More specifically, a male peacock’s feather display shows to the female that he is willing to mate. It in turn is the female’s response on whether she would like to or not. What attracts the female to the male is sometimes its dance or “courtship ritual” or its feathers. The feathers of the peacock are what make it so attractive, because they are very colorful and can form patterns that are appealing to the female. Essentially, the structure of the feathers and the way they are displayed are for the function of attracting its mate.

The population aspect of the theme Form fits Function deals with the interaction between organisms of the same species.  between species in an environment can happen in many ways, but one crucial way is by visual communication. The main goal for an organism is to be able to survive and reproduce. In order to sexually reproduce, the organism needs a mate. The way they do this is fascinating. More specifically, a male peacock’s feather display shows to the female that he is willing to mate. It in turn is the female’s response on whether she would like to or not. What attracts the female to the male is sometimes its dance or “courtship ritual” or its feathers. The feathers of the peacock are what make it so attractive, because they are very colorful and can form patterns that are appealing to the female. Essentially, the structure of the feathers and the way they are displayed are for the function of attracting its mate.

Community

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The community aspect deals with the interaction between organisms of different species. This goes hand in hand with the concept of mutualism. Mutualism is the relationship between any two species that benefits both species. An example of mutualism is within coral reefs. More specifically, the relationship between the coral that forms the reef and the dinoflagellates is a mutualistic relationship. The dinoflagellates are benefited because of the structure of the coral. The coral (polyp) is basically a hollow cylinder fringed on top with small tentacles. The tentacles capture small organisms and sweep it into the cylinder where it is digested. Between the cells of the coral polyp cylinder are the dinoflagellates, which are single celled green algae. This is where the mutuality relationship lies. The polyp sweeps organic material from the water (with its tentacles) and metabolizes this material forming carbon dioxide and nitrogenous wastes. The dinoflagellates use the carbon dioxide and nitrogenous wastes in photosynthesis to form oxygen that is used by the coral polyps as well as the dinoflagellates in their metabolism.

Biosphere

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Geographic regions of the earth that have many ecosystems are known as biomes. A type of biome that everyone knows is a tropical forest. Tropical forests hold the greatest diversity of species. These are found everywhere- Africa, Asia, South America, and many other places. If they are near the equator they are rainforests, but in other areas that have dry seasons there just typical dry forests. Rainforests are very large in size and have thousands of tall trees that form a very thick covering. Because of this, not a lot of sunlight can reach through, leaving not a lot of life growing on the ground. Rainforests are structured by many layers including the overstory, canopy, understory, shrub layer, and ground level. The canopy makes up the overstory, and it covers so much space that much sunlight can reach through, leaving not a lot of life growing on the ground. This is important, because the canopy provides shelter, food, and protection from predators.

The canopy cover is so large that it provides a lot of surface area for photosynthesis to occur. When the sunlight is captured by the leaves, its converted into simple sugars, and leaves when the leaves or fruit is eaten by other organisms that decided to live in the forest. The humid climate adds a lot of water being produced which is necessary for survival. The sun shines all the time in a tropical rainforest, leaving no food shortage in this ecosystem. An immense amount of nutrients (water and carbon most important) are found within tropical rainforests, which makes it appealing for so many species to live there. As you can see, the many parts of the rainforest fit its specific function. The canopy’s large leaves and long span provides a great surface area for photosynthesis to occur. Along with that and the stems and roots of trees, it provides a home and a source of protection for the species that live there. Overall, every part of the forest provides a positive atmosphere for multiple species to live in.