Introduction to Human Biology Concepts

All right, welcome to Biology 107 or Human Biology. This is going to be our first chapter, the study of life, and this chapter is going to be kind of an overview of where we're going to be headed in the next several weeks as we go through this course. So first, life itself is highly varied on our planet. Everything that's alive as we know it is going to have very similar characteristics. If we look at one of the largest animals on the planet the humpback whales and then one of the smallest the bacteria the giant sequoia is the largest organism by mass or by weight euglena's these are a single-celled organism they live in the oceans we can talk about ourselves which will spend most of this course especially the latter two-thirds of this course we'll be talking about the human species and even fungi or mushrooms are all interrelated But one thing we do have in common is we do all live on this single planet. Now, some of the characteristics that make up all living organisms, whether it's that bacteria or it's ourselves, first and foremost, we're organized. When we get to start to look at the tissues in the human form, we're going to see that they're made up of very organized cells all coming together to form individual organs. Even the unicellular organisms like the bacteria or the eucalyptus that we looked at on the previous slide, internally they're very organized, especially with their DNA. Everything that's living has to acquire materials and energy to grow and then to reproduce. And so everything, again, all the way up to ourselves, all the way down to that single organism, has to take something in. It's either by ingestion through something like our mouths, or a lot of organisms can simply absorb it right across their cell walls. Now, to maintain the species on the planet, we have to have the ability to reproduce. Cells come from cells. Cells just don't spontaneously pop up, and we get something new every time. You have to have reproduction. And again, this is going to be from that single-celled bacteria all the way up to something as large as that humpback whale. Everything that's alive responds to stimuli. This could be as simple as hot and cold. You want to stay comfortable so you can move away from either one of those extremes. All organisms are homeostatic. Now homeostatic, if we break this word down a little bit, homeo means the same. Static means equilibrium or staying the same. So everything that's alive wants to maintain homeostasis, stasis. For example, our body temperatures, we want to maintain a very normal range. The pH of our blood is right at 7.45. We don't want to go over or under that. So everything is constantly fighting to keep that equilibrium. Everything must grow and develop. Every living thing on this planet started from a single cell. And to reproduce, to grow, we have to replicate those cells. Everything alive has the capacity to adapt. Now that adaptation could be over millions of years or it can be simply in the course of a day, like moving in and out of a hot or a warm environment into a cooler environment. So one thing, life exists almost everywhere on earth and that's true. Even up in the sky, up in the clouds, there are living organisms floating around up there. Small. Bacteria, you look up, you see the birds flying around and insects. The surface of the Earth, tons of things, all the plants, that's where we walk. Even down in the ground below the soil surface, if you were to take a shovel in your backyard and dig up in some moist earth, you would find tons of organisms living just below that surface. Earth possesses a great variety of diverse life forms. Currently there's anywhere from about 5 million to 40 million different types on this planet. that's what gives the diversity to our planet. And then those characteristics that we just mentioned on the previous slide, every living thing is going to have those in common. So we're going to start out with a little bit talking about organization of life. And again, this is going to be for all life. The next chapter, chapter two, we're actually going to start with a little bit of a chemistry lesson. We're going to talk a lot about atoms and we're going to talk a lot about Molecules. These things aren't living. Atoms are the building blocks that are going to make up the molecules. And then once we get the molecules, we can talk about cells, individual cells. If this is an animal, we can talk about an individual nerve cell. If this is going to be a plant, we can talk about that plant cell, which is a little bit different than an animal cell. We'll discuss those differences as we move forward in this course. Now, tissue is when we take several of the cells and bring them together in a structure. Usually, all of these cells are very similar, like all nervous tissue, all leaf tissue, if we're talking about a plant. And then when we combine those with two or more other tissues, we can get organs. And so the brain, part of the nervous system of most higher organisms, and then that leaf tissue becomes a component of the leaf of that plant. Now, if we take the organs and we tie them all together into something that works for the body, we can talk about organ systems. The nervous system, for example, in humans, and then a branch on a leaf. is a series of different organs and tissues that form a functional organ system. We move up a little bit further from an individual system. We can talk about a whole organism like a human or a tree. Species are like individuals, like all the humans on the planet or all the oak trees on the planet of a specific kind. Population is a group of same species living in a particular area. a community. This is everything that's alive living within that particular area. An ecosystem takes into account all of the living organisms plus all of the non-living organisms. And then the biosphere is where everything is housed. So this is planet Earth. It goes up into the sky several thousand feet, down into the depths of the oceans, and down into the soils is everything where the biosphere is. And again, This chapter is really a general intro, but we're going to start chapter two here, and then eventually we're going to start talking about the human form, and we're going to follow this pathway all the way up into the whole human. First thing we need, we need energy. Every cell in your body, in fact every cell on this planet, needs some type of energy so it can do its job internally. And so everything living has to take in that energy. An energy for the cell is the capacity to do work, whether it's growth or whether it's reproduction. So organisms have to reproduce. You have to have offspring. You came from your parents. You're going to eventually have children, possibly. And then your children would have grandchildren, all reproducing the human species. To ensure that we get the same species in each cell, we have something called DNA. Now we're going to spend a chapter on, but this essentially is the coding information for you. This is a blueprint for you as an individual and everyone as we talk, we'll go forward, we're going to see that everyone's unique. Reproduction, that's where two like species come together and then reproduce the new generation. And it is DNA that's going to direct all of those processes. So again, all organisms start as a single cell. Here we have a human egg cell produced by the female and then multiple sperm cells produced by the male. Upon fertilization, you still have a single cell, but now it's fertilized. And then that cell will divide until we get the whole human right through birth, right through death. Your cells are going to continuously divide. So everything has to start as a cell. Cells come from cells. Organisms must respond to stimulus. So organisms respond to external stimuli. This is things coming from the outside and then if it's favorable they'll move towards it or if it's harmful they can move away from that. Organisms can use a variety of mechanisms for movement. Our cells, we just get up, we can walk away. Single-celled organisms have little structures called flagella where they can swim or move away or towards something. A movement of that organism is going to dictate where it lives and it's part of this behavior. And then that behavior of movement is really trying to find homeostasis, where that organism will be happy. So that homeostasis again means staying the same. We will all want to be in equilibrium. We all prefer a certain temperature in our houses, a certain amount of food every day. This is going to be true of every organism. As I mentioned before, the human body is going to want to maintain a very constant temperature. It's very important for internal workings of the body. We have to maintain a very specific amount of oxygen. Our blood has to maintain a very specific, very narrow range of pH and then hundreds of other systems are constantly trying to maintain that homeostasis. Growth and development. Everything grows and it has to grow if it's going to reproduce. And so here's an example of an oak tree sprouting from a single seed as a young tree. And then eventually that tree grows into a reproducing component of this population. So we can go right back here. We can start the next generation. And then development is everything from conception, everything from fertilization of the egg right through death. And we can break that up into multiple pieces. Organisms have to adapt. It's thought that life has been on this planet for about 4 billion years. That's supported by the fossil record and some chemical work done on the DNA in most cells. But one thing that's happened is the environment has constantly changed. We've gone through warm periods and cold periods, and it's cyclic. And so everything on this planet has to adapt to that. Some individuals of the species. do better in certain environments and it's those individuals that do better in those environments they're going to leave more offspring they're going to reproduce and there's a tendency for those traits that made them a little better to handle the new environment they're going to be carried on and that's what's going to drive natural selection so individuals better adapted to the environment tend to reduce more offspring and Those adaptions that have made them do better in that environment are going to be carried on from generation to generation. If you don't do so well in an environment and you don't have offspring, that's going to be lost. That's going to stop right there. This process is known as natural selection. Always selecting for the things that work in a particular environment at that time. This is a whole. is evolution and this is really going to root the basis of most biology. Things change through time, through the populations adapting to their environments. So I mentioned there's millions of individual species on this planet and scientists have to keep away to organize them and so they use taxonomy, they use systematics. This is a way of grouping organisms that are similar. And then they also look at that information to see the relationship between those individuals. To further classify, all organisms on Earth are broken down into domains, kingdoms, phylums, class, order, family, genus, and then finally individual species. So starting with domains. These are the largest classification that we have for the planet, for Earth. And there are three of them. They're based on structure, they're based on biochemical and genetic evidence, and they're constantly changing. But right now, we have those three domains. We have Archeria, we have Bacteria, and then we have the Eukarya. The Eukarya is the domain that we belong to as humans. Now domains are curia and bacteria. These include unicellular. Unicellular means one cell. Prokaryotic cells. Prokaryotic cells are small, relatively simple. And one characteristic that gives them away is they don't have a structure called a nucleus. A nucleus we're going to find in the eukaryotes. And in the eukaryotes, the nucleus is going to house the DNA. And the DNA is the coding for each and every. cells. So the eukarya or the eukaryotic cells, these have a true nucleus and we're also going to find out they have various other structures called organelles within them. Now the eukarya are adapters. They live in extreme environments, too hot, too cold, too dry, too salty, too much pH, too little pH. So these are the survivors. They can live on the edges of hot springs. Hot springs, if you've ever been lucky enough to go to Yellowstone, there's numerous hot springs there and all the colors inside of those pools. are made up not only of the minerals coming out of there but all of these are curia living in these boiling pools where literally that water is approaching 180 190 degrees fahrenheit that would give you a good skull but these things can actually live in there so percuria live in extreme environments now bacteria are the most proliferic organism on the planet they are literally everywhere They can be found floating around in the air. They can be found on any surface, any surface in your house. If you were to swab it, you would find bacteria there, bacteria inside of your digestive system, which are beneficial, like E. coli helps you kind of break down the end products of digestion. Some bacteria, as we know, can cause us problems. Botulism, if it gets into our food, can cause us issues. Salmonella. can cause us issues if we ingest that. Some are actually beneficial and they help not only ourselves but they help to clean up the environment. One thing about bacteria is they are so numerous that they outweigh us 10 to 1. So for example if you're 150 pounds there are 10 times as many bacteria by weight than you weigh. So they are literally everywhere. Very very prolific. Now when we get back to the eukaryotes, there are breakdowns into four kingdoms. So these are going to be a subdivision of the eukaryote. The protist. Protist is kind of a catch-all right now for unicellular organisms. Most of these need water. But as we do more genetic research on them, we're going to see that probably they're going to get broken down into their own individual kingdoms. Next one, fungi. Fungi are the fungus. These are things like mushrooms and yeast cells. We'll talk about their differences. Plantae. Plantae are all the plants. Everything from the mosses, the ferns, the trees, all of the flowering plants. And Amalia, this is the kingdom that we belong to along with all the insects, the fish, the birds, and all of the other mammals that are associated with us. And so we had the three domains and now we have... The smaller kingdoms, and right now currently there are four. So here's a better look at those kingdoms. So the protist, again, kind of a catch-all for all these unicellular organisms. Most of these are going to absorb across their outside parts of their cells. Some ingest. Some actually are really good at photosynthesis. We'll talk about that. The fungi. These all absorb, they absorb through their tissues. This could be the mold on your bread or that rotting piece of fruit in your crisper. This is the yeast that helps to bake your bread, the mushrooms that grow on the forest floor, or maybe if you have that nice juicy steak with a side of mushrooms on top of it, or fungi that are breaking down dead materials in our forest. Plants. Photosynthesis is the key to all plants. whether it's the mosses that cover the boulders at a stream's edge the ferns the pine trees or any flowering plant all of these are going to have the ability to photosynthesize and amelia these are all multi-cellular every one of them has to ingest food and these are anything from sea stars earthworms finches raccoons and then of course ourselves so those are the four current kingdoms But remember protista maybe even your lifetimes these will be broken down into more kingdoms. Here's a graphic showing the domain Archeria. Remember the Archeria are survivors. They live in extreme environments. Bacteria they are literally everywhere and they outweigh us 10 to 1. And then the Eukarya broken down into the four kingdoms. So classification goes a little bit further than kingdoms. So we started at the top with domains. Kingdoms. Kingdoms are broken down into phylums. Phylums are broken down into classes, which are broken down into orders, families, genus, and then finally the individual species. Most inclusive, so this has everything in it. Least inclusive, this is the most specific. Again, to classify, we are currently using systematics. This is going to help biologists better understand the variety of life on Earth. And a lot of this done is done at the genetic level, where we look at differences in DNA. Also, a lot of this is done by the way things looked. We can make assumptions on how close they're related. But it's really systematics when we look at the molecular level. that's allowing us to classify things. So breaking down humans, we start out in the domain Eukarya. All Eukaryotes have cells with nuclei. In Amelia, we are all multicellular, we can move, and we have to ingest food. For Dada, this is how we're going to have a structure called a dorsal supporting rod and a nerve cord. So this is part of our nerve system. Mammalia is where we really start to get set ourselves apart. All mammals have hair and then structures called mammillary glands that are going to nurture the newborn. This is how we're going to feed the newborn to all mammals. Border primates, we're adapted to climb trees. We have prehensile tails. We have fingers that work together to grasp and grab. Hominidae. adapted to walk upright so we can walk on two legs genus homo relatively large brain so a developed nervous system and we have the ability to use things in our environment like simple tools homeo sapiens this is who we are and this is going to stretch back to about 100 000 years ago but now we're all starting to look the same body characteristics characteristics are similar to modern humans And we all relatively have the same features and abilities. So scientific names. Everything that's been named on the planet has a scientific name. It has a genus and then it has the individual species name. The genus in print is always capitalized and both words are always in italics. So for example, us. Homo is our genus. Sapiens is our species name. So this is our complete name. It's like your first and last name. Like my name is Archie Meyers, so I have two names. So this is a very specific name. Phism, Cetadium. This is the common garden pea. So these are the green peas that you might grow in your garden or you might have for dinner. Felis domesticus. This is your common house cat and we use scientific names because these are rooted in Latin and so this allows any scientist on the planet to use this name and we know automatically that we're talking about the same thing so scientists can communicate that way. So back to the biosphere. We learned a little bit earlier that the biosphere is all-encompassing. It's the planet. It's the air above, it's the water in the oceans, and it's the soil beneath our feet. Some more definitions. A population is all the members of a single species within a particular area. For example, we can talk about all of the people in the Victor Valley. This is the population of the Victor Valley. We can talk about the population of Hawaii. We can talk about the population of the United States. So we're just talking about a unit of area and then one species. Now, community is all of the living organisms within the same area. So if we go back to the Victor Valley, we're not only now talking about all the humans, but we're talking about all the birds, the plants, all the insects, all the other animals that live. in that area. So population, single species, community, all the species. Now an ecosystem is a community interacting with themselves and the physical environment. The physical environment is the non-living component. So this is the soil, the rocks, the air, the rain, the weather, the wind, the sun, all now interacting with everything that's alive. in that area. Now within ecosystems we have something called chemical cycling. And so this is chemicals moving from one species to another, to another, another, and eventually getting recycled within that ecosystem. So chemicals don't leave an area. They constantly just move around from organism to organism. Energy flow. All ecosystems on this planet, with just a very few exceptions, are going to get their primary energy from the sun. The sun shines down on the planet. the plants photosynthesize they make food and then other things eat that foods but the ultimate source of energy is the sun here's a graphic showing that we solar energy again is the primary source first stop that sun is going to impact the leaves or come into contact with the leaves those leaves will do photosynthesis we're going to talk more about that but photosynthesis simply is sun plus CO2, water, and we can make food from that. We can make sugars and starch. Next stop, herbivores. Herbivores eat plants. And so the bunny, this mouse, they're going to eat the plants. They're going to use that energy to grow and develop. And so that energy is then, and then the chemicals are going to be cycled through these two organisms. Now the next stop would be the predators. For example, this rattlesnake might eat this mouse and so all of the energy that was bound up in this mouse to build it is now transferred into the snake. And then this other predator, this hawk, might come down and eat the snake. And so everything starting at the sun has now cycled through the plant, the rat and the mouse, through this first predator, and then back up into this top predator. We don't all live forever, so eventually this organism is going to perish. And so it's going to fall back to the ground, it's going to be decomposed, and then all of those components are going to be recycled, and then we're going to start back with the plants, and then the cycle is going to go over and over and over. So an ecosystem is really dependent on where it is on the planet and what type of weather. is actually controlling that ecosystem. For example, we live in the desert. The Victor Valley is in the desert. We're relatively dry, warm summers, relatively cool winters. We could talk about the ecosystems of the oceans. We could talk about the ecosystems in the forest. Now the two most productive ecosystems on the planet are the tropical rainforest and the coral reefs located in the oceans. And these are going to occur where there's more solar energy. more solar energy we have more energy going into a system and so we can have more growth in those environments here's an example of a coral reef again you have sunlight coming in coral reefs are relatively shallow so that sunlight can come in to the plants and organisms that photosynthesize on the floor they're going to provide food for the produce structures called plankton these are going to be eaten by smaller organisms and then all that energy transfer is going to be taken up into the larger organisms until eventually we get into the predators that are using that energy that started again at the sun they're going to produce waste products and eventually they're going to perish they float back down to the bottom they break down and then that whole cycle can start over Now the human species is unique for this planet because we definitely have the ability to modify our own environment. We can build our houses, we can put up shopping malls, we can do all of this stuff to make things more comfortable for ourselves. Now tropical rainforests and those coral reefs are impacted by the human species when they start to infringe on their edges. So we're changing those a little bit. But... We as humans still depend on the planet for all our food, our medicine, and raw materials. So we've got to find that balance so we don't hurt ourselves but still have the ability to live our lives. Biodiversity. Now, biodiversity, bio is living. Diversity is diversity. It's going to be how much is in a given ecosystem, how many species are there. So it's dependent again on the total number of species within a given area. variability in their genes how much variability is there in a species and then of course the ecosystems in which they live as I mentioned before there are over 5 million species it's thought there might be 30 to 40 million species on earth we're constantly finding new organisms on the planet most of these are in the oceans most of these are going to be in the tropical rainforest But it is thought that human activities are linked to the extinction of about 400 species per day. So we've got to be a little bit careful. We might want to think a little more. So the process of science. Now, the process of science is truly that. It is a process and has been going on ever since we became human species. Think about this just for a little bit. That computer that you're watching this on, or the monitor or your phone that you're watching this particular lecture on, all started with the process of science. Had to isolate metal, we had to figure out electricity, we had to figure out photography. All of these things are a process that we continually improve on even today. And it's even true with biology. We're constantly... discovering new things about the life on this planet. It all starts with a hypothesis. Now a hypothesis is really an educated guess or a statement and then we go on to test if that is true. And overall this is known as the scientific method and you use this every day. If you walk into a room and it's a dark room You automatically come up with a couple ways to illuminate that room. You'll walk over, you'll flip on the light switch. If the light switch doesn't work, then you automatically start thinking about the light bulb being off, or maybe the power's off. That is the scientific method. You have something that confronts you or interests you, and then you figure out a way to solve that problem. And so it all starts really with an observation. This is what's going to generate. the question. This could be a brand new observation, something has piqued your interest or if you can build on previous studies and just come up with a unique question and then eventually a statement. Now that statement is going to be your hypothesis. Hypothesis needs to be testable. We need to do experiments if we're going to validate that hypothesis. Now the experiment is something that you're going to test to see if your hypothesis is true. You know, going back to when you walked into that dark room, you flip on the switch, one of the first things you're going to do is probably check the light bulb. If that doesn't work, then you're going to move on to something else. So that's a very simple experiment, and then these experiments can be quite elaborate. So the experiment and the observations that come out of that is the experiment That's going to give you some data, and that's eventually going to give you results that you can come to some type of conclusion. You can agree with your hypothesis, or you can reject it. Now, at this point, we can go right back up to the hypothesis and formulate a new question. Figure out why our hypothesis was invalid. Now, when a hypothesis is used multiple times, and then we have experiments, They're all coming to the same conclusion. This is where we get scientific theory. And again, this is after many experiments are going to support the same idea. So again, first it starts with that observation. Scientists, and frankly all of us, tend to be pretty curious about what's around us and why. And so those things that pique our interest are better understood by observing closely. and then eventually studying them. Scientists, or all of us, we use our senses. These are your your eyes, your ears, your sense of smell, your sense of taste, tactile observations. That's how we gather information. And then scientists can use other things like thermometers and microscopes and pH meters to gain more information about something that really interests us. So after we have the Observation, we're going to formulate that hypothesis. This is something called inductive reasoning. This is when we use our creative side, our creative thinking, where we're going to combine things that we know. isolated facts, and then turn them into a statement. So when a scientist states a hypothesis, it is a tentative or a temporary explanation for a natural event through the observation. It has to be worded so it can be found false. And so you want to word it so it's false, so that when you do the observations on your data, you can either accept or deny your hypothesis. What we don't want to do is allow personal experiences, political influences that are going to influence science. Science needs to be straightforward, and then again, all your hypotheses should be testable. So that leads to the experiment, and this is done to determine how to test a hypothesis, and then we use deductive reasoning. For example, we might reason that if all organisms are composed of cells, then the exclamation of an organism should reveal VO cells. And so we take something that's relatively large, we take a part of it, put it under the microscope, and indeed what we should see eventually are individual cells making up that organism. That's called cell theory. And this is where the theories come from. Because... everything that we know to be alive, if you look at it under a microscope, always has cells. And so that's what a theory is. Again, it's a very strong set of results. To test their hypothesis, scientists conduct more experiments. So experimental design is just the design in which the scientist is going to conduct or look at one variable within an experiment. The experimenter should ensure that testing is specific, so we want to narrow it down again to just looking at one thing, and then the results we can quantify or they'll be meaningful to our hypothesis. Now, control is something that should be included in every experiment, and a control is what we're testing but without the variable. And so scientists often use a model, a representation of an actual subject. For example, we can use computers, very powerful computers, to model and study climate change. And in fact, this is how the weather is determined now. We put all the variables into computers, and then we can get those two, three, even 10 day predictions into the future. Other models we might use instead of doing cancer research on humans, we can use mice that are also mammals to test treatments for cancer research. So we might use something that's similar just to see the results. Now we're going to get data. These are the results of the experiment. To have data they must be observable and they must be objective. Again, no bias in there. Mathematical data is displayed as tables and graphs. Statistical data is used to rule out the results were due to chance. We would use several formulas to see if our data set is valid and then you would get a yes or no. And then you can look at your graph to see the information. After that, we form a conclusion. It's the analysis of the data to determine if the hypothesis can be supported. And even if our hypothesis supported it is likely to lead to another hypothesis for testing so science never really stops if the results do not support the hypothesis then we can use those results to formulate an alternate hypothesis we're going to look for something else we're going to look at something a little bit differently this time so again theories are well supported hypotheses that I have been tested multiple times and the example I gave you a little bit earlier was cell theory. Everything that is alive is always going to have a cellular component to it. So again a theory supported by a broad range of observations, lots of experiments, lots of data, and then another one that we're going to talk about occasionally as we go through this course is the theory of evolution, which is again the unifying concept of biology. Now, a controlled study has that control group that I mentioned earlier. And so first, we're going to have a control group that receives no... treatment we're not going to test a variable the experimental group is going to receive the treatment which is going to have the variable now the experimental variable is also known as the independent variable this does not change in our experiment we're going to do this to everything that we're testing except for the control group which won't have it in its treatment So the independent variable is the factor being tested. Now after we do the experiment, the data we collect is done on the dependent variable. These are the things that are going to change in the presence of the variable. And this is the data that's going to be generated. And ultimately this data is what we're going to use to evaluate our hypothesis. So let's run through a sample. experiment. So a little bit of background. We can use nitrogen fertilizers on crops and we use these in our yard as well, but nitrogen fertilizers increase crop yields in the short term. Unfortunately a lot of the nitrogen fertilizers are made from inorganic, even sometimes petroleum products, that we're going to put into the soil. Then these can cause pollution, especially if they run off. into different parts of the water or get into our water tables. Altered soil properties lead to reduced crop yields and this can happen if we do too much fertilization. One solution is let the land kind of heal itself and leave it unplanted for several years. We're going to test this a little bit. Let's look into this a little more. So an alternate to nitrogen fertilizers that's been used in the past are Legumes. Now legumes is a type of plant like peas and beans, but they have the ability to harbor bacteria on their roots in structures called nodules. And those bacteria can actually take the nitrogen out of the atmosphere, convert it to a component or a different form that the plants can use as a natural fertilizer. And so in our experiment... We're going to test to see if the legume crops can be rotated with other crops. Cereal crops are things like corn, wheat, barley, over the years to increase the yield or how much food we can get off the land. So our hypothesis is a type of legume called a pigeon pea, and then after that, the next year, we're going to plant a type of wheat called winter wheat. Now that alternating rotation will cause the legume to grow. cause winter wheat production to increase as well or better than the nitrogen fertilizer. So that's our hypothesis, and this can be accepted or it can be denied. This could be proven or it could be falsified. So it's very specific in the writing. Out of that, we get a prediction, the wheat production following the growth of the pigeon peas will surpass or increase wheat biomass following nitrogen fertilizer. So the experiment, we're going to start off again with those control plots. We're going to plant the wheat but with no fertilizer and no legumes. We're not going to do any treatment to it but we're still going to plant the wheat. We're going to give it the same water. We're going to plant in the same soil. We're going to give it exactly the same light and everything else except for the fertilizing component. Now the test pots are going to be in three different types. We're going to have the wheat with nitrogen fertilizer at a relatively low rate we're going to have the wheat in the pots with the soil with the nitrogen fertilizer at a higher rate and then we're going to have the wheat's planted in pots where the pigeon peas have been planted before and now we're going to kind of rotate those wheat plants in so here's a picture of all of the different testing pots so the control pot again has no fertilizer in it this is going to be treated the same it's got the same light same amount of soil same type same water our first pot has a little bit of nitrogen in it a lower amount again same other conditions like soil water whatever the next one has more double the amount of nitrogen and then our third is going to have the pigeon peas the winter wheat rotation or we're alternating the plantings in the soil. So again to remember if we're testing a variable we have to keep all the other conditions. constant. We only want to test one thing. So the following spring, wheat plants were dried and weighed, and then the overall weight was this then determined for each of the treatments. Biomass is the mass of the organic compound. So this is a graph, and this is where all the data was compiled for that three-year study. Blue is our control. This orange color is going to be our low nitrogen, green is high nitrogen, and then this kind of reddish color is going to be our pigeon pea or legume with wheat kind of rotating. Year number one, nitrogen did the job. We had more yield. That's what these taller graphs or these taller bars are going to indicate. Year two, what we see is a little bit of an increase. for the control a little bit of increase for the low nitrogen but what we're starting to see is because we put too much of that fertilizer on the soil we're losing some of that productivity and then what we really see because of the nitrogen coming from that natural source so those bean plants is we're starting to see that particular pot increase in yield year three With the control, we've depleted all of the nitrogen in the soil, because remember, we didn't add anything to that. We've lost production even when we added nitrogen. Even when we doubled that nitrogen, we're doing worse. But the one that really outshines is the natural treatment, where we just planted the natural provider of nitrogen with the wheat back and forth. So this is an example of a complete scientific process, the data. And then we use this to look back at our hypothesis and determine whether we can accept it or we need to falsify it. Again, control pot, everything's the same, a little bit of nitrogen, a lot of nitrogen, and then our natural treatment in our third test. So the results. In year one, biomass is higher in the test pots than control pots. Overall, you know you've added nitrogen in them, either it was natural or chemical. Those pots with low nitrogen had a slightly higher biomass. The pots with lots of nitrogen had nearly twice as the biomass. And the pots with the pigeon pea plants tilling the soil did not have a biomass greater than the control pots. Year two... we could support our hypothesis because now we're starting to see the yield of those pots that were rotated with the natural fertilizer if you will we're starting to see those really come up they did better than the other pot types and then year three we saw that on that graph that um the pigeon pea rotation with the winter wheat did much much better than the others and we actually saw losses in the other three treatments And so what we can gain from this is that we can support our hypothesis and the rotation of legumes versus wheat every other year is going to give us overall more biomass, more harvest, if you will. And a lot of farmers in the Midwest, they actually use this where they'll plow their fields, they'll plant legumes one year, they'll plow those under, and then the next year they'll plant wheat. And they're seeing their yields go way up without... putting any of these chemical fertilizers in the ground. So that's the scientific method, and that's going to lead us to the end of this chapter.

Everything that's alive as we know it is going to have very similar characteristics. If we look at one of the largest animals on the planet the humpback whales and then one of the smallest the bacteria the giant sequoia is the largest organism by mass or by weight euglena's these are a single-celled organism they live in the oceans we can talk about ourselves which will spend most of this course especially the latter two-thirds of this course we'll be talking about the human species and even fungi or mushrooms are all interrelated But one thing we do have in common is we do all live on this single planet. Now, some of the characteristics that make up all living organisms, whether it's that bacteria or it's ourselves, first and foremost, we're organized.

When we get to start to look at the tissues in the human form, we're going to see that they're made up of very organized cells all coming together to form individual organs. Even the unicellular organisms like the bacteria or the eucalyptus that we looked at on the previous slide, internally they're very organized, especially with their DNA. Everything that's living has to acquire materials and energy to grow and then to reproduce.

And so everything, again, all the way up to ourselves, all the way down to that single organism, has to take something in. It's either by ingestion through something like our mouths, or a lot of organisms can simply absorb it right across their cell walls. Now, to maintain the species on the planet, we have to have the ability to reproduce. Cells come from cells.

Cells just don't spontaneously pop up, and we get something new every time. You have to have reproduction. And again, this is going to be from that single-celled bacteria all the way up to something as large as that humpback whale. Everything that's alive responds to stimuli. This could be as simple as hot and cold.

You want to stay comfortable so you can move away from either one of those extremes. All organisms are homeostatic. Now homeostatic, if we break this word down a little bit, homeo means the same. Static means equilibrium or staying the same.

So everything that's alive wants to maintain homeostasis, stasis. For example, our body temperatures, we want to maintain a very normal range. The pH of our blood is right at 7.45.

We don't want to go over or under that. So everything is constantly fighting to keep that equilibrium. Everything must grow and develop.

Every living thing on this planet started from a single cell. And to reproduce, to grow, we have to replicate those cells. Everything alive has the capacity to adapt.

Now that adaptation could be over millions of years or it can be simply in the course of a day, like moving in and out of a hot or a warm environment into a cooler environment. So one thing, life exists almost everywhere on earth and that's true. Even up in the sky, up in the clouds, there are living organisms floating around up there. Small. Bacteria, you look up, you see the birds flying around and insects.

The surface of the Earth, tons of things, all the plants, that's where we walk. Even down in the ground below the soil surface, if you were to take a shovel in your backyard and dig up in some moist earth, you would find tons of organisms living just below that surface. Earth possesses a great variety of diverse life forms. Currently there's anywhere from about 5 million to 40 million different types on this planet.

that's what gives the diversity to our planet. And then those characteristics that we just mentioned on the previous slide, every living thing is going to have those in common. So we're going to start out with a little bit talking about organization of life.

And again, this is going to be for all life. The next chapter, chapter two, we're actually going to start with a little bit of a chemistry lesson. We're going to talk a lot about atoms and we're going to talk a lot about Molecules. These things aren't living. Atoms are the building blocks that are going to make up the molecules.

And then once we get the molecules, we can talk about cells, individual cells. If this is an animal, we can talk about an individual nerve cell. If this is going to be a plant, we can talk about that plant cell, which is a little bit different than an animal cell.

We'll discuss those differences as we move forward in this course. Now, tissue is when we take several of the cells and bring them together in a structure. Usually, all of these cells are very similar, like all nervous tissue, all leaf tissue, if we're talking about a plant.

And then when we combine those with two or more other tissues, we can get organs. And so the brain, part of the nervous system of most higher organisms, and then that leaf tissue becomes a component of the leaf of that plant. Now, if we take the organs and we tie them all together into something that works for the body, we can talk about organ systems.

The nervous system, for example, in humans, and then a branch on a leaf. is a series of different organs and tissues that form a functional organ system. We move up a little bit further from an individual system. We can talk about a whole organism like a human or a tree. Species are like individuals, like all the humans on the planet or all the oak trees on the planet of a specific kind.

Population is a group of same species living in a particular area. a community. This is everything that's alive living within that particular area.

An ecosystem takes into account all of the living organisms plus all of the non-living organisms. And then the biosphere is where everything is housed. So this is planet Earth.

It goes up into the sky several thousand feet, down into the depths of the oceans, and down into the soils is everything where the biosphere is. And again, This chapter is really a general intro, but we're going to start chapter two here, and then eventually we're going to start talking about the human form, and we're going to follow this pathway all the way up into the whole human. First thing we need, we need energy.

Every cell in your body, in fact every cell on this planet, needs some type of energy so it can do its job internally. And so everything living has to take in that energy. An energy for the cell is the capacity to do work, whether it's growth or whether it's reproduction. So organisms have to reproduce.

You have to have offspring. You came from your parents. You're going to eventually have children, possibly.

And then your children would have grandchildren, all reproducing the human species. To ensure that we get the same species in each cell, we have something called DNA. Now we're going to spend a chapter on, but this essentially is the coding information for you. This is a blueprint for you as an individual and everyone as we talk, we'll go forward, we're going to see that everyone's unique. Reproduction, that's where two like species come together and then reproduce the new generation.

And it is DNA that's going to direct all of those processes. So again, all organisms start as a single cell. Here we have a human egg cell produced by the female and then multiple sperm cells produced by the male. Upon fertilization, you still have a single cell, but now it's fertilized.

And then that cell will divide until we get the whole human right through birth, right through death. Your cells are going to continuously divide. So everything has to start as a cell.

Cells come from cells. Organisms must respond to stimulus. So organisms respond to external stimuli. This is things coming from the outside and then if it's favorable they'll move towards it or if it's harmful they can move away from that. Organisms can use a variety of mechanisms for movement.

Our cells, we just get up, we can walk away. Single-celled organisms have little structures called flagella where they can swim or move away or towards something. A movement of that organism is going to dictate where it lives and it's part of this behavior.

And then that behavior of movement is really trying to find homeostasis, where that organism will be happy. So that homeostasis again means staying the same. We will all want to be in equilibrium.

We all prefer a certain temperature in our houses, a certain amount of food every day. This is going to be true of every organism. As I mentioned before, the human body is going to want to maintain a very constant temperature.

It's very important for internal workings of the body. We have to maintain a very specific amount of oxygen. Our blood has to maintain a very specific, very narrow range of pH and then hundreds of other systems are constantly trying to maintain that homeostasis.

Growth and development. Everything grows and it has to grow if it's going to reproduce. And so here's an example of an oak tree sprouting from a single seed as a young tree.

And then eventually that tree grows into a reproducing component of this population. So we can go right back here. We can start the next generation.

And then development is everything from conception, everything from fertilization of the egg right through death. And we can break that up into multiple pieces. Organisms have to adapt. It's thought that life has been on this planet for about 4 billion years.

That's supported by the fossil record and some chemical work done on the DNA in most cells. But one thing that's happened is the environment has constantly changed. We've gone through warm periods and cold periods, and it's cyclic. And so everything on this planet has to adapt to that.

Some individuals of the species. do better in certain environments and it's those individuals that do better in those environments they're going to leave more offspring they're going to reproduce and there's a tendency for those traits that made them a little better to handle the new environment they're going to be carried on and that's what's going to drive natural selection so individuals better adapted to the environment tend to reduce more offspring and Those adaptions that have made them do better in that environment are going to be carried on from generation to generation. If you don't do so well in an environment and you don't have offspring, that's going to be lost.

That's going to stop right there. This process is known as natural selection. Always selecting for the things that work in a particular environment at that time.

This is a whole. is evolution and this is really going to root the basis of most biology. Things change through time, through the populations adapting to their environments.

So I mentioned there's millions of individual species on this planet and scientists have to keep away to organize them and so they use taxonomy, they use systematics. This is a way of grouping organisms that are similar. And then they also look at that information to see the relationship between those individuals.

To further classify, all organisms on Earth are broken down into domains, kingdoms, phylums, class, order, family, genus, and then finally individual species. So starting with domains. These are the largest classification that we have for the planet, for Earth.

And there are three of them. They're based on structure, they're based on biochemical and genetic evidence, and they're constantly changing. But right now, we have those three domains.

We have Archeria, we have Bacteria, and then we have the Eukarya. The Eukarya is the domain that we belong to as humans. Now domains are curia and bacteria. These include unicellular. Unicellular means one cell.

Prokaryotic cells. Prokaryotic cells are small, relatively simple. And one characteristic that gives them away is they don't have a structure called a nucleus.

A nucleus we're going to find in the eukaryotes. And in the eukaryotes, the nucleus is going to house the DNA. And the DNA is the coding for each and every.

cells. So the eukarya or the eukaryotic cells, these have a true nucleus and we're also going to find out they have various other structures called organelles within them. Now the eukarya are adapters.

They live in extreme environments, too hot, too cold, too dry, too salty, too much pH, too little pH. So these are the survivors. They can live on the edges of hot springs. Hot springs, if you've ever been lucky enough to go to Yellowstone, there's numerous hot springs there and all the colors inside of those pools. are made up not only of the minerals coming out of there but all of these are curia living in these boiling pools where literally that water is approaching 180 190 degrees fahrenheit that would give you a good skull but these things can actually live in there so percuria live in extreme environments now bacteria are the most proliferic organism on the planet they are literally everywhere They can be found floating around in the air.

They can be found on any surface, any surface in your house. If you were to swab it, you would find bacteria there, bacteria inside of your digestive system, which are beneficial, like E. coli helps you kind of break down the end products of digestion. Some bacteria, as we know, can cause us problems.

Botulism, if it gets into our food, can cause us issues. Salmonella. can cause us issues if we ingest that.

Some are actually beneficial and they help not only ourselves but they help to clean up the environment. One thing about bacteria is they are so numerous that they outweigh us 10 to 1. So for example if you're 150 pounds there are 10 times as many bacteria by weight than you weigh. So they are literally everywhere. Very very prolific.

Now when we get back to the eukaryotes, there are breakdowns into four kingdoms. So these are going to be a subdivision of the eukaryote. The protist.

Protist is kind of a catch-all right now for unicellular organisms. Most of these need water. But as we do more genetic research on them, we're going to see that probably they're going to get broken down into their own individual kingdoms.

Next one, fungi. Fungi are the fungus. These are things like mushrooms and yeast cells.

We'll talk about their differences. Plantae. Plantae are all the plants. Everything from the mosses, the ferns, the trees, all of the flowering plants. And Amalia, this is the kingdom that we belong to along with all the insects, the fish, the birds, and all of the other mammals that are associated with us.

And so we had the three domains and now we have... The smaller kingdoms, and right now currently there are four. So here's a better look at those kingdoms.

So the protist, again, kind of a catch-all for all these unicellular organisms. Most of these are going to absorb across their outside parts of their cells. Some ingest. Some actually are really good at photosynthesis.

We'll talk about that. The fungi. These all absorb, they absorb through their tissues. This could be the mold on your bread or that rotting piece of fruit in your crisper. This is the yeast that helps to bake your bread, the mushrooms that grow on the forest floor, or maybe if you have that nice juicy steak with a side of mushrooms on top of it, or fungi that are breaking down dead materials in our forest.

Plants. Photosynthesis is the key to all plants. whether it's the mosses that cover the boulders at a stream's edge the ferns the pine trees or any flowering plant all of these are going to have the ability to photosynthesize and amelia these are all multi-cellular every one of them has to ingest food and these are anything from sea stars earthworms finches raccoons and then of course ourselves so those are the four current kingdoms But remember protista maybe even your lifetimes these will be broken down into more kingdoms. Here's a graphic showing the domain Archeria.

Remember the Archeria are survivors. They live in extreme environments. Bacteria they are literally everywhere and they outweigh us 10 to 1. And then the Eukarya broken down into the four kingdoms.

So classification goes a little bit further than kingdoms. So we started at the top with domains. Kingdoms. Kingdoms are broken down into phylums.

Phylums are broken down into classes, which are broken down into orders, families, genus, and then finally the individual species. Most inclusive, so this has everything in it. Least inclusive, this is the most specific. Again, to classify, we are currently using systematics.

This is going to help biologists better understand the variety of life on Earth. And a lot of this done is done at the genetic level, where we look at differences in DNA. Also, a lot of this is done by the way things looked.

We can make assumptions on how close they're related. But it's really systematics when we look at the molecular level. that's allowing us to classify things.

So breaking down humans, we start out in the domain Eukarya. All Eukaryotes have cells with nuclei. In Amelia, we are all multicellular, we can move, and we have to ingest food. For Dada, this is how we're going to have a structure called a dorsal supporting rod and a nerve cord. So this is part of our nerve system.

Mammalia is where we really start to get set ourselves apart. All mammals have hair and then structures called mammillary glands that are going to nurture the newborn. This is how we're going to feed the newborn to all mammals. Border primates, we're adapted to climb trees.

We have prehensile tails. We have fingers that work together to grasp and grab. Hominidae.

adapted to walk upright so we can walk on two legs genus homo relatively large brain so a developed nervous system and we have the ability to use things in our environment like simple tools homeo sapiens this is who we are and this is going to stretch back to about 100 000 years ago but now we're all starting to look the same body characteristics characteristics are similar to modern humans And we all relatively have the same features and abilities. So scientific names. Everything that's been named on the planet has a scientific name. It has a genus and then it has the individual species name.

The genus in print is always capitalized and both words are always in italics. So for example, us. Homo is our genus. Sapiens is our species name. So this is our complete name.

It's like your first and last name. Like my name is Archie Meyers, so I have two names. So this is a very specific name. Phism, Cetadium. This is the common garden pea.

So these are the green peas that you might grow in your garden or you might have for dinner. Felis domesticus. This is your common house cat and we use scientific names because these are rooted in Latin and so this allows any scientist on the planet to use this name and we know automatically that we're talking about the same thing so scientists can communicate that way.

So back to the biosphere. We learned a little bit earlier that the biosphere is all-encompassing. It's the planet.

It's the air above, it's the water in the oceans, and it's the soil beneath our feet. Some more definitions. A population is all the members of a single species within a particular area. For example, we can talk about all of the people in the Victor Valley.

This is the population of the Victor Valley. We can talk about the population of Hawaii. We can talk about the population of the United States.

So we're just talking about a unit of area and then one species. Now, community is all of the living organisms within the same area. So if we go back to the Victor Valley, we're not only now talking about all the humans, but we're talking about all the birds, the plants, all the insects, all the other animals that live.

in that area. So population, single species, community, all the species. Now an ecosystem is a community interacting with themselves and the physical environment. The physical environment is the non-living component.

So this is the soil, the rocks, the air, the rain, the weather, the wind, the sun, all now interacting with everything that's alive. in that area. Now within ecosystems we have something called chemical cycling.

And so this is chemicals moving from one species to another, to another, another, and eventually getting recycled within that ecosystem. So chemicals don't leave an area. They constantly just move around from organism to organism. Energy flow. All ecosystems on this planet, with just a very few exceptions, are going to get their primary energy from the sun.

The sun shines down on the planet. the plants photosynthesize they make food and then other things eat that foods but the ultimate source of energy is the sun here's a graphic showing that we solar energy again is the primary source first stop that sun is going to impact the leaves or come into contact with the leaves those leaves will do photosynthesis we're going to talk more about that but photosynthesis simply is sun plus CO2, water, and we can make food from that. We can make sugars and starch.

Next stop, herbivores. Herbivores eat plants. And so the bunny, this mouse, they're going to eat the plants. They're going to use that energy to grow and develop.

And so that energy is then, and then the chemicals are going to be cycled through these two organisms. Now the next stop would be the predators. For example, this rattlesnake might eat this mouse and so all of the energy that was bound up in this mouse to build it is now transferred into the snake. And then this other predator, this hawk, might come down and eat the snake.

And so everything starting at the sun has now cycled through the plant, the rat and the mouse, through this first predator, and then back up into this top predator. We don't all live forever, so eventually this organism is going to perish. And so it's going to fall back to the ground, it's going to be decomposed, and then all of those components are going to be recycled, and then we're going to start back with the plants, and then the cycle is going to go over and over and over.

So an ecosystem is really dependent on where it is on the planet and what type of weather. is actually controlling that ecosystem. For example, we live in the desert. The Victor Valley is in the desert.

We're relatively dry, warm summers, relatively cool winters. We could talk about the ecosystems of the oceans. We could talk about the ecosystems in the forest.

Now the two most productive ecosystems on the planet are the tropical rainforest and the coral reefs located in the oceans. And these are going to occur where there's more solar energy. more solar energy we have more energy going into a system and so we can have more growth in those environments here's an example of a coral reef again you have sunlight coming in coral reefs are relatively shallow so that sunlight can come in to the plants and organisms that photosynthesize on the floor they're going to provide food for the produce structures called plankton these are going to be eaten by smaller organisms and then all that energy transfer is going to be taken up into the larger organisms until eventually we get into the predators that are using that energy that started again at the sun they're going to produce waste products and eventually they're going to perish they float back down to the bottom they break down and then that whole cycle can start over Now the human species is unique for this planet because we definitely have the ability to modify our own environment.

We can build our houses, we can put up shopping malls, we can do all of this stuff to make things more comfortable for ourselves. Now tropical rainforests and those coral reefs are impacted by the human species when they start to infringe on their edges. So we're changing those a little bit. But... We as humans still depend on the planet for all our food, our medicine, and raw materials.

So we've got to find that balance so we don't hurt ourselves but still have the ability to live our lives. Biodiversity. Now, biodiversity, bio is living. Diversity is diversity.

It's going to be how much is in a given ecosystem, how many species are there. So it's dependent again on the total number of species within a given area. variability in their genes how much variability is there in a species and then of course the ecosystems in which they live as I mentioned before there are over 5 million species it's thought there might be 30 to 40 million species on earth we're constantly finding new organisms on the planet most of these are in the oceans most of these are going to be in the tropical rainforest But it is thought that human activities are linked to the extinction of about 400 species per day. So we've got to be a little bit careful. We might want to think a little more.

So the process of science. Now, the process of science is truly that. It is a process and has been going on ever since we became human species.

Think about this just for a little bit. That computer that you're watching this on, or the monitor or your phone that you're watching this particular lecture on, all started with the process of science. Had to isolate metal, we had to figure out electricity, we had to figure out photography.

All of these things are a process that we continually improve on even today. And it's even true with biology. We're constantly...

discovering new things about the life on this planet. It all starts with a hypothesis. Now a hypothesis is really an educated guess or a statement and then we go on to test if that is true.

And overall this is known as the scientific method and you use this every day. If you walk into a room and it's a dark room You automatically come up with a couple ways to illuminate that room. You'll walk over, you'll flip on the light switch.

If the light switch doesn't work, then you automatically start thinking about the light bulb being off, or maybe the power's off. That is the scientific method. You have something that confronts you or interests you, and then you figure out a way to solve that problem.

And so it all starts really with an observation. This is what's going to generate. the question. This could be a brand new observation, something has piqued your interest or if you can build on previous studies and just come up with a unique question and then eventually a statement. Now that statement is going to be your hypothesis.

Hypothesis needs to be testable. We need to do experiments if we're going to validate that hypothesis. Now the experiment is something that you're going to test to see if your hypothesis is true.

You know, going back to when you walked into that dark room, you flip on the switch, one of the first things you're going to do is probably check the light bulb. If that doesn't work, then you're going to move on to something else. So that's a very simple experiment, and then these experiments can be quite elaborate.

So the experiment and the observations that come out of that is the experiment That's going to give you some data, and that's eventually going to give you results that you can come to some type of conclusion. You can agree with your hypothesis, or you can reject it. Now, at this point, we can go right back up to the hypothesis and formulate a new question. Figure out why our hypothesis was invalid.

Now, when a hypothesis is used multiple times, and then we have experiments, They're all coming to the same conclusion. This is where we get scientific theory. And again, this is after many experiments are going to support the same idea. So again, first it starts with that observation.

Scientists, and frankly all of us, tend to be pretty curious about what's around us and why. And so those things that pique our interest are better understood by observing closely. and then eventually studying them. Scientists, or all of us, we use our senses.

These are your your eyes, your ears, your sense of smell, your sense of taste, tactile observations. That's how we gather information. And then scientists can use other things like thermometers and microscopes and pH meters to gain more information about something that really interests us. So after we have the Observation, we're going to formulate that hypothesis.

This is something called inductive reasoning. This is when we use our creative side, our creative thinking, where we're going to combine things that we know. isolated facts, and then turn them into a statement.

So when a scientist states a hypothesis, it is a tentative or a temporary explanation for a natural event through the observation. It has to be worded so it can be found false. And so you want to word it so it's false, so that when you do the observations on your data, you can either accept or deny your hypothesis.

What we don't want to do is allow personal experiences, political influences that are going to influence science. Science needs to be straightforward, and then again, all your hypotheses should be testable. So that leads to the experiment, and this is done to determine how to test a hypothesis, and then we use deductive reasoning. For example, we might reason that if all organisms are composed of cells, then the exclamation of an organism should reveal VO cells.

And so we take something that's relatively large, we take a part of it, put it under the microscope, and indeed what we should see eventually are individual cells making up that organism. That's called cell theory. And this is where the theories come from.

Because... everything that we know to be alive, if you look at it under a microscope, always has cells. And so that's what a theory is.

Again, it's a very strong set of results. To test their hypothesis, scientists conduct more experiments. So experimental design is just the design in which the scientist is going to conduct or look at one variable within an experiment. The experimenter should ensure that testing is specific, so we want to narrow it down again to just looking at one thing, and then the results we can quantify or they'll be meaningful to our hypothesis.

Now, control is something that should be included in every experiment, and a control is what we're testing but without the variable. And so scientists often use a model, a representation of an actual subject. For example, we can use computers, very powerful computers, to model and study climate change. And in fact, this is how the weather is determined now.

We put all the variables into computers, and then we can get those two, three, even 10 day predictions into the future. Other models we might use instead of doing cancer research on humans, we can use mice that are also mammals to test treatments for cancer research. So we might use something that's similar just to see the results. Now we're going to get data.

These are the results of the experiment. To have data they must be observable and they must be objective. Again, no bias in there. Mathematical data is displayed as tables and graphs. Statistical data is used to rule out the results were due to chance.

We would use several formulas to see if our data set is valid and then you would get a yes or no. And then you can look at your graph to see the information. After that, we form a conclusion.

It's the analysis of the data to determine if the hypothesis can be supported. And even if our hypothesis supported it is likely to lead to another hypothesis for testing so science never really stops if the results do not support the hypothesis then we can use those results to formulate an alternate hypothesis we're going to look for something else we're going to look at something a little bit differently this time so again theories are well supported hypotheses that I have been tested multiple times and the example I gave you a little bit earlier was cell theory. Everything that is alive is always going to have a cellular component to it. So again a theory supported by a broad range of observations, lots of experiments, lots of data, and then another one that we're going to talk about occasionally as we go through this course is the theory of evolution, which is again the unifying concept of biology. Now, a controlled study has that control group that I mentioned earlier.

And so first, we're going to have a control group that receives no... treatment we're not going to test a variable the experimental group is going to receive the treatment which is going to have the variable now the experimental variable is also known as the independent variable this does not change in our experiment we're going to do this to everything that we're testing except for the control group which won't have it in its treatment So the independent variable is the factor being tested. Now after we do the experiment, the data we collect is done on the dependent variable.

These are the things that are going to change in the presence of the variable. And this is the data that's going to be generated. And ultimately this data is what we're going to use to evaluate our hypothesis.

So let's run through a sample. experiment. So a little bit of background.

We can use nitrogen fertilizers on crops and we use these in our yard as well, but nitrogen fertilizers increase crop yields in the short term. Unfortunately a lot of the nitrogen fertilizers are made from inorganic, even sometimes petroleum products, that we're going to put into the soil. Then these can cause pollution, especially if they run off.

into different parts of the water or get into our water tables. Altered soil properties lead to reduced crop yields and this can happen if we do too much fertilization. One solution is let the land kind of heal itself and leave it unplanted for several years.

We're going to test this a little bit. Let's look into this a little more. So an alternate to nitrogen fertilizers that's been used in the past are Legumes. Now legumes is a type of plant like peas and beans, but they have the ability to harbor bacteria on their roots in structures called nodules. And those bacteria can actually take the nitrogen out of the atmosphere, convert it to a component or a different form that the plants can use as a natural fertilizer.

And so in our experiment... We're going to test to see if the legume crops can be rotated with other crops. Cereal crops are things like corn, wheat, barley, over the years to increase the yield or how much food we can get off the land.

So our hypothesis is a type of legume called a pigeon pea, and then after that, the next year, we're going to plant a type of wheat called winter wheat. Now that alternating rotation will cause the legume to grow. cause winter wheat production to increase as well or better than the nitrogen fertilizer.

So that's our hypothesis, and this can be accepted or it can be denied. This could be proven or it could be falsified. So it's very specific in the writing. Out of that, we get a prediction, the wheat production following the growth of the pigeon peas will surpass or increase wheat biomass following nitrogen fertilizer.

So the experiment, we're going to start off again with those control plots. We're going to plant the wheat but with no fertilizer and no legumes. We're not going to do any treatment to it but we're still going to plant the wheat.

We're going to give it the same water. We're going to plant in the same soil. We're going to give it exactly the same light and everything else except for the fertilizing component. Now the test pots are going to be in three different types. We're going to have the wheat with nitrogen fertilizer at a relatively low rate we're going to have the wheat in the pots with the soil with the nitrogen fertilizer at a higher rate and then we're going to have the wheat's planted in pots where the pigeon peas have been planted before and now we're going to kind of rotate those wheat plants in so here's a picture of all of the different testing pots so the control pot again has no fertilizer in it this is going to be treated the same it's got the same light same amount of soil same type same water our first pot has a little bit of nitrogen in it a lower amount again same other conditions like soil water whatever the next one has more double the amount of nitrogen and then our third is going to have the pigeon peas the winter wheat rotation or we're alternating the plantings in the soil.

So again to remember if we're testing a variable we have to keep all the other conditions. constant. We only want to test one thing. So the following spring, wheat plants were dried and weighed, and then the overall weight was this then determined for each of the treatments.

Biomass is the mass of the organic compound. So this is a graph, and this is where all the data was compiled for that three-year study. Blue is our control. This orange color is going to be our low nitrogen, green is high nitrogen, and then this kind of reddish color is going to be our pigeon pea or legume with wheat kind of rotating.

Year number one, nitrogen did the job. We had more yield. That's what these taller graphs or these taller bars are going to indicate.

Year two, what we see is a little bit of an increase. for the control a little bit of increase for the low nitrogen but what we're starting to see is because we put too much of that fertilizer on the soil we're losing some of that productivity and then what we really see because of the nitrogen coming from that natural source so those bean plants is we're starting to see that particular pot increase in yield year three With the control, we've depleted all of the nitrogen in the soil, because remember, we didn't add anything to that. We've lost production even when we added nitrogen. Even when we doubled that nitrogen, we're doing worse. But the one that really outshines is the natural treatment, where we just planted the natural provider of nitrogen with the wheat back and forth.

So this is an example of a complete scientific process, the data. And then we use this to look back at our hypothesis and determine whether we can accept it or we need to falsify it. Again, control pot, everything's the same, a little bit of nitrogen, a lot of nitrogen, and then our natural treatment in our third test. So the results.

In year one, biomass is higher in the test pots than control pots. Overall, you know you've added nitrogen in them, either it was natural or chemical. Those pots with low nitrogen had a slightly higher biomass. The pots with lots of nitrogen had nearly twice as the biomass. And the pots with the pigeon pea plants tilling the soil did not have a biomass greater than the control pots.

Year two... we could support our hypothesis because now we're starting to see the yield of those pots that were rotated with the natural fertilizer if you will we're starting to see those really come up they did better than the other pot types and then year three we saw that on that graph that um the pigeon pea rotation with the winter wheat did much much better than the others and we actually saw losses in the other three treatments And so what we can gain from this is that we can support our hypothesis and the rotation of legumes versus wheat every other year is going to give us overall more biomass, more harvest, if you will. And a lot of farmers in the Midwest, they actually use this where they'll plow their fields, they'll plant legumes one year, they'll plow those under, and then the next year they'll plant wheat. And they're seeing their yields go way up without... putting any of these chemical fertilizers in the ground.

So that's the scientific method, and that's going to lead us to the end of this chapter.

Transcript for:Introduction to Human Biology Concepts

Transcript for:
Introduction to Human Biology Concepts