1. The origin of life
2. Biological evolution and adaptation to environments
3. Ancestry of humans
4. Evolution of hominids and humans
5. Ecosystems
6. The flow of energy
7. Biogeochemical cycles
8. The human population
9. Use of natural resources and pollution
10. Biodiversity
1. The basic principle of life is that all living things are made of cells. All cells come from a pre-existing cell. Some believe that this process began as a chemical evolution. Taking this further, they believe that over billions of years the earth was probably formed from dust particles and debris. The solar system came at a later time. At first the earth was very hot due to hot gasses from volcanoes.
The earth then cooled because water that was first a gas then formed thick clouds causing rains over many years to become oceans. This early earth had sources of energy like volcanoes, meteorites, radioactive isotopes, lightning and UV radiation. The gasses may have then reacted with each other to form small organic compounds like nucleotides and amino acids. The small organic molecules may have joined to cause organic macromolecules. The following are two hypotheses about how this may have happened: the RNA first states that only the RNA was necessary to advance toward the first cell. The Protein first hypothesis states that amino acids collected in puddles and the sun’s intense heat initiated the formation of proteinoids. These proteinoids are then returned to water where they form microspheres (contain many of the properties of a cell but formed only of protein). Protocells are cells that can metabolize but cannot reproduce. Supporters of each hypothesis have their own conclusions about how the first true cell came into existence. RNA first supporters say that RNA specified protein synthesis which produced enzymes, one of these enzymes may have been one like reverse transcriptase used RNA to form DNA and then DNA replication happened as usual. Protein first supporters say that the protocell had some proteins that evolved the ability to synthesize DNA from nucleotides found in its surroundings. From there DNA could specify protein synthesis.
2. The first cells were probably prokaryotic cells which evolved into eukaryotic cells and from there formed fungi, plants and animals. The term biological evolution refers to the process of a species evolving over time. This means that all living things have a common chemistry and cellular structure. Another important aspect of biological evolution is adaptation (adjusting to better fit a specific environment). The theory of evolution was first thought of by 22 year old Charles Darwin in about 1831.
2. The first cells were probably prokaryotic cells which evolved into eukaryotic cells and from there formed fungi, plants and animals. The term biological evolution refers to the process of a species evolving over time. This means that all living things have a common chemistry and cellular structure. Another important aspect of biological evolution is adaptation (adjusting to better fit a specific environment). The theory of evolution was first thought of by 22 year old Charles Darwin in about 1831.
He used fossils as evidence for evolution because he believed they dated back to 10,000 to billions of years ago. Fossils are found in a wide variety from footprints to droppings to bones and impressions of plants. Much can be learned from the study of fossils.
Fossils are dated by the layer of stratum they are found in. The hard parts of organisms are what are preserved in fossils such as teeth and bones. Mineralization is the process by which these parts are preserved. Paleontology is the study of life in prehistoric times using evidence in fossils. The fossil record is the recorded history as seen through fossils, this record is the most conclusive proof that evolution has occurred. Transitional fossils are those that show characteristics of two different groups, therefore sowing who is related to whom. The theory of evolution is also supported by biogeographical evidence, which is the placement of plants and animals in different parts of the world. This supports the hypothesis that life forms evolved in a particular location and then spread out throughout the world. Anatomical evidence is anatomical similarities between organisms’ shows a common decent. Homologous structures are similar because they share a common ancestor. Analogous structures do not share the same ancestry but do serve the same function. Vestigial structures are features that are developed in some creatures but serve no purpose in other creatures. Biochemical evidence shows that almost all living organisms use the same basic biochemical molecules (DNA, ATP and enzymes) and some of these genes are shared from worms to humans. Natural selection is a mechanism for adaptation which has two critical elements and an adaptation is the result. The first element is variation- the physical variations between different members of a species. The second element is competition for limited resources. The members of a species with advantageous traits reproduce and others die off. This theory is also known as survival of the fittest.
3. Humans are classified by their evolutionary relatedness. Binomial names refer to the names that give the genus and species. Primates are placental mammals that have adapted to living in trees. Humans are in this classification of mammals. Prosimians include lemurs, tarsiers, and lorises and anthropoids include monkeys, apes and humans. Primates have mobile limbs and sometimes an opposable thumb and big toe, binocular vision, a large complex brain and a reduced reproduction rate. The genomes of humans and chimpanzees are 99% identical but that one percent difference accounts for the number of differences between chimpanzees and humans.
4. Our branch of the evolutionary tree is known as the hominid branch. The features of a hominid include walking on two feet, the shape of the face and the size of the brain. Human features evolved gradually and at an unequal rate. An incorrect assumption is that humans evolved from apes, we are actually more like distant cousins to the ape. Fossils have been found that seem to be from the time of the ape/human lineage split, these fossils are known as Sahelanthropus tchadensis. This fossil was found in central Africa. Other fossils of early hominids have been found in eastern Africa. It seems that the hominids decent began with australopithecines which evolved and diversified in Africa. Some of them were short and slender and known as gracile and others were more powerful and had larger upper bodies and were termed robust. One fossil in particular found in eastern Africa was found over 20 years ago by a team led by Donald Johanson. This fossil had a smaller brain, but walked bipedally.
3. Humans are classified by their evolutionary relatedness. Binomial names refer to the names that give the genus and species. Primates are placental mammals that have adapted to living in trees. Humans are in this classification of mammals. Prosimians include lemurs, tarsiers, and lorises and anthropoids include monkeys, apes and humans. Primates have mobile limbs and sometimes an opposable thumb and big toe, binocular vision, a large complex brain and a reduced reproduction rate. The genomes of humans and chimpanzees are 99% identical but that one percent difference accounts for the number of differences between chimpanzees and humans.
4. Our branch of the evolutionary tree is known as the hominid branch. The features of a hominid include walking on two feet, the shape of the face and the size of the brain. Human features evolved gradually and at an unequal rate. An incorrect assumption is that humans evolved from apes, we are actually more like distant cousins to the ape. Fossils have been found that seem to be from the time of the ape/human lineage split, these fossils are known as Sahelanthropus tchadensis. This fossil was found in central Africa. Other fossils of early hominids have been found in eastern Africa. It seems that the hominids decent began with australopithecines which evolved and diversified in Africa. Some of them were short and slender and known as gracile and others were more powerful and had larger upper bodies and were termed robust. One fossil in particular found in eastern Africa was found over 20 years ago by a team led by Donald Johanson. This fossil had a smaller brain, but walked bipedally.
The term homo is given to a fossil of the brain size is large enough, the jaw and teeth resemble those of humans and the use of tools is evident. Early homo is termed Homo habilis. It had a large brain and cheek and teeth structures that indicate being omnivorous. They also made tools out of stone. The part of the brain that is associated with speech is enlarged, indicating that they could hunt cooperatively. Homo erectus fossils have been found in Africa, Asia, and Europe. There are different species associated with the name Homo erectus. Homo erectus in comparison to Homo habilis has a larger brain and a flatter face with a projecting nose. They were taller, stood erect and were very muscular. Homo erectus used fire and advanced tools. It is believed that Homo sapiens most likely evolved from Homo erectus in several different regions of the world including Asia, Africa and Europe. Neandertals were first discovered in Germany. The brain of the neandertal was larger than that of the Homo sapiens. They show signs of being culturally advanced such as building houses, using stone tools, controlling fire, and buried their dead with flowers and possibly had a religion. Cro-Magnons are designated as Homo sapiens. Their DNA is different from neandertal DNA and therefore it is believed that they did not interbreed. They made more advanced stone tools, possibly were the first to throw spears; they may have even had a language and lived in small groups and their culture included art. It is believed that human variations arose from adaptations to a particular environment some of these that we can see today are skin color, body shape, hair texture and shape of the lips.
http://www.scienceclarified.com/images/uesc_06_img0297.jpg
5. The term ecosystem is given to a place where organisms interact among themselves and with the physical and chemical environment. These interactions between organisms keep the ecosystem intact and therefore the biosphere. There are a few different classifications of ecosystems referred to by scientists; temperate forests, deserts, tropical grasslands, tropical rainforests, temperate grasslands, taiga and tundra are the major classifications of terrestrial ecosystems. Aquatic ecosystems are composed of those that have fresh water and those that have salt water. There are two freshwater ecosystems, those with standing water (lakes and ponds) and those with running water (rivers and streams). Saltwater ecosystems include marshes which are where rivers meet the ocean and coral reefs are off the shore. Ecosystems include abiotic and biotic components (living and nonliving) and are categorized according to their food source. Autotrophs are producers that only require inorganic nutrients and an outside energy source for survival. Heterotrophs require organic nutrients for survival and are therefore the consumers of an ecosystem. Classifications of Heterotrophs are herbivores that eat only plants and algae, carnivores eat only other animals and insects, omnivores eat both plants and animals and detritus feeders eat decomposing particles of organic matter. A particular organism’s role in an ecosystem is known as its niche. All ecosystems are characterized by its energy flow and chemical cycling. Energy flow is the process of the producers of the ecosystem absorbing energy from the sun and chemical cycling is the producers taking inorganic nutrients from the environment. The producers then make organic nutrients for themselves and other populations of the ecosystem.
5. The term ecosystem is given to a place where organisms interact among themselves and with the physical and chemical environment. These interactions between organisms keep the ecosystem intact and therefore the biosphere. There are a few different classifications of ecosystems referred to by scientists; temperate forests, deserts, tropical grasslands, tropical rainforests, temperate grasslands, taiga and tundra are the major classifications of terrestrial ecosystems. Aquatic ecosystems are composed of those that have fresh water and those that have salt water. There are two freshwater ecosystems, those with standing water (lakes and ponds) and those with running water (rivers and streams). Saltwater ecosystems include marshes which are where rivers meet the ocean and coral reefs are off the shore. Ecosystems include abiotic and biotic components (living and nonliving) and are categorized according to their food source. Autotrophs are producers that only require inorganic nutrients and an outside energy source for survival. Heterotrophs require organic nutrients for survival and are therefore the consumers of an ecosystem. Classifications of Heterotrophs are herbivores that eat only plants and algae, carnivores eat only other animals and insects, omnivores eat both plants and animals and detritus feeders eat decomposing particles of organic matter. A particular organism’s role in an ecosystem is known as its niche. All ecosystems are characterized by its energy flow and chemical cycling. Energy flow is the process of the producers of the ecosystem absorbing energy from the sun and chemical cycling is the producers taking inorganic nutrients from the environment. The producers then make organic nutrients for themselves and other populations of the ecosystem.
http://www.visitandlearn.co.uk/topicalfactfiles/images/ecosystems2.gif
6. The flow of energy is represented by a food web and there are different types of food webs such as a grazing food web and a detrital food web. A food chain is a diagram that shows a single path of energy flow. Within a food chain are different trophic levels (all the organisms that feed on a particular link in the chain) food chains are relatively short due to the loss of energy between the trophic levels. The loss of energy is very significant only about 10% of the energy available to one trophic level is available to the next level.
6. The flow of energy is represented by a food web and there are different types of food webs such as a grazing food web and a detrital food web. A food chain is a diagram that shows a single path of energy flow. Within a food chain are different trophic levels (all the organisms that feed on a particular link in the chain) food chains are relatively short due to the loss of energy between the trophic levels. The loss of energy is very significant only about 10% of the energy available to one trophic level is available to the next level.
http://www.jenningsk12.net/WE/peimann/Science/FoodChains/food_chain.jpe
7. All organisms in an ecosystem require organic and inorganic nutrients. Chemicals circulating through the ecosystem create a biogeochemical cycle. These cycles can be gaseous or sedimentary. One of these cycles is the water cycle which begins with water evaporating from the ocean and net condensation occurs meaning that a gas is changed to a liquid. The water that has evaporated from the ocean condenses and then falls back to the earth as precipitation. Water can also be evaporated from the land and plants the water that is on the land is eventually returned to the sea by the process of runoff. Some precipitation does not runoff back into the ocean but seeps into the earth to a certain level. Aquifers are a layer of permeable rock, sand, or gravel through which ground water flows and they contain water that supplies wells and springs. Human activities can greatly affect the water cycle in three ways 1. Taking water from aquifers 2. Clear vegetation from the land and build roads which in turn prevent water from seeping into the ground 3. We add pollutants to water through sewage and chemicals we use. The carbon cycle is a biogeochemical cycle where the atmosphere serves as the exchange pool. On land plants take up carbon dioxide then the organisms respire releasing carbon into the atmosphere as carbon dioxide. In an aquatic ecosystem carbon dioxide combines with water to produce bicarbonate ion. The bicarbonate in the water is in equilibrium with the carbon dioxide in the air. Dead and living organisms hold organic carbon and are reservoirs for the carbon cycle. Due to human activities more carbon dioxide is being released into the atmosphere than is being removed. This is unfortunately contributing to the global warming trend we are seeing. Another biogeochemical cycle is the nitrogen cycle. Nitrogen makes up about 78% of the atmosphere. In the nitrogen cycle, nitrogen gas is converted to ammonium which plants can utilize. Plants use nitrates as a source of nitrogen. The process of producing nitrates during the nitrogen cycle is called nitrification, this process happens in different ways; Nitrogen gas is converted to nitrate in the atmosphere, ammonium is converted to nitrate by soil bacteria, nitrate-producing bacteria convert ammonium to nitrate, nitrate producing bacteria convert nitrite to nitrate, plants take up ammonia and nitrate and produce proteins and nucleic acids. Dentrification is the process of turning nitrate back to nitrogen gas. The phosphorous cycle is another biogeochemical cycle where phosphorous is trapped in the ocean and then released onto the land where plants use it, and then animals eat the plants and turn the phosphate into teeth, bones and shells, death and decomposition of the animals and their teeth and bones once again makes phosphate available to the producers.
8. The population of the world has now grown to about 7 billion people. The world is currently experiencing a time of exponential growth meaning that it is steadily increasing. About 78 million people are added to the world each year. The term growth rate refers to the difference between the amount of people born and the amount of people that die per year. The maximum growth rate under ideal conditions in the world is known as the biotic potential. The carrying capacity of the environment is called the carrying capacity. Two classifications of countries in the world today are the more developed countries (MDC’s) and the less developed countries (LDC’s). More developed countries have a lower population increase rate while in the LDC’s the population continues to rise steadily.
7. All organisms in an ecosystem require organic and inorganic nutrients. Chemicals circulating through the ecosystem create a biogeochemical cycle. These cycles can be gaseous or sedimentary. One of these cycles is the water cycle which begins with water evaporating from the ocean and net condensation occurs meaning that a gas is changed to a liquid. The water that has evaporated from the ocean condenses and then falls back to the earth as precipitation. Water can also be evaporated from the land and plants the water that is on the land is eventually returned to the sea by the process of runoff. Some precipitation does not runoff back into the ocean but seeps into the earth to a certain level. Aquifers are a layer of permeable rock, sand, or gravel through which ground water flows and they contain water that supplies wells and springs. Human activities can greatly affect the water cycle in three ways 1. Taking water from aquifers 2. Clear vegetation from the land and build roads which in turn prevent water from seeping into the ground 3. We add pollutants to water through sewage and chemicals we use. The carbon cycle is a biogeochemical cycle where the atmosphere serves as the exchange pool. On land plants take up carbon dioxide then the organisms respire releasing carbon into the atmosphere as carbon dioxide. In an aquatic ecosystem carbon dioxide combines with water to produce bicarbonate ion. The bicarbonate in the water is in equilibrium with the carbon dioxide in the air. Dead and living organisms hold organic carbon and are reservoirs for the carbon cycle. Due to human activities more carbon dioxide is being released into the atmosphere than is being removed. This is unfortunately contributing to the global warming trend we are seeing. Another biogeochemical cycle is the nitrogen cycle. Nitrogen makes up about 78% of the atmosphere. In the nitrogen cycle, nitrogen gas is converted to ammonium which plants can utilize. Plants use nitrates as a source of nitrogen. The process of producing nitrates during the nitrogen cycle is called nitrification, this process happens in different ways; Nitrogen gas is converted to nitrate in the atmosphere, ammonium is converted to nitrate by soil bacteria, nitrate-producing bacteria convert ammonium to nitrate, nitrate producing bacteria convert nitrite to nitrate, plants take up ammonia and nitrate and produce proteins and nucleic acids. Dentrification is the process of turning nitrate back to nitrogen gas. The phosphorous cycle is another biogeochemical cycle where phosphorous is trapped in the ocean and then released onto the land where plants use it, and then animals eat the plants and turn the phosphate into teeth, bones and shells, death and decomposition of the animals and their teeth and bones once again makes phosphate available to the producers.
8. The population of the world has now grown to about 7 billion people. The world is currently experiencing a time of exponential growth meaning that it is steadily increasing. About 78 million people are added to the world each year. The term growth rate refers to the difference between the amount of people born and the amount of people that die per year. The maximum growth rate under ideal conditions in the world is known as the biotic potential. The carrying capacity of the environment is called the carrying capacity. Two classifications of countries in the world today are the more developed countries (MDC’s) and the less developed countries (LDC’s). More developed countries have a lower population increase rate while in the LDC’s the population continues to rise steadily.
http://www.sustainablescale.org/images/uploaded/Population/World%20Population%20Growth%20to%202050.JPG
9. Humans have needs that are fulfilled by resources, resources can be classified into renewable, which can be replenished and non renewable, which are irreplaceable and limited in supply. One of the resources humans need is land, we need land to live on, farm on and for a variety of other buildings. Humans living on and using land for crops and other uses can have detrimental effects on the land making it difficult or impossible to use in the future. Water is a resource that should be available to all humans, but the overuse of freshwater for the irrigation of crops deems it almost impossible for water poor areas of the world to have adequate water. The use of dams and aquifers are two ways humans increase the freshwater supply, both of these definitely have adverse effects on the earth. The increase in the supply of food in the last 50 years has come along with these harmful practices; planting crops with few variations which will eventually deem the land unusable for future crops, use of fertilizers pesticides and herbicides which have negative effects on the earth and those that consume them, irrigation which wastes a copious amount of water and finally overuse of fuel for production of these foods. There are both renewable and non renewable energy sources non renewable energy resources are fossil fuels oil, natural gas and coal. The use of these fuels unfortunately contributes to global warming. Renewable energy sources are hydropower, geothermal, wind and solar energy which are all better for the environment than the fossil fuels. Minerals are those non renewable resources that can be extracted (mined) and then used by humans in a variety of ways.
10. There is variety to life on earth and this is known as biodiversity. Many factors are contributing to the loss of biodiversity in the form of extinction including loss of habitat, alien species, pollution, overexploitation, and disease. There are many benefits to maintaining biodiversity including medicinal value because many medicines come from living organisms. Agricultural value comes from maintaining a diverse group of crops in the world. Another important aspect of biodiversity is human consumption, keeping a consumable amount of animals and fish will greatly benefit the human population. There are indirect values of maintaining biodiversity as well these are waste disposal by means of decomposers breaking down dead organic matter for use by producers in an ecosystem. Provision of freshwater is another indirect value of maintaining biodiversity, many organisms need freshwater for survival and maintaining our supply of freshwater will be invaluable. The prevention of soil erosion, biogeochemical cycles, climate, and ecotourism will also benefit the biodiversity of the earth. In today’s word it is important to make the smallest ecological footprint possible and thereby maintaining a sustainable society. Especially in America we need to focus on saving our earth for future generations by consuming less water, energy, food, and other natural resources while creating as little waste as possible.
9. Humans have needs that are fulfilled by resources, resources can be classified into renewable, which can be replenished and non renewable, which are irreplaceable and limited in supply. One of the resources humans need is land, we need land to live on, farm on and for a variety of other buildings. Humans living on and using land for crops and other uses can have detrimental effects on the land making it difficult or impossible to use in the future. Water is a resource that should be available to all humans, but the overuse of freshwater for the irrigation of crops deems it almost impossible for water poor areas of the world to have adequate water. The use of dams and aquifers are two ways humans increase the freshwater supply, both of these definitely have adverse effects on the earth. The increase in the supply of food in the last 50 years has come along with these harmful practices; planting crops with few variations which will eventually deem the land unusable for future crops, use of fertilizers pesticides and herbicides which have negative effects on the earth and those that consume them, irrigation which wastes a copious amount of water and finally overuse of fuel for production of these foods. There are both renewable and non renewable energy sources non renewable energy resources are fossil fuels oil, natural gas and coal. The use of these fuels unfortunately contributes to global warming. Renewable energy sources are hydropower, geothermal, wind and solar energy which are all better for the environment than the fossil fuels. Minerals are those non renewable resources that can be extracted (mined) and then used by humans in a variety of ways.
10. There is variety to life on earth and this is known as biodiversity. Many factors are contributing to the loss of biodiversity in the form of extinction including loss of habitat, alien species, pollution, overexploitation, and disease. There are many benefits to maintaining biodiversity including medicinal value because many medicines come from living organisms. Agricultural value comes from maintaining a diverse group of crops in the world. Another important aspect of biodiversity is human consumption, keeping a consumable amount of animals and fish will greatly benefit the human population. There are indirect values of maintaining biodiversity as well these are waste disposal by means of decomposers breaking down dead organic matter for use by producers in an ecosystem. Provision of freshwater is another indirect value of maintaining biodiversity, many organisms need freshwater for survival and maintaining our supply of freshwater will be invaluable. The prevention of soil erosion, biogeochemical cycles, climate, and ecotourism will also benefit the biodiversity of the earth. In today’s word it is important to make the smallest ecological footprint possible and thereby maintaining a sustainable society. Especially in America we need to focus on saving our earth for future generations by consuming less water, energy, food, and other natural resources while creating as little waste as possible.
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