Science
In the beginning, 13.7billion years ago, the observable universe, all matter and energy, was compressed into a hot, dense mass. It expanded and went bang. A little later thisnew universe cooled enough for atoms of hydrogen to formand coalesce into the first hydrogen stars; which after several billion years of their own life,they died andwent supernova; (bang), again! Theirejective mass contained the newly cooked heavier elements and this star dust once againcoalesced into a cloud of gas, and starting all over again, bringing together the ingredients for our solar system to form.Little bits of dust began to cluster, making bigger lumps, and it began to pull together under its own gravity, our current sun was born. Over millions of years - not 6 days nights - that is scientifically ridiculous -the dust clustered into planetesimals(little planets) and eventually into full planets.
Nowto be fair, let me show you an alternate idea to Earth’s formation. There is an Africantribe, whose religion dictates thattheir God made the universe in the following way. Their God had a pain from a stomachache, vomited up the sun. The sun dried up some of the water, leaving land. Still in pain, he then vomited up the moon, the stars, and then some animals finally, some men. Either the world formed from vomit or it did not. I don’t have the answers you decide based on evidence.
Unscientific babble about superstitionscannot be countenanced, for with it comes suffering. Suffering brought about by voodoo ideas: likehomeopathy. Moreover, peopleare making horrible health choices for their own children; such as refusing to have them treated with modern life saving vaccines.Ignorantly believing vaccinations cause things like autism. Eventually this vaccine avoidanceputs the entire population at risk; this is one of the most excellent reasons why bad ideas must be challenged.One ought to question everything and everyone and demand that without proof.You are certainly welcome to make up an opinion but you cannot make up the facts.
Scientific Method:
This is a much-revered process of discovery. It is the way one should carry out good experiments. If you wanted to prove that, "Light is required for plants to grow", how would you do it? Well, quite simply you do an experiment, say, put many plants in the light and many others in the dark for awhile (keeping all other factors constant). But, if you forget to water the ones in the dark, while always watering the plants in the light, then the death of the plants in the dark may not be due to the absence of light. If this experiment is to give any useful information, then it has to be controlled. Whatever you do for the plant in the light, you should do for the plant in the dark. You should water both plants, feed, and talk to both plants. Whatever you do for the one in the light you should do for the one in the dark; the only exception is the variable (or factor) that you are testing. In this case the light or absence of light. This is the only thing that should be different in the experiment.
Dependant Variable: is the factor that you measure, here the growth of the plants.
Independent Variable: causes the changes in the experiment. It is the main control device of the experimenter. The presence or absence of light was the independent variable.
Controlling Other Variables (Factors):As was said earlier, all other factors in the experiment have to be consistent. The amount of water each plant receives, the amount of food, the type of plant and soil used, the type and size of the pot, had to be the same for both experiments.
ECOLOGY AND ECOSYSTEMS UNIT (Ch 1 to 4)
ECOLOGY can be defined as the interactions between organisms (biotic) and the nonliving (abiotic)
FLOW OF ENERGY IN ECOSYSTEMS:The most important factor determining how many (& kind) organisms that can live in an ecosystem is the amount of ENERGY available. This passage of this energy is called a food chain, it FLOWS from the SUN to plants then onto organisms that eat the plants called primary consumers (or herbivores like cows) then to carnivores (secondary consumers). Interwoven food chains are called food webs, which are categorized thusly:
A. Decomposers –feed on remains of Dead Plants and Animals called detritus.
B. Herbivores –– Eat Producers or Plant Eaters.
C. Carnivores –– Eat other Consumers. Meat Eaters.
D. Omnivores –– Eat Both Producers and Consumers (humans).
E. Detritivores –– Feed on the wastes and dead matter of an Ecosystem.
In an Ecosystem, Producers and Consumers are placed in Trophic Levels (Feeding Levels)
A. Producers are the 1st Trophic Level.
B. Herbivores are the 2nd Trophic Level.
C. Carnivores are the 3rd, Fourth and Fifth Trophic Levels.
When energyis transferred some energy is Lost. Producers absorb energy from the sun to become part of the plants body, or is lost as HEAT. At each Trophic Level, the energy stored in an organism is about 1/10th of the trophic level below it. Because energy diminishes at each successive Trophic Level, ecosystems usuallyhaveno more than 4 Trophic Levels.
We call the Surface of the Earth the BIOSPHERE (AIR, WATER, and LAND) where living things exist. The Biosphere is composed of smaller units called Biomes. The largest level of organization of organisms is a biome, like a Rain Forest or Desert. Populations of organisms occupy biomes.Smaller areas called ECOSYSTEMS. Ecosystems can be as large as we decide. Any area you decide to study can be considered an Ecosystem, from your back yard to a pond.
Populations
A Population includes all the members of the same species that live in one place at one time. All the different populations that live in a particular area make up a COMMUNITY; and their location is called aHABITAT. Each organism has a ROLE and this is the organisms NICHE. A species’ niche is its way of life, it includes the conditions that the species can tolerate, the methods by which it obtains needed resources, and all its other interactions with its environment.
ECOSYSTEM RECYCLING (Matter is recycled , energy is NOT) Living things take materials from the environment and as they use these materials they will eventually give them back to the environment; we say materials are recycled.
Energy is different, for it cannot be recycled, it needs to be input constantly. The source of this energy is the sun. Energy is lost as it is transferred through an ecosystem. But matter (periodic table of matter) is present in a fixed amount, and must be recycled. Energy Flows through an ecosystem BUT Nutrients ReCycle.
This “give and take” by organisms in the ecosystem ensures a continuous renewal of materials in the ecosystem to provide a State of Equilibrium. By things changing constantly, things remain the same. This is equilibrium. This recycling occurs through Biogeochemical Cycles. (Ex: the carbon or nitrogen cycles) These cycles ensure a continuous supply of basic elements. The basic structure of any biogeochemical cycle is as follows:
- Organisms obtain elements (O,C,& N) from food.
- The elements are used to produce living tissue viametabolism.
- Organisms die and give off wastes. Decomposersbreakdown and return the elements to the earth.
- Other organisms (mainly plants) take up and use these same elements.
In an Ecosystem the Three Primary Nutrient Cycles:
A. The Water Cycle
B. The Carbon Cycle
C. The Nitrogen Cycle
THE WATER CYCLE
To availability of water determines the Diversity of Organisms in an Ecosystem. The availability of WATER is one of the key Factors that determine the type of living conditions, or the type of BIOME,organisms live in.Lakes, Rivers, and the Oceans contain a substantial percentage of the Earth’s Water. The atmosphere also contains water, as water Vapour (some water is found below ground known as aquifers). The Movement of Water follows these steps (KNOW HOW TO DRAW)
A. EVAPORATION from lakes, rivers, and oceans. OR/AND
B. TRANSPIRATION from plants and trees.
C. CONDENSATION –– Cloud Formation
D. PRECIPITATION –– Rain, Snow, Sleet, Hail.
E. RUN OFF, or RETURNED back into the Cycle.
THE CARBON CYCLE
Together, Photosynthesis and Cellular respiration form the basis of the Carbon Cycle. The Earth’s atmosphere contains Carbon as CO2. During photosynthesis, plants link many CO2 together to make glucose C6H12O6. Thus storing the Carbon for themselves.Both Autotrophs and Heterotrophs then use oxygen to then break down this glucose during Cellular Respiration. Glucose is then reconverted to Carbon Dioxide (breathing releases CO2 back to the atmosphere). As a side note, CO2 is also released from volcanoes and fossil fuel or wood burning. KNOW HOW TO DRAW THIS, see text book pic. The Carbon Cycle is found on pg 62.
Rates of Cycling
The rates at which elements cycle through the biogeochemical cycles is linked to the rate of decomposition. Temperature and oxygen levels are the two most important abiotic factors regulating decomposition.
Rapid Cycles: occurs in Tropical Rain Forests where organic matter decomposes relatively quickly. Warmth, moist soil and the vast number of diverse and specialized decomposers permit a cycle to be completed in as little as a few months.
Slow Cycles occurs in the Tundra where organic matter decomposes relatively slowly. Cold, permafrost based soil and limited types and numbers of decomposers cause cycles to take up to 50 years to be completed.
Carbon Cycle
Carbon is the key element for all living organisms and therefore of all organic substances. Organic substances always contain atoms of carbon and hydrogen (and oxygen and nitrogen). These atoms go to makeup proteins, carbohydrates, and fats.
Carbon can be classified as follows:
A. Living organisms and detritus. Carbon is available to organisms when they feed on one another.
B. Fossilized deposits once living organisms become such as coal or oil
C. Carbon compounds dissolved in water, soil and air.
D.Carbon contained within sedimentary rocks such as limestone which is made from the discarded shells and
bones of living organisms. This is the largest reservoirs of the Earth’s carbon.
During photosynthesis, plants use light energy to combine carbon dioxide and water to produce glucose (sugar) and oxygen. Photosynthesis occurs in a chain of reactions, but it can be summed up in the following equation:
6 CO2 + 6 H2O+ light ---->C6H12O6 + 6 O2
Carbon dioxide + water + light ---->glucose + oxygen
(reactants) (products)
During cellular respiration, oxygen and glucose react releasing energy, water and carbon dioxide.
C6H12O6 + 6 O2------>6 CO2 + 6 H2O
Glucose + oxygen ------>carbon dioxide + water
(reactants) (products)
THE NITROGEN CYCLE
ALL Organisms need Nitrogen, an important nutrient, to make proteins and nucleic acids. Most Nitrogen is found in the Atmosphere (80%) as N2() and most living things cannot use it as it is an unbreakable triple bond. ALL Organisms rely on the actions of Bacteria that are able to transform in a more usable form. Nitrogen Fixing Bacteria (Cyanobacteria and Rhizobium) play a key role in the Nitrogen Cycle. They live in the soil and in the roots of some kinds of plants, such as beans, clover, and alfalfa. These Bacteria can break the atmospheric N2 bonds. Nitrogen atoms are then free to bond with hydrogen atoms to form Ammonia (NH3). This conversion is called Nitrogen Fixation.
Ammonia can be absorbed by Plants from the Soil, and is used to make Proteins, and enters food webs. Consumers obtain nitrogen from eating the plants. Decomposers also return the nitrogen back to the soil from recycling the nitrogen in waste and dead matter. This process is known as AMMONIFICATION. Without ammonification, nitrogen that would be lost is recycled back into the Ecosystem.
Nitrogen is returned to the Atmosphere through DENITRIFICATION. Denitrification occurs when Anaerobic Bacteria break down Nitrates and release Nitrogen Gas back into the Atmosphere.
Plants can absorb nitrates and ammonia from the soil. Animals obtain Nitrogen in the same way they obtain Energy (by eating the plants and other organisms). Plants are therefore DEPENDENT on Nitrogen Fixing Bacteria, and All other Organisms including YOU Are DEPENDENT ON THEM! KNOW HOW TO DRAW THIS CYCLE
1. Most of the N2moves through nitrogenous compounds found in soil and water, not the atmosphere
2. Nitrogen fixing bacteria may be found in two places within an ecosystem:
A.Soil:Most are located here.
B.Root Nodules:on plants called legumes. Some forms of legumes include clover, soybeans, peas and alfalfa (refer to pg67,fig.2). Nitrogen fixing bacteria make more nitrate (NO3-)than the plant can use. The excess moves into the soil, providing a source of nitrogen for other plants. The traditional agricultural practices of inducing legumes in crop rotation to capitalize bacterial nitrogen fixation.
Phosphorus Cycle
Phosphorus is a key element in cell membranes, in molecules that help release chemical energy, in the making of the long molecules of DNA, and in the calcium phosphate of bones. Phosphorus tends to cycle in two ways: A long term cycle involving the rocks of the Earth’s crust, and a short-term cycle involving living organisms (refer to page 68, fig. 5).
Long-term Cycle:
A.Phosphorus, in the form of phosphate (PO43-) is dissolved from bedrock.
B.The dissolved phosphates are either absorbed by photosynthetic organisms and pass into foodchains or are carried by water from the land to rivers, and then to the oceans.
C.Some of the phosphate is used to make bones, teeth and shells. When the organismsprocessing these
structures die, these hard remains form deposits on the ocean floor. Coveredwith sediment, the deposits
eventually become rock, ready to be brought to the surface again.This cycle can take millions of years.
Agriculture and Nutrient Cycles
As crops are harvested, the valuable nitrogen and phosphorus in these plants are removed. This diversion of nitrates and phosphates from the local cycles would soon deplete the soil unless the farmer replaced the missing nutrients. Fertilizers are used to restore nutrients. Fertilizers containing nitrogen and phosphates can double yields of crops; but fertilizers must be used responsibly due to the following reasons:
1.Soil bacteria convert the nitrogen content of fertilizers into nitrates but the presence of high levels of nitrates may result in an increase in the amount of nitric acid in the soil.
2.Spring run-off carries decaying plant matter and fertilizer-rich soil to streams and lakes, the nitrates allow algae in the water to grow more rapidly in what is called an “algal bloom”. When the algae die, bacteria use oxygen from the water to decompose them. Because decomposers flourish in an environment with such an abundant food source, oxygen levels drop quickly, so fish and other animals may begin to die.
Population Studies
Populations are groups of individuals of the same species occupying a given area at a given time. Population studies looks at the factors that affect that population. These factors include:
- Natality :Birth rate; increases population numbers.
- Mortality: Death rate; decreases population numbers.
- Immigration: members of a species moving into a population; increases population
- Emigration: members of a species moving out of a population; decreases population
The four factors involved in population growth can be expressed mathematically by the formula:
Pop growth = (births + immigration) – (deaths + emigration)
Population Growth
Population growth is the change in the size of a population.The density (D) of any population is calculated by dividing the total numbers counted (N) by the space (S) occupied by the population. D = Nnumbers / Sspace
Example: Population density of a population of 200 moose in an area of 100 km2 is calculated as:
D = N/SD = 200/100 km2 D = 2 moose per km2
Exponential Growth Curve . Occurs under ideal conditions, food is continuously supplied and waste products are continuously removed. There are no limits to growth, but common sense says that cannot last. The graph is a J-shaped line caused by the fact that the larger the population becomes the faster it increases in size.In nature this type of growth is usually short lived because there are limiting factors to growth.
S Growth Curve: This is the most common type of growth curve, which represents a single population in a specific area. There are four specific intervals in a logistic or S-shaped curve:
1) Lag phase : It is the time when a new organism is introduced into a new area. The organism must adapt to its new environment and this takes time and therefore growth is slow.
2) Growth stage: Once the species is adapted to the new environment it reproduces rapidly with few controls on the population. This rapid growth is called Biotic Potential. Biotic Potential is the highest rate of reproduction possible for a population under ideal conditions or the maximum possible birthrate. Organisms achieve their Biotic Potential only for a limited time
3) Slow down phase: It is caused by limiting factors which slow growth. Examples include food availability, water, space, disease and competition. The total of all limiting factors in the environment that prevent a population from reaching its biotic potential is referred to as environmental resistance.
4) Stationary phase: It is the point in the development of the population when the birthrate and death rate and emigration and immigration are equal. The population is gaining and losing individuals at the same rate. The environment has reached its carrying capacity or has reached the maximum number of organisms it can support.