PDS APES 8th Period 2009-10

There are four basic math problems that we have to know for the exam.  These problems deal with basic algebra so there is NO need for a calculator.

Energy/Power:

When dealing with these problems, you must remember that energy is the ability to work and power is a rate.  For power, P=E/T and the units are in watts.  For energy, E=P x T and the units are in Joules.

Heat Transfer:

This is important for active heating. Why do we need to know this? Any time we use energy, we need to heat the water that turns our turbines and generators.  This formula seems difficult but is quite easy, Q=mc(delta)T. This quation is equal to calories or BTU( British Thermal Units).  The m stands for the mass, the c is the specific heat of water, which is equal to one, and the delta time, is the change in temperature.  When solving these problems units are a key factor and will cost you points if you forget them!

Price:

These problems deal with very simple algebra, but sometimes the problems can come across confusing.  It has a basic formula of #units x price/unit=price($).  These problems are easy to do in your head, but when you do them on paper writing down the units can help you determine your answer.  This becomes important when you are doing your energy bills at home.

Energy Efficiency:

These problems become important when you are trying to determine how efficient the light bulb you are using may be.  The efficiency can never be 100% because of the second law of thermodynamics, in the energy transfer, some energy is always lost in heat.  The formula for these problems is input=output/efficiency.  Normally efficiency is given in a percentage so you just need to convert it to a decimal to use it in the problem.

This may be a stupid question but i was confused on the difference between artificial selection and GMO.  I understand that GMos are genetically modified but when people artificially select for a certain gene are they almost doing the same thing? I have heard a lot of controversy over GMOs but never artificial selection and for some reason when i was reading through my book i got a little confused.  If someone could clear this up for me that would be great! thanks!

I am a little confused on how wildlife farms help protect the species.  In the book it states that they help raise individual species who are threatened and use their meat or hides in commercial sales.  How is selling their products for our profit saving them?  Are we not killing them and therefore not helping grow in number? I must be missing some piece about this because it does not make any sense.  If someone one could clear this up that would be great!

When you are talking about an elements cycle like nitrogen, do they have to go through all the hemispheres?  For example does nitrogen have to go through the biosphere, geosphere, lithosphere, atmosphere, and the rest?  Or do some elements skip some hemispheres or never reach them? This confused me back when we were learning it and i am still confused.  If someone could help me that would be great!

Sorry if this sounds stupid, but I remember Caroline asking this question in class but I just wanted to clear it up.  When they country is in an economic boom do people have more or less children.  If people are making more money than they are able to have more children because they can afford it.  Or, is it that they have less because the cost of living is increasing?  I am not sure which is the correct one so i am not sure if the economy will cause a bust or a boom in the population.  If someone could clear this up that would be great!

I understand the definition of a keystone species, but couldn’t any animal be considered a keystone species?  If you remove a species from an ecosystem then it will affect the population in some way.  You are removing some animals food source which will change they way they feed and maybe the animal that feeds on them.  By taking away some species, you are bound to disrupt the food web.  So what makes a keystone species different from the rest?

I know in class today i asked about this when Sydney was giving her presentation, but it still isn’t clear for me.  When you are getting closer to the shore it makes more sense, at least in my head, that the salinity would become higher because there is less water to dilute it.  When you get deeper out into the ocean there would be a better balance and so the salinity would decrease.  I am a little confused on how it works in the opposite way.  Maybe i am looking at it in the wrong way but something is not clicking for me.  If someone could clear this up that would be great! thanks

Within biodiversity, the only one that isn’t clicking for me is functional diversity.  I know the definition and i know it looks easy and simply, but how is there a diversity for these processes.  Is it the diversity in the amount they do the process or is it the different types of processes? Because we all need energy flow and recycling in our communities so how would that be diverse? Or is it about the rate at which these processes go? I understand the energy flow and all the cycles i just dont get how that could be diverse.  Sorry if this seems easy!

Today in class, soil was our main topic with the question of how does it form? In an ecosystem their are two components of biotic and abiotic. Under abiotic, there are four major elements: energy, water, air, and soil. With soil being our major topic, we looked into the formation of soil and how elements go into the soil and out. As someone in class, soil is really very small rocks. These small rocks are either sand, silt, and clay (the smallest). They make the up the different components of the soil. If soil are small rocks then it must come from big rocks right? Yes, the starting point of soil formation is a big rock, but in order to produce soil the big rocks undergo either weathering or erosion.
There are two types of weathering: chemical and mechanical. Under chemical weathering, the actually composition of the rock changes. Water is a key agent in this process. The primary equation is H20+CO2=H2CO3. This is the formation of carbonic acid. Since water is very important, the climate of an area greatly affects chemical weathering as well. If you live in a place with a lot of rainfall, then the rain will decompose more rocks than in a dessert with little to no rain. Also, chemical reactions perform faster in warm temperatures, so if you live in a place that is warm with rain, there will be a lot of chemical weathering. The rate of the weathering is controlled by climate.
Also, by the chemical reactions with the rocks and water, it can free elements and allow them to be reused. For example, limestone is CaCO3, so when limestone is decomposed it frees up the element Ca which can be used in other forms such as a shell for an animal. The other type of weathering is mechanical. This does not change the composition of the rocks but more of the position or shape. Mechanical weathering has a lot to do with tectonic activity like the shifting of plates under the earth’s surface. The pressure is released and forces the rocks to expand and surface the earth. The expansion causes the rocks to crack and create crevices and the sharp peaks of a mountain. Ice wedging also falls under the category of mechanical weathering. If there is a crack in the road or a rock, water can seep into them. Water is the only element that expands when freezing. So, when the water freezes it expands and cause the rocks to push farther away forming a larger crack. This does not change the composition but it is a physical change. Erosion is the other way to form soil. We will go into this topic more later on, but we did touch on it. When you think of erosion you should think transport or the movement of materials. The two agents of erosion are water and wind. Water being the primary and wind being the secondary. The small rocks move into a stream and can form into silt, clay or sand. Erosion is more commonly known than weathering but not more important. Once the weathering has decreases the size of the rocks, erosion can transport them to different places and they can turn into sand for example. Both are very important in the cycle of soil formation.
*i know this is about the sea but you can see how the sand, silt, and clay are formed.

Hey guys! I looking over our study guide for chapter 1 and when I looked over question three I was a little confused.  I am not sure how to differentiate between natural resources and natural services.  I know that a resource is something we use and the service is what we get in return, but I’m not sure how they would go together.  What would be an example of a natural service?  Also, there is no way to replenish the natural capital right?