Day 1: Photosynthesis & Respiration & Chemical Energy.
- Work on your vocabulary
Day 2: Food Web & Flow of Energy
- What is the sequence of energy transfer in an ecosystem? (i.e. chemical --> light etc.)
- What is the chemical reaction sequence of photosynthesis & respiration?
- Why is the energy pyramid wide at the bottom and small at the top?
- What is the difference between a food web and a food chain?
Day 4: Symbiotic Relationships
- What form and what % of energy move up the pyramid?
- What forms and what % of energy is released and does NOT move up the pyramid?
- What symbiotic relationship is a mosquito to a human?
- Describe a commensalistic relationship.
- According to your graph, if more critters require more energy, what would happen to the population of the critters if all of your available energy (food) is utilized?
Day 7: Survivor Island
- Why is a predator important in a healthy ecosystem?
Point of the Lesson Highlights
Photosynthesis: (Like Endothermic Rxn’s)
Plants take in Water and Carbon Dioxide. Plants take in Light energy from the sun and transform it into chemical energy by making sugar and Oxygen. Sugar and oxygen have a high level of chemical energy.
What qualifies any chemical as having more or less chemical energy is it's reactivity. If it gives off a lot of energy during reaction - that's because it has a lot of stored chemical energy.
You can test this idea out in a few ways.
- What happens when you give a kid a lot of sugar? (Hint: they get hyper - because they have a lot of energy)
- What happens if you take powdered sugar and puff a cloud of it over a fire? (Hint: it creates a ball of fire)
- What does every fire need in order to react? (Hint: Heat, fuel & oxygen)
This is like taking a mousetrap that is set and tripping it off.
Respiration: (Like Exothermic Rxn’s)
Animals breath in Oxygen and eat the sugar from plants. Animals then metabolize the sugar and oxygen and convert it back into Carbon Dioxide and Water. This process releases the stored chemical energy and converts it into mechanical and heat energy.
Carbon Dioxide and Water do not have a lot of chemical energy. In fact, they are pretty stable. This is why it's considered lower levels of chemical energy - they're not very reactive. In fact, they are usually the end-product of most chemical reactions that stem from fire. In fact, water and carbon dioxide are usually the chemicals they use to put out fires.
Respiration reactions take the chemicals that have high levels of chemical energy (sugar and oxygen) and extract the energy so that they can move (mechanical energy) and keep themselves warm (heat energy). In that process they make water and carbon dioxide. These chemicals go back to the plant to be re-energized.
These reactions are very similar to the mousetrap. A mousetrap that is set has a lot of pent up energy. But, once the trap is tripped, all of that pent up energy is released. In the end, you have a mouse trap that is at a lower form of pent up energy that will not snap any further. This is like the chemicals that are used between photosynthesis and respiration. We cycle between chemicals that have higher forms of energy and lower forms of energy and then use outside forms of energy (light) to put back that chemical energy - much like we use a hand to reset the trap.
We need food in order to survive. Reason being - that is the source of energy that we need to move and keep us warm. All critters (organisms) get their food from their surrounding environment. This is what makes up an ecosystem.
An ecosystem is an area of nature in which living things (Biotic) and non-living things (Abiotic) interact to exchange energy and materials. Without Energy and Abiotic factors, life would not survive.
There are many different types of biomes and ecosystems - but the basic set up is the same.
First, you have your producers - or plants which produce the food. This is why you go to the "Produce" section of the grocery store to get your fruits and vegetables - after all, fruits and vegetables are the original source of food produced. Plants get their energy from the sun.
Second, you have your primary consumers - or animals that eat the food that was produced (Herbivores). These guys get their energy from the plants that got it from the sun.
Third, you have your secondary consumers - or animals that eat the animals that ate the food that was produced (Carnivores). These guys get their energy from the critters that got the energy from the plants that got it from the sun. Got it?
If you're confused - look at the diagram below.
Using the diagram above, we can look at it this way. If 1000 Joules of sunlight is utilized by the plant, 900 Joules (90%) is used by the plant for growth and other bio-processes. 100 Joules of energy (10%) is left over in the forms of sugar and oxygen (chemical energy).
When the sugar / oxygen is consumed by the deer (primary consumer/herbivore), of the 100 Joules of energy that it got from the plant, 90 Joules (90%) is utilized for the animals ability to move (mechanical) and keep its self warm (heat). The other remaining 10 Joules (10%) is used to (re)-grow muscle fibers, fat, and other body tissues. These are made out of proteins and fat (chemical energy).
When the deer (herbivore) is consumed by the cougar (secondary consumer) - of the remaining energy left over, 10 Joules of energy, 9 Joules of energy go into allowing the cougar (secondary consumer) to move (mechanical) and keep warm (heat), and 1 joule of energy is used for building proteins and fats for (re)-building body tissues.
This is why it takes a lot of plant material to make enough meat to be consumed by 1 mountain lion.
Above was a food chain - or a simple way of how energy flows through an ecosystem. Below is an example of a food web - which is a more complicated and holistic view of how energy flows through an ecosystem. A food web is simply a complicated food chain that represents a more specific ecosystem/environment.
Today, you read the article on page 15 and created a food web based on the article below.
Aspen trees are biodiversity hot spots in the west. (Remember high biodiversity is good) They are home to a variety of songbirds (which eats seeds and insects). In 1997 Aspen trees were on the decline in Yellowstone and no one knew why. William J. Ripple, a scientist, went to Yellowstone to try to solve the mystery.
He took core samples from 98 aspen trees and discovered that only two had begun to grow after the 1920’s- around the time the last substantial populations of wolves were killed or driven off. He found big trees and tiny trees but nothing in between, because nothing new grew from the 1930’s to the 1990’s. It was the first concrete evidence of a “wolf effect.”
The wolf-effect theory holds that wolves kept elk numbers at a level that prevented them from gobbling up every tree or willow that poked its head above ground. When the wolves were exterminated in the park as a menace, elk numbers soared, and the hordes consumed the vegetation (put it down in the food web under vegetation), which drove out many other species of plants and animals. For instance, without young trees on the range, beavers, for example, had little or no food, and indeed they had been absent since at least the 1950’s. Without beaver dams and the ponds they create, fewer succulents (water rich plants) could survive, and these plants are critical food for grizzly bears when they emerge from hibernation. (They need a lot of these plants to replenish themselves after hibernation).
In 1995 the wolves were re-introduced, if the wolf-effect hypothesis is correct, and wolves are greatly reducing elk numbers since then, the vegetation should be coming back for the first time in seven decades. They have indeed found trees and willows rebounding in Yellowstone as wolf numbers have climbed- but that is only part of the change occurring in the park.
Other changes accompany the re-growth of vegetation. In the river there is a small beaver dam-one of the first documented in 50 years. Because of the re-growth beavers have something to eat again. Also as more vegetation grows along the river, it will stabilize the banks and stop some erosion.
The wolf seems to have an effect on the Yellowstone food web as well. One of its most dramatic effects has been on the coyotes. Coyotes have sacrificed a great deal to make room for the much larger wolves. The number of coyotes in the park is down 50%.
With fewer coyotes, their prey- such as the voles (which eat mostly vegetation and seeds), mice, (which also eat vegetation, seeds and insects), and other rodents-have exploded in number. This has greatly benefited the red fox, which also prey upon songbirds as well. The concern, however, is that with more foxes in the ecosystem could mean a possible reduction of birds in the future.
But, are the wolves really the engine driving these changes? Most scientists think so. One scientist stated that wolves are the primary force shaping the ecosystem in Yellowstone.
Other researchers, however, are not convinced about the effects of the wolf. One researcher stated a strong correlation between the return of the wolves and the new growth is far from demonstrated. The ecosystem in Yellowstone is an interactive system, and there is never a single cause; for instance, as the wolves are coming back the climate is warmer. It will take 20 years or more before we know for sure. So the mystery remains unsolved for now. What do you think?
At this point, you've already learned about the trophic relations - i.e. Producer / Consumer, Predator / Prey. But there are other ecological relationships - a sort of buddy relationship between two dissimilar organisms. We call these relationships symbiotic relations.
1.Mutualism - where both species benefit each other.
2.Commensalism - where one species benefits, the other is neither benefited or harmed.
3.Parasitism - where one species benefits, the other is harmed, but not killed.
Below are the slides that describes each of these different relationships.
On page 20-23, you will be studying how the increase of a population in a highly fictitious prairie environment consumes the available energy. I say highly fictitious because the growth of the population is not real. But that's not the point. The point is to see how the increase of the population size puts more pressure on the consumption rate of the carry capacity of the environment.
The data should look something like this.
On this day we examine both of these graphs and apply it to the real life - with the understanding that the graph pertaining to the prairie system is highly manipulated. (Critters don't populate like that - and there really is no predation in this example). Nevertheless, it does serve to explain many aspects of how a population size puts demands and stresses on the environment.
For instance, if we were to replace the prairie system with a cow pasture - it may make more sense. If I had 10 acres of field grasses to raise cattle, how many cows could it support? 1 cow would be just fine. But what about 5? I'm sure it would be equally just fine. But what about 15 or more? There comes a point where the grasses on the field cannot keep up with the demands and rates of consumption. Eventually, a few things start to happen on the field that we begin to witness.
- Starvation: There's not enough grass to go around. In fact since many of the grasses can't grow back fast enough, many cows start to pull up the roots. This leads us to #2.
- Overgrazing: When cows eat (or "graze") more (another word for "over") than what can grow back, it puts stress on the field, and the field can no longer support the critters who depend on it.
This is why a predator pray relationship is highly important. It's one of the ways nature keeps the populations in check, or balance. If you will notice, in the Wolf v. Elk population graph, you may have noted that there were two columns as to why elk would leave the population - that is... death through predation or death through starvation. This, of course, adversely affects the elk population. But also note that as the wolf population grew after being re-introduced, the elk population eventually got to a point where it was no longer consuming more than the environment could handle - in other words, they were no longer starving. It's really a matter of ecological economics. I loosely coin the phrase after the basic study of economics, or the study of supply and demand. Meaning - the environments ability to provide food (supply) and the population of critters that can be supported by the food supply (demand).
Below are a few population graphs. One is where there is an unlimited supply and no predator to hamper the critters population. Another is a Predator / Prey graph, and last is a limiting factor.
When a population is unimpeded, or nothing stands in the way of allowing the population of the species to grow; meaning, it has no predators and an ample supply of food, space, shelter etc., then the population can grow exponentially. This chart is assuming that we only double every generation, with older generations dying off naturally.
Generational population is determined by how many offspring any species can produce during reproduction.
Predators are vitally important to an ecosystem. As noted before, without them, the elk were dying through starvation because they were over consuming what the environment could produce.
Predators keep other populations in balance. As noted in the Wolves v. Elk exercise:
- as the population of the prey increase, so does the population of the predator.
- As the population size of the predator increases, it puts a strain on the population size of the prey, thus reducing it.
- As the population of the prey is reduced, the population of the predator also decreases - through starvation.
- As the population of the predator decreases, it puts less stress on the prey population and it starts to increase again.
- It repeats - thus keeping balance.
When a critter depends on certain factors within an environment - such as food, space, shelter etc., but the environment only has a limited supply of it, then the size of that critters population can get affected. For instance, back to the cattle in the 10 acre field - that field can only carry so many cattle. After it reaches that point - several events take place - namely, starvation & overgrazing. Thus the population can no longer grow beyond the capacity of that environment.
Humans are critters too, and we need a place to stay and food to eat too. Many may consider the human population growth controversial topic - and that depends on your point of view. But listed below are just one of several impacts humans have on the environment.
–Literally translates into City & spread out.
–When our population grows, we generally start off as a small cluster and start to branch out and take up more space. When that happens we consume more space used to farm which makes food for us and we simultaneously take up habitats of other critters.