Chapter 3:
Chapter 3: Nutrient Cycles and Other Important Cycles
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Chapter 3: Nutrient Cycles and Other Important Cycles
Chapter 3: Nutrient Cycles and Other Important Cycles
Summary of Chapter
Summary of Chapter
Basic Intro video (coming soon)
Key Terminology of this Chapter:
Key Terminology of this Chapter:
Producer/Autotroph: An organism which makes its own food and synthesizes its own energy by one of two processes (listed below). Producers are preyed on by primary consumers. (Auto meaning self, and troph meaning energy/nourishment)
Photoautotroph: Producers which perform the chemical reaction of photosynthesis (converting the sun's energy and carbon dioxide into breathable oxygen, water and glucose (which it uses for food/energy). Plants and blue-green algae (cyanobacteria) are photoautotrophs.
Chemoautotroph: Producers which convert inorganic chemical compounds into organic ones, getting energy from chemical reactions and gain organic compounds from carbon dioxide. Certain bacteria species are chemoautotrophs. They often live in extremely hostile places such as deep sea vents.
Consumer/Heterotroph: Organisms which can't create their own energy, and thus must eat either producers, other consumers, or both. Are classified as herbivores, omnivores, and carnivores.
Primary Consumer: An organism which doesn't eat other consumers, and only eats producers. Is preyed upon by secondary consumers, which are in turn preyed upon by tertiary consumers, which are preyed on by quaternary consumers.
Note: in a food web, an organism which is one level of consumer, can simultaneously be another level of consumer as well.
For example.
One path could be: Grass -> Mouse -> Snake -> Hawk (Mouse is primary consumer)
and another path could be: Grass -> Grasshopper -> Mouse -> Snake -> Hawk (Mouse is secondary consumer which bumps up snake and hawk to the levels above)
Carnivore: A species which mainly or fully eats other consumers. Not to be confused with omnivores which eat both other consumers, and producers as well.
Hypocarnivore: 50% or less of their diet consists of meat. Sometimes grouped into the omnivore category. Examples include: the grizzly bear, the brown bear, and the kinkajou.
Mesocarnivore: 50 - 70% of their diet consists of meat. The rest consists of non-vertebrate animals including insects, as well as plant matter or fungi. Examples include: The red fox, the raccoon, and the mongoose
Hypercarnivore: More than 70% of their diet consists of meat. The rest consists of plant matter or fungi. Examples include: the lion, the polar bear, and the tiger.
Decomposer: Organisms which break down detritus for their own nourishment, thus allowing the nutrients locked in the detritus to be accessed by producers, thus re-starting the nutrient cycle. Examples of decomposers include many bacteria and fungi species, as well as some animals such as earthworms.
Detritus: Matter made up of dead animal or plant matter, as well as organic waste material (from animals)
Food Chain: A linear representation of which organisms eat each other, the transition of energy from one organism to another as it is consumed. Often decomposers are omitted from the food chain because they connect to all the members of the food chain.
(Image right)
Food Web: A combination of intertwined, interconnected food chains, usually representing a specific community. It shows the connections between organisms: everything an organism eats and is eaten by.
Note: As in food chains, decomposers are not included in food chains because they would be metabolizing the detritus of every organism in the food chain, thus making it too complicated: They would be connected to all the organisms.
(Image right: Source: https://ib.bioninja.com.au/standard-level/topic-4-ecology/42-energy-flow/food-webs.html)
Trophic Level: Level of dilution of energy. For example, producers get pure, undiluted energy from the sun, primary consumers can only get 10% of that energy, secondary consumers get only 10% of that and so on. (See why in Two Laws of Thermodynamics)
1st Trophic Level: Producer/Autotroph
2nd Trophic Level: Primary Consumer
3rd Trophic Level: Secondary Consumer
4th Trophic Level: Tertiary Consumer
5th Trophic Level: Quaternary Consumer
Pyramids of Biomass, Energy, and Numbers:
Three styles of pyramids which are used to show how much biomass, energy, and population there is on different tropic levels. Generally, there is less biomass, energy, and population as you go up trophic levels, as more is needed on the bottom levels to sustain the top levels.
Biomass is the amount of biological mass an organism has, minus water.
Note, All categories are a pyramid shape, except on the pyramid of numbers, where there might be an unusual shape.
In a pyramid of numbers, there are scenarios where, for example, the primary consumers would be far more numerous than the producers: If the primary consumers would be certain types of insects and other small animals, feasting on the leaves of massive redwood trees.
Image source: https://www.slideshare.net/MarcosRodriguez39/igcse-biology-edexcell-41-417
Activities:
Activities:
Ecology Activity: Make a Food Chain and a Food Web.
Ecology Activity: Make a Food Chain and a Food Web.
Do either Option 1 or Option 2
Recall your notes from the very first Ecology Activity: Backyard Biodiversity. (Go outside to your backyard, or to a local park. Observe the biodiversity in the park, see how the organisms, animals, plants are connected. Then, record those observations. ).
a. Make a food chain that includes a producer, a primary consumer, a secondary consumer, and a tertiary consumer
b. Make a food web that includes at least three producers, three primary consumers, two secondary consumers, and a tertiary consumer
Make your own food chain and food web
a. Do some research on the urban ecosystem of Toronto and
i. Make a food chain that includes a producer, a primary consumer, a secondary consumer, and a tertiary consumer
ii. Make a food web that includes at least three producers, three primary consumers, two secondary consumers, and a tertiary consumer
Content
Content
Content: Two laws of Thermodynamics
Energy (and matter) cannot be created or destroyed, only cycled between forms). Because in nature things always cycle.
2. An organism can only obtain up to 10% of the energy contained in its food.
For example: an acorn will get 100% of the energy from the sun, but a squirrel will only be able to get, at very most, 10% of that energy an acorn has. So to have the energy contained in 1 acorn, a squirrel would need to eat 10 acorns. A snake would only be able to obtain 10% of the energy contained in the squirrel, and so on.
Note that 10% is a best-case scenario, if the animal manages to eat all the edible parts of the animal, which it usually won't. So the actual percentage of energy it will get is probably far less than that. But just for the purposes of this lesson, we will assume all animals get 10% of the energy stored in its food.
So where does the other 90% of energy go? It's either locked in the inedible parts of the animal/plant, such as bones, fur, teeth, antlers, or was dissipated and returned to the energy cycle via processes such as maintaining the organism's body temperature, developmental processes and other metabolic processes such as digesting food, expending energy for motion and activity, and reproduction.
Think back to the three pyramids. That means, that for, lets say, a squirrel, to get the energy equivalent to that stored in 1 acorn, it would have to eat 10 acorns. A snake would have to eat 10 squirrels, and so on.
In the diagram, if a snake wanted to obtain 1000kj, it would need to eat 10 squirrels, which each only provide 10% of the energy, at most.
This is why there is more energy at bottom levels of the pyramid, to sustain the higher levels of the pyramid. There's more energy (and biomass, which contains the energy) at the bottom so that there is enough energy to sustain the top levels. See the pyramid example
Usually, if an organism is smaller, the consumer which eats it will need to eat more of the organism of the organism it consumes. For example, a snake will need to eat several mice to fill it.
However, if an organism is a larger organism, such as a moose, it will have accumulated a massive amount of energy, and even 10% of that energy will be a large amount, so many predators can eat one animal.
Chapter Quiz
Chapter Quiz
This short quiz is to test your knowledge on the biodiversity chapter in the ecology unit.
It will be out of 20 points.
Good luck! Remember, this isn't a real quiz. Just to test your knowledge on the unit. So don't stress, just keep calm, and don't worry. This whole site was intended as a study aid. If you do well, good job! Kudos to you. If you don't do so well, it just means you may need to study the section again.
Don't cheat. Please. The chapter quizzes are built into the site as Google Forms, unlike the unit tests, which are external, secure links.
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