BIOLOGY!!!! Help please?

Question

I have a question that reads:

Contrast the movement of energy and matter through the ecosystem. (Hint: check out the various biogeochemical cycles ie. carbon cycle, nitrogen cycle, and determine why even the longest food chains have only 5 trophic or feeding levels.)

Also, what is meant by ecological succession? What happens to biodiversity, interrelationships, and biomass during succession? What is the climax community and how are they important?

Would a hawk be on the 5th trophic level? Where could I find a food chain for a hawk, or an owl?

Would a bird be on the 2nd or 3rd trophic level?

Oh, and does anyone know what the difference between a density dependent control and a density independant contol would be?

No need to answer all of the questions if you only know one or two. Just please let me know in you answer if you are sure of your answer or your just guessing or something. Thanks so much for any help and for reading!!!

Answer 1

Holy smokes, you're asking for an entire course.   Let's start with the trophic system.  The earth is a circle, as are the systems upon its surface...  The cycles of nutrient and energy flow are mostly closed (meaning there is nothing introduced (input) or taken away (output).  The sun and the earth's core are the primary inputs of energy into the system.  Autotrophic organisms (or organisms that can make their own energy, ie. plants that use the sun in photosynthesis or thermophiles that use energy from volcanic vents in the trenches of the ocean) are known as "producers" for they have the capability to convert energy from sources external to the closed system (like the sun) and convert that into energy for life.  However, producers can only absorb a small portion of the available energy from the sun, and roughly 90% of the energy is lost, deflected as albedo. These producers become stores, or "pools" of nutrients and energy.  Organisms that consume the producers in an attempt to obtain the energy they've converted are known as "primary consumers".  They are the second tier in the trophic system.  They are able to obtain roughly 10% of the total available energy (much is lost through inefficiencies in digestion, primarily the inability to break down certain molecules of energy present).  Examples of primary consumers are herbivours like ungulates or human vegetarians.  The organisms that consume primary consumers are secondary consumers.  They are also only able to obtain ten percent of the primary consumer's energy.  Thus with every successive tier in the trophic system, the energy becomes less efficient.  Decomposers break down organisms from each of the trophic levels when the organism dies, converting the once living cells to energy for themselves are pools for other organisms.   This is a very general overview giving a slight glimpse into the many multifaceted and complexities involved with the trophic system.

Answer 2

First of all, it would probably be better to individually ask these questions so as to get the most specific and accurate answers in the future. =D

1) Even the longest food chains can only maintain 5 or fewer trophic levels due to "the 10% Law" which states that 10% of energy is lost at each trophic level. Due to the decrease of 10%, a food web cannot support that many levels because eventually, there wouldnt be any remaining energy left.

2) Ecological succesion is, to put it simply, the changing of communities. Primary sucession is the development of life without soil, while secondary sucession is with soil.

The climax community is just what it is... a climax. It is the last stage in ecological succession.

3) Yes, a hawk, an owl, or any other bird of prey would typically be found on the 3rd, 4th, or 5th level depending on the food web.

4) Due to the wide biodiversity of birds, it is difficult to say which level specifically birds belong in.

5) Density dependent control depends on the population density while density independent factors do not.

Hope this helped~!