Ecology B/C

[Benewcomb]

hey, my friend wants to know what type of test this is, do you know?

[MissAmargasaurus]

hey, my friend wants to know what type of test this is, do you know?

It usually depends I think. If I'm reading your question right, it can be either a powerpoint, on paper, or stations. Questions can be short answers, multiple choice, fill in the blank, etc.

If you mean the test subject.. Well uh, ecology! The biome topics this year are Deserts and Grasslands. If you want to know other kinds of questions that can be given, I'd check out the event rules, as it gives examples of what you'd need to know.

[Nerd95]

The Kansas City Regionals exams -- both B and C divisions -- have been uploaded on the Test Exchange!

I wrote the exams, so comment here with any questions about the test, and I'll answer them.

Find the exams here: https://scioly.org/wiki/index.php/2018_ ... ge#Ecology

[gryphaea1635]

I'm having some trouble with a population growth question. Does anyone know how to solve it?

The smaller of the two herds is growing in a previously uncolonized area. The area is restricted in resources and as a result can only support 70,000 individuals. Presently, the herd numbers at only 12 thousand. With a generation time of 1 year, at time 3 years, the new population stands at 20,000 individuals. What is the maximum rate of growth?

Thanks so much!

[allopathie]

I'm having some trouble with a population growth question. Does anyone know how to solve it?

The smaller of the two herds is growing in a previously uncolonized area. The area is restricted in resources and as a result can only support 70,000 individuals. Presently, the herd numbers at only 12 thousand. With a generation time of 1 year, at time 3 years, the new population stands at 20,000 individuals. What is the maximum rate of growth?

Thanks so much!

Given that generation time is given, this is probably a discrete logistic growth problem, so N_t+1 = N_t + N_t * r_0 * (1 - N_t/K). Assuming "time 3 years" to mean that 2 generations have elapsed, we have a system of equations to solve: x = 1200 + 1200 * r * (1 - 12000/70000) and 20000 = x + x * r * (1 - x/70000). From this I get x = 15604.3 and r = 0.3625. The maximum growth rate is at K/2 = 35000 individuals, so r * 35000 * (1 - 35000/70000) = 6344 individuals/year.

Instead assuming "3 years" to mean 3 generations I use a system of 3 equations to get r = 0.2339, generation N_t+1 to be 14326, generation N_t+2 to be 16991, and generation N_t+3 to be 20000. Observe that the change in N is increasing each generation. From this the maximum growth rate is 4093 individuals/year.

If we instead assume a continuous logistic model, we use the equation N_t = K/(1 + (K/(N_0 - 1)) * e^(-rt)) to solve for r. From this, I get r = 0.21975, so dN/dt = rN(1-N/K) at 35000 individuals is 3845.625 individuals/year.

I may be interpreting this question entirely the wrong way though ... is there an answer key or something? You can't do the first two equations at competition with a nongraphing calculator; WolframAlpha certainly makes it easier.

[allopathie]

I’m actually really fed up about this event in general; even the best of the tests (MIT, Golden Gate) end up being nothing more than fact recall when there’s so much opportunity for more ... if I end up supervising for Water Quality next year, I’d hope to include more case studies that involve deeper critical thinking than just, for example, copying down the techniques for restoring biodiversity (say, take the data from an article in the Journal of Ecology and ask the test taker to come up with the conclusion while asking some in depth questions about the background of the investigation). I think Robyn Fischer attempted this at C division nationals last year but accomplished nothing more than asking the tester to read numbers off a graph.

http://onlinelibrary.wiley.com/store/10 ... e808bfb628

http://onlinelibrary.wiley.com/store/10 ... 291bc2e0c2

Here’s two graphs from the most recent issue of JoE about drought induced forest dieback ... why not have the test taker analyse the two and apply their understanding of desertification, climate change, and plant physiology instead of asking mundane standardised test questions?

There’s a mentality that having a stations test distinguishes those who truly understand the material from those who don’t. I think MIT accomplishes this very well. But this reduces the complexity of questions that can be answered, and for a topic as subjective as ecology, lends itself to questions with correct answers that are debatable (speaking from past experience here), or questions that test unnecessary trivia. This event ought to be one that prepares participants to do research in the future, and not a replica of an AP environmental science.

[Fridaychimp]

I’m actually really fed up about this event in general; even the best of the tests (MIT, Golden Gate) end up being nothing more than fact recall when there’s so much opportunity for more ... if I end up supervising for Water Quality next year, I’d hope to include more case studies that involve deeper critical thinking

I actually can't agree more; at this point, most high level tests are basically just straight vocabulary, and then a few short answers that don't do much to change around placings. I gotta say I'm a little guilty of this too, but in my defense, obscure MC vocab is a lot easier to write than lengthy case studies. I feel like next year with Water Quality will be a little better because the ID will lower the amount of "you know it or you don't"; you can actually make educated guesses.

[Nerd95]

I’m actually really fed up about this event in general; even the best of the tests (MIT, Golden Gate) end up being nothing more than fact recall when there’s so much opportunity for more ... if I end up supervising for Water Quality next year, I’d hope to include more case studies that involve deeper critical thinking

I actually can't agree more; at this point, most high level tests are basically just straight vocabulary, and then a few short answers that don't do much to change around placings. I gotta say I'm a little guilty of this too, but in my defense, obscure MC vocab is a lot easier to write than lengthy case studies. I feel like next year with Water Quality will be a little better because the ID will lower the amount of "you know it or you don't"; you can actually make educated guesses.

I agree –– but I will say, having been an event supervisor for many years, it's a tricky balance to strike. You need the simple vocabulary questions because, often, even those can be challenging for teams that haven't prepared well. But it's the case studies and data analysis that truly dive into the meaning of Ecology. It's a balance I tried to strike with the KC Regionals exam (https://scioly.org/wiki/index.php/2018_ ... ge#Ecology), but as I wasn't in Kansas City to grade it, I had to write the exam to be fully multiple choice / fill-in, which isn't an ideal format (though you'll still see a long case study section, and even the traditional multiple choice all involve analyzing figures). If I were there to grade, it would've been predominantly short answer. Though I'm also a big fan of drawing sections as I think they test knowledge and are also a bit more fun (see Section 3 of the KC test).

[Fridaychimp]

You need the simple vocabulary questions because, often, even those can be challenging for teams that haven't prepared well.

I definitely agree that simple vocabulary has a place, but I feel like some of the really obscure knowledge that test writers like to throw at us is a little absurd. For instance, I believe last year's MIT test asked about the founder of the food web concept, and it turned out to be this random Italian dude from the 19th century. (Overall though, the test was great. It's just this specific question that I don't love.) While knowing basic terms is vital to actually understanding eco, my bigger qualm is with questions like these, which as far as I can tell, do nothing to advance a test-taker's knowledge of the topic.

[glitchedgirl]

Hi. I'm new to the Ecology event and to the Science Olympiad. What mathmatical formulas will help me in Division C regionals?