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Midterm

# PCB 4043C Study Guide - Midterm Guide: Spartina Alterniflora, Biological Pest Control, Pioneer Species

12 pages47 viewsSpring 2014

Department
Agronomy
Course Code
PCB 4043C
Professor
Christou
Study Guide
Midterm

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Page 1 of 12
GENERAL ECOLOGY (PCB 4043)
Spring 2010
EXAM 2
Write your code on all the pages
Make sure that all pages are attached.
You may not use calculators, cell phones, brain chips, or other electronic aids. The math
needed to solve a problem should be relatively simple. If you can't do the math, just
show what needs to be calculated (e.g., "answer = .5 x .3")
If you get hung up on a problem, skip it; return to it after you’ve answered the “easy
problems.
PAGE POINTS POSSIBLE SCORE
1 2 _____
2 6 _____
3 8 _____
4 8 _____
5 10 _____
6 10 _____
7 6 _____
8 11 _____
9 10 _____
10 11 _____
11 8 _____
12 10 _____
_____ _________
TOTAL 100 _____
1-1. (2 points for either answer) Are you interested in being an undergraduate TA for this
course next year? ( YES, NO )

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Page 2 of 12
2-1. A student doing an independent project (Zoo 4905) monitored Daphnia growth in a
lake, and based on their performance was able to describe how the per capita growth
rate varied as a function of density. Her data are shown below.
a) (4 points) Given enough time, to what density will the population converge if
initiated at the following densities:
UFinal Density
N
0 = 1
N
0 = 3
N
0 = 7
N
0 = 14
b) (2 points) Give a biologically plausible explanation for this hump-shaped function
(your answer must be sufficiently complete to explain both the rise and fall of
the curve).
-0.4
-0.2
0
0.2
0.4
0 2 4 6 8 10 12 14
Per Capita Growth Rate,
dN/Ndt
(per week)
Daphnia Density (no. / 10 ml)

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Page 3 of 12
3-1. (2 points) Dr. I.M. Green monitored a plant population’s density through time (note
the logarithmic scale):
Over which time period does the plant population exhibit the greatest per capita
growth rate (circle the correct option)?
i. 0-3 yrs
ii. 3-6 yrs
iii. 7-10 yrs
iv. The answer can’t be obtained from the data available
3-2. The dynamics of three species can be described using the following equations (where
N is density, in no./m2):
dN1/N1dt = +1.0 – 0.1N1 – 0.1N2
dN2/N2dt = +0.6 – 0.2N1 – 0.2N2 – 0.1N3
dN3/N3dt = –0.1 + 0.1N2
For each of the following, choose (i.e., circle) the best option from the those available
within parentheses:
a) (1 point) Species 1 and 2 are:
( competitors; predator and prey; mutualists, do not interact directly )
b) (1 point) Species 1 and 3:
( competitors; predator and prey; mutualists, do not interact directly )
c) (4 points) In the absence of Species 3, Species 1 and 2 will:
( both persist; only species 1 will persist; only species 2 will persist;
neither will persist; there is not enough information provided )
hint: for c) apply the concept of invisibility.
1
10
100
1000
012345678910
Density
time (years)