Lab Exam 2: Lab 8 Flashcards
What is linear growth?
A fixed number of cells reproduce in each generation
What is an example of linear growth?
A corn seed
What is the active cell division of a corn seed called?
Apical meristem
How do corn seeds represent linear growth?
When they divide, four new cells are created; two of them mature and two remain relatively immature and are ready to divide again
What is the equation for linear growth?
N = ct + No
N (population size)
c (rate of increase)
t (time; in generations)
No (initial population size)
What is the growth rate on a linear growth plot?
The slope (rate of increase) which are constant
What is unrestricted exponential growth?
A fixed proportion of cells reproduce
What is the equation of unrestricted exponential growth?
N = Noe^(rt)
N (population size)
No (initial population size)
e (Euler’s number)
r (intrinsic rate of increase)
t (time; in generations)
What is the growth rate on the unrestricted exponential growth plot?
The slope (rate of increase) which are NOT constant beware are proportional to population size; as population growths, growth rate increases
What is logistic growth?
A type of exponential growth that occurs in environments where various factors restrict growth
What is the lag phase of logistic growth?
The number of births is greater than the number of deaths, but the growth is slow because of the small number of individuals in the population
What is the log phase of logistic growth?
The organisms are reproducing, and there are many of them reproducing, thus accelerating growth
What is the result of the log phase of logistic growth?
Eventually, food becomes scarce, room runs out, and pollution rises which tend to increase the death rate and lower the birth rate and population growth slows
What is the stationary phase of logistic growth?
The population size does not change because the birth and death rates are equal
What is carrying capacity?
The number of individuals in a population that an environment can support indefinitely
What variable represents carrying capacity?
K
What are examples limit population growth?
Resources and space limitation
What is the equation for logistic growth?
dN/dt = rN ((K-N)/K)
If N«K, what does that mean for logistic growth?
= rN
If N is approaching K, what does that mean for logistic growth?
Approaching zero
If N=K, what does that mean for logistic growth?
No growth (=0)
If N>K, what does that mean for logistic growth?
Negative growth
How does the intrinsic rate of increase (r) affect the rate of growth?
When the intrinsic rate of increase is larger, it results in a faster rate of growth; a population will reach carrying capacity quicker
How does “r” affect carrying capacity?
It does not
How does the initial population size affect the time required to reach carrying capacity?
If the initial population size is larger then it will reach carrying capacity quicker
How does the initial population size affect the carrying capacity?
It does not
What happens when the population size initially exceeds the carrying capacity?
It will decrease until it reaches carrying capacity
What does the first overshoot (oscillation) of the population around the carrying capacity mean, in terms of of effect of time to maturity?
As the time to mature increases, the oscillation of the population around the carrying capacity increases because at first, more people are being born and also require less energy which is why there is the first overshoot above the carrying capacity
Why does the first overshoot (oscillation) decrease after some time?
Because the population exceeds carrying capacity, the environment cannot sustain the young members who grow older and require more energy so the population decreases (older members die off) and go back down below carrying capacity
After the decrease from the overshoot (oscillation), how does the cycle start over again?
Once the decrease occurs, the environment then can replenish its resources which allows again for any overshoot and they cycle repeats
Explains the relationship between the single resource and carrying capacity?
At lower levels of the resource, it is a limiting factor because it directly influences the carrying capacity. However, at higher levels it not longer influences carrying capacity because the population stops growing and stays constant regardless of the increase of the resource
Explain the relationship between a single harmful factor and carrying capacity.
At low levels of the resource, it does not influence carrying capacity but at high levels it limits the carrying capacity
What is an example of a resource that would limit carrying capacity?
Toxins and pollutants
Given a chart of resources and the change it has on carrying capacity, how can tell which of the resources is the limiting factor?
The limiting factor is the one that when it increases, so does the carrying capacity. For the other factors, changing the amounts of it does not truly change the carrying capacity
What is a niche of an organism?
The range of resources an organism can use
Paramecium caudate is an aquatic single called protist, what is one factor that determines its niche?
The amount of oxygen dissolved in the water that surrounds it
Why does competition occur?
When niches overlap as two or more organism attempt to simultaneously use the same limited resource
Why is it important to first determine the carrying capacity for each population when their niches do no overlap?
It gives reference to when populations are isolated from one another and what their sizes are like when they use different resources
How can you tell which population is the more efficient competitor?
The population that remains steady even as the degree of overlap increases while the other population continues to decrease until it gets wiped out
Explain why the “losers” might persist when the level of overlap is not large enough for them to die off.
There are still some resources available to the small population of “losers” so they will still continue to fight for them, yet as soon as the level of overlap is large enough, they can no longer compete with the “winners” and will die off
How does E. coli benefit humans?
They produce Vitamin K, a substance used by the liver to make blood clotting factors
What is one side effect of taking antibiotics?
Not only do they kill the harmful bacteria but they also might kill some of the resident bacteria that we need
Even though the antibiotic has a negative impact on the carrying capacity of C. difficile, why is it doing so well under these conditions?
E. coli is much more negatively affected by the antibiotic so as it dies off, there are more resources available for C. difficile to thrive on
In the absence of antibiotics, how is E. coli helping its host (other than making Vitamin K)
Limits the amount of C. difficile (a harmful pathogenic)
By looking at a graph, how can determine which is the predator? The prey?
The predator has a smaller population size while the prey will have a larger one
Explain the oscillation for the predator population.
Increase in population is due to increase in prey population so more food. Decrease in population because prey start become more scarce so harder to find food. Cycle starts again.
Explain the oscillation in the prey population.
Increase in population is due to absence in predator. Decrease is due to more predator hunting the abundance of prey. Cycle starts again.
Differentiate between linear, unrestricted exponential, and logistic growth.
Linear = growth rate is constant and independent of population size
Unrestricted exponential = growth rate is proportional to population size
Logistic = growth rate is influenced by the difference between carrying capacity and population size
Compare the birth rate and death rate during the lag, log, and stationary phases of logistic growth.
Lag = birth rate exceeds death rate, but since population is small growth is slow
Log = birth rate exceeds death rate, the population is large, so growth is rapid
Stationary = birth rate equals death rate, no growth
