Response To Environment, Energy & Flow
Define heterotrophs
Organisms that cannot make their own food and hence must consume food
If ample nutrients are available and there are no natural predators in the habitat, the population should undergo what form of growth?
exponential growth
The definition of a population vs. the definition of a community
Population is a single species, community is all living components of the ecosystem.
Describe the impact of deforestation on biodiversity
Deforestation removes the natural habitat of many species. Particularly in tropical rain forests which are biodiversity hot spots, this reduces the biodiversity of the Earth.
A relationship where one benefits and the other is unaffected.
Commensalism
How is population growth rate calculated using birth rate and death rate?
Population growth rate = birth rate - death rate
What percentage of energy is transferred between trophic levels, and why is most energy lost?
10% is transferred; most energy is lost as heat due to metabolic processes
What defines a keystone species in an ecosystem?
A keystone species has a disproportionately large impact on its ecosystem; removing it causes major changes.
What is El Niño, and how can it affect ecosystems?
El Niño is a warming of Pacific Ocean surface waters that alters climate patterns. It can change nutrient availability, sometimes increasing nutrient runoff and causing algal blooms, or decreasing nutrients and reducing productivity depending on the region.
Name one density-dependent factor that regulates population size.
competition, disease, or predation
The smaller the organism, what is true of the metabolic rate per gram of body tissue
higher metabolic rate
Why do bacteria have a higher maximum population growth rate (rmax) than large animals like leopards?
Bacteria reproduce much faster due to shorter generation times.
How do predator and prey populations typically change over time?
There is a negative feedback component to the relationship. They cycle: prey increases → predator increases → prey decreases → predator decreases.
What process makes atmospheric nitrogen usable for organisms, and who performs it?
Nitrogen fixation by bacteria
This type of succession occurs after a disturbance where soil remains.
Secondary succession
Red deer males exchange signals that suggest fighting ability, such as roaring. These signals in many cases eliminate an actual fight from occurring, as both parties accept the outcome of the roaring comparison. Why is signaling (instead of fighting) beneficial for red deer males?
Reduces injury and energy loss, increasing survival and reproductive success.
What happens to population growth as it approaches carrying capacity (K)?
As population size (N) gets closer to carrying capacity (K), the amount of available resources (like food, space, and mates) decreases. This causes the growth rate to slow down. In the logistic growth equation, the term (K−N)/K gets smaller, which reduces the overall growth rate (dN/dt). When N is very close to K, growth nearly stops because births and deaths are about equal...hence the plateau in a graph
Describe how a single lake can be an example of niche partitioning
Different areas of the lake, different depths of the lake, different temperature zones of the lake, different prey species in the same areas of the lake, etc.
What process leads to algal blooms due to excess nutrients?
Eutrophication
This type of behavior is genetically programmed.
Innate behavior
Vervet monkeys produce a cough call when airborne predators (such as eagles) approach. Describe the evolutionary significance of this behavior?
Warns the other members of the population about the predator so the population can seek appropriate cover in the vegetation and avoid predation
Which community has a higher Simpson’s Diversity Index: one where all 10 species have equal population sizes (10 individuals each), or one where 5 species have 15 individuals each and the other 5 species have 5 individuals each? Explain your answer.
The community where all 10 species have equal population sizes (10 individuals each) has the higher Simpson’s Diversity Index. (0.9 vs. 0.875)
Describe how the reintroduction of Wolves to Yellowstone National Park was an example of a trophic cascade
By controlling the elk population (the intermediate species here), the wolves indirectly promoted the population sizes of the species at lower trophic levels consumed by the elk
Describe the impact of the removal of wolves from Yellowstone National Park
Wolves are an apex predator and a keystone species. The elk population expanded massively without their natural predator (the wolves), and the expanded elk population altered the balance of many of the other populations in the ecosystem.
A nonvenomous snake resembles a venomous coral snake. What is this called and what is the advantage?
Batesian mimicry. It reduces predation due to mistaken identity.