Definitions
the maximum population size of a species that can be sustained by that specific environment, given the food, habitat, water, and other resources available
carrying capacity
The population of rabbits on our nature trail hill has a carrying capacity of 100 rabbits. Their limiting factor is the amount of food available. In the last few weeks, the rabbits had a lot of babies. There are now 150 rabbits living on the hill. What will happen next, and why?
The rabbit population will decrease due to insufficient food supply for the extra rabbits
A student draws a food chain of an environment near their high school. This food chain includes 8 different organisms, from the producer at to bottom to 7 trophic levels of consumers above them. What is unrealistic about this scenario?
There are too many trophic levels. The 10% rule would prevent enough energy from being passed that many times to sustain animals at the top.
Quaternary consumers: 10 kcal
Producers: ? kcal
Quaternary consumers: 10 kcal
Tertiary consumers: 100 kcal
Secondary consumers: 1,000 kcal
Primary consumers: 10,000 kcal
Producers: 100,000 kcal
The purpose is to decrease competition for resources by using them in different ways.
Example: plant roots growing in different areas of the soil, predators hunting at different times, birds using different parts of the same tree.
Symbiotic relationship between a tick and the animal it kills
predation
Imagine a scenario where there are two species of tree in a forest. One of the two trees grows faster than the other, absorbs nutrients quicker, grows above the other species and deprives them of sunlight, and eventually outcompetes them and completely removes them from the area. What is this scenario called?
Competitive exclusion
Picture a trophic pyramid. What would occur if you removed a tertiary consumer from the top? Be specific.
Trophic cascade: secondary consumers boom, primary consumers crash, producers boom
Most plants absorb more nitrogen from the soil than they release. Legumes (such as beans and peas) are a type of plant that return more nitrogen to the soil. How can this be beneficial?
Decreased need for synthetic fertilizer in crop fields, which lowers risk for algal blooms and other environmental problems
Is resource partitioning more closely related to habitat or niche? Explain.
Niche. Habitat is just where organisms find resources, whereas niche is where & how. The "how" is important because organisms can use the same space and resources, but in different ways (resource partitioning)
a carbon sink that humans have turned into a source
fossil fuels
A population of bacteria are growing in a flask of ideal medium at optimum temperature over a 24-hour period. They have no limiting factor other than space, and it will take them weeks to reach that point. What will their population growth curve look like after the 24 hours?
It will be exponential growth (they have not reached carrying capacity yet)
Humans are what type of survivorship curve? Prior to technological and medical advancements, what type of curve were we?
We are now type I, but we used to be more similar to type II
Burning fossil fuels over the last 100+ years has created a "legacy load" of excess carbon in the atmosphere. Even if we ceased all use of fossil fuels today, the legacy load would continue to negatively affect the global climate. What is one realistic way to correct this?
More plants (absorb CO2)
Name one way that humans are negatively impacting each biogeochemical cycle.
Water cycle: overuse of groundwater
Carbon cycle: deforestation, burning fossil fuels
Nitrogen cycle: use of synthetic fertilizer
Phosphorus cycle: use of synthetic fertilizer
an animal that eats animals that eats plants
secondary consumer
A flood passes through an ecosystem. The ecosystem has two dominant species. One species is densely populated and the other is sparsely populated. Which will be more affected by the flood, and why?
Neither (floods are a density-independent limiting factor)
What are two things all symbiotic relationships have in common?
1) between two different species 2) at least one organism benefits
Why don't R-strategists follow carrying capacity very closely? Name two distinct reasons.
1) Their environment is typically low quality, so their population is not strictly limited by competition
2) They have many offspring at one time and high mortality early in life, making their population numbers less stable
Why are most density-dependent factors biotic?
Biotic factors are typically involved in ecosystem relationships (like predator-prey numbers or symbiotic relationships), which tend to be density-dependent
two terms required: an organism that has few offspring and high parental investment
K-strategist, Type I
Compare a desert biome to a temperate forest biome. What biodiversity levels would you expect?
A desert biome would probably have lower biodiversity than a temperate forest biome due to very low precipitation levels.
Imagine the water cycle, which is driven by the heat of the sun. We said that due to climate change, many biomes will experience increases in temperature, and increases in precipitation. Why would increased temperature go hand-in-hand with increased precipitation?
A ranch adds antibiotics (which kill bacteria) to their animals' water in order to prevent disease. This water becomes runoff into a neighboring forest ecosystem. What do you expect to happen and why?
Bacteria are required to bring nitrogen from the air into the soil. If the bacteria are killed, plants would run out of nitrogen to build proteins, leading to illness/death. This could lead to a trophic cascade/ecosystem collapse.
What month has the most birthdays in the United States?
August
(this will not be on the test)