UNIT 1:
ECOSYSYTEMS
ECOSYSYTEMS
These organisms form the base of most ecosystems by converting sunlight into energy through photosynthesis, supporting all other trophic levels.
This process, often caused by habitat loss and climate change, occurs when a species completely disappears from Earth.
Extinction
Give the equation for finding the crude birth rate (%)
Crude birth rate = (births ÷ population) x 1,000.
Name a provisioning service.
Food, water, and raw materials.
Define ecological sucession.
Succesion is the natural and gradual change in species structure.
What is a trophic level in a food chain?
A trophic level represents the position of an organism in a food chain, based on what it eats.
Differentiate between species richness and species evenness.
Richness = number of species; evenness = relative abundance.
Describe how carrying capacity limits population growth.
When population nears carrying capacity, resources become limited slowing growth.
What is a regulating service?
A regulating service is an ecosystem function that helps maintain environmental stability by regulating processes like climate, water quality, and pest control.
In a population of birds, individuals with longer beaks are more successful at obtaining food from deeper flowers, giving them a better chance of survival and reproduction. Over time, this trait becomes more common in the population. What evolutionary process is described in this scenario?
nataural selection
Explain the 10% rule.
Only about 10% of energy transfers from one trophic level to the next; the rest is lost as heat.
Describe how invasive species reduce native biodiversity.
Invasives outcompete natives, altering food webs and reducing ecosystem resilience.
A population of birds in a forest has been steadily declining over the past decade. Researchers notice that habitat destruction, pollution, and predation by invasive species have all increased. Which of these factors is most likely contributing to the population decline?
Habitat Destruction.
Describe how invasive species reduce native biodiversity.
Invasive species outcompete natives, altering food webs and reducing ecosystem resilience.
Define genetic drift.
random change in allele frequencies in a population, often having a greater effect in small populations, leading to a loss of genetic diversity over time.
Describe the nitrogen cycle.
The nitrogen cycle involves the conversion of nitrogen between different chemical forms, including nitrogen fixation and denitrification.
This large-scale ecological event, which occurs every few years, dramatically alters the abundance of species in the Pacific Ocean, due to shifts in ocean temperatures and currents.
El Nino
A population of rabbits in a grassland ecosystem has been steadily increasing in number over several years. However, the population growth has begun to slow, even though food and water are abundant. Which factor is most likely causing this slowdown in growth?
A) Increased competition for mates
B) Reaching the population's carrying capacity
C) Decrease in birth rates due to environmental stress
D) Reduced migration of new individuals into the population
B
A coastal wetland experiences an increase in pollution due to nearby urban development. The wetland's ability to filter pollutants from water and reduce flooding is disrupted. Which of the following is the ecosystem service most impacted by this disruption?
A) Climate regulation
B) Pollination
C) Water purification
D) Soil formation
C
Explain the significance of indicator species and give an example.
Indicator species reveal pollution or ecosystem stress due to their sensitivity. (ex: lichens, amphibians, and certain insects)
What is GPP and NPP in terms of energy flow?
GPP (gross primary productivity) is the total energy captured by producers, while NPP (net primary productivity) is the energy left over for consumers after producers’ energy use.
Evaluate how natural selection and adaptation contribute to long-term biodiversity.
Natural selection drives adaptations and speciation, creating genetic diversity.
A population of wolves grows from 1,000 individuals to 1,400 individuals over 5 years. What is the annual growth rate of the population?
7.18 %
Urban development causes the destruction of wetlands, which were previously acting as buffers to absorb excess rainfall. What ecosystem service is most directly lost due to wetland destruction?
Flood regulation
A population of rabbits in a forest has a growth rate of 3% per year. Using the Rule of 70, how many years will it take for the population to double in size?
23.33 years
Doubling = 70/growth rate = 70/3 =23.33 years.