Energy Flow & Nutrient Cycles (8.2)
Why does energy flow and nutrients cycle?
Energy moves in a one-way flow from lower trophic levels to higher ones, with most being lost as heat. Nutrients cycle and can be reused again by changing form.
What is a population?
Group of the same species living in a defined area
What are the 2 ways to measure the structure of a community?
Species composition & species diversity
What happens to an ecosystem if the keystone species is removed?
Ecosystem will collapse
What is heterozygote advantage?
This is when the heterozygous genotype is more advantageous than either homozygous genotype.
Name and explain the 2 essential processes for the carbon cycle in living things
Photosynthesis: carbon dioxide is taken in by plants to produce glucose
Cellular respiration: glucose is broken down into ATP and carbon dioxide is released
Name 2 ways populations can grow and 2 ways they can shrink
Growth: birth rate and immigration rate
Shrink: death rate and emogration rate
Explain a trophic cascade
This is when a change at 1 trophic level will negatively impact all other trophic levels that depend on it
What are 2 defining features of a keystone species?
Small population Effect is disproportionate to population size
Explain how an adaptation can lead to speciation
New traits that are advantageous become adaptations and more common in the population. Over time this leads to more diversity and potentially new species forming.
Draw a trophic pyramid with 5 levels, showing energy and nutrient flow
See Picture on Board
Explain the meaning of a carrying capacity
This is the maximum population size that can be sustained by the environment
Describe niche partitioning
This is when the habitat is split into different niches so this reduced competition between species over similar resources
Explain how the removal of decomposers could lead to ecosystem collapse
Decomposers recycle nutrients, without them nutrients could be lost and ecosystems will suffer
Why are invasive species so successful?
They exploit new niches and outcompete native species because they lack native predators.
Explain why bacteria are vital to the Nitrogen cycle. Explain 2 processes that they assist with.
Bacteria help plants and animals access nitrogen.
Nitrogen fixation: bacteria take in nitrogen gas and turn it into ammonia in the soil
Denitrification: bacteria take nitrogen from the soil and put it back into the atmosphere
Give 2 examples: 1 of a density-dependent factor and 1 of a density-independent factor
Dependent: disease, food, water, shelter
Independent: natural disasters
Give an example for each of the following: Competition, predator/prey, parasitism, mutualism, and commensalism
Explain how wolves were a keystone species to Yellowstone
Wolves are responsible for keeping elk populations in check. WIthout them elk will devastate the vegetation and lead to fewer species in the community
Describe how human activities lead to changes in ecosystem structure and dynamics
Human impacts accelerate change (deforestation, industry, pollution, etc.) which can lead to species being introduced or killed in an ecosystem, changing the dynamics
Describe the 2 types of autotrophs and how they differ
Photosynthetic autotrophs can use energy from the sun to make chemical energy
Chemoautotrophs use energy from small inorganic molecules where oxygen is absent
Explain the logistic growth model: how does the graph look and how do you calculate this?
Graph is an “S” shape with a carrying capacity
Explain how interactions within and among communities influence community structure
Positive interactions can aid in community structure whereas negative interactions could lead to smaller communities and fewer species
Describe the relationships between ecosystem diversity and its resilience to changes in the environment
How did the meteor impact lead to dinosaur extinction?
The meteor caused lots of dirt and dust to block the sun. This lead to less photosynthesis which caused plants to die so consumers lost food sources.