Ecology - Week 12 Flashcards
What is a biome?
classifying communities by dominant vegetation
Where are distinct biomes found?
throughout the world
Do abiotic or biotic factors generally have a greater impact on the distribution of biomes?
abiotic factors
What abiotic factors impact the distribution of biomes?
- precipitation (water)
- topography (landforms and terrain)
- temperature
- sunlight
- wind
- nutrients
What are nutrients influenced by?
both biotic and abiotic factors
What are terrestrial biomes determined by?
climate
What do biomes represent?
different niches
Describe the tropical rainforest.
have to tolerate moisture and heat
Describe the temperate forest.
have to tolerate temperature variation
Describe the temperate rainforest.
have to tolerate temperature variation and moisture
Why are western red cedars well-adapted to the temperature rainforest biome?
they have:
- natural anti-fungal properties (prevents their wood from rotting if it stays wet for a long period of time)
- scaly, needle-like leaves make the trees more tolerant of climates in which temperature, sunlight, moisture and nutrients vary seasonally
What is an essential nutrient?
required for growth and reproduction (usually a limited resource)
(ie. nitrogen)
Where is nitrogen required in the cell?
- nucleotides
- amino acids
- ATP
Why is nitrogen a limiting nutrient in terrestrial ecosystems?
- organisms can only use nitrogen if it’s been “fixed” (converted into a usable form)
- most organisms are incapable of fixing oxygen
What is nitrogen fixation?
nitrogen is fixed = converted into a usable form (N2 → NH3)
What organisms can fix nitrogen?
only prokaryotes can fix atmospheric nitrogen
ie. bacteria in roots, lichen
How does nitrogen circulate within our ecological systems?
through the nitrogen cycle
Nitrogen Cycle - look at diagrams
-
What is nitrogen gas used for in industries?
- liquid nitrogen
- nitrogen gas
- nitroglycerin
- fertilizers
What is liquid nitrogen used for?
- freezing & transportation of food products
- cryopreservation
- coolant for superconductors
What is nitrogen used for?
- scuba diving
- anaesthetic (as NO2)
- to increase engine performance (as NO2)
What is nitroglycerin used for?
dynamite (used in demolition)
What forms do fertilizers come in?
in solid, liquid and gaseous forms
What is carbon?
an essential nutrient
Where can carbon be found in the body?
- nucleotides
- ATP
- lipids
- amino acids
- sugar
A giant cedar tree starts as a tiny seed. What provided most of the mass that enabled the tree to grow so large?
molecules in the air
CO2 + H20 –> O2 + glucose (cellulose)
Why is carbon NOT a limiting nutrient in terrestrial ecosystems?
unlike nitrogen, there are lots of terrestrial organisms that can fix carbon (ie. plants)
What collectively holds the most carbon?
oceans
Describe the world’s oceans as carbon banks.
the world’s oceans are huge carbon banks that have been storing a lot of the extra carbon we’ve been releasing through burning fossil fuels
What is the downside to oceans as carbon banks?
there’s a limit to how much the oceans can hold, especially once they start to heat up
Carbon Cycle - look at diagrams
-
Ocean Acidification due to Increasing CO2 - look at diagram
-
What is a dead zone?
where dissolved oxygen is too low to support most life
Describe the dead zone cycle.
- the addition of large amounts of a limiting nutrient to an aquatic ecosystem will lead to an increase in producer biomass (ie. algae)
- not all of these algae are good food for zooplankton and fish, so instead of being eaten they accumulate in the water, die, and decompose
- the bacteria that feed on the dead algae consume oxygen
- the decomposition of mass amounts of dead algae reduces the amount of dissolved oxygen to lethal levels
- organisms that require oxygen either leave, or die
Why is the dead zone in the northern Gulf of Mexico one of the largest in the world?
- partly due to the fact that the Mississippi river basin, which dumps into the Gulf of Mexico, covers a huge land area
- all the sewage and agricultural runoff in the drainage area ultimately ends up in the Gulf of Mexico
What is the atmosphere?
primary reservoir of inorganic carbon and nitrogen for terrestrial ecosystems
When can organisms use carbon and nitrogen?
if it’s been “fixed”
Where is carbon and nitrogen primarily stored?
in the atmosphere
What is a population?
group of individuals of same species, living in same place at same time
What is a community?
interacting group composed of different species
= multiple populations
What is an ecosystem?
interacting system composed of biotic & abiotic factors
= community + abiotic environment
What does an ecosystem consist of?
- abiotic factor
- primary producers
- consumers
- decomposers
What is an autotroph?
can produce their own food using light or chemical energy
What is a heterotroph?
cannot produce their own food (relies on autotrophs for food)
What is net primary productivity (NPP)?
rate at which producers make energy available to ecosystem
- we can think of productivity as the rate at which producers grow and reproduce
ie. the rate at which they produce biomass which consumers and decomposers will then be able to eat
Why is the biomass of producers generally greater than that of consumers?
because not all energy in producers is available to consumers
How does productivity vary with trophic levels?
productivity tends to decrease as trophic level increases
What are primary producers?
autotrophs
What are primary consumers?
herbivores
What are secondary consumers?
consumes herbivores
What are tertiary consumers?
consumes carnivores
What are detrivores?
consumes decaying/dead materials
Think about also why the trophic levels diagram is shaped like a pyramid.
– Why is the bulk of the productivity (ie. biomass) at the bottom? What would happen if the tertiary consumers made up the bulk of the biomass?
- energy it takes to support a secondary/tertiary consumer can be quite high
- as humans, we require a lot of nutrients in the form of meat (ie. beef, pork)
Describe the productivity of a lower trophic level?
lower trophic level = higher productivity
Describe the relationship between biomass and productivity.
biomass increases as productivity increases
Describe the biomass of a lower trophic level?
higher biomass = lower trophic level
