C.2 Communities and ecosystems Flashcards
(31 cards)
What is a biome?
A biome is a community of plants and animals that occupy a major habitat or region eg. tropical rainforest.
What is a trophic level?
The position of an organism in a food chain.
What are food webs?
They show possible combination of food chains within a community. A food web is made out of multiple food chains.
What is biomass?
The total of dry mass in organisms or ecosystem.
Explain feed conversion ratio and its implication.
FCR refers to the rate which animals assimilate the food that they consume in order to build biomass and grow. It is important as it affects farmers in economic terms. They determine the food mass required to feed an animal and compare it with the biomass they produce.
Feed ratio: Mass of food consumed (kg) / Body mass gain (kg)
Define Poikilotherm
Is an animal that has variable body temperature according to its surroundings (Atlantic salmon has lower FCR because of this.)
Define Homeotherm.
Is an animal that maintain regulated body temperature through physiological mechanism
What is the difference between climate and weather?
It is a matter of time. Climate refers to temperature and precipitation patterns during a longer period of time. While weather refers to the temperature and precipitation during a shorter time period.
What can climate be affected by?
Altitude, longitude, nearby bodies of water such as lakes or rivers. An example is the Caucasus mountains where temperature at sea level is 15C while at higher altitude decreases to 6C. (lower temperature leads to higher rainfall)
What is the difference between a biome and an ecosystem?
A biome refers to a community that is shaped by common environmental conditions while an ecosystem refers to interaction between biotic and abiotic factors. There can exists multiple ecosystems in a biome.
Describe Robert Whitakers system of biomes.
He classified 9 biomes based on precipitation and temperature. Tropical rainforests, tropical seasonal forest, temperate rainforest, temperate deciduous, Woodland, Taiga, Savanna, desert, tundra,
Explain how precipitation and temperature affects biomes
Temperature can affect cellular respiration, photosynthesis, decomposition of organic matter. Precipitation provides water to plants and animals increasing biomass and it connects to temperature to ensure that communities adapt and thrive.
How much energy is lost between each trophic level and why?
Typically 90% of energy is lost between each trophic level. This is due to multiple reasons:
- Energy is lost as heat from cellular respiration
- Not all biomass of organisms are consumed, and is broken down by decomposers and lost as heat
- Energy is lost through faeces and urine which is broken down by decomposers and lost as heat
- Some of the biomass is indigestible and excreted, and broken down by decomposers and lost as heat
Define excretion
Is the removal of waster products from metabolic reactions.
Define egestion
Removal of undigested materials from the body.
How is energy represented and what unit is used?
Energy at each trophic level is represented by the pyramid of energy which uses a unit of Kj m-2 yr-1.
What is the Gersmehl nutrient cycle?
It brings together abiotic and biotic factors. It is a graphical representation of how Biomass, Litter and Soil is interconnected to recycle nutrients for plants and animals living within an ecosystem.
How does a tropical rainforest look like according to Gersmehl nutrient cycle?
The majority of the nutrients are in the biomass and not in litter and soil. There is a fast rate of nutrient transfer between stores. This is due to high temperatures and precipitation causing high productivity and many layers of vegetation. There is also high rate of decomposition by decomposers.
How does a desert look like according to Gersmehl nutrient cycle?
Biomass and litter have few nutrients while the soil has the most nutrients. This is due to the low rainfall resulting in low biomass and therefore low litter in form of dead leaves and other vegetation.
How does a taiga look like according to Gersmehl nutrient cycle?
In taiga Litter contains the most nutrients. Soil contains low nutrients due to low temperatures restricting weathering. Low temperature also reduces the rate of breakdown due to low saprotroph activity.
Why are topical rainforests important ecosystems?
They account for a large uptake of the carbon dioxide in the atmosphere and release of oxygen. They also contain great biodiversity.
How does human interference affect rainforest and in turn the environment?
Humans cut down rainforests for farming of wood or for land to farm cattle, agriculture, road networks and so on. This increases amount of carbon dioxide in the atmosphere, reduces protection of moist soil from the heat.
What is ecological succession?
It is when there are continual changes in a community until a climax community is reached. Where an ecosystem develops from a simpler colonised community to a climax community.
What is primary succession?
It begins with lifeless land.
- Then there are pioneer species that refers to lichens or moss.
- After many years the lichens will breakdown barren land into soil
- Now simple grass can grow
- Grass modify the soil in which other vegetation can grow.
- this continues until a stable climax community is reached.
