Ecology and Ecosystems QUIZ Flashcards
Discuss the relationship between atmospheric carbon dioxide levels and global temperatures.
There is a STRONG, POSITIVE CORRELATION between atmospheric carbon dioxide levels and global temperatures. Atmospheric carbon dioxide concentrations are increasing due to a number of anthropogenic (human-induced) activities, such as: industrial practices (combustion of fossil fuels), deforestation (less CO2 transferred to the biosphere), agriculture (land clearing and methane production). This leads to an enhanced greenhouse effect, which increases global atmospheric temperatures. This, in turn, leads to more frequent extreme weather conditions, causing changes to ocean currents and threatening the viability of different ecosystems.
Know definition of autotrophs.
Autotrophs synthesize their own organic molecules from simple, inorganic substances (CO2 nitrates).
Ex: Phytoplankton, cyanobacteria, plants
Know definition of consumers.
Heterotrophs that ingest organic matter that is living (or that has recently been killed).
Ex: carnivores, herbivores, omnivores, scavengers
Know definition of detritivores.
Heterotrophs that ingest non-living organic matter such as detritus (decaying/dead organic matter, faeces) and humus (dead/decaying mixed in with topsoil).
Ex: earthworms, “bottom feeders,” woodlice, dung beetles
Know definition of saprotrophs.
Heterotrophs that feed on/decompose non-living organic matter by secreting digestive enzymes and then absorbing the products (internal digestion).
Ex: bacteria, fungi
Distinguish between autotrophs and heterotrophs.
Autotrophs synthesize organic molecules from INORGANIC NUTRIENTS within the environment, such as light (from the sun/photoautotrophs) or oxidation (chemoautotrophs).
Heterotrophs obtain organic molecules from OTHER ORGANISMS via a variety of feeding methods and food sources. Examples include; consumers ingest other living organisms, detritivores ingest detritus/decomposing matter and faeces, saprotrophs externally digest dead organisms.
Explain how energy enters, flows through and is lost from food chains/ food webs (and how this limits the number of trophic levels/ biomass at each trophic level).
Energy cannot be recycled - there must be a constant influx of energy within an ecosystem (ex: light from the sun). Light is the initial source of energy for almost ALL communities, though some producers derive energy from chemical processes. Producers/autotrophs convert light energy into chemical energy via photosynthesis. That chemical energy is the obtained by heterotrophs via feeding.
However, not all of an organism is swallowed/ingested when heterotrophs feed, as there are parts left to decay. Also, not all of the ingested food is absorbed and converted into energy, as metabolic wastes are turned into faeces. Most of the energy is “lost” as heat: the energy stored in organic molecules is released via cellular respiration in both heterotrophs and autotrophs to make ATP, which creates heat as a byproduct. Living organisms cannot transform this heat into other usable forms of energy, so it is released into the atmosphere, “lost,” and must be constantly replenished by an external source. At each trophic level, the amount of energy available is only -10% of the available trophic level before it. The inefficiency of energy transfer between trophic levels LIMITS the length of food chains and the amount of biomass of higher trophic levels.
Explain how increasing carbon dioxide levels in the atmosphere can lead to ocean acidification and coral death.
The oceans are a major carbon sink (stores CO2 from the atmosphere). Some of the CO2 remains dissolved, but most of it is chemically converted into carbonic acid, which dissociates to release H+ ions. However, an increase in greenhouse gasses may lead to an enhanced greenhouse effect, increasing atmospheric temperatures, causing more frequent and extreme weather conditions (heat waves, tropical storms, forest fires, etc.). This could cause changes to ocean currents and increase ocean acidity. Increased ocean acidity lowers the ocean’s pH and carbonate levels, which is required for shells and exoskeletons. These conditions can cause coral to expel mutualistic algae, leading to coral bleaching.
What results in the greatest loss of energy from food chains/food webs?
Cellular respiration, as it produces the MOST heat.
Outline the role of methanogenic archaeans in the carbon cycle.
Methanogenic archaeans produce methane from organic compounds in ANAEROBIC CONDITIONS (ex: wetlands, marine sediments, digestive tract of ruminants). Methane then diffuses into the atmosphere or accumulates underground to form deposits. In the atmosphere, methane is oxidized to form carbon dioxide and water.
Outline the formation of peat (including the environmental conditions required for its formation)
Peat forms when organic materials is not fully decomposed because of acidic and/or anaerobic conditions in waterlogged soils. Saprotrophs break down dead organisms and return their nutrients to the soil (nutrient cycling). This decomposition is an AEROBIC process. Waterlogged soils create anaerobic conditions. Anaerobic respiration in these soils creates organic acids. Saprotrophs are inhibited by acidic conditions, so organic matter is not fully decomposed and carbon-rich molecules remain in the soil, forming peat.
Explain the movement of inorganic nutrients in ecosystems.
Nutrients must be recycled. So, saprotrophs break down dead/decaying organic matter into simpler organic forms, returning carbon, nitrogen, and other nutrients to the soil, water, and atmosphere to be used by producers to create organic compounds again. Carbon dioxide and oxygen are cycled through photosynthesis and cellular respiration.
Outline the general characteristics of an ecosystem.
All ecosystems:
- Are sustainable (productive and successful for long periods of time).
- They recycle nutrients.
- Energy flows through them.
- They contain producers and decomposers/saprotrophs.
Outline the features of ecosystems that make them sustainable.
Ecosystems must have available energy and a constant input of energy (producers make energy rich carbon compounds from inorganic nutrients in the abiotic environment, which are used by producers and passed on to consumers through feeding). This chemical energy is transformed into heat by biological processes such as cellular respiration, so energy must always be replenished by the sun.
Nutrients must also be recycled. So, saprotrophs break down dead/ decaying organic matter/ compounds into simpler inorganic forms, returning carbon, nitrogen etc. to the soil, water, and atmosphere to be used by producers to
create organic compounds again.
Water must be available (via rainfall, water cycle, transpiration, etc.)
Know the definition of population.
Group of organisms of the same species, living in the same area at the same time.
Ex: a population or rabbits in a meadow.
