Ecology Flashcards
Define species.
Organisms which can interbreed and produce fertile offspring.
What are the two conditions of interbreeding offspring?
- Members from one species can’t produce fertile offspring with members of another species.
- When members from two species do produce offspring by crossbreeding, the hybrid is reproductively sterile (Eg. mules).
Define population.
A group of organisms of the same species living in the same area at the same time.
How do different populations of the same species exist?
Distance creates reproductive isolation, but if those populations can functionally interbreed they are still classified as the same species.
Define community.
A group of organisms living and interacting with each other in an area.
Define habitat.
The environment in which a species normally lives/the location of a living organism.
Define ecosystem.
A self sustaining community of organisms living an a physical environment.
Define ecology.
The study of relationships between living organisms and their environment.
What are autotrophs?
Organisms which synthesise organic molecules from inorganic substances - self feeding.
What are the two ways autotrophs produce their own organic molecules?
- Photosynthesis - photoautotrophs which make organic compounds using energy derived from the sun.
- Chemosynthesis - chemoautotrophs make organic compounds using energy derived from the oxidation of chemicals.
Why are autotrophs referred to as producers?
Because they synthesise their own organic molecules.
What are heterotrophs?
Organisms which obtain organic molecules from other organisms.
What are the three types of heterotrophs and how do each obtain their organic molecules from other organisms?
- Consumers - Ingest organic matter which is either living or recently killed.
- Detrivores - Ingest non-living organic matter.
- Saprotrophs - Feed on non-living organic matter by secreting digestive enzymes and absorbing the products.
Why are heterotrophs referred to as consumers?
Because they cannot produce their own organic molecules and obtain it from other sources.
What are mixotrophs?
Organisms which can use both forms of nutrition depending on resource availability.
Which environment do autotrophs obtain their nutrients? Which nutrients are common?
Abiotic environment.
Carbon, nitrogen, hydrogen, oxygen and phosphorous.
What is the initial energy source for most communities?
Light (sun).
What are consumers?
Heterotrophs which feed on living organisms by digestion.
Name and describe the three types of consumers.
- Herbivores - feed on plant matter
- Carnivores - feed on animal matter
- Omnivores - feed on plant and animal matter
What are scavengers?
Types of consumers which feed on dead, decaying matter rather than hunting live prey.
What are detrivores?
A type of heterotroph which obtain nutrients from non-living organic sources, via internal digestion.
What are saprotrophs?
Organisms that live on non-living organic matter and release enzymes to absorb nutrients.
Why are saprotrophs commonly referred to as decomposers?
Because they facilitate the breakdown of dead organic material.
What is nutrient cycling and why is it imperative?
The process by which inorganic nutrients are maintained.
Imperative because the supply of inorganic nutrients on Earth (like chemical elements) is finite.
Describe photosynthesis.
Light energy to chemical energy/Inorganic molecules to organic molecules.
What is the significance of feeding (in the terms of food chains)?
Feeding is the way by which chemical energy in carbon compounds flows through food chains.
What happens to chemical energy after photosynthesis?
Chemical energy is stored in carbon compounds and transferred to heterotrophs by feeding.
Define trophic level.
The position an organism occupies within a feeding sequence.
What does a food chain show?
The linear feeding relationships between species in a community.
Energy stored in organic molecules can be released by ___ to form ___.
Respiration
ATP
Where is some energy stored in organic molecules lost instead of being transferred by heterotrophic feeding?
Excretion Remain unconsumed (leftovers)
Name three of the forms chemical energy produced by an organism can be transformed into.
- Kinetic energy (muscles)
- Electrical energy (nerve impulses)
- Light energy (bioluminescence)
What do all the forms chemical energy produced by an organism have in common?
All these reactions are exothermic and produce heat as a by-product.
What is made of the by-product that is heat of the forms chemical energy can be converted into? What is the conclusion then?
This heat can’t be used as other forms of energy, so it is lost from the ecosystem. Therefore, ecosystems require a constant influx of energy from an external source (like the sun).
Define biomass.
The total mass of a group of organisms - consisting of the carbon compounds in the cells and tissues.
What is the impact of energy loss between trophic levels on food chains?
Energy loss between trophic levels restrict the length of food chains and the biomass of higher trophic levels.
What is the 10% rule in relation to energy flow in a food chain?
The amount of energy that passes from one trophic level to the next is 10% of the previous trophic level.
Water can diffuse gases in an atmosphere under which conditions?
A diffusion gradient.
What is the carbon cycle?
A biochemical cycle whereby carbon is exchanged between the different spheres of the Earth.
What are the four spheres?
- Atmosphere - air
- Lithosphere - ground
- Hydrosphere - water/oceans
- Biosphere - living things
Name the four main forms carbon is majorly present as.
- Atmospheric gases
- Oceanic carbonates
- As organic materials
- As non-living remains
Name three effects of global warming.
- Combustion (burning of fossil fuels) - makes CO2 (and H2O) which blocks radiation from bouncing back into space.
- Changes in climate - longer summers and shorter winters; changes in distribution of insect vectors
- Rising sea levels - concern along coasts
Describe the greenhouse effect.
Solar energy passes through the atmosphere, warming the earth -> some of the suns energy is reflected back into space -> greenhouse gasses trap some of this heat that is trying to escape.
What is the difference between incoming radiation and re-radiated energy?
Incoming radiation is all wave lengths of the spectrum; re-radiated energy is just the long waves (infrared).
What are the main four greenhouse gases and where they excreted, for example?
- Water vapour - naturally
- CO2 - fossil fuels, cement production
- Methane - fossil fuels, waste dumps, rice paddies, livestock
- HFC’s - electronics, refrigerants, used to be air spray propellents
What is the precautionary principle?
When a human induced change will have a large effect on the environment, those responsible for the change must prove that it will not do harm before acting.
What are (minimum four) possible solutions for global warming?
- Set strict emission standards
- Reduce fossil fuel usage
- Develop alternate sources of energy
- Remove CO2 from emissions at the source
- Eliminate use of chlorofuorocarbons
- Reduce deforestation
- Develop agricultural techniques that release less CO2
