The Living Environment Flashcards
What does the term ‘ecology’ mean?
Ecology is the science of ecosystems. It is the scientific study of the distribution and quantity of the organisms, and their interactions with their environment.
On what islands did Charles Darwin undertake research?
The Galapagos Islands.
Describe what a habitat is.
This is a place where an organism lives e.g. a pond. It supplies the needs of the organism such as food, water, oxygen and nutrients.
Describe what a population is.
A group of organisms of the same species e.g. a shoal of fish, oak trees in a wood and the human inhabitants of a town.
Describe what an ecosystem is.
A biological community of interacting organisms and their physical habitat.
Describe what a community is.
The sum total of all the populations of plants, animals and micro-organisms living in the ecosystem together.
Describe what biodiversity is.
The range of animals and plants in a given area.
Describe what a consumer is.
An organism that obtains its energy by eating other organisms.
Describe what a producer is.
Plants that begin food chains by producing food using the sun’s energy through the process of photosynthesis.
Describe what an autotroph is.
An organism that has the ability to produce its own food by converting the sun’s energy into chemical energy by the process of photosynthesis. Autotrophs are the producers in food chains. Green plants (including algae and plankton) are referred to as autotrophs.
Explain how green plants create food and energy.
Green plants absorb light energy using chlorophyll, a green pigment which is found in cells in their leaves. They use it to react carbon dioxide with water to make simple sugars such as glucose which provide food and energy for the plant to grow.
Carbon dioxide + Water = Glucose + Oxygen
Describe what a heterotroph is.
An organism that cannot produce its own food. Heterotrophs are consumers as they must consume plants or other animals in order to stay alive and grow. There are three main categories: herbivores, carnivores and omnivores.
What is a herbivore?
Herbivores (e.g. sheep) eat plant or vegetable matter only.
What is a carnivore?
Carnivores (e.g. lions) consume meat only.
What is an omnivore?
Omnivores (e.g. pigs) eat a mixture of plant and animal matter.
Describe what interdependence is.
When two or more organisms are reliant on one another.
Describe what respiration is.
The chemical change that takes place inside living cells, which uses glucose and oxygen to produce the energy organisms need to live. Carbon dioxide is a by-product of respiration.
Glucose + Oxygen = Carbon dioxide + Water + Energy
Describe what a food chain is.
A sequence of organisms, each of which feeds on a type of organism from the preceding food level.
In a food chain, the direction of arrow indicates the transfer of energy (energy flow).
Almost all food chains within an ecosystem are interconnected showing the interdependence between species, and form complex food webs.
State the different feeding or trophic levels.
- Primary producers include green plants, algae, and blue-green bacteria
- Primary consumers are herbivores which feed on green plants e.g. caterpillars
- Secondary consumers fed on primary consumers, e.g. spiders
- Tertiary consumers are at the top of the food web e.g. owls. They eat animals from all 3 levels below them, although may concentrate specifically on secondary consumers
Describe what a niche is.
A niche is the role or function of an organism in an ecosystem.
Describe what detritus is.
Detritus includes partly broken down dead plant and animal material, such as fallen leaves, seeds and berries, animal faeces and dead organisms. This material still has critical value to the flow of energy within an ecosystem and supports populations of detritivores and decomposers.
Describe what detritivores are.
Detritivores are organisms which feed on partly broken down dean plant and animal matter (detritus), e.g. wood lice and earthworms.
Describe what decomposers are.
Decomposers are micro-organisms which chemically break down waste materials and dead organisms using enzymes, e.g. bacteria and fungi. They also put nutrients into the ecosystem.
Describe what energy loss in ecosystems means.
Technically energy is not “lost” but converted to other forms such as heat and sound energy. Within ecosystems, energy is said to be “lost” when it is not made available to the trophic level above. Generally only 10% of the energy consumed by an organism is made available to the next trophic level, and food chains can usually sustain no more than six energy transfers before all the energy is used up.
State the two main reasons why energy is lost in ecosystems.
- Animals use up energy to build up their body weight. However when some of this is eaten by a predator, some parts may have no nutritional value such as cellulose, bones, skin or horns. These are left uneaten or expelled as undigested waste or faeces, and as a result energy is effectively “lost” from the food chain.
- Energy gained by a consumer in its food is used for moving around, and in warm blooded animals such as mammals, for keeping warm. Only a tenth of the energy taken in is used for building up body tissue, with most being lost as heat or through respiration.
Describe what ecological productivity is.
The productivity of an ecosystem is the rate of production or the amount of organic matter (biomass) formed or accumulated per unit area in unit time.
What is the definition of biomass?
The mass of living material.
Describe what gross productivity is.
Gross productivity is the measure of all photosynthesis, or creation of chemical energy, that occurs in an ecosystem.
Describe what net productivity is.
Net productivity is the energy which is left after losses as a result of respiration, growth, heat and movement.
How would you calculate the net productivity.
If a plant makes 100 molecules of glucose from photosynthesis but only uses 35 molecules to grow, the net productivity is 65 molecules, which is available to consumers.
Explain what an endotherm is.
Endotherms are organisms which can control their internal body temperature (e.g. mammals and birds). They have high metabolic rates and have to eat frequently to obtain energy.
Explain what an ectotherm is.
Ectotherms are organisms that cannot control their internal body temperature and rely on their external environment for temperature control (e.g. invertebrates, most fish, reptiles and amphibians). They have lower metabolic rates and feed less regularly. Physical activity is restricted to certain times of the day (night time).
What are the four primary ecological events which affect the density of a population?
There are four primary ecological events which affect the density of a population: births, deaths, emigration (organisms moving away) and immigration (organisms moving in).
How do you calculate the change in population density?
Change in population density = (births + immigrants) – (deaths + emigrants)
Describe what the carrying capacity is in an ecosystem.
The maximum number of individuals of a species that can be supported by an ecosystem. If the population of a species exceeds the carrying capacity, death rates may exceed reproduction and a population crash may result.
Describe what a density dependent factor is.
These include rates of predation, the competition between species of the same population and with other species, rates of disease and symbiotic relationships such as parasitism.
Describe what a density independent factor is.
These are conditions which will affect an ecosystem, regardless of the number of species within a particular area including weather related events such as heavy rainfall, freezing temperatures and factors such as a decrease in the concentration of oxygen (aquatic ecosystems) and the risk of fire.
Describe what inter-specific competition is.
The competition which occurs between organisms of different species for a common resource within an ecosystem.
Describe what intra-specific competition is.
The competition between organisms within the same species for a common resource in an ecosystem.
Describe what symbiosis is.
Members of two different species having a type of ecological interaction that affects both populations.
Describe what parasitism is.
An interaction between two species where one organism benefits and causes harm to the other organism.
Describe what commensalism is.
A type of relationship between two organisms where one organism benefits but the other is unaffected.
Describe what mutualism is.
A type of relationship where both organisms benefit from the proximity of one another.
