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Flashcards in The Living Environment Deck (43)
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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.