Ecology Flashcards
Ecosystem
A community of organisms and its
environment, and the interactions between them.
Biodiversity
The full range of different living things in a region
Biodiversity can be described at different levels…
Species diversity, ecosystem diversity, all ecosystems in the biosphere.
Biotic factors
Living factors within an ecosystem, such as animals or plants.
Abiotic factors
The nonliving components of an ecosystem. They are not living, but they affect living things.
Examples of abiotic factors
Temperature, soil texture and pH, wind speed and direction.
Importance of biodiversity for humans
Contributes to food production, purified water and air, fuels, pharmaceuticals, tourism, culture.
Importance of biodiversity for ecosystem health
Photosynthesis provides oxygen, nutrient cycling uses organic and inorganic matter from dead organisms to support new life, population interactions maintain balance and diversity, pollination is essential for reproduction.
The original source of all energy, how it flows and its ultimate fate in ecosystems.
The sun.
Photosynthesis
The process used by plants to turn sunlight, carbon dioxide, and water into energy (glucose/sugars) and oxygen.
(Cellular) respiration
The metabolic process of chemical breakdown of organic matter to release energy. Producers also perform this.
Cellular respiration equation.
Glucose + oxygen –> carbon dioxide + water + energy
Photosynthesis equation
Carbon dioxide + water (light energy+chlorophyll) –> glucose + oxygen
Different relationships between organisms
Predation, mutualism, parasitism, competition, pollination, disease, commensalism
Predation
One organism (the predator) kills another organism (the prey) and consumes some or all of it for food
Mutualism
An interactive relationship where both organisms benefit.
Parasitism
One organism, usually physically smaller of the two (the parasite) benefits and the other (the host) is harmed.
Competition
When individuals compete for a resource that limits their survival (food, habitat) and reproduction.
Pollination
An interactive relationship where both organisms benefit.
E.g. Pollination. The pollinator benefits from feeding on the nectar and the plant benefits by being pollinated.
Disease
The interaction between a disease-causing organisms and the host can affect the biodiversity of an ecosystem
e.g. Chlamydia (bacteria) can cause disease in koalas, affecting their ability to produce offspring.
Interspecific competition
Occurs between members of different species.
Intraspecific competition
Occurs between members of the same species.
Adaptation
The adjustment of organisms to their environment in order to improve their chances at survival.
Three types of adaptation
Structural, behavioural, and functional (physiological)
Structural adaptation
Unique features of the body that help the organism survive in its environment. Example: sharp claws in koalas to help them grip tree trunks.
Behavioural adaptation
Something an animal does in response to external stimuli in order to survive. An example is hibernating in winter.
Functional/physiological adaptation
Processes inside an animal’s body that help it survive in its environment. Example: snakes produce venom to paralyse their prey and make them easier to digest.
The sun
The primary source of energy. It provides energy to earth as heat and light. It is the major source of energy that drives the diverse ecosystems on earth.
Autotrophs/producers
They are also known as producers. They use the energy from the sun and simple inorganic substances to manufacture organic matter (food). Examples: plants, some bacteria, algae.
Photosynthesis chemistry
Energy is stored in the chemical bonds and is released when the chemical bonds are broken.
Food chains and food webs
Qualitative, predictive models that allow ecologists to monitor the sustainability of feeding relationships in an ecosystem.
Trophic level
Each position an organism has in a chain is referred to as a trophic level. Energy and matter are transferred progressively from one trophic level to the next.
Energy flow in food chains.
Each organism in a food chain feeds on, and therefore obtains its energy and matter from, the preceding one.
Food webs
Integrated food chains. A group of food chains that are linked together showing the interactions between food chains in a community.
Difference between a food chain and web
The feature that distinguishes a food chain from a food web is that an organism can occupy different trophic levels in different food chains.
Members of populations can
Move in and out of food chain/webs at different times e.g. birds feeding off seeds in different ecosystems depending on their needs.
Energy flow from plant to herbivore is
Not 100% efficient. ~10% energy transfer from producer to consumer. Not all plant material is eaten or absorbed from the gut. And energy is lost through movement and respiration.
Decomposers
Bacteria and fungi recycle matter. Dead plant and animal material is broken down to become available by plants.
Energy in ecosystems
Energy is lost in ecosystems. Heat loss and energy transfer. Energy is NOT recycled.
Matter
Matter is RECYCLED through interconnecting cycles.
Trophic levels
Producers, primary consumers, secondary consumers, tertiary consumers/apex predator.
Consumers
Acquire energy and matter by consuming other organisms eg. animals, most bacteria, fungi.
Primary consumers/herbivores
The second trophic level. They eat primary producers (plants or algae). They extract the energy stored in the chemical bonds by cellular respiration.
Heterotrophs
Cannot synthesise their own organic compounds from inorganic materials. (ie. they can’t make their own food). Depend on autotrophs directly or indirectly for energy needs and supply of matter.
Secondary consumers
Organisms that eat primary consumers for energy. Secondary consumers can either be carnivores or omnivores. Carnivores only eat other animals, and omnivores eat both plant and animal matter.
Tertiary consumers/apex predator
Usually at the top of food chains, capable of feeding on secondary consumers and primary consumers. Tertiary consumers can be either fully carnivorous or omnivorous. Humans are an example of a tertiary consumer.
Importance of nitrogen for living things
Nitrogen is used to make RNA and DNA as well as proteins.
Importance of the nitrogen cycle
Organisms can’t use nitrogen directly from the air in N2 (gas) form. It must be converted to nitrates.
Steps of the nitrogen cycle
Nitrogen fixing, decomposition and ammonification, nitrification, denitrification.
Nitrogen fixing
Lightning (only small amount) N2 converted into NO2
Nitrogen fixers in soil (bacteria in soil).
- Free living – absorb nitrogen gas from air spaces in soil and build it into amino acids
Nitrogen fixers in nodule bacteria
- Specialised bacteria invade the fine root hairs of plants causing the formation of nodules.
- This symbiotic relationship provides the bacteria with carbon, and the bacteria deliver additional nitrogen to the plants.
Decomposition (nitrogen cycle)
Decomposers break down dead organisms, urine and faeces returning nitrogen to the soil as ammonia (NH3)
After nitrogen fixing
Plants absorb the nitrogen from the nitrogen fixing stage
The absorbed nitrogen is built into;
proteins and
nucleic acids
Animals consume nitrogen in food (plants/ animals)
Ammonification
Bacteria or fungi present within the soil, convert the organic matter back to ammonium. (NH4+) Nitrogen Cycle
Nitrification
Plants struggle to absorb ammonium
Nitrifying bacteria convert ammonium to nitrite
Nitrites cannot be absorbed by plants
Other nitrifying bacteria convert nitrites into nitrates
Nitrates can be absorbed by plants
Denitrification
Denitrifying bacteria turn nitrate (NO3-) into nitrogen gas (N2)
The nitrogen gas is released back into the atmosphere
The Denitrifying process also releases oxygen which can be used by plants growing in waterlogged soils where oxygen is in short supply
Nitrogen gas in the atmosphere composes…
70-80% of air.
Impact of fire on Australian ecosystems
Habitat loss, death, reduced biodiversity, increased air pollution, reduced food sources for animals.
Impact of drought on Australian ecosystems
Kills plant and animal life, food loss/shortage, soil erosion.
Impact of flooding on Australian ecosystems
Water contamination, habitat loss, death of plants and animals.
Types of pyramids
Numbers, biomass, energy.
Pyramid of numbers
The width of each level represents the relative numbers of organisms per level.
Pyramid of biomass
The amount of organic matter per trophic level.
How can small populations of primary consumers support larger populations of secondary consumers?
They reproduce fast.
Pyramid of energy
Show the rate of energy transfer between trophic levels. Organisms at the top only get a small amount of energy, so they have to eat a lot to fulfil their needs.
