Ecosytems 🌍 Flashcards
Define ecosystem
An ecosystem is a community of organisms and the physical environment they live in
What is a community?
Populations of different species that live and interact with each other
What is a population
All the organisms of a particular species living in the same are
What does interdependence mean
All the organisms depend on each other for resources
What is a habitat
A place in which the organism lives
What are the two main ways energy is lost in a food chain
Waste materials
Different living processes such as movement or growth
3 ways to improve efficiency of a food chain
Reduce the number of stages in a food chain
Limit the animals movement or keep it warm
Use plant hormones to regulate the ripening of fruit (ethene )
What are abiotic factors
Non living factors eg. temperature, rainfall
What are the effects of too hot temperatures (abiotic factors)
Raining temp causes sea ice to melt and so habitat size is decreasing.
Affects organisms such as polar bears living in the Arctic
What are the effects of too cold temperatures (abiotic factors)
Both plants and animals would be affected as it would become increasingly difficult to regulate internal body temperatures- chemical reactions wouldn’t be able to take place
What are the effects of too much water (abiotic factors)
Excessive moisture in the soil decreases oxygen levels which causes the plant growth to slow or even stop
What are the effects of too little water (abiotic factors)
Plants lacking water means they can’t photosynthesise
What are the effects of too little light (abiotic factors)
Without adequate light plants can’t photosynthesise and so die
What are the effects of too much light (abiotic factors)
Too much light can cause the breakdown of chlorophyll in the leaf and eventually they die
What are biotic factors
The organisms in an ecosystem that affect other living organisms
What are the 2 biotic factors
Predation
Competition
What is predation
Where one organism predates on another
What is competition
Occurs between species when they both need a limited resource
What is symbiosis
The ecological relationship between 2 or more organisms living closely together with some sort of feeding relationship involved
What is mutualism
Where both organisms benefit
(Eg. A bumble bee and a pollinating flower)
What is Commensalism
Where one organism benefits and the other is not harmed
(Eg. Cattle egrets & livestock)
What is Parasitism
Where one organism is benefited and causes harm to the other
(Eg. Endoparasites & ectoparasites)
What is an endoparasite and give 2 examples
Parasites that live inside the host
Eg. Tapeworms and roundworms
What is an ectoparasite and give 2 examples
A parasite that lives outside the body of the host
Eg. Lice & ticks
What is nitrogen used for in living organisms
To make proteins and dna
Why can’t the nitrogen be used directly by our cells
Although the atmosphere is 80% nitrogen it can’t be used directly as it is UNREACTIVE
What is the role of nitrogen fixing bacteria in the nitrogen cycle
Converts nitrogen back into nitrates
What is the role of denitrifying bacteria in the nitrogen cycle
Breaks down the nitrates in the soil and released nitrogen gas back into the air
What is the role of nitrifying bacteria in the nitrogen cycle
Breaks down the proteins in dead organisms or excrements which releases nitrates back into the soil
What are the two ways nitrogen fixing bacteria releases nitrates
Releasing them straight back to the plant (by root nodule bacteria)
Releasing them to the soil (by soil bacteria)
What other method (not bacteria) can release nitrates back into the soil
Lightning
What is the name of the general fertiliser farmers use to improve leaf growth
NPK fertiliser
What is the effect if pollutant levels are too high (abiotic factors)
Air pollutants such as sulfur dioxide are released from the burning of coal.
Lichens cannot survive if the concentration of sulfur dioxide is too high.
What is fish farming
Producing more fish in a small enclosed spaces to reduce over fishing of wild fish
What are the pros of fish farming
Numbers increase rapidly (more fish are harvested)
Wild fish are not fished on as much
What are the cons of fish farming
1 Too many fish kept in small spaces means that diseases or parasites spread more easily
2 Uneaten food and faeces sink to the bottom and change conditions of the water possibly harming the organisms that live there
What are indigenous or native species
Organisms that have always lived there
Why do humans introduce species to an environment
Often to reduce numbers of another species within the ecosystem which has got out of control
What is eutrophication
When lots of nutrients are added to the environment or ecosystem such as a river
How does eutrophication decrease biodiversity of a river
Nutrients added to the water cause an increase in growth of algae
Means plants under the water don’t get enough light to photosynthesise so die
An increase in dying plants provides food for decomposer bacteria so their number grown rapidly
Oxygen concentration decreases due to as well as the plants not releasing any oxygen into the water the bacteria also consume a lot
Therefore animals (fish) can’t get enough and so die
How can eating farmed fish protect biodiversity in the wild
Less wild fish are caught = enables population to stabilise
What is desalination
Obtaining fresh water from seawater
How is co2 removed from the atmosphere
Photosynthesis - use carbon to make complex molecules such as proteins carbohydrates and fats
How is co2 returned to the atmosphere
Respiration & combustion
How is co2 passed form one organism to the next
Decomposers eating waste material &
Animals feeding
Give a step by step process for the carbon cycle
Co2 enters atmosphere from respiration and combustion
Co2 is absorbed by producers to be used in photosynthesis
Animals feed on plants passing carbon compounds along. Most is exhaled in respiration. Animals and plants eventually die
Dead organisms are eaten by decomposers (carbon in their bodies is returned to the atmosphere as co2)
What is used to sample plants
A quadrat
What is essential about how you place quadrats when sampling populations in an area
That they are placed RANDOMLY
What are the 3 things we can find out using quadrats
Population size
Species richness
Percentage cover
What is population size (sampling)
The total number of individuals of one species eg daisies
What is species richness (sampling)
The number of different plant or animal species (not the number of individuals within the species)
What is percentage cover (sampling)
Percentage of quadrat covered by 1 species (can do this by looking at wether the species is present in each square of the quadrat)
What is the equation for population size (sampling)
Population size = number of organisms in all quadrats x total size of area where the organism lives
———————————————————
total area of quadrats
When is random sampling used
Used to sample a large area, usually for a population size estimate
When is transect sampling used
To investigate a gradual change in a habitat
A line across a habitat or part of a habitat is sampled with number of organisms being recorded at regular intervals
What can we measure when describing vegetation (sampling)
Density
Percentage frequency
Percentage cover
Biomass
Height
Leaf area
What is an indicator species
A species that can indicate the presence, absence of abundance of a specific environmental condition.
What does an area with high levels of lichens show?
Low pollution
What does an area with NO lichens show?
High pollution
What does the presence of black spot fungus indicate?
Low levels of sulphur pollution
What 3 species indicate low water pollution levels?
Stonefly nymph
Dragonfly nymph
Freshwater shrimp
What 2 species indicate a high level of water pollution
Blood worms
Sludge worms
What CONDITIONS are best for a fast rate of decomposition?
Microorganisms that cause decay work best in…
WARM & MOIST conditions, many also require OXYGEN to aerobically respire
Rate of decomposition =
Mass lost ÷ number of days
How can reducing water content of foods help preserve them?
Decomposers need water for growth and reproduction
How can pickling with vinegar preserve food?
Reduces the pH - slows down decomposer reactions
Why does crop rotation improve soil fertility ?
Different crops remove different nutrients from the soil
Some plants eg.clover have nitrogen fixing bacteria in their roots - adds nitrates to the soil
