Ecosystems and biodiversity; quadrats; pyramids of Number, biomass and energy; Energy transfer and Food Webs Flashcards
What is a habitat?
The place where an organism lives, e.g. a rocky shore or a field.
What is a population?
All the organisms of one species in a habitat.
What is a community?
All the different species in a habitat.
What is an ecosystem?
All the organisms living in a particular area and all the non-living (abiotic) conditions, e.g. temperature, climate, soil-type.
What is biodiversity?
The variety of different species of organisms on Earth, or within an ecosystem.
Why is high biodiversity important?
It ensures that ecosystems are stable because different species depend on each other for shelter and food.
What human actions are reducing biodiversity?
Deforestation, pollution, and global warming.
How do environmental changes affect communities?
They can cause population sizes to increase or decrease, or change the distribution of populations.
What is an example of an abiotic factor affecting communities?
Environmental conditions: The distribution of bird species in Germany is changing due to a rise in average temperature.
What are toxic chemicals and their effect on ecosystems?
Chemical pesticides can build up in food chains through bioaccumulation, leading to toxic doses in top predators.
What is eutrophication?
A process caused by excess fertilizers released into lakes and ponds, leading to the death of organisms.
How does food availability affect populations?
In a bumper year for berries, the population of blackbirds might increase due to sufficient food. So they are more likely to survive and reproduce.
How does the number of predators affect prey populations?
If the number of predators decrease, the number of prey might increase due to fewer being eaten.
What is competition in ecosystems?
Organisms compete with other species and members of their own species for resources like light, space, water, and food.
What abiotic factors could affect the population size of a species?
Examples include temperature and light intensity.
What is a quadrat?
A quadrat is a square frame enclosing a known area to compare the population size of an organism in two samples areas
How do you use a quadrat to study population size?
1) Place a 1 m² quadrat randomly in the sample area. 2) Count the organisms of interest. 3) Repeat steps 1 and 2 multiple times. 4) Calculate the mean number of organisms per quadrat. 5) Repeat in a second sample area. 6) Compare the two means.
How do you estimate population size from a quadrat sample?
Multiply the mean number of organisms per m² by the total area of the habitat.
What is the formula to calculate mean number of organisms per m²?
Mean = total number of organisms ÷ number of quadrats.
How do you use belt transects?
1) Mark out a line in the area of study. 2) Collect data using quadrats placed next to each other. 3) Count organisms or estimate percentage cover. 4) Record additional data (e.g. mean height, abiotic factors). 5) Repeat and find means, then plot graphs.
What is the purpose of using quadrats in ecology?
To measure biodiversity and study the distribution of organisms across different habitats.
What should you ensure when placing a quadrat?
Place the quadrat in a random location to ensure representative results.
Estimate the total population of buttercups in a 1200 m² field with a quadrat area of 0.25 m² and a mean of 0.75 buttercups per quadrat.
Total population = (Mean per m²) × (Total area) = (0.75 ÷ 0.25) × 1200 = 3600 buttercups.
What do food chains start with?
Food chains always start with a producer, e.g. a plant.
What do producers do?
Producers make (produce) their own food using energy from the Sun.
What are primary consumers?
Primary consumers are organisms that eat producers.
What are secondary and tertiary consumers?
Secondary consumers are eaten by tertiary consumers.
What do decomposers do?
Decomposers break down (decompose) dead material and waste.
What is a trophic level?
Each stage (e.g. producers, primary consumers) is called a trophic level.
What is an example of a food chain?
5000 dandelions → 100 rabbits → 1 fox.
What does each bar on a pyramid of numbers represent?
Each bar shows the number of organisms at that stage of the food chain.
How does the number of organisms change in a pyramid of numbers?
Every time you go up a trophic level, the number of organisms goes down.
What does a pyramid of biomass show?
It shows the mass of living material at that stage of the food chain.
What shape are biomass pyramids typically?
Biomass pyramids are practically always the right shape.
What do pyramids of energy show?
They show the energy transferred to each trophic level in a food chain.
What shape are pyramids of energy transfer?
Pyramids of energy transfer are always the right shape — a nice, regular pyramid.
What should you know when interpreting a pyramid?
Make sure you know if it’s a pyramid of number, biomass or energy transfer.
What does the arrows represent?
The transfer of energy
What is the primary source of energy for nearly all life on Earth?
Energy from the Sun is the source of energy for nearly all life on Earth.
How do plants use energy from the Sun?
Plants use energy from the Sun to make food during photosynthesis.
What happens to energy as it moves through the food chain?
Energy works its way through the food chain as animals eat the plants and each other.
What percentage of energy is typically lost at each trophic level?
Around 90% of the energy is lost in various ways.
What are some reasons energy is not passed on to the next trophic level?
Some parts of food aren’t eaten, and some parts are indigestible, passing out as waste.
What explains the pyramids of biomass and energy in food chains?
Material and energy are both lost at each stage of the food chain.
How is energy used by organisms?
A lot of the energy taken in is used for staying alive, i.e., in respiration.
What happens to most of the energy taken in by organisms?
Most of this energy is eventually transferred to the surroundings by heat.
What percentage of total energy becomes biomass?
Only around 10% of the total energy available becomes biomass.
What do food webs illustrate?
Food webs show how food chains are linked within an environment.
What does interdependence in a food web mean?
All species in a food web are interdependent, meaning changes in one species affect all others.
What happens if a species in a food web decreases significantly?
If a species decreases, it can lead to less food for its predators and an increase in the prey population.
How are food webs typically structured in nature?
Food webs are normally tangled together and interlinked like a bowl of spaghetti.
