Ecosystems Flashcards
What is a habitat?
The place where an organism lives
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 particularly area and all the non-living (abiotic) conditions
What can you use to estimate a population size?
A quadrat - a square frame enclosing a known area
Describe an experiment to estimate a population size
- Place 1m2 quadrat on the ground at a random point within the area you’re investigating
- Count all the organisms within the quadrat
- Multiply the number of organisms by the total area of the habitat
- Repeat in another area and compare the population sizes (get an average)
What do you need to think about when using the counting method?
Sample may he not representative of the population - may be different in other places
Sample size affects the accuracy - the bigger the sample, the more accurate your estimate of the total population is likely to be
What else can the quadrats be used to investigate?
Distribution of organisms
Describe an experienced to show the distribution of organisms
- Mark out a line (transect) in the area you want to study
- Collect data along that line using quadrats placed next to each other
What do food chains show?
What’s eaten by what in an ecosystem
What does a food chain always start with?
A producer which makes its own food using the energy from the the sun
What are producers eaten by?
Primary consumers which are then eaten by secondary consumers which are eaten by tertiary consumers
What happens to all the organisms eventually?
- They die and get eaten by decomposers like bacteria.
- Decomposers break down dead material waste
What is each stage of a food chain called?
A tropic level
What does each bar on a pyramid of numbers show?
The number of organisms at the stage of the food chain
What goes at the bottom of a pyramid of numbers?
The organisms that are at the bottom of the food chain
What is a typical pyramid of numbers looks like?
Every time you go down the tropic level, the number of organisms decreases
What does a pyramid of biomass show?
The mass of the living material at that stage of the food chain (how much all organisms at each level weigh together)
What re pyramids of biomass always the same of?
The right shape
What are pyramids of energy transfer always the shape of?
Pyramids the right way up like a regular pyramid
What do pyramids of energy show?
The energy transferred to each trophic level in a food chain
What is energy from the sun a source of for all?
A source of energy for nearly all life on earth
What do plants use light energy for?
Photosynthesis from the sun - this energy then works its way through the food chain as animals eat the plants and each other
Why is not all the energy that’s available to the organisms in a tropic level passes on to the next level?
90% of energy is lost in varied ways
Give some of the examples of how energy is lost
- Not all food is eaten (e.g the roots and bones)
- Some parts of the food are indigestible (e.g. fibre) so pass through and come out as waste
- Energy is used for respiration
- Energy lost to the surroundings as heat
How much of the total energy becomes biomass?
10% as it’s stored or used for growth (only energy transferred to the next trophic level)
What do food webs show?
How food chains are linked as there are many different species within a environment which means a lot of possible food chains
What are all the species in a food web?
Interdependent - if one species is affected, all the others are
