Distribution of organisms Flashcards
Why is light intensity important for plants?
They need light for photosynthesis
What does moisture describe?
Not just how much rain falls but also how much moisture is in the air and how much moisture stays in the soil
How can we shift pH?
Acid rain
Volcanic activity
Chemical pollution
What can pH impact?
Air
Soil
Water
What is acid rain linked to?
Air pollution
What does volcanic activity produce?
Chemicals that dissolve in water
What do all living things have?
A temperature range that they can live in
What happens to enzymes if temperature gets too hot?
They will denature and stop working
What could a small shift in temperature mean?
The difference between surviving and not surviving
What do abiotic factors usually do?
Combine, to create a huge variety of different habitats
What are conditions like in rainforests?
Hot, wet, shade
What are conditions like in deserts?
Hot, dry, sun
What does every organism have?
A tolerance curve for all sorts of different factors such as temperature
What is closely tied to the size of its prey population?
The number of predators
How can you tell what a predator has been eaten?
By studying faeces or regurgitated pellets
What can we also use faeces to determine?
Toxins accumulated in living things
When does grazing occur?
When herbivores eat the plants in an ecosystem
What can grazing have major effects on?
Biodiversity
How does low grazing affect biodiversity?
The most aggressive species pretty much take over. Nothing else gets a chance
How does moderate grazing affect biodiversity?
The most aggressive are held in check, allowing others to grow
How does high grazing affect biodiversity?
Only the most robust survive. Most are destroyed
What can disease cause?
Populations numbers to fall, reducing competition
How can disease indirectly affect predator populations?
It causes population numbers to fall which means predators have less to eat
How can disease indirectly affect plant populations?
They may be grazed less intensively as population numbers have fallen
What do all living things require?
Energy
What happens if there is a food shortage?
Some individuals may die. Whole species may not survive
Why do we measure abiotic factors?
We can begin to understand why different organisms are present in an ecosystem and which conditions they prefer
How can we discuss organism’s distribution?
Comparing the abundance of dif organisms and dif abiotic factors and how these abiotic factors impact their distribution
How can we measure light intensity?
Light meter
Name the possible sources of error when using a light meter
Light sensitive panel shaded by user
Weather conditions affect readings
How do we use a light meter?
Make sure the light sensitive panel is pointed towards the light source
How can we minimise errors using a light meter
Hold it at arms length
Don’t stand between sensor & light source
Take reading at the same time of day
How can we measure pH and moisture?
pH meter and moisture probe
How can we use a pH meter and moisture probe?
Stick them into the soil
What are possible sources of error when using a moisture probe?
Probe not cleaned between tests
How can we minimise error when using a pH meter and moisture probe
Always wipe probes between tests to avoid cross-contamination
How can we measure temperature?
Thermometer / temperature probe
What are some possible sources of error when using a thermometer / temperature probe
Probe not inserted deeply enough
Thermometer bulb held in user’s hand
How can we minimise error when using a thermometer / temperature probe
Push probe into soil to half its depth
Ensure bulb exposed to the air
What is sampling used to do?
Which organisms are present in an ecosystem, how abundant they are and to investigate why they are living there
How can we estimate the total number of organisms present in a whole ecosystem
By counting organisms found at random parts of an ecosystem
What are pitfall traps used to do?
Study mobile invertebrates in a soil ecosystem
What are the possible sources of error when using a pitfall trap?
Not representative
Animals eaten by birds
Animals eaten by other trapped animals
Traps too high above soil/animals would avoid
Traps left too long
How can we minimise these sources of errors when using a pitfall trap?
Not representative- Several samples taken
Animals eaten by birds- Disguise opening
Animals eaten by other trapped animals- Check regularly or use preservative solution
Traps too high- Ensure that the top of the trap is level with the soil surface
Traps left too long- Fill the trap with ethanol to kill organisms thus preventing predation
What is kick sampling used to do?
Sample aquatic invertebrates in water ecosystems
How do we do kick sampling?
Hold net downstream and scuff in the gravel above the net to dislodge the invertebrates
What happens to animals caught in kick sampling?
Animals are caught and stored in jars contains water from the ecosystem, and can be identified later
Why is a pooter set up?
So you can suck up the insects and collect them for identification
How do you treebeat and what does it allow?
Hold a white sheet or tray and shake the branches above.
It allows you to collect the insects that are on the branches
What is the main trick to sweep netting?
Closing/catching the net to catch the insects after sweeping through the air or water
What are quadrants used to do?
Estimate the number of plants or slow moving animals in an ecosystem
What are transects used to do?
To show how the distribution or species varies across an ecosystem and how the distribution of organisms depends on abiotic factors
How do we identify organisms that are collected or sampled?
Branched or paired statement key
What do branched keys do?
Ask a series of questions with yes/no answers which lead you to the identity of an organism
How does a paired statement key work?
Each number of statements which splits your group into 2
Each pair sends you to another number
You follow the statements until you get an answer
How can human activities impact the environment?
Reduces biodiversity by:
habitat destruction by deforestation (for farming, housing ect)
Reduction of numbers and biodiversity through overfishing and hunting
Desertification
Air and water pollution
How is pollution cause?
The presence of a substance (pollutant) which is harmful to the environment or it’s unsightly.
What four main ecosystems can pollutants affect?
Air
Freshwater
Sea
Land
What is an indicator species?
A species that shows how polluted or unpolluted an environment is through their presence or absence
What is organic pollution?
Any material from living or once living organisms
What does organic pollution include?
Manure
Sewage
Dead plants or animals
What does raw sewage contain?
Faeces
Food fragments
Bacteria
In raw sewage in river ecosystem what happens to dissolved oxygen?
Drops rapidly when sewage enters the river, then starts to recover downstream
Why does this happen to dissolved sewage?
Large numbers of bacteria use up the dissolved oxygen as they break down sewage.
In raw sewage in river ecosystem what happens to BOD?
Rises rapidly as sewage enters the river, then decreases steadily as you go downstream
In raw sewage in river ecosystem what happens to suspended solids?
These are particles of sewage. There are high levels as the sewage enters the river, then they decrease as you go downstream
Why does this happen to BOD?
The large numbers of bacteria in the sewage have a high demand for oxygen, which they use in respiration
Why does this happen to suspended solids?
The large particles are gradually broken down by the bacteria and eventually disappear
