TOPIC 3 LIFE PROCESSES Flashcards
Examples of biotic factors
- Food supply
- Pollination
- Seed dispersal
- Disease
Examples of abiotic factors
- Light
- pH
- Water
- Mineral nutrients
Wat is a random mutation?
A random change in the DNA sequence of an organism
Why is a species with a large gene pool more likely to survive?
Larger range of traits and potential adaptations to occur
What is likely to happen when a species receive a random advantageous mutation?
Increase their chance of survival and ability to reproduce
What is likely to happen when a species receive a random negative mutation?
Most likely to be outcompeted and killed
What is Ecological succession?
The process by which the mix of species and habitat in an area changes over time
What is a Sere?
The sequence of changes in Ecological Succession during which an uncolonised habitat develops into the climax community
What are Seres often named after?
The conditions at the beginning of succession
eg. Water: Hydrosere;
Bare Rock: Lithosere;
Sand: Psammosere.
What is the Climatic Climax Community?
The sequence of new species colonising, thriving, then dying out, continues until a final community of species develops which remain dominant as long as the climate does not change.
What are the first organisms to colonise called?
Pioneer species
What is a plagioclimax community?
A Plagioclimax community is an area or habitat in which the influences of the humans have prevented the ecosystem from developing further
Example of plagioclimax community?
Sand dune to do erosion from walking
List the FIVE approaches used to manage the plagioclimax in the UK include
- Grazing
- Burning
- Mowing
- Ploughing
- Felling at intervals of 8 to 20 years
Why do we manage plagioclimax
To maintain an area
What does Grazing do?
Prevents habitats such as water meadows from becoming overgrown. It arrests (stops) succession and the dominance of large species
What does mowing do?
Preserves lawns and fields
How can burning be used?
To maintain habitats rich in plants such as Heather
How can regular felling help sustain plagioclimax?
- Encourages diversity
- Allows branches to re-grow
What 4 things affects population size?
birth rates
death rates
immigration
emigration (moving away)
What is the maximum sustainable yield?
an estimate of the greatest exploitation that is possible, without causing unsustainable long-term population decline
What are R-selected species?
Species that respond RAPIDLY to low survival rates
What can r-selected species do and an example?
reach sexual maturity quickly
eg.spiders
What are K-selected species?
Species that recover SLOWLY from a decline in population
