HUMAN IMPACT Flashcards
(30 cards)
Define endangered species
Species whose number has fallen drastically and in serious risk of extinction
Define extinct species
No living members of species remaining
4 ways extinction may occur
Deforestation
Over hunting
Drainage of wetlands
Hedgerow loss
What is an advantage of new mutations
Can give arise to advantageous alleles / genes
Define natural selection
Organism adapts to changing environments
When new mutations can’t occur quickly enough for survival what happens to the once established characteristics
They become selected against the altered environment
What is a non contiguous population
When a small group of species are isolated from each other and are unable to interbreed
This causes lack of genetic diversity and may lead to extinction
What is an example of a non contiguous species
Black rhino from Africa
Examples of wetlands
Edges of lakes, ponds, marches, low lying areas
What might wetlands be drained for
Agriculture or building
Why might removal of hedgerows be useful for farmers
Allows larger machinery on open fields to harvest more crops
Why 3 things might loss of hedgerows cause negative effects on biodiversity
Removes breeding and feeding sites and wildlife corridors which allow animals to move from one area to another
Increase soil erosion by rainfall where hedgerows are removed
Increased predation by crops by insects that would normally be preyed on by predators from the hedgerows
How does crop sow if seeds during autumn instead of spring cause extinction
Plants are at unsuitable height for birds to build nests
What 4 things might overhunting be used for
Overfishing
Traditional medicine
Trophies
Agricultural exploitation
Why might overfishing when overhunting be a disadvantage
Nets can catch other non target fish
What are 2 examples of pollutants
Oil spills
Polychlorinated biphenyl (PCBs)
What are PCBs
Industrial waste products or chemicals
What 4 things can contribute to the global climate change of deforestation
Machines used
Saprophites feeding on dead vegetation - cellular respiration
Trees cut down
Trees burnt
Define biodiversity
Number of species and number of individuals of each species within a defined area
Why is removal of top soil a particular problem?
Top soil is fertile
And so the soil below is not suitable for crop growth
What are 4 results for Soil quality for plant growth
- Evaporation vs transpiration
- Less oxygen in soil
- Soil temperature
- Denitrifying bacteria
Explain evaporation vs transpiration for soil quality (3)
More evaporation from soil surface , less transpiration from plants
Evaporation returns water more slowly to atmosphere than transpiration
This leads to reduced local rainfall and accelerates desertification
Explain less oxygen in soil for soil quality
As soil becomes wetter, water fills the soils surface o less oxygen is available in roots
Root cells need oxygen for aerobic respiration - less ATP production
Explain soil temperature for soil quality
It takes wet soil longer to warm up than dry soil, this means after deforestation soil is cold
This reduces germination and root activity
