Energy Transfers Flashcards
Environmental problems with deforestation
Soil erosion/mud slides/flooding/leaching of minerals- trees no longer protect from rain
Increased co2- global warming
Less diversity/loss of species/loss of habitats/niches/ecosystem
Changed rainfall patterns/drought-less transpiration from trees
What is biological control
Using a predator/pathogen to control a pest organism
Give example
Advantages/disadvantages of biological control
Advantages
- if well screened a biological control agent only attacks pest/maintains low level of pest
Forms self perpetuating population (only one application required/does not need repeated treatment)
Cheaper e.g. saves cost of using chemicals
Safer because does not leave chemical in environment/no chemical residue
Organisms do not become resistant
Disadvantages
- doesn’t completely eradicate pest
- cost of research/setting up a biological control system
- must be well screened/ biological control may turn a pest
- Slower to get rid of pest than chemicals
More subject to environmental factors
Process of genetic engineering and benefits over selective breeding
Use of restriction endonuclease
Cuts dna at specific base sequence/recognition site
Vector
Same endonuclease to cut vector/host dna
Use of Lucas’s enzyme to join dna strands
It is much quicker/more efficient/several genes can be inserted at once compared to selective breeding
Effective pest management schemes include..
Use of insecticide
Selective breeding of resistant palms
Release sterile males/females
Introduce a virus
Benefits of an integrated pest management scheme(biological control and artificial methods)
If one method fails, other still partially effective
Reduces amount of pesticide needed/less chemicals used
Increased yield/ less chance of resistant species
Less effect on food webs
Biological control gives longer term control of pests
Limitations of biological control
Effect on non target species
Population explosion/lack of natural predators
Not all pests killed
Difficulty in maintaining population of control organism
Concerns of leaching
Increased growth of algae Results in eutrophication Increase in microoorganisms feeding on dead organisms Deoxygenatiin Increased nitrate in drinking water Causing human illness
Productivity on farmland v woodland
Plants smaller/ less vegetation/grazing
Less area for phs
removed in harvesting
Advantages/limitations of using inorganic fertilisers
Advantage: Ions in readily available form Effects relatively rapid Easy to apply Quantities applied can be controlled
Disadvantage
Quickly leached
More likely to cause pollution
Relatively expensive
What is monoculture
Cultivation of single species/ variety of crop: named crop/one crop grown over a large area
Two benefits of hedge removal
More space for crop Easier to use machines Removes habitat for pests Lower labour costs in maintenance Less competition with crop plants
How can pesticides lead to the death of animals that are not pests
Food source killed by pesticides Insufficient food for survival/ lack of alternative sources Or Pesticide passed through food chain Bio accumulation(organisms at higher trophies levels eat large numbers of organisms at lower trophies levels) Or Stored in fat/released over time Or Leached into rivers Kills aquatic life
How selective breeding can reduce the unwanted part of the crop
Use plants with smallest amount of unwanted material
Cross pollination/select and repeat cross
Measurements needed to measure rate of phs
Oxygen produced/co2 used
Per unit time
