chapter 20: human influences on ecosystems Flashcards
(20 cards)
describe 5 ways humans have increased food production
- agricultural machinery to use larger areas of land and improve efficiency
- chemical fertilisers to improve yield
- insecticides to improve quality and yield
- herbicides to reduce competition with weeds
- selective breeding to improve production by crop plants and livestock
describe the advantages and disadvantages of large-scale monocultures of crop plants
advantages
1. increased farming efficiency
2. reduced labour costs
3. higher yields
disadvantages
1. reduced biodiversity
2. increase in pest populations
3. harmless species getting killed due to use of insecticides
4. increased use of insecticides
describe the advantages and disadvantages of intensive livestock production
advantages
1. less land required to produce large amounts of food
2. food can be produced all year long due to controlled environments
3. food can be sold cheaper due to low cost of production
disadvantages
1. ethical issues
2. destruction of natural habitats
3. reduction in biodiversity
4. overgrazing and soil erosion
5. excessive pollution
describe biodiversity
the number of different species that live in an area
describe 3 reasons for habitat destruction
- increased area for housing and farming
- extraction of natural resources
- freshwater and marine pollution
Explain 5 undesirable effects of deforestation, including a reduction in biodiversity, extinction, loss of soil, flooding, and an increase of carbon dioxide in the atmosphere
- reduce in biodiversity: loss of large numbers of plant and animal species
- extinction: many native species gone can lead to extinction
- loss of soil: lack of tree roots allows for the erosion of soil and washed away (leaching)
- flooding: topsoil will be washed away, increasing the risk of flash flooding and landslides
- increase in carbon dioxide: no photosynthesis :(
describe the effects of untreated sewage and excess fertiliser on aquatic ecosystems
causes eutrophication
explain the process of eutrophication
- increased nitrate, phosphate or ammonia concentration in water
- causes increased growth of producers on the surface of the water, they block light
- underwater producers die because they are unable to photosynthesise
- increased decomposition of producers
- increased aerobic respiration by decomposers resulting in the death of organisms requiring dissolved oxygen in water
describe the effects of non-biodegradable plastics in aquatic ecosystems
- animals try to eat the plastic or become caught in it, leads to injury or death
- plastic can release toxins when it breaks down
- enters the food chain when it breaks down into very small particles and is ingested
describe the effects of non-biodegradable plastics in terrestrial ecosystems
- landfills where plastics are buried contain toxins released by the plastics, so the land is no longer usable
describe a sustainable resource
a resource that is produced as rapidly as it is removed from the environment so that it does not run out
describe sustainable development
development providing for the needs of an increasing human population without harming the environment
outline some conflicting demands
- the need for local people to be able to utilise the resources they have in their immediate environment with the needs of large companies to make money from resources such as fish and forests
- the need for balancing the needs of humans for resources with the needs of animals and plants that live in the areas the resources are taken from
- the need to balance what current populations need with that future populations need
explain how forests can be conserved
- replanting similar tress when mature one are cut down
- quota for number of tress cut with the introduction of several schemes designed to monitor logging companies
- education to ensure logging companies are aware of sustainable practices and consumers are aware of the importance of buying products made of sustainable resources
- protected areas to conserve biodiversity
explain how fish stocks can be conserved
- education: fisherman to laws and consumers to know types of fish that are not produced sustainably
- closed seasons: protect fish during spawning seasons and prevent overfishing
- protected areas: conserve biodiversity
- controlled net types and mesh size: let young fish free
- quotas: prevent overfishing
- monitoring: prevent overfishing and unsustainable fishing
explain why organisms become endangered or extinct
- climate change and pollution
- habitat destruction
- hunting
- overharvesting
- introduced species
describe how endangered species can be conserved
- education programmes
- captive breeding programmes
- monitoring and legal protection of the species and of their habitats
- seed banks as a conservation measure for plants, new plants may be grown in the future
describe the reasons for conservation programmes
- maintaining/increasing biodiversity: allows ecosystems to remain stable
- reducing extinction: helps to retain iconic species and maintain biodiversity
- protecting vulnerable ecosystems and keeping damage to food chains and food webs to a minimum
- maintaining ecosystem functions to protect our future food supply, maintain nutrient cycles and possible sources of future medical drugs and fuels
describe the use of AI and IVF in captive breeding programmes
- used to maintain biodiversity
— - AI: inserting sperm from a make into the reproductive tradt of a female
- sperm can be transported around the world between different zoos, reducing the need to transport animals
— - IVF: using sperm to fertilise egg cells in a lab, fertilised egg implanted into female for development
- allows gametes with known alleles to be used, so next generation is genetically diverse
explain the risks to a species if its population size decreases
- harder to find mates, inbreeding occurs
- species will experience reduced genetic variation
- species more susceptible to environmental change
- species less resilient, greater risk of extinction
