Human Impact On The Environment Flashcards
What is monoculture ?
Vast cultivated population of one type of crop plant whose members are genetically identical.
What is an advantage of monoculture?
Increased level of food production.
What is a disadvantage of monoculture ?
Dependant on the use of chemicals
What is intensive farming?
Producing high yield crops and ‘battery-farming’ animals indoors
What is an advantage of intensive farming?
Enables farmers to increase fool yield per hectare and rear more animals
What is a disadvantage of intensive farming?
Requires use of chemicals and restricts animals to cramped conditions causing stress
Give one of the types of chemicals had in monoculture ?
Fertilisers
What are the 3 essential elements for plant growth?
Nitrogen
Phosphorus
Potassium
(NPK)
What does nitrogen encourage ?
Leafy growth
What does phosphorus encourage ?
Root development
What does potassium encourage ?
Fruit and flower development
What can excess fertilisers end up making their way into?
Freshwater such as rivers and lochs
What do high levels of nitrates promote ?
The growth of algae, leading to algal bloom
What does algal bloom spread over ?
The surface of water
What does algal bloom prevent?
Light from reaching organisms below the surface.
Describe the effects of algal bloom?(5)
- Fertilisers from fields leach into rivers/lochs.
- Excess nitrate promotes rapid growth of algae forming an algal bloom.
- Bacteria populations in the water will increase hugely as they use algae as a food source.
- Bacterial respiration uses up dissolved oxygen in the water.
- The reduction in the water’s oxygen causes many species to die (decreasing biodiversity)
Since the human population is increasing at an incredible rate, what is a consequence of this ?
Humans need to produce far more food.
What is a pesticide ?
Is a substance used to prevent , destroy or repeal pests
What are the 3 different pesticides and what do they kill?
Insecticide - insects
Herbicides - unwanted plants (weeds)
Fungicides - fungi (mould/mildew)
What is the major problem of using pesticides ?
They can accumulate along food chains and poison wildlife
What is bioaccumulation ?
When animals at each level need to eat lots of the food, so the animals higher up in the food chain will build up a higher concentration of pesticides in their bodies.
The toxic molecules become more concentrated at each level of the food chain and are non-biodegradable
High concentrations accumulate in the tissues of the final consumer and can reach fatal levels
What is an indicator species ?
Organisms whose presence or absence provides information on the environmental quality or pollution levels found in a specific area
What do freshwater invertebrates differ in?
Their ability to tolerate the varying oxygen levels found in a river polluted with organic waste
What 2 species can be found in clean water ?
Stonefly nymph
Mayfly nymph
What 2 species can be found in very badly polluted water ?
Sludge worms
Rat tailed maggots
What is biological control?
A way of controlling the population of a pest species by introducing a natural enemy such as a parasite or a predator
What can biological control in some cases result in ?
A reduction in the use of chemical pesticides
What are ladybirds used to control ?
Aphids
What can the virus, myxomatosis kill?
Rabbits
