Energy and Food Prodcuction Flashcards
What are ways agricultural productivity is increased?
- Using fertilisers
- Using chemical pesticides, biological agents or pest control
- Intensive rearing
Why do cultivated ecosystems need fertiliser?
In natural ecosystems, ions are recycled when they die. However in cultivated ones, plants are removed and cannot breakdown, leading to less recycling.
This means fertilisers must be added to restore ions.
Why do plants need nitrogen?
To produce proteins and DNA, which are needed for growth.
Soil has enough nitrates will produce plants with a higher growth rate -> plants have greater leaf area -> higher rate of photosynthesis -> increase productivity
What are the different types of fertilisers?
- Organic -> from waste material like manure
- Inorganic -> Manufactured powders or pellets containing nitrogen, phosphorous and potassium
What are the pros and cons of organic fertiliser?
Pros:
- Ions released slowly giving a steady supply over a long period
- Slow release reduces risk of leaching
- Adds organic matter to soil and improves its structure, therefore increasing it water holding capacity
- Cheap
Cons:
- Bulky and applied in large amounts so high transport costs
- Difficult to spread
What are the pros and cons of inorganic fertiliser?
Pros:
- Exact composition known _> quick release, good for periods of max growth
- Low transport costs as low amount needed
- Easy to apply
- Clean
- Soluble so immediately available
Cons:
- Soluble so chance of leaching
- Doesn’t improve soil structure
- Costly to produce
What happens if too much fertiliser is used?
A decrease in yield
High ion concentration lowers water potential of soil
Water moves out roots via osmosis so dehydration in plant`
What are environmental impacts of using fertilisers?
- Reduced species diversity (Plants more adapted to high soil nitrates out compete other species)
- Leaching (More ions taken up by the soil than the plants need so ions dissolve into the water and are washed into lakes and rivers)
What is eutrophication?
- Ions wash into water sources
- High conc of ions cause rapid growth of algae
- Algae blocks the light and less light goes into water
- Plants at bottom cant photosynthesise so die
- Algae starts to die
- Large increase of bacteria that decompose plants
- Bacteria respire and reduce O2 concentration
- Aerobic organisms like fish cant survive
How can energy conversion rates be increased in human food chain?
- Restricting movement
- Controlling temperatures
- Optimum food
- Exclude predators
- Selective breeding
- Hormones
- Slaughter when young
What is a monoculture?
The presence of only one species in an areaW
What are the pros and cons of monocultures?
Pros:
- More space
- Easier access for machinery
- Removes habitat pests
- Less weeds to compete with
Cons:
- Easy for disease to spread and insects to travel between plants
- Removal of habitats and food sources
- Same nutrients removed from soil so more fertilisers needed
“Write and essay on how energy is transferred within and between organisms.”
What topics would you write about?
Topic areas:
Photosynthesis
Energy transfer through ecosystems
Food production
Digestion (as in fuel)
Absorption (by cells)
Mass transport
Respiration
ATP
Stimuli and responses
Muscle contraction
Nerve impulses
“Write an essay on how cells and organisms carry out exchanges with their external environment to maintain their internal environment”
What topics would you write about?
Cells and organisms carry out exchanges with their external environment to maintain their internal environment.
Topic areas:
Homeostasis (concept of)
Digestion and absorption
Cells
Lung function
Gas exchange
Passage of water through plant
Nutrient cycles
Response to stimuli
Neurones
Temperature control
Tissue fluid and its formation
Control of blood glucose concentration
Negative feedback
Gene expression
What are ethical issues of intensive rearing?
- Low quality animal food
- Takes lots of space
- Disease spreads quick
- Animal welfare issues
- Pollution
- Reduced genetic diversity
- Use of fossil fuels
