B6.2 Feeding the Human Race 1 Flashcards
What is food security?
The ability of the human population to access affordable food of sufficient quality and quantity
Some factors that threaten food security
- increasing human population
- changing diets
- climate change
- new pests and pathogens may evolve
- increasing agricultural costs=higher prices
How does changing diets affect food security?
People become more wealthy and tend to eat a more varied diet
Often = more meat = more energy intensive to produce
How does climate change affect food security?
Scientists predict that global warming will result in more droughts, expansion of deserts = harder to farm
HOWEVER increase in levels of CO2 in atmosphere may = increasing yield of some crops?
Ways to increase food production
- maximising photosynthesis
- fertilisers
- removing competition + pests (eg. Herbicides to kill weeds, insecticides to remove insects, fungicides to destroy disease-causing fungi)
- planting varieties of pest resistant crops or that produce a higher yield
How to maximise photosynthesis
Control light levels, temperature, water supply in industrial glasshouses
What does using fertilisers do?
As a plant grows it removes minerals from the soil, fertilisers help land remain fertile
Aim of intensive farming
To produce maximum food product yield from minimum area of land
What techniques is intensive farming achieved through?
- using fertilisers and pesticides to aid plant growth
- maximising animal growth rates
- minimising labour inputs through machinery use
What is organic farming?
Farming through use of more natural methods of producing crops and rearing animals, avoiding use of artificial chemicals.
Yields generally smaller = products more expensive
Sustainable food production
Producing food in ways that can be continued indefinitely
Eg. fish farming
Results of overfishing
Reductions in populations of some fish species so that they cannot regenerate
What have international organisations done to combat fish farming?
Introduce fishing quotas so that enough fish can survive an reproduce to maintain their population
- limits of numbers + types of fish caught in area
- limit mesh size of nets (bigger holes = young, smaller fish can escape)
What is fish farming?
When fish are bred and reared in large cages in the sea or rivers
Advantages of fish farming
- Protection from predators
- easier to catch fish
- allows wild populations to recover
Disadvantages of fish farming
- fish kept close together = disease can spread quickly
- risk of disease spreading to wild populations
What do farmers use instead of artificial fertilisers?
Replace soil nutrients by spreading manure
What does crop rotation do?
Different crops take different nutrients from the soil, by planting different crops in the same soil each year =
- soil recovers
- maximises plant growth
- prevents build up population of particular crop pest
What is biological control?
Using the natural predators of crop pests to kill the pests
Predators (usually other insects) are bred in large numbers and are released onto crops where they eat the pests
(Instead of spraying pesticides which may damage other organisms like in intensive farming)
How are scientists developing crop varieties?
Through gene technology
Creating crop varieties more resistant to pests and disease
What is a hydroponic system?
Growing a plant in water containing dissolved minerals to ensure that it is receiving necessary minerals
Advantages of hydroponic systems
- Enables plants to grow quickly
- Glasshouse may contain several rows of hydroponic plants stacked above each other = many plants grown in same space
- mineral solution not absorbed is collected and recycled
What is selective breeding?
When, in order to produce the highest yields, farmers breed their best plants/animals in order to produce desired characteristic in offspring
5 steps to selective breeding
- Decide on desired characteristic
- Select parents with high levels of this characteristic
- Breed from these individuals
- Select best offspring and breed again
- Repeat for many generations
How has selective breeding changed the characteristics of wheat?
Small ears + few seeds —> large ears + many seeds
Brittle stalks + ears fall often —> stronger stalks + ears stay on
Ears ripen at different times —> ears ripen at same time
Stalks grow to different height —> stalks grow to same height
Disadvantages of selective breeding?
- reduced gene pool / number of alleles of a species = less variation (disease, more likely to become extinct)
- increased chances of inheriting genetic disease (eg. pugs + short stubby noses = breathing problems)
