Food Production Flashcards
What is population explosion?
A sudden large increase in the size of a population.
What does increasing the human population lead to?
A need for increased food yield
Why do fertilisers increase crop yield?
They produce chemicals like nitrates.
What do fertilisers do?
Fertilisers replace nutrients that have been removed from the soil when a crop is harvested (which helps plants grow)
What is a pesticide?
A pesticide is a chemical sprayed onto crops to destroy insects or other organisms harmful to the crops.
What do insecticides kill?
Insects
What do fungicides kill?
Fungal infections
What do herbicides kill?
Weeds that compete with the crops
Why is nitrogen so important in fertiliser?
Nitrogen is an important element to all living things as it’s one of the four elements that join together chemically to make protein (protein is needed to make muscles and enzymes) which is part of every living organism,
Nitrates dissolved in soil water are absorbed into plants. Nitrates are used to produce amino acids which are synthesised into plant proteins.
When fertiliser is added to soil the nitrate content of the soils increases.
What is the problem with fertiliser?
Fertilisers can leach (rain can wash them away)
The leaching of fertilisers adds extra unwanted nitrates, that increase the algal population and can cause algal bloom. Algal blooms reduce light levels killing aquatic plants. The dead plants and dead algae become good for bacteria. The bacteria multiply and use up large quantities of oxygen, reducing the oxygen availability for other organisms.
What is the problem with pesticides?
Many pesticides aren’t biodegradable so they build upon the bodies of animals and are passed along food chains.
BIOACCUMULATION
BIOACCUMULATION is when pesticides build up in the body of an animal during its lifetime, this happens because many pesticides can’t be be broken down so the they are stored in body fat.
As pesticides are passed along food chains the toxicity increases and can reach lethal levels.
Pesticides can end up affecting top predators.
What alternatives are there to the use of chemicals?
Natural fertilises like manure- less soluble so is less likely to be leached into rivers
Crop rotation- increases fertility of the soil
Genetically modified crops- higher yields so less need for fertilisers and can be resistant to pests
Biological controls- can be used instead of pesticides ( a biological control is introducing a natural predator or parasite of the pest species to keep it under control) they can be risky as the species itself may be a new pest
