Pesticides and Fertilisers Study Notes

Pesticides:
  - Used to control, repel, or kill unwanted organisms classified as pests.
  - Purpose of pesticides includes:
    - To kill insects and pests.
    - To protect crops from damage and loss.
Fertilisers:
- Applied to replenish soil nutrients.
- Aim to maximize crop yields.

Certain pesticides do not break down easily in the environment, leading to bioaccumulation.
Definition of Bioaccumulation:
- The process by which certain substances accumulate in the bodies of organisms over time, resulting in increased concentration of toxins.
Characteristics:
  - Toxin levels increase at each trophic level (the levels of the food chain).
  - Example Chain:
    - Plants → Insects → Frogs → Birds
  - Implication: Top predators, such as birds, are most affected due to the higher concentration of toxins accumulated from lower trophic levels.

Fertilisers contain nutrients such as nitrates and phosphates.
When excessive fertiliser is used:
- Rainwater washes the excess nitrates and phosphates into rivers and lakes.
Consequences of nutrient influx:
- The extra nitrates and phosphates result in the rapid growth of algae, known as an algal bloom.
- Algal blooms can significantly disrupt aquatic ecosystems.

While they increase food production, they also pose risks to environmental health and biodiversity.
Need for balanced use to mitigate harmful impacts on food chains and ecosystems.

Describe how pesticides can increase food production.
Discuss the issues related to nitrates and phosphates entering food chains and their effects on organisms.