Natural selection and genetic modification study guide

Charles Darwin and Alfred Russel Wallace independently developed the theory of evolution by natural selection. Both observed that within any population, individuals exhibit variation, and that organisms produce more offspring than can survive. They reasoned that individuals with characteristics better suited to their environment are more likely to survive and reproduce, passing on those advantageous traits to their offspring. Over generations, this process leads to a gradual change in the population, as beneficial traits become more common. Their combined work, particularly Darwin's publication of 'On the Origin of Species' in 1859, provided a powerful, evidence-based mechanism for how life evolves. This theory fundamentally reshaped biological thought, moving it from explanations based on fixed species to a dynamic view of life constantly adapting and diversifying. It underpins modern genetics, ecology, and conservation, providing a unifying framework for understanding biodiversity and the relationships between all living things.

A growing human population continually increases the demand for food. Agricultural practices need to intensify and become more efficient to meet this demand. Two key solutions are the use of fertilisers and biological control. Fertilisers, containing essential mineral ions like nitrates, phosphates, and potassium, enhance crop yields by providing nutrients for plant growth. This directly boosts the amount of food produced per unit area. However, excessive use can lead to environmental issues such as eutrophication of water bodies, where algal blooms deplete oxygen and harm aquatic life. Biological control involves using natural predators, parasites, or pathogens to manage pests, reducing the need for chemical pesticides. This method is generally more environmentally friendly, as it avoids chemical pollution and reduces harm to non-target species. Its limitations include the potential for the control agent to become a pest itself if not carefully chosen, and it can be slower-acting and less predictable than chemical methods. Both strategies aim to increase food production but come with distinct benefits and environmental trade-offs.