This topic explores the theory of evolution by natural selection, examining how genetic variation and environmental pressures drive changes in populations over generations. It also covers the classification of biodiversity, the threats posed by human activity, and the scientific and ethical considerations involved in protecting Earth's ecosystems.
Chapter B6: Life on Earth – past, present and future explores the incredible diversity of life on our planet and how it has changed over billions of years. You will learn about the evidence for evolution, including fossils and DNA, and how natural selection drives the adaptation of species to their environments. This topic also covers the impact of human activities on biodiversity and ecosystems, and the strategies we can use to protect life on Earth for future generations.
Understanding this chapter is crucial because it connects the history of life with current environmental challenges. You will see how evolution explains the variety of organisms we see today, and how human actions like deforestation, pollution, and climate change threaten this biodiversity. The knowledge you gain here is not only essential for your exams but also for becoming an informed citizen who can contribute to conservation efforts.
This topic builds on earlier work on cells, genetics, and ecosystems. It fits into the wider subject of Combined Science by linking biology with chemistry (e.g., carbon cycle) and physics (e.g., climate change). By the end of this chapter, you should be able to explain how life has evolved, why biodiversity is important, and what we can do to sustain it.
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