Darwin's Theory and Modern Evidence Revision Notes | GCSE OCR Foundation Biology

What this lesson covers

Understand how Darwin's theory of evolution by natural selection became widely accepted and examine the modern evidence that supports it, including gene...

• Explain how Darwin's theory of evolution by natural selection became widely accepted
• Describe the evidence that supports Darwin's theory from genetics and inheritance
• Analyse how fossil records provide evidence for evolution
• Evaluate how antibiotic resistance in bacteria demonstrates natural selection in action

Key ideas to keep in view

Use this lesson to stay inside B5.2 Natural selection and evolution while connecting the detail back to the wider B5: Genes, inheritance and selection topic.

• B5: Genes, inheritance and selection
• B5.2 Natural selection and evolution
• GCSE OCR Foundation Biology

Lesson notes preview

Read the core explanations from Darwin's Theory and Modern Evidence before testing yourself from memory.

• In 1859, Charles Darwin published a book that changed everything we thought we knew about life on Earth. His theory of evolution by natural selection was controversial at first, but today it's widely accepted by scientists worldwide. Here's why his idea was so powerful - and why it took time to catch on.
• Darwin noticed something fascinating during his voyage on HMS Beagle. Animals on different islands looked similar but had slight differences. Finches on the Galápagos Islands, for example, had different beak shapes depending on what food was available on their particular island.
• The scientific explanation that species change over time through the survival and reproduction of individuals with advantageous characteristics
• Darwin's theory had four key parts: variation exists within species, some variations are inherited, more offspring are produced than can survive, and those with advantageous traits are more likely to survive and reproduce. This process, repeated over many generations, leads to evolutionary change.
• 2. The Missing Piece - How Traits Are Passed On
• Darwin had one major problem with his theory. He could see that offspring resembled their parents, but he didn't know HOW characteristics were passed from one generation to the next. This was the missing piece that made some scientists sceptical.
• The breakthrough came decades later when scientists discovered genes. We now know that characteristics are passed on to offspring through genes - sections of DNA that code for specific traits. This discovery provided the mechanism Darwin's theory needed.
• Sections of DNA that control the development of specific characteristics and are passed from parents to offspring
• **Trap**: Many students think characteristics are 'blended' like mixing paint. Actually, genes are discrete units that can be dominant or recessive. A brown-eyed parent and blue-eyed parent don't produce a child with 'medium brown' eyes - the child gets either brown or blue eyes depending on which genes are dominant.
• Fossils are like a photo album of life on Earth, showing us what organisms looked like millions of years ago. The fossil record provides compelling evidence for Darwin's theory by showing how species have changed over time.

Continue through the topic

Move to the related lessons or back to the topic page when you need the wider sequence before exam-style practice.