Edexcel GCSE Biology: Natural Selection And Geneti
Edexcel GCSE Biology: Natural selection and geneti
Exam (elaborations)
Edexcel GCSE Biology: Natural selection and genetic modification
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Edexcel GCSE Biology: Natural selection and geneti
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Edexcel GCSE Biology: Natural Selection And Geneti
Edexcel GCSE Biology: Natural selection and genetic modification
Evidence for Human Evolution Based on Fossils
1. Ardi (Ardipithecus ramidus) - 4.4 million years ago - Discovery: Found in Ethiopia. - Physical Characteristics: - Climbing adaptations evident in foot structure. - Long arms and leg...
Edexcel GCSE Biology: Natural selection and genetic modification
Evidence for Human Evolution Based on Fossils
1. Ardi (Ardipithecus ramidus) - 4.4 million years ago
- Discovery: Found in Ethiopia.
- Physical Characteristics:
- Climbing adaptations evident in foot structure.
- Long arms and legs indicating more ape-like than human traits.
- Brain size comparable to that of a chimpanzee.
- Leg structure suggests bipedalism, while hand bone structure indicates she did not walk on her
hands.
2. Lucy (Australopithecus afarensis) - 3.2 million years ago
- Discovery: Also found in Ethiopia.
- Physical Characteristics:
- Arched feet, suggesting better adaptation for walking rather than climbing.
- Arm and leg proportions similar to both apes and humans.
- Slightly larger brain than Ardi, but still indicative of early hominins.
- Leg bone structure is more efficient for upright walking compared to Ardi.
3. Leakey’s Discoveries - 1.6 million years ago
- Findings: Fossil hominids discovered by Louis Leakey and his team.
- Notable Specimen - Turkana Boy: A Homo erectus skeleton.
- Represents both ape-like and human-like features, more similar to Lucy.
- Shorter arms and longer legs, resembling modern human proportion.
- Brain size significantly larger than that of Lucy, indicating cognitive evolution.
- Leg and foot structure suggests enhanced adaptation for upright walking.
### Evidence for Human Evolution Based on Stone Tools
, 4. Dating Stone Tools: Methods
- Structural Features: Simpler tools are often older, allowing for chronological insights.
- Stratigraphy: The geology of rock layers; tools found in deeper layers tend to be older.
- Carbon-14 Dating: Stone tools frequently found with organic materials that can be carbon-dated,
further establishing age.
5. Development of Stone Tools Over Time
- Early Tools: Simple designs suitable for skinning animals or cutting meat.
- Advancements: More recent tools exhibit sophistication, being smaller and sharper, reflecting
improved human dexterity and cognitive skills.
### Principles of Evolution
6. Darwin's Theory of Evolution by Natural Selection
- Genetic Variation: Individuals exhibit genetic variation due to differences in alleles.
- Selection Pressures: Factors such as predation, competition for resources, and disease influence
survival and reproduction rates.
- Natural Selection: Individuals with advantageous traits are more likely to survive and reproduce,
leading to the propagation of beneficial alleles.
- Long-Term Trends: Over time, beneficial characteristics become common within populations.
7. Emergence of Resistant Organisms and Natural Selection
- Antibiotic Resistance in Bacteria: Mutations may confer resistance, offering a survival advantage in
the presence of antibiotics.
- Evidence of Evolution: Rapid reproduction of resistant bacteria demonstrates natural selection, as
advantageous alleles are passed down through generations.
### Contributions of Darwin and Wallace
8. Charles Darwin
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