GCSE Biology - Variation and Evolution (2026/27 exams)

Summary

This video explains how genetic and environmental factors contribute to variation in individuals and how these differences can lead to the evolution of new species through natural selection. It highlights the role of mutations in genetic diversity and the process of survival of the fittest, first described by Charles Darwin. Over time, advantageous traits become more common, leading to evolutionary changes within populations. The video also touches on the evidence for evolution, including antibiotic resistance and fossil records, demonstrating how species evolve from simple life forms over billions of years.

Takeaways

• 😀 Genes and environment both contribute to the variation observed in individuals within a population.
• 😀 A phenotype refers to the observable traits of an individual, shaped by their genes and environmental factors.
• 😀 Every person (except identical twins) has a unique genome, resulting in variations in traits like appearance and function.
• 😀 Environmental factors like diet, sleep, and sun exposure can influence physical characteristics, even in genetically identical individuals.
• 😀 Most traits are influenced by the interaction of multiple genes and environmental factors, not just one or the other.
• 😀 Mutations, which are changes in DNA, create genetic variation by altering protein structures and may occasionally be beneficial.
• 😀 Beneficial mutations can lead to traits that improve an organism's survival and reproduction, such as disease resistance or enhanced speed.
• 😀 Charles Darwin's concept of 'survival of the fittest' refers to the idea that individuals with beneficial traits are more likely to survive and reproduce.
• 😀 Natural selection is the process where advantageous traits are passed down, contributing to the evolution of species over time.
• 😀 Evolution by natural selection suggests that all current species evolved from common ancestors, and simple life forms existed over 3 billion years ago.
• 😀 Darwin's theory of evolution, once controversial, is now widely accepted due to evidence from antibiotic resistance and fossil records.

Q & A

What is the relationship between genes and environment in determining an individual's phenotype?

An individual's phenotype is determined by the interaction of both their genes and their environment. While genes provide the blueprint for an organism's traits, environmental factors such as nutrition, climate, and lifestyle can influence how these traits are expressed.

What is a mutation, and how does it contribute to genetic variation?

A mutation is a change in the DNA sequence that can alter the proteins encoded by genes. Mutations contribute to genetic variation by creating new versions of genes, which can lead to different phenotypes. Although most mutations have no effect, some can be beneficial and increase an organism's survival chances.

How do beneficial mutations impact natural selection?

Beneficial mutations give certain individuals an advantage in surviving and reproducing in their environment. As a result, these individuals are more likely to pass on their genes to the next generation, leading to the spread of the advantageous traits through the population. This process is a key mechanism of natural selection.

What is the concept of 'survival of the fittest' as introduced by Charles Darwin?

'Survival of the fittest' refers to the idea that individuals with traits best suited to their environment are more likely to survive and reproduce, passing on those traits to their offspring. This concept forms a core part of Darwin's theory of natural selection.

How did Charles Darwin's understanding of evolution differ from modern knowledge?

While Darwin proposed the concept of natural selection, he did not know about genes or mutations. Modern genetics has confirmed that variations in DNA, often due to mutations, are the underlying causes of the traits Darwin observed being passed on through natural selection.

What is the role of natural selection in the evolution of new species?

Natural selection can lead to the development of new species over time. When genetic changes in a population accumulate and cause individuals in different populations to become so genetically different that they can no longer interbreed, a new species may form.

How does the theory of evolution explain the diversity of life on Earth?

The theory of evolution by natural selection explains that all species are the result of gradual changes over time, driven by genetic variation and environmental factors. Over millions of years, these changes lead to the formation of new species, which account for the vast diversity of life on Earth.

What evidence supports the theory of evolution, according to the transcript?

Evidence supporting the theory of evolution includes the development of antibiotic resistance in bacteria, where we can directly observe evolution in action, and fossil records, which show the gradual changes in species over time.

What is meant by the statement, 'most of our traits are influenced by lots of different genes and environmental factors'?

This means that most traits, such as height or skin color, are not determined by a single gene or environmental factor. Instead, they are the result of complex interactions between multiple genes and various environmental influences.

What does the concept of evolution imply about the origin of current species?

The concept of evolution implies that all current species have evolved from different species in the past. If we trace back far enough in time, all life on Earth can be traced to simple organisms that first appeared over 3 billion years ago.