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Biology639 views·Updated May 31, 2026·2 pagesUnderstanding B13: Variation and Evolution Simplified
grace@grace_studies
1
of 2
Understanding Variation
Variation is basically why no two people (except identical twins) look exactly the same. These differences come from your genes, your environment, or usually a mix of both.
There are two main types: continuous variation and discontinuous variation . Your height depends on multiple genes plus how well you eat, whilst tongue rolling is controlled by just one or two genes.
This variation is crucial for evolution by natural selection. Think of it like this: organisms are constantly competing for resources. Those with the best characteristics for their environment are more likely to survive, reproduce, and pass on their advantageous genes.
Mutations - random changes in DNA - also create new variations when cells divide. Most mutations don't do much, but occasionally they give an organism a helpful advantage that gets passed down through generations.
Quick Tip: Remember that evolution isn't about being the "strongest" - it's about being the best suited to your specific environment!
2
of 2
Selective Breeding vs Genetic Engineering
Selective breeding is like being a matchmaker for animals and plants. Farmers choose individuals with desirable traits (like cows that produce more milk) and breed them together, then repeat this process over many generations.
This traditional method helps create disease-resistant crops, faster-growing livestock, and better-quality food. However, it's quite slow and you can only work with characteristics that already exist in that species.
Genetic engineering is much more direct - scientists actually cut out specific genes from one organism and insert them into another. This can be done between completely different species, like putting human insulin genes into bacteria to mass-produce medicine.
Genetic engineering is much faster than selective breeding and opens up amazing possibilities like gene therapy for genetic disorders. However, it raises concerns about "gene jumping" (genes spreading to unintended organisms) and mixing DNA from very different sources.
Real World Example: Most insulin used by diabetics today comes from genetically engineered bacteria, not from animal pancreases like it used to!
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Biology639 views·Updated May 31, 2026·2 pagesUnderstanding B13: Variation and Evolution Simplified
grace@grace_studies
Ever wondered why you look different from your mates or how farmers create bigger, juicier strawberries? It all comes down to variation - the differences between living things that make life so diverse and interesting.
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Understanding Variation
Variation is basically why no two people (except identical twins) look exactly the same. These differences come from your genes, your environment, or usually a mix of both.
There are two main types: continuous variation and discontinuous variation . Your height depends on multiple genes plus how well you eat, whilst tongue rolling is controlled by just one or two genes.
This variation is crucial for evolution by natural selection. Think of it like this: organisms are constantly competing for resources. Those with the best characteristics for their environment are more likely to survive, reproduce, and pass on their advantageous genes.
Mutations - random changes in DNA - also create new variations when cells divide. Most mutations don't do much, but occasionally they give an organism a helpful advantage that gets passed down through generations.
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of 2Sign up to see the content. It's free!
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Selective Breeding vs Genetic Engineering
Selective breeding is like being a matchmaker for animals and plants. Farmers choose individuals with desirable traits (like cows that produce more milk) and breed them together, then repeat this process over many generations.
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