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Updated Mar 18, 2026

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2 pages

Understanding Inheritance, Variation, and Evolution: GCSE Biology

aishaaa

@ishii.3149

Ever wondered how you inherited your eye colour or why... Show more

# Inheritance

ONA
a polymer made up
of two strands colled.
into a double helix

Genome
entire genetic material
of an org organism
4 genes l

The Basics of Inheritance and DNA

Think of DNA as nature's instruction manual - it's a twisted ladder (double helix) made of two strands that contain all the information needed to build you. Your genome is your complete genetic package, and scientists use it to trace diseases and even work out how humans migrated across the planet.

Genes are like individual recipes within that instruction manual, each coding for specific proteins your body needs. When your cells need to make a protein, they use transcription - copying the gene's instructions onto mRNA, which then travels to ribosomes where the actual protein gets built from amino acids.

Mutations happen when the DNA sequence changes, but don't panic - most mutations don't actually affect how proteins work. However, some can cause inherited disorders like polydactyly (extra fingers or toes), which is a dominant trait, meaning you only need one copy of the gene to have the condition.

Quick Tip: Remember that your genotype is the actual genes you have, whilst your phenotype is what you can actually see (like your height or hair colour).

Evolution, Breeding, and Modern Genetics

Charles Darwin and Alfred Russel Wallace figured out that species change over time through natural selection - basically, the organisms best suited to their environment survive and reproduce. This was revolutionary thinking, even though Darwin didn't have enough evidence to convince all scientists at the time.

Selective breeding lets humans speed up this process by choosing the best animals or plants to reproduce together for multiple generations. That's how we get everything from gentle dogs to disease-resistant crops. Cloning takes this further - scientists can create genetically identical organisms through embryo transplants or adult cell cloning.

Genetic engineering is where things get really sci-fi. Scientists can transfer genes between completely different species, like putting human insulin genes into bacteria or creating GM crops with bigger yields. However, antibiotic-resistant bacteria like MRSA show us that organisms evolve quickly when we put pressure on them.

Remember: Understanding fossils and the Linnaean classification system (Kingdom, Phylum, Class, Order, Family, Genus, Species) helps us see how all life on Earth is connected through evolution.

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Biology

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Updated Mar 18, 2026

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2 pages

Understanding Inheritance, Variation, and Evolution: GCSE Biology

aishaaa

@ishii.3149

Ever wondered how you inherited your eye colour or why some people look so much like their parents? This topic covers everything from DNA and genes to evolution and genetic engineering - basically, how life passes on information and changes... Show more

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The Basics of Inheritance and DNA

Quick Tip: Remember that your genotype is the actual genes you have, whilst your phenotype is what you can actually see (like your height or hair colour).

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Evolution, Breeding, and Modern Genetics

Remember: Understanding fossils and the Linnaean classification system (Kingdom, Phylum, Class, Order, Family, Genus, Species) helps us see how all life on Earth is connected through evolution.