• Characteristic ➡️ a feature of an organism, sun as its size, colour or behaviour; many characteristic are coded for by genes
• Some characteristic look like those of one parent and some of the other !!!

Do you remember about the topic of DNA in I/GCSE Biology?

Inherit characteristic from parents

• Formed when a sex cell (gamete called egg) from mother fused with sex cell (gamete called sperm) from father
• Nucleus of each gamete has chromosomes – made up of genes
• We receive genes from each parent
• Chromosomes carry thousands of genes ➡️ height, hair colour, blood type, length + shape of bones etc.
• Genes affect the way you grow
• All have different combination of genes except twins (all look different)

• characteristic are controlled by genes
• Gene OCA2 found on chromosome 15 – carries instructions for making the substance which gives eyes, hair, and skin colour
• Some differences not from genes e.g. muscle strength
• Variation controlled by environment e.g. height ➡️ continuous variation
• Variation caused by single gene ➡️ categoric
• characteristic affected by environment and genes e.g. 2 tall parents ➡️ genes for tallness – if not grown well as a child then not grown as tall as genes allow

And we're done with this topic! Well Done!

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Drafted by Alyssa (Biology)

References:

1. "IGCSE Biology Notes: 3.2", https://lh4.googleusercontent.com/93iZDu_lQSGitP0tiVWcQpdhxISjyQINhKOYJ24MQg7iakSvipG8qkv0bTKlIjm5nWiZP7TqEb2F2Gc99GE-oDJTRobVaHQp4IoBPx9tZcKmsuGlb6ei-USXJCG4COn1fwCdbCy1
2. "Continuous, discontinous". Photo from the internet.