# Punnet Squares - Biology B2

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1. I dont understand how you determine whether the person is DD, Dd or dd. (Any letter). After this I find it easy however before knowing the information I am usually stuck on how to work it out.
2. (Original post by FitzpatrickR)
I dont understand how you determine whether the person is DD, Dd or dd. (Any letter). After this I find it easy however before knowing the information I am usually stuck on how to work it out.
Ok so the question will always tell you what genotype the parents of the offspring are so all you need to know are two main definitions. The first word is homozygous, and this means that the parent has two of the same gene (e.g. DD or dd). The second word is heterozygous, and this means that the parent has two different genes (e.g. Dd). What the question will also tell you is if the parent has a dominant or a recessive gene type. This is vital because it will help you to decipher the genotype of the parent. If the parent has a heterozygous dominant gene, then their gene will be Dd, for instance, and if they has a homozygous dominant gene, then their gene will be DD.

I hope this helps
3. (Original post by NoahSwinden)
Ok so the question will always tell you what genotype the parents of the offspring are so all you need to know are two main definitions. The first word is homozygous, and this means that the parent has two of the same gene (e.g. DD or dd). The second word is heterozygous, and this means that the parent has two different genes (e.g. Dd). What the question will also tell you is if the parent has a dominant or a recessive gene type. This is vital because it will help you to decipher the genotype of the parent. If the parent has a heterozygous dominant gene, then their gene will be Dd, for instance, and if they has a homozygous dominant gene, then their gene will be DD.

I hope this helps
D and d are different alleles (read: versions) of the same gene, not different genes. Be careful. If you call D and d genes in an exam, you'll probably be marked down.
4. (Original post by anosmianAcrimony)
D and d are different alleles (read: versions) of the same gene, not different genes. Be careful. If you call D and d genes in an exam, you'll probably be marked down.
Cheers man
5. Same i dont get it???

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