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4 marksGenetic Concepts

CSEC Biology · May/June 2012 · Paper 2 · Question 4(c)

Haemophilia is caused by an X-linked recessive gene. Two parents with the normal phenotype have a haemophiliac child. Use a genetic diagram to show how this is possible. (Xᴺ = normal; Xʰ = gene for haemophilia)

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  1. 4(a)(i)Distinguish between the following pairs of terms: Allele and gene[6 marks]
  2. 4(a)(ii)Distinguish between the following pairs of terms: Phenotype and genotype[6 marks]
  3. 4(a)(iii)Distinguish between the following pairs of terms: Dominant and recessive[6 marks]
  4. 4(b)Black fur colour is controlled by a dominant allele, B, and brown fur colour by its recessive allele, b. This characteristic is NOT sex-linked. Give the…[5 marks]

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