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2 marksPatterns of Inheritance

CAPE Biology Unit 1 · 2011 · Paper 2 · Question 2(a)(ii)

In Leghorn chickens, coloured feathers are due to a dominant gene, F; white feathers are produced by its recessive allele, f. Another dominant gene, A, carried on a different chromosome, inhibits colour expression in birds with genotype FF or Ff. Consequently, both F_A_ and ff _ are white.

Define the terms 'allele' and 'dominant'.

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Other parts of this question

  1. 2(a)(i)State the term which describes the interaction of these two genes.[1 mark]
  2. 2(a)(iii)In the space provided, draw a genetic diagram to explain the cross.[5 marks]
  3. 2(b)(i)Based on the type of cross, deduce the expected ratio of the phenotypes.[1 mark]
  4. 2(b)(ii)formulate a possible null hypothesis for the Chi-square test.[1 mark]
  5. 2(b)(iii)State the formula for, and determine the number of degrees of freedom in the Chi-square test performed in (b)(ii), briefly explaining any terms used.[2 marks]
  6. 2(b)(iv)Use the calculated value of χ² (10.81) and the probabilities provided in Table 2 to find the probability of the results of the cross departing significantly by…[1 mark]
  7. 2(b)(v)What conclusion may be drawn from the probability found in (b)(iv)?[2 marks]

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