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5.2 Natural selection and evolution

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Question 1

An aquaculture company aims to selectively breed Atlantic salmon (Salmo salar) to optimize two key traits for commercial sea pens: maximum growth rate and maximum resistance to sea lice (Lepeophtheirus salmonis). A lower mean number of attached lice per fish indicates greater resistance.

The performance data for four candidate breeding strains are shown below:

  • Strain A: Mean attached lice = 1.4 per fish; Specific Growth Rate (SGR) = 0.9% day−10.9\%\text{ day}^{-1}0.9% day−1
  • Strain B: Mean attached lice = 5.2 per fish; Specific Growth Rate (SGR) = 2.3% day−12.3\%\text{ day}^{-1}2.3% day−1
  • Strain C: Mean attached lice = 2.8 per fish; Specific Growth Rate (SGR) = 1.7% day−11.7\%\text{ day}^{-1}1.7% day−1
  • Strain D: Mean attached lice = 3.9 per fish; Specific Growth Rate (SGR) = 1.1% day−11.1\%\text{ day}^{-1}1.1% day−1

Which two strains should the company cross to produce offspring that inherit both desired traits?

A

Strain A and Strain C

B

Strain B and Strain D

C

Strain A and Strain B

D

Strain B and Strain C

Markscheme

5.2 Natural selection and evolution Questions

  1. GCSE
  2. /Biology
  3. /5.2 Natural selection and evolution

38 exam-style questions on OCR GCSE Biology 5.2 Natural selection and evolution, covering 5.2.1 Genetic variation within a population, 5.2.2 Developments in classification systems, 5.2.3 How evolution occurs through natural selection, 5.2.4 Evolution as change over time, 5.2.5 Evidence for evolution, and 5.2.6 Darwin and Wallace. Each one has a worked solution and a mark scheme showing where the marks go.

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