A breeder has selected only the highest-yielding plants for many generations. Their descendants have little genetic variation. A new fungal disease infects most of them.
Which change would best help develop a resistant, high-yielding variety?
Cross with a resistant variety, then select resistant offspring with high yields.
Cross with a resistant variety, then select offspring only for high yields.
Cross the original plants at random, then grow their offspring with fungicide.
Cross the surviving plants at random, then stop selecting in later generations.
44 exam-style questions on Edexcel GCSE Biology 4.3 Selective breeding and genetic modification, covering 4.3.1 Selective breeding and its impact, 4.3.2 Tissue culture, 4.3.3 Genetic engineering overview, 4.3.4 Main stages of genetic engineering, 4.3.5 Advantages and disadvantages of GM organisms, 4.3.6 Agricultural solutions for a growing population, and 4.3.7 Evaluating genetic engineering and breeding. Each one has a worked solution and a mark scheme showing where the marks go.