The Table shows the mean milk yield per cow per year in one country between 1950 and 2010.
Table
| Year | Mean milk yield per cow in litres per year |
|---|---|
| 1950 | 2500 |
| 1970 | 4200 |
| 1990 | 6100 |
| 2010 | 7900 |
Calculate the mean rate of increase in milk yield per cow between 1950 and 2010.
Give your answer in litres per year.
Explain how selective breeding caused the increase in milk yield.
Over the same period, the fertility of the cows decreased.
Suggest why selective breeding for high milk yield may have caused this.
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.