Chickens that are grown for meat have been selectively bred to grow quickly.
Scientists compared the growth of chickens from 1957 with chickens from 2005.
The Table shows the results.
Table
| Year the type of chicken was bred | Mean mass at 56 days old in kg\text{kg}kg |
|---|---|
| 1957 | 0.9 |
| 2005 | 4.2 |
Calculate how many times heavier the 2005 chickens are than the 1957 chickens at 56 days old.
Give your answer to 1 decimal place.
Describe how farmers selectively bred chickens to grow more quickly.
Many of the 2005 chickens have problems with their legs.
Suggest why.
Give one way that breeding chickens to grow more quickly could help food security.
127 exam-style questions on OCR GCSE Biology 6.2 Feeding the human race, covering 6.2.1 Biological factors affecting food security, 6.2.2 Agricultural solutions to growing demand, 6.2.3 Selective breeding, 6.2.4 Genetic engineering, 6.2.5 Steps in genetic engineering, 6.2.6 Benefits and risks of gene technology in agriculture, and 6.2.7 Biotechnological solutions to growing demand. Each one has a worked solution and a mark scheme showing where the marks go.