A group of scientists investigated the total mass of carbon dioxide released when animals and plants are farmed and then used as food for humans.

1. (a)The total mass of carbon dioxide released for each food in the study included the mass released • during production of the food by farming • after the food left the farm and before it was eaten. Suggest and explain how human activity may result in the release of carbon dioxide after food has left the farm on which it was produced.[3]
2. (b)(i)Some of the results of the investigation are shown in the table. [Table 5.1] food produced mass of CO₂ released per kg of food produced/kg lamb 39.2 salmon 11.9 chicken 6.9 rice 2.7 beans 2.0 tomatoes 1.1 A farmer decides to change production from lamb to beans. Calculate the percentage change in carbon dioxide released per kg of food produced. Space for working.[3]
3. (b)(ii)An increasing number of people in some countries choose to eat a diet consisting only of plants. Use the results in the table and your scientific knowledge to explain how this choice of diet may benefit the environment.[4]