Obesity and smoking are two risk factors in coronary heart disease. An increase in either of these gives a higher than average mortality risk.

A person with a body mass index (BMI) of 30 or above is described as obese.

The graph below shows the relationship between the BMI and the mortality risk of groups of smokers and non-smokers.

1. Question:
   

   1. Describe how the BMI of an individual is obtained.

      (2 marks)
      Question:
      

   2. Name one tissue that increases in masses an individual becomes obese.

      (1 mark)
      
2. Question:
   

   1. Using the information in the graph, calculate the increase in mortality risk for non-smokers with a BMI of 31 if they were to start smoking. Show your working.

      (2 marks)
      Question:
      

   2. Compare the effect of smoking and increasing BMI on the mortality risks for individuals whose BMI is greater than 26.

      (3 marks)
      Question:
      

   3. Suggest one reason why smoking is a risk factor in coronary heart disease.

      (1 mark)
      
   Question:
   

3. Explain how people who are obese can reduce their body mass index.

   (2 marks)