2.2 Carbohydrates & Lipids

Draw a molecular diagram of a 10-carbon saturated fatty acid.

[2 marks]

Explain why unsaturated fatty acids form different shaped-triglycerides whereas saturated fatty acids do not. 

[2 marks]

Below is a typical label printed on a piece of food packaging.

The product in question is a cookie-style snack food, sold in small packets with see-through plastic packaging. 

Suggest and explain one aesthetic reason why a food company might wish to market such a food product despite its high saturated fat content. 

[2 marks]

Doctors recommend that the majority of dietary fat intake should come from monounsaturated and polyunsaturated fats. 

Explain why. 

[2 marks]

Typical energy content values of various food group molecules are given in the table below. 

State the molecular feature of fats that allows them to contain more energy per gram than carbohydrates or proteins.

[2 marks]

The diagram shows a cell with a role in storage.

Identify structures X, Y and Z in this diagram.

[3 marks]

Suggest which tissue this cell forms part of.

[1 mark]

A person's body mass index is 26.4 and their mass is 78.3kg.

Calculate the person's height in metres, to 2 decimal places. The formula for BMI is shown below:

[2 marks]

A newspaper heading states that "High fat diets lead to weight loss!" based on the following study and data. 

Scientists carried out a study across five years in which 8254 participants followed one of three diets:

• a Mediterranean diet with added extra virgin olive oil
• a Mediterranean diet with added nuts
• a low fat diet 

None of the diets involved reducing calories or increasing physical activity.

The graph below shows the results of weight loss in participants after five years.

Use the data and information provided to evaluate the newspaper's claim. 

[4 marks]

Explain why cholesterol forms associations with proteins called lipoproteins eg. LDL (low density lipoproteins) and HDL (high density lipoproteins).

[2 marks]

Outline the series of events by which low density lipoproteins (LDLs) raise the risk of a person suffering from coronary heart disease. 

[4 marks]

Many claims about the health benefits and drawbacks of food are made. One such is the claim that a high consumption of trans- fats causes coronary heart disease. 

Evaluate this claim. 

[3 marks]

One mark is available for clarity of communication throughout this question.

Compare and contrast the compounds glycogen and starch. 

[8 marks]

Sketch a labelled diagram of the part of a trans-fatty acid that identifies its chemical structure as trans-.

[3 marks]

A healthy 35 year-old man of height 1.75m has a mass of 95kg. 

He calculated correctly that his Body Mass Index was 31, which places him in the 'obese' category. Online sources he read gave him cause for concern about his future health prospects. 

Evaluate the claim that a BMI of 31 is detrimental to his health. 

[4 marks]