Photo AI
A balanced diet contains proteins and fats as well as carbohydrates - VCE - SSCE Chemistry - Question 4 - 2002 - Paper 1
Question 4
A balanced diet contains proteins and fats as well as carbohydrates. Although carbohydrates are the immediate energy source for living things, both proteins and fats... show full transcript
Worked Solution & Example Answer:A balanced diet contains proteins and fats as well as carbohydrates - VCE - SSCE Chemistry - Question 4 - 2002 - Paper 1
Step 1
Give two functions, other than energy sources, for each of proteins and fats in humans.
Answer
Functions of Proteins:
-
Muscle Development: Proteins play a crucial role in the growth and repair of muscle tissues, facilitating movement and physical activity.
-
Enzymatic Functions: Proteins act as enzymes that catalyze biochemical reactions in the body, essential for digestion and metabolic processes.
Functions of Fats:
-
Energy Storage: Fats serve as a concentrated source of energy, stored in adipose tissues for later use during periods of energy deficit.
-
Protection of Organs: Fats provide cushioning and protection to vital organs, helping to prevent injury and maintain physical integrity.
Step 2
Calculate the energy content of the oil in kJ g⁻¹.
Answer
To calculate the energy content of the oil, first determine the change in temperature ( ΔT):
Next, calculate the total heat absorbed by the water using the formula:
Where:
- m = mass of water (in kg) = 1.00 L × 1 kg/L = 1.00 kg
- c = specific heat capacity of water = 4.18 J/g°C (or 4180 J/kg°C)
Now, substitute values:
Finally, divide the total energy by the mass of the vegetable oil:
ext{Energy content} = rac{149.61 ext{ kJ}}{4.75 ext{ g}} = 31.5 ext{ kJ/g}Step 3
What is the function of an emulsifier in salad dressing and how does it achieve this function?
Answer
An emulsifier, such as soya bean lecithin, functions to blend two immiscible liquids, like oil and water, by reducing the surface tension at the interface. It achieves this by stabilizing the emulsion, allowing the oil droplets to disperse evenly throughout the dressing, preventing separation and ensuring a smooth consistency.
Step 4
What is the function of an antioxidant in salad dressing and how does it achieve this function?
Answer
Antioxidants function to prevent the oxidation of fats and oils in salad dressing, which can lead to rancidity and loss of flavor. They achieve this by scavenging free radicals and interrupting oxidative chain reactions, thereby prolonging the shelf life and maintaining the quality of the dressing.