Humans need to eat a balanced diet. This really means some of every food group, but not too much or too little of a particular one.
The two groups that provide energy (through respiration) are lipids and carbohydrates. Per mass lipids have about 10x more energy in them than carbohydrates. The energy in food is measured in Calories (equivalent to 4.2 kJ). In order to keep our bodies functioning (i.e. heart beating, basic respiratory requirement)
- Males need to consume 2500 Calories a day
- Females need to consume 2000 Calories a day
However, this will change if;
- You exercise🚴
- You are growing👶🧒
- You are ill😷
- You are pregnant🤰
- You are old🧓
You need to know an experiment that can show how much energy there is in food in I/GCSE Biology. The easiest way of doing this is to burn a sample of food and use it to heat a fixed volume of water. If you record the change in temperature of the water you can use the equation below to find out the energy the food gave to the water;
Energy = change in temp. x volume of water x 4.2J/g/°C
A potential problem is that not all the food will burn. To control this, you measure the start and end mass of the food and calculate the mass that actually burned. To standardize this in I/GCSE Biology, you can divide your calculated energy value by the change in mass to give you the change in mass per gram of food (which will allow you to compare values fairly between different food samples)
Sources and functions of minerals and vitamin 🗻
You need to know the specific sources and functions of the following minerals and vitamin in I/GCSE Biology.
Vitamin A：Present in fish, cheese and eggs. It forms an essential part of the pigment in rods and cones that detects light. Lack of Vitamin A can lead to blindness.
Vitamin C : Present in citrus fruit. It forms an essential part of collagen protein, which makes up skin, hair, gums and bones. Lack of Vitamin C causes scurvy
Vitamin D : Present in fish, but made naturally by our body when sunlight shines on the skin. It is essential for regulating the growth of bones. Lack of Vitamin D can cause rickets.
Calcium : Present in milk, cheese & dairy foods. It is essential for bone growth and muscles. Lack of calcium can lead to osteoporosis.
Iron：Present in red meat and some vegetables (e.g. spinach). Is part of haemoglobin. Lack of iron causes anaemia.
That's the end of the topic!
Drafted by Joey (Biology)
Reference:
https://getrevising.co.uk/resources/biology_revision_notes8