Diet and Food Production
- define the term balanced diet
A balanced diet is a diet that contains appropriate amounts of all necessary nutrients required for healthy growth and activity. This includes:
- Carbohydrates – for energy
- Fats – for energy and insulation
- Proteins – for growth and repair
- Fibre – helps with the digestive system
- Minerals/Vitamins – essential for body functions/chemical processes
- Water – essential for body function and for transport
Health is about:
- Having a good nutrition
- Being free from disease
- Having a good well-being (physical, mental and social)
- Having suitable housing
- explain how consumption of an unbalanced diet can lead to malnutrition with reference to obesity
Malnutrition is having a lack of proper nutrition, caused by not an unbalanced diet – not having enough to eat or not eating enough of the right things.
Obesity is when a person’s body weight is 20% or more than the recommended weight for their height. It’s caused by:
- Eating too much
- Doing sufficient exercise
- Energy intake is more than energy use
- Having an unbalanced diet consisting mostly of fats, sugars, carbohydrates and alcohol
Obesity is thought to be the most important dietary factor in the following health problems:
- Cardiovascular disease
- Type 2 diabetes
You can measure whether a person is obese or not using their BMI (Body Mass Index):
Problems with BMI – why might someone be placed in the wrong health category based on BMI score?
- There are differences between male and female:
- Women have a higher percentage of body fat
- A woman may be pregnant
- BMI doesn’t measure actual fat
- The person may have more/less muscle/bone than normal
- Muscle/bone is heavier than fat
- BMI is only for adults
- discuss the possible links between diet and coronary heart disease
Coronary heart disease (CHD) is the result of atherosclerosis. Atherosclerosis is the deposition of fatty substances in the walls of coronary arteries. It narrows the size of the lumen restricting blood flow to the heart muscle, which may cause oxygen starvation.
The endothelium (inner lining) of the artery can become damaged. The damage is repaired by of white blood cells (phagocytes)encouraging the growth of smooth muscle and the deposition of fatty substances. The deposits (atheromas) include cholesterol from low-density lipoproteins (tiny balls of fat and protein that are used to transport cholesterol around in the blood), fibre, dead blood cells and platelets. The build-up of atheromas occurs under the endothelium, in the wall of the artery. It eventually forms a plaque, which sticks out into the lumen of the artery, leaving the artery wall rougher and less flexible as well as creating a narrower lumen, reducing blood flow.
- discuss the possible effects of a high blood cholesterol level on the heart and circulatory system, with reference to high-density lipoproteins (HDL) and low-density lipoprotein (LDL)
Cholesterol is essential to the normal functioning of the body. They are found in cell membranes to improve stability and used to make steroid sex hormones and bile. Therefore cholesterol must be transported around the body, however it is not soluble in water so must first be converted to a form that will mix with water. It is therefore transported in the form of lipoproteins (tiny balls of fat combined with protein). There are two types of lipoprotein: high-density lipoproteins (HDL) and low-density lipoproteins (LDL). They are both released into the blood and can be taken up by cells that have the correct receptor sites.
We do not eat lipoproteins, but our diet has a significant effect on the lipoprotein concentration in our blood. LDLs are associated with greater deposition in the artery walls so is best to maintain a low proportion of LDLs. HDLs are associated with reduced deposition in the artery walls so is best maintain a high proportion of HDLs in our blood.
- Eating saturated (animal) fats will increase the concentration of LDLs
- Eating a low-fat diet will reduce the overall concentration of lipoproteins
- Eating unsaturated fats increases the concentration of HDLs
- Eating polyunsaturated fats reduces the concentration of LDLs
- Eating monounsaturated fats reduces the concentration of LDLs
- explain that humans depend on plants for food as they are the basis of all food chains
- Plants start off all food chains. They carry out photosynthesis, where they convert light energy into chemical energy – absorb carbon dioxide from the air and make carbohydrates. They also absorb minerals, such as nitrates, from the soil and manufacture a range of other biological molecules
- Herbivores make use of the biological molecules that the plants make when they eat and digest plants
- Carnivores eat herbivores and the energy moves along the food chain
- Humans are omnivores and eat a combination of plants and animals so we gain our energy both directly from plants and indirectly by eating animals.
- outline how selective breeding is used to produce crop plants with high yields, disease resistance and pest resistance
Selective breeding involves selecting plants with good characteristics (e.g. high yields, disease resistance or pest resistance) to reproduce together in order to increase productivity.
- Select plants with good characteristics that will increase crop yield and breed them together
- Select offspring with the best characteristics and breed them together
- Continue this over several generations causing the required characteristic to become more exaggerated
- outline how selective breeding is used to produce domestic animals with high productivity
Selective breeding can be used to increase the productivity of animals.
- Select animals with good characteristics that will increase meat yield, e.g. largest cows and bulls, and breed them together
- Select offspring with the best characteristics, e.g. largest, and breed them together
3. Continue those over several generations until cows with very high eat yields are produced, e.g. very large cows
- describe how the use of fertilisers and pesticides with plants and the use of antibiotics with animals can increase food production
- describe the advantages and disadvantages of using microorganisms to make food for human consumption
Microorganisms can spoil food in 4 ways:
- Visible growth – colonies of Mucor and Penicillium can grow on food turning it either black or blue/green.
- External digestion process – they release enzymes into the food and absorb the nutrients released by breakdown of the food molecules and the food eventually will be reduced to a mush.
- Releasing Toxins – the bacterium Clostridium botulinum produces a toxin called botulin, causing botulism, which is very dangerous and harmful.
- Infection – e.g. Salmonella bacteria can be present in poultry products and attack the lining of the stomach and digestive system
Microorganisms have been used for many years in the manufacture of food and drinks. Examples include:
- outline how salting, adding sugar, pickling, freezing, heat treatment and irradiation can be used to prevent food spoilage by microorganisms