Option A: Human nutrition and health
A1 Components of the human diet 5 hours
Assessment statement Obj Teacher’s notes A.1.1 Define nutrient. 1 Nutrient: a chemical substance found in foods that is
used in the human body. A.1.2 List the type of nutrients that are essential in 1 Essential nutrients are those that cannot be the human diet, including amino acids, fatty synthesized by the body. Carbohydrates are not acids, minerals, vitamins, water. included because in certain traditional human diets
energy is obtained from other sources without ill
A.1.3 State that non-essential amino acids can be 1 synthesized in the body from other nutrients.
A.1.4 Outline the consequences of protein deficiency 2 Protein deficiency is shortage of one or more essential malnutrition. amino acids. The consequences are lack of blood
plasma proteins and subsequent tissue fluid retention, with swelling of the abdomen. Development of
children is likely to be both mentally and physically
Aim 8: Patterns of global malnutrition could be looked
at, both over time and over geopolitical areas, using
data downloaded from the Internet. A.1.5 Explain the causes and consequences of 3 The name of the gene and enzyme concerned are not phenylketonuria (PKU) and how early required. Limit the causes to a mutation of a gene for diagnosis and a special diet can reduce the an enzyme that converts the essential amino acids consequences phenylalanine to tyrosine. A.1.6 Outline the variation in the molecular structure 2 Include omega-3 fatty acids as an example. of fatty acids, including saturated fatty acids, cis and trans unsaturated fatty acids,
monounsaturated and polyunsaturated fatty
A.1.7 Evaluate the health consequences of diets rich Aim 8: There are marked differences in the traditional 3 in the different types of fatty acid. diets of human societies around the world and also
differences in the rates of coronary heart disease and
other diseases that have been linked to diet. This is a
chance to compare human societies—the Maasai, for
example, are a striking example of people with a low
rate of heart disease.
TOK: The distinction between correlation and cause
could be made here and the need for carefully
controlled experiments to test whether a correlation is
due to a causal link.
Epidemiological data could be examined and the
problems in interpreting it discussed. The link between
consumption of saturated fatty acids and coronary
heart disease is not a simple correlation and genetic
factors are also important. A.1.9 Outline two of the methods that have been 2 Include brief details of one method involving human used to determine the recommended daily subjects and another involving small mammals. intake of vitamin C. Aim 8: Some of the experiments used to determine
necessary levels of vitamin consumption were done
using conscientious objectors during the second world
war. This raises ethical questions about trials in which
Assessment statement Obj Teacher’s notes
the experimental subjects could be harmed or suffer.
TOK: Recommended intakes of nutrients have been
published in some countries. The recommendations
vary, and this raises questions about how the levels
are decided by scientists or doctors. A2 Energy in human diets 4 hours
Assessment statement Obj Teacher’s notes
A.2.1 Compare the energy content per 100 g of 3 Students should know that carbohydrates contain
carbohydrate, fat and protein. approximately 1,760 kJ per 100 g, protein- 1,720 kJ
per 100 g, and fats- 4,000 kJ per 100 g.
A.2.2 Compare the main dietary sources of energy 3 Include ethnic groups using rice, wheat, cassava,
in different ethnic groups. maize, fish and meat as their staple energy source
Aim 8: This is another opportunity to look at diversity
in human societies.
A.2.3 Explain the possible health consequences of 3 The consequences of an excess of each of the three
dets rich in carbohydrates, fats and proteins. types of nutrient should be explained separately.
Aim 8: Especially in the developed world, there are
social issues relating to inappropriate diets, and highly
effective marketing of unhealthy foods by profit-
TOK: This is another case where correlation and
cause need to be very carefully distinguished.
Examples of bad advice based on flawed science can
easily be found, with newspapers on an almost daily
basis drawing conclusions based on loose correlation
rather than on carefully controlled trials. A.2.4 Outline the function of the appetite control 2 Only a simple account is expected. Hormones are
centre in the brain. produced by the pancreas and small intestine after
eating and by adipose tissue in response to fat storage. These pass to an appetite control centre in
the brain, which makes the person feel that they have
A.2.5 Calculate body mass index (BMI) from the 1 BMI = (mass in kg)/(height in m)
body mass and height of a person. 2 A.2.6 Distinguish, using the body mass index, 2 BMI Status
between being underweight, normal weight, below 18.5 underweight overweight and obese. 18.5–24.9 normal weight 25.0–29.9 overweight 30.0 and above obese
Assessment statement Obj Teacher’s notes A.2.7 Outline the reasons for increasing rates of 2
clinical obesity in some countries, including
availability of cheap high-energy foods, large
portion sizes, increasing use of vehicles for
transport, a change from active to sedentary
Aim 8: The social issues relating to this condition A.2.8 Outline the consequences of anorexia 2
nervosa. need to be handled delicately, as it may affect
students in the class, but discussion of them could
prove very worthwhile. A3 Special issues in human nutrition 6 hours
Assessment statement Obj Teacher’s notes A.3.1 Distinguish between the composition of 2 Include lactose versus glucose, human milk protein human milk and artificial milk used for bottle-versus other proteins, differences in fatty acid feeding babies. composition, and lack of antibodies in artificial milk.
Aim 8: There is an ethical issue involved here, as
profit-making companies produce artificial milk. There
are concerns that restrictions on the advertising of
artificial milk in the developed world has led to a
greater marketing of it in developing countries, with
health consequences for these babies.
Aim 8: The bonding between mother and child, and A.3.2 Discuss the benefits of breast-feeding. 3
social attitudes to breastfeeding in public could be
TOK: This is an example of the need for research
findings to be passed on effectively from the scientific
community to mothers worldwide. A.3.3 Outline the causes and symptoms of type II 2 Include differences in susceptibility between ethnic
TOK: The nature of risk factors and the difficulties of
making decisions about the relative influence of
nature and nurture could be discussed.
There are clear differences in susceptibility to type II
diabetes, with some populations of Native Australians
(Aboriginal Australians) and Maoris having higher
rates of incidence. This could lead to a wider
consideration and appreciation of the diversity in
human societies combined with the need for parity of
A.3.4 Explain the dietary advice that should be 3
given to a patient who has developed type II
A.3.5 Discuss the ethical issues concerning the 3
eating of animal products, including honey,
eggs, milk and meat.
TOK: As with the earlier topic of fatty acids and A.3.6 Evaluate the benefits of reducing dietary 3
cholesterol in lowering the risk of coronary disease, this is a topic where the distinction between
heart disease. correlation and cause can be drawn.
Assessment statement Obj Teacher’s notes
A.3.7 Discuss the concept of food miles and the 3 Food miles are simply a measure of how far a food
reasons for consumers choosing foods to item has been transported from its site of production
minimize food miles. to its site of consumption. Transport of food causes air
pollution, traffic congestion and greenhouse gas
emissions. Transport of food also allows continuity of
supply and increased choice for consumers.
Aim7: Databases and spreadsheets could be used.
Aim 8: A discussion of the conflicts between
responsibility as global citizens and the right to exert
personal freedoms might be appropriate.
TOK: Some concepts or theories offer a new
perspective, which can change our attitudes
significantly. Here, food miles allow us to assess how
much we, as individuals, are contributing to global
warming by our selection of foods.