IB Standard level Biology Dulwich College Shanghai
Option A: Human Nutrition
2/28/2011 8:14:00 AM
A2
Energy in human diets
A2.1 Compare the energy content per 100 g of carbohydrate (1760 kJ), fat
(4000 kJ) and protein (1720 kJ).
A2.2 Compare the main dietary sources of energy in different ethnic groups
(include ethnic groups using rice, wheat, cassava, maize, fish and meat as
their staple energy source).
A2.3 Explain the possible health consequences of diets rich in
carbohydrates, fats and proteins.
A2.4 Outline the function of the appetite control centre in the brain.
A2.5 Calculate body mass index (BMI) from the body mass and height of a
person. BMI = mass (kg)/ height (m2)
A2.6 Distinguish, using the body mass index, between being underweight,
normal weight, overweight and obese.
A2.7 Outline the reasons for increasing rates of clinical obesity in some
countries, including availability of cheap high-energy foods, large portion
sizes, increasing use of vehicles for transport and a change from active to
sedentary occupations.
A2.8 Outline the consequences of anorexia nervosa.
2/28/2011 8:14:00 AM
A2
Energy in human diets
A2.1 Compare the energy content per 100 g of carbohydrate (1760 kJ), fat (4000
kJ) and protein (1720 kJ).
Ref:
Orange book  pg. 279
Green book  pg. 197
State the energy content in KJ of 100g of each of the 3 nutrients discussed below.
The 3 types of nutrient that supply most energy in human diets are carbohydrates,
fats (lipids) and proteins. Fats provide the most energy per gram. Proteins and
carbohydrates have a similar energy content.
2/28/2011 8:14:00 AM
A2
Energy in human diets
A2.2 Compare the main dietary sources of energy in different ethnic groups
(include ethnic groups using rice, wheat, cassava, maize, fish and meat as their
staple energy source).
Ref:
Orange book  pg. 279
Green book  pg. 197
Complete the table below:
Dietary source of energy
Ethnic group/country eating this source
of energy
Rice
Wheat
Cassava (woody shrub with edible
starchy tuberous root)
Fish
Meat
Diets around the world vary due to variety of food resources readily available.
Religion and tradition also have an influence on diet with diets varying between
ethnic groups. Usually a few foods provide the main energy source. These are eaten
in large quantities.
View the website below as a little background reading.
http://www.fas.usda.gov/info/agexporter/2000/Apr/diets.htm
2/28/2011 8:14:00 AM
A2
Energy in human diets
A2.3 Explain the possible health consequences of diets rich in carbohydrates, fats
and proteins.
Ref:
Orange book  pg. 279
Green book  pg. 197
Read the relevant information and then summarise the benefits and harmful
effects of diets rich in carbohydrates, fats and proteins.
A balanced diet requires the intake of all the essential nutrients as well as fibre
and carbohydrates in the correct amounts. A diet too rich in carbohydrates,
proteins or fats becomes unbalanced which could have an impact on health. The
website below gives information on the ‘Atkins diet’- a controversial low-carb diet
first introduced in 1972 by a cardiologist Robert Atkins.
http://www.healthguidance.org/entry/5134/1/Atkins-Diet---Good-or-Bad.html
Diet rich in carbohydrates:
Pros-
ConsDiet rich in proteins:
Pros-
Cons-
Diet rich in fats:
Pros-
Cons-
2/28/2011 8:14:00 AM
A2
Energy in human diets
A2.4 Outline the function of the appetite control centre in the brain.
Ref:
Orange book  pg. 279
Green book  pg. 198
Read the information below and in the text books and then complete the notes
below:
Location of appetite control centre:
Stimulus:
Role:
The hypothalamus is the location for the appetite control centre of the brain.
When we have eaten enough food the control centre gives us the feeling of being
full. Hormones control this. These hormones era insulin which is secreted from the
pancreas when blood glucose levels are high, PYP secreted by the small intestine
when there is food in it and leptin secreted by adipose tissue (fat tissue). View the
link below to read a news article about UK based scientists identifying circuits in
the body that control what we eat.
http://news.bbc.co.uk/1/hi/health/7041546.stm
2/28/2011 8:14:00 AM
A2
Energy in human diets
A2.5 Calculate body mass index (BMI) from the body mass and height of a person.
BMI = mass (kg)/ height (m2)
Ref:
Orange book  pg. 279
Green book  pg. 198
To assess whether a persons body mass is at a healthy level the body mass index
can be calculated- this is more accurate than basing conclusions on weighing them
alone due to the variation in size between adults.
Calculate your own body mass index using the animation below and make a note of
the calculation in your notes:
http://www.explania.com/en/animations/detail/calculate-your-body-mass-indexbmi
2/28/2011 8:14:00 AM
A2
Energy in human diets
A2.6 Distinguish, using the body mass index, between being underweight, normal
weight, overweight and obese.
Ref:
Orange book  pg. 279
Green book  pg. 198
Complete the table below to show the conclusions drawn about a persons weight
after body mass index has been calculated:
Body mass index
Below 18.5
18.5-24.9
25.0-29.9
30.0 or more
Conclusion
2/28/2011 8:14:00 AM
A2
Energy in human diets
A2.7 Outline the reasons for increasing rates of clinical obesity in some countries,
including availability of cheap high-energy foods, large portion sizes, increasing use
of vehicles for transport, and a change from active to sedentary occuptions.
Ref:
Orange book  x
Green book  pg. 199
Go to the website below:
http://www.who.int/topics/obesity/en/
Read the relevant information and the text book page and then complete the
following tasks:
1. Define ‘obesity’ and ‘clinical obesity’.
2. Distinguish between ‘overweight’ and ‘obese’
3. State the health consequences of being overweight.
4. State the reasons for obesity in modern society – it may be a good idea to
record this as a spiderdiagram to help you remember them.
2/28/2011 8:14:00 AM
A2
Energy in human diets
A2.8 Outline the consequences of anorexia nervosa.
Ref:
Orange book  x
Green book  pg. 199
Read the information below and in the green text book and then visit the websites
listed.
Describe what is meant by ‘Anorexia nervosa’ and describe symptoms of the
condition.
Anorexia nervosa is a disease that mostly affects girls and women. The condition is
a challenge for all those involved due to its complex variety of causes. People with
Anorexia Nervosa do not eat enough carbohydrate or fat for use in cell respiration
and protein is therefore broken down for use as a respiration substrate. The
effects are as follows:
Loss in muscle mass
Weakness/fatigue
Brittle, thinner hair
Hair loss
Dry skin which bruises easily
Slower heart
Poor circulation
Menstrual cycles halt, therefore the woman becomes infertile
Effects on friends and family trying to support the sufferer are also common, such
as feelings of guilt over not being able to help and anxiety over the harm that the
condition causes.
http://www.nhs.uk/conditions/anorexia-nervosa/Pages/Introduction.aspx- Read
the information and watch the video.
http://www.bbc.co.uk/health/emotional_health/mental_health/disorders_eating.sh
tml- Read the information.2