Describe a method that could be used to measure the energy content of a sample of food.
a. determine the initial and final/change in mass of the food sample
b. determine initial and final/change in temperature of water
c. ignite sample and place burning sample under a known volume/mass of water
d. energy content is determined using formula
e. divide energy of water by mass of the food sample OWTTE
The graph below shows the oxygen dissociation curve at a low CO2 concentration.
Outline the main changes in the lungs that occur in patients with emphysema.
State a treatment for emphysema.
An increase in metabolic activity results in greater release of CO2 into the blood. On the graph, draw the oxygen dissociation curve during intense exercise when the CO2 concentration of the blood is high.
Explain how the increase in CO2 concentration affects the release of oxygen to respiring cells.
a. air sacs/alveoli break down/rupture
b. creating one larger air space instead of many small ones / reduces the surface area of the lungs
c. loss of elasticity of lung tissue
supplemental oxygen / breathing techniques / bronchodilators / inhaled steroids / lung surgery to remove damaged tissue / lung transplant
curve has to be towards the right and starting together
Must start together but can finish slightly below the original curve.
a. increased levels of CO2 lower the pH of the blood
b. «which results in» decreased affinity of the hemoglobin for oxygen / greater release of oxygen
c. this shifts the oxygen dissociation curve to the right/Bohr shift
A study was undertaken to determine the most effective method to delay the onset of type II diabetes in high-risk patients. Three groups were given either a placebo (control), a medicine that suppresses glucose production by the liver (anti-diabetic drug) or a lifestyle-modification program (lifestyle). The results for four years are shown in the graph.
Analyse the use of the anti-diabetic drug in delaying the onset of type II diabetes.
List features that would increase a person’s risk of developing diabetes.
a. less incidence of diabetes/more effective than placebo/control
b. but less effective than change in lifestyle
c. incidence nevertheless increases over the years
d. possibly ideal would be to combine both «anti-diabetic drugs and lifestyle»
lifestyle and anti-diabetic drugs not tried together «so we do not know the outcome»
a. overweight patients
b. sedentary lifestyle
c. high glucose diet
high glucose level in blood
d. genetic predisposition
e. other valid risk factor
The table summarizes the relative content of essential amino acids in different foods. Cysteine and tyrosine are classified as being “conditionally essential”. The quantity of each amino acid in a hen egg is set as 1.0 and all other values are relative to the hen egg standard.
Outline what is meant by the term essential amino acid.
Phenylalanine is converted to tyrosine by the enzyme phenylalanine hydroxylase.
(i) Deduce the reason that tyrosine is considered to be a conditionally essential amino acid.
(ii) When infants with the condition phenylketonuria (PKU) are left untreated, they have a build-up of phenylalanine in the blood and high levels of phenylalanine in the urine. State the cause of this condition.
Evaluate human milk as an overall source of essential amino acids.
Outline the control of milk secretion by oxytocin and prolactin.
The diagram represents a lobule from a mammary gland. The mammary gland is an example of an exocrine gland.
Identify two features of an exocrine gland visible in the diagram.
«Essential amino acids» must be obtained from the diet
They cannot be synthesized by the body
They cannot be synthesized from other amino acids
(i) Tyrosine can only be synthesized when phenylalanine is in the diet (Accept inverse: if phenylalanine is not in the diet the person will not
be able to synthesize tyrosine).
(ii) Recessive inherited «genetic» condition
They lack «the enzyme» phenylalanine hydroxylase
Mutated form of PAH gene
Contain all of the essential amino acids
Human milk has higher levels of 5 «out of 9» essential amino acids than cow milk
Human milk has the same or more of essential amino acids except histidine and lysine compared to cow milk
Human milk is the same or higher in all essential amino acids except histidine compared with hen egg
Human milk has higher levels of 4 «out of 9» essential amino acids compared with hen egg
Produced by the anterior pituitary
Stimulates mammary glands to grow
Stimulates the production of milk
Produced in neurosecretory cells «in hypothalamus»
stored/secreted by posterior pituitary
Suckling/nursing stimulates oxytocin release
example of positive feedback
«Contractions» cause ejection/release of milk from mammary glands
Award [2 max] if response only mentions one of the hormones.
Presence of ducts
Presence acini/acinar/secretory cells
Ducts leads to a body surface/cavity/gut
The cholesterol-lowering effect of Lactobacillus bacteria was studied. Forty rats were divided into groups and fed either a normal or high cholesterol diet. Some rats fed the high cholesterol diet were also supplemented with L. fermentum or L. plantarum. After a six week feeding period, the concentration of cholesterol in liver tissue and the mass of bile salts in feces were measured.
State the concentration of cholesterol in liver tissue and the mass of bile salts in feces for the normal diet, giving the units.
Concentration of cholesterol:
Mass of bile salts:
Calculate the percentage increase in the concentration of cholesterol in liver tissue, caused by feeding the rats a high cholesterol diet without supplementing with bacteria. Show your workings.
Deduce the effects of supplementing the diet with Lactobacillus on the concentration of cholesterol in liver tissue and on the mass of bile salts in feces.
Scientists hypothesized that Lactobacillus could be used in diets to reduce the incidence of coronary heart disease (CHD). Evaluate the evidence for and against this hypothesis provided by the data.
concentration of cholesterol: ;
(accept answer in the range of 10.5 mgg–1 to 11.5 mgg–1)
mass of bile salts: 12 mgday–1;
(accept answers in the range of 11.5 mgday–1 to 12.5 mgday–1)
Units are required.
(accept answers in the range of 72.7(%) to 81.0(%))
supplementation decreases liver cholesterol in high cholesterol diet;
not enough to bring it to the level of a normal diet;
no difference between L. plantarum and L. fermentum in the decrease of liver cholesterol;
supplementation increases bile salts levels;
greater increase in bile salts levels with L. plantarum / lesser/(perhaps) non-significant increase with L. fermentum;
Evidence for hypothesis:
Lactobacillus/supplements lower liver cholesterol (in high cholesterol diet) which is a risk factor for CHD;
Lactobacillus/supplements increase bile salts in feces which implies some cholesterol may be eliminated;
Evidence against hypothesis:
not known if cholesterol ends up in blood instead thus increasing risk for CHD;
no data about benefit for normal diet/actual decrease of incidence of CHD;
data/results based on rat experiments / may not apply to humans;
WTTE of taking into account difference in bile salt level between L. fermentum and L. plantarum;
The table shows the death rate due to coronary heart disease (CHD) in two different countries.
Using the table below, outline three named factors that could be responsible for the differences between the two populations.
State four glands secreting digestive juices into the alimentary canal.
Award  for a factor and a corresponding outline.
Award  for two correct glands.
wall of the small intestine;