SL Paper 3
A study undertaken in West Virginia, USA, shows the relationship between body mass and the probability of having hypertension or type II diabetes. The test subjects in the study were classified as normal, overweight or obese according to their body mass index (BMI).
Identify the increased probability of an obese person having hypertension relative to someone who has normal weight.
Explain how the administration of a drug that stimulates the leptin receptors in the hypothalamus could help treat obesity.
The table shows the nutritional information for two different types of milk as it is displayed on the carton. The information in both tables is based on a 250 g serving and shows the recommended daily allowance (RDA) for each nutrient.
Calculate how many grams of protein should be consumed each day. Working is not required.
State one function of sodium in the diet.
Identify, with a reason, which milk provides more energy in a 250 g serving.
Suggest, with reasons, which milk would be recommended for someone with osteomalacia.
The scanning electron micrograph (SEM) shows a cell in the liver responsible for the breakdown of erythrocytes. The cells are found in the lining of the sinusoid walls.
Identify cell X shown in the diagram.
Outline the role of the cell in recycling iron in the body.
Explain reasons for the dual blood supply to the liver.
Vitamin D is converted from an inactive form to an active form by exposure to sunlight. The graph shows the mortality (death rate) from falls in women over 75 as a function of latitude (distance from the equator).
[Source: Food and Agriculture Organization of the United Nations, 1997, B E C Nordin,
Calcium in Health and Disease, www.fao.org/3/W7336T/w7336t04.htm#calcium%20in%20health%20
and%20disease. Reproduced with permission]
Vitamin D deficiency can cause low blood calcium concentrations (hypocalcemia). Very low blood calcium can have an impact on heart function. The first ECG is for a patient with normal blood calcium concentrations. The second ECG is for a patient who has very low blood calcium concentrations.
[Source: © International Baccalaureate Organization 2019]
Osteomalacia is a condition that can be caused by Vitamin D deficiency. Outline one effect of osteomalacia.
Outline the relationship shown in the graph.
Suggest reasons for this relationship.
Compare and contrast the two ECG traces.
Outline one event that occurs in the heart during the T wave.
Outline one consequence for the heart of the eating disorder anorexia nervosa.
The micrograph shows cardiac muscle.
[Source: https://commons.wikimedia.org/wiki/File:Musculocardiaco.jpg by Goyitrina,
licensed Creative Commons Attribution-Share Alike 3.0]
The structure labelled X in the micrograph is a junction between two cardiac muscle cells. Identify the structure labelled X.
Gastric juice is secreted by the wall of the stomach. Explain how the timing of secretion is controlled, with reference to the content of the juice.
State one role of fibre in the diet.
Outline control of digestive juice secretion so that digestive juices are only secreted into the gut when there is food present.
Outline the role of intestinal villi.
Explain the possible health risks of being overweight.
Breastfed infants with rickets sometimes have seizures due to low blood calcium levels. A study was carried out to investigate the relationship between maternal blood vitamin D levels and the incidence of these infant seizures.
Describe the relationship between the maternal blood vitamin D levels and the incidence of seizures.
Deduce the reason for rickets in these infants.
Identify the reason for vitamin D not being considered to be a typical vitamin.
Outline the reason for some amino acids being classified as essential amino acids.
The diagram shows the use of a sphygmomanometer in the measurement of blood pressure.
Identify the systolic pressure and diastolic pressure for this adult male.
Systolic pressure (mm Hg):
Diastolic pressure (mm Hg):
Explain the meaning of systolic and diastolic pressure.
The photomicrograph shows cardiac muscle. Label the structures I and II.
Explain the heart sounds.
A student recorded their dietary consumption over a 24-hour period into diet tracker software. The record of their consumption is shown in the table.
The bar chart shows the degree to which the student’s diet met the recommended daily target for five food groups.
Using the bar chart, determine the percentage of the recommended daily target of protein consumed by the student.
Suggest which essential dietary requirement might be missing if insufficient protein is consumed by the student.
The tracker indicated that the student had exceeded the recommended intake of dietary sodium. Overconsumption of dietary sodium can lead to hypertension. Explain what is meant by hypertension, referring to specific diastolic and systolic values.
The recommended daily intake of vitamin D is 15 μg. This student consumed just 4 μg. State two potential health consequences of vitamin D deficiency.
The liver receives blood from the digestive system via the hepatic portal vein as shown.
Compare and contrast the composition of the blood in the hepatic portal vein with the composition of the blood in the hepatic vein.
Outline how the liver recycles the components of red blood cells.
The diagram shows changes in the pressure and volume of the left ventricle during normal heartbeat. The phonocardiogram records heart sounds during the cardiac cycle.
[Source: Wiggers, Carl J. 1923. Modern Aspects of the Circulation in Health and Disease, 2nd ed. Philadelphia: Lea & Febiger, p. 97.]
State the relationship between pressure and volume in the left ventricle.
Explain the events that cause the sound shown on the phonocardiogram at the start of systole.
Outline reasons for fitting an artificial cardiac pacemaker.
State two roles of hydrochloric acid in gastric juice.
Role 1:
Role 2:
Pancreatic juice is secreted into the pancreatic duct which carries these secretions to the small intestine.
The hormone secretin is released by the small intestine when hydrochloric acid enters it from the stomach. The data below show the volume of pancreatic juice released after an injection of secretin.
Pancreatic secretions contain sodium hydrogen carbonate, making them basic.
Deduce the significance of the response by the pancreas to secretin.
State one cause of stomach ulcers.
A study was carried out to monitor mortality rates resulting from coronary heart disease (CHD) in people with and without diabetes. The data show the coronary heart disease mortality rates for two time periods.
Compare and contrast the data for the two time periods.
Using the data, evaluate the claim that patients with diabetes have a higher risk of mortality from CHD.
Outline two factors that are related to increased risk of developing CHD.
Explain how materials from red blood cells are recycled by the liver.
State a cause and a consequence of jaundice.
Cause:
Consequence:
Discuss the causes and treatments of phenylketonuria.
Hypochlorhydria is a condition whereby patients produce low quantities of stomach acid. Outline the effect this might have on the normal processes within the stomach.
Explain the mechanisms that regulate the composition of gastric juices.
Body mass index (BMI) was calculated for 37 674 men over 20 years of their life, between the ages of 25 and 45. Percentile BMI values were then determined for each age and plotted on the graph. For example, along the 75th percentile, 75 % of the population at a given age will have a BMI lower than the BMI indicated by the graph and 25 % of the population will have a higher BMI. The graph also shows the 50th percentile BMI curves for the men in this study who developed diabetes.
[Source: The New England Journal of Medicine, A Tirosh, et al., Adolescent BMI Trajectory and Risk of Diabetes
versus Coronary Disease, 364 pages 1315–1325 © 2011 Massachusetts Medical Society.
Reprinted with permission from Massachusetts Medical Society. ]
State the relationship between BMI and age in men.
Evaluate the data to assess whether a high BMI is a risk factor for the development of diabetes.
Explain the relationship between infection by the bacterium Vibrio cholerae and dehydration.
Severe dehydration can lead to cardiac arrest. Outline the use of defibrillation to treat life-threatening cardiac conditions.
Discuss the causes and consequences of malnutrition in humans.
The diagram shows the liver. The arrows show the direction of blood flow into and out of the liver.
[Source: © International Baccalaureate Organization 2017]
Identify the blood vessel labelled B.
Outline the function of the blood vessel labelled B.
Distinguish between the structure of liver sinusoids and capillaries.
The micrograph shows a section through part of the liver. The diagram illustrates the details of what is found within the marked area.
[micrograph] Micrograph of liver. https://undergraduate.vetmed.wsu.edu/courses/vph-308/histology/lab-1-histologycells-
and-organelles/liver-slide-wsu_2_052 courtesy of Patrick D. Wilson, MS, DVM, Clinical Associate Professor,
Veterinary Integrative Biosciences, College of Veterinary Medicine & Biosciences, Texas A&M University.
[diagram] Reprinted by permission from Springer Nature, Nature Reviews Immunology, “Aberrant homing of mucosal
T cells and extra-intestinal manifestations of inflammatory bowel disease” by Adams and Eksteen ©2006. https://www.nature.com/nri/.
Identify the phagocyte labelled X.
Identify the blood vessel labelled Y which brings blood from the intestines.
Explain the function of hepatocytes in protein metabolism.
Compare and contrast the structure of sinusoids and capillaries.
The graph shows the relationship between gastrointestinal (GI) damage and gastric acidity in 37 healthy human volunteers.
[Source: Republished with permission of Elsevier Science and Technology Journals, from ‘Integrated gastric acidity can predict the prevention of naproxen-induced gastroduodenal pathology in normal subjects’, John Plachetka, Gaetano Morelli, Carolyn Hines, Julie Borland, Alison Lyke, Diane Littlefield, Jerry D. Gardner Gastroenterology, Vol. 124, Issue 4, 2003; permission conveyed through Copyright Clearance Center, Inc.]
State the relationship between gastric acidity and GI damage.
GI damage can include ulcers. Outline the treatment of stomach ulcers.
Other than gastric acidity, state a primary cause of stomach ulcers.
The diagram shows metabolic pathways for lactate in humans.
[Source: © International Baccalaureate Organization 2019]
State the name of the blood vessel through which lactate from muscles reaches the liver
Compare and contrast the possible metabolic pathways for lactate in hepatocytes and in mitochondria-rich tissue.
List two functions of hepatocytes other than regulating lactate levels in the blood.
1.
2.
The bar chart shows the percentage loss of mass by various organs and tissues of the body of a person due to starvation. The overall body mass loss was 40 %.
Outline how the data indicate that protein was being used as an energy source.
Outline the reason for such a high percentage reduction in mass of adipose tissue.
Discuss whether the mass losses shown in the bar chart could be due to anorexia nervosa.
The diagram is of a liver sinusoid.
[Source: © International Baccalaureate Organization 2019]
List the two blood vessels that supply the sinusoids.
1.
2.
State one feature in the diagram that identifies the structure as a sinusoid.
Excess nutrients absorbed in the intestine can be stored. State one example of a nutrient stored in the liver.
Explain a method to quantify the energy content in food.
An electrocardiogram (ECG) records the electrical activity of the heart over a period of time using electrodes placed on the skin. The ECG shown is from a patient whose heart was beating irregularly until it was treated using a defibrillator (arrows) which restored normal electrical activity.
State how many normal heartbeats are shown in the ECGs.
Outline how a defibrillator is used to restore normal heartbeat.
Explain what is occurring in the heart during the peak of electrical activity as indicated by the R wave on the ECG.
Rats were injected with antibodies that induced phagocytosis of red blood cells (erythrocytes) leading to their breakdown. The graph shows the percentage of intact and partially digested erythrocytes in cells of the liver as observed under the microscope.
State the name of the cells that perform the breakdown of erythrocytes in the liver.
Describe the breakdown of erythrocytes by liver cells.
Outline the fate of the iron from the erythrocytes.
The drawing shows the typical action potential waveforms with the different phases of the cardiac cycle recorded in different regions of a human heart.
[Source: J M Nerbonne and R S Kass, (2005), Physiological Reviews, 85, pages 1205 –1253 doi:10.1152/physrev.00002.2005]
Describe the structure of cardiac muscle cells.
State the name of the valves that prevent blood flowing from the arteries back into the heart.
Distinguish between the different phases of the cardiac cycle in the atria and in the ventricular muscle.
Sketch the pattern seen in a typical electrocardiogram (ECG) trace for one complete cardiac cycle, including labels of the main features.
The cladogram shows where mutations probably occurred in ancestral lines resulting in some animal species being unable to produce ascorbic acid (vitamin C).
[Source: Drouin, G., Godin, J.-R. and Pagé, B., 2011. The Genetics of Vitamin C Loss in Vertebrates. Current
Genomics, 12(5), pp.371–378.]
On the cladogram, label with an M, the point at which a mutation occurred, preventing the gibbon from synthesizing ascorbic acid.
Outline the reason for ascorbic acid being described as an essential nutrient in the diet of humans.
A small box of orange juice contains these details on the side of the package:
[Source: © International Baccalaureate Organization 2020.]
Calculate the volume of juice needed to obtain the recommended daily requirement of vitamin C.
. . . . . . . . . . . . . . . . . . .mL
The apparatus used to measure energy content of food contains some water. Explain how this water is used when measuring the energy content of a food.
The table shows the origin and function of gastric secretions in the digestive system.
Identify the missing items by completing the table.
Explain how Helicobacter pylori can cause stomach ulcers.
The stomach secretes hydrochloric acid into its lumen.
The electron micrograph below shows part of an epithelial cell from the digestive system.
[Source: Louisa Howard, Katherine Connollly – Dartmouth Electron Microscope Facility]
State one mechanism that controls gastric secretion.
State the type of gland that secretes juices into the digestive system.
State where this type of cell can be found in the digestive system.
Outline two adaptations of this cell to its function that are visible in this electron micrograph.
The graph below shows a normal electrocardiogram (ECG) trace.
Using the letters provided, identify the parts of the ECG where the ventricle muscles are contracting.
State what is represented by the period between the points R and R’.
Outline the use of artificial pacemakers for patients with a heart condition.
The image shows a section through the ileum as viewed under the light microscope.
On the diagram, label the epithelial cell layer.
Explain how the epithelial cells are adapted for absorption.
The diagram below shows the liver and main vessels associated with it.
Suggest advantages of the blood supply from the pancreas passing directly into the liver.
Three groups of human volunteers were given different amounts of almond nuts added to a controlled diet for a period of 68 days. During that period the amount of energy released in their feces was measured.
[Source: Janet A Novotny, Sarah K Gebauer, David J Baer, Discrepancy between the Atwater factor predicted and
empirically measured energy values of almonds in human diets, The American Journal of Clinical Nutrition,
Volume 96, Issue 2, August 2012, Pages 296–301, https://doi.org/10.3945/ajcn.112.035782]
Using the data, discuss the implications for the advice given by dieticians to patients.
Describe how the energy content of food may be measured by combustion.
State one material not produced by the human body that is egested from the digestive system.
Explain the stages involved in the recycling of erythrocytes by the liver.
The QT interval corresponds to the time it takes for the ventricles of the heart to contract and then start to refill with blood before beginning the next contraction. Measures of QT interval were taken from 15-year-old female patients with anorexia nervosa and compared to healthy females of the same age. The body mass, heart rate and the mass of the left ventricle were also measured and the mean values are shown in the table.
Outline the reasons that the female patients with anorexia nervosa have a lower mean ventricle mass than healthy females.
Suggest a reason for the difference in QT interval between females with anorexia nervosa and healthy females.
State the two causes of normal heart sounds.
The diagram shows a cell in the lining of the stomach.
Outline the importance of the proton pumps in the digestion of foods.
Explain the use of proton pump inhibitors to treat patients complaining of stomach pain.
The bar chart indicates that both males and females in the US eat, on average, less fibre than is recommended.
Explain the importance of dietary fibre.
The micrograph shows a section through the human liver.
The cell labelled X is only found in the liver and is associated with the wall of a sinusoid.
(i) Identify cell X.
(ii) Outline the function of cell X.
Explain the importance of bilirubin in the onset of jaundice.