HL Paper 3
The human stomach kills pathogenic bacteria while allowing some benefi cial bacteria to survive. The diagram shows how mucus lining the stomach helps in this process.
[Source: Kavanaugh, D., O’Callaghan, J., Kilcoyne, M., Kane, M., Joshi, L. and Hickey, R.M., 2015. The intestinal glycome and
its modulation by diet and nutrition. Nutrition Reviews, 73(6), pp.359–375 by permission of Oxford University Press on behalf
of the International Life Sciences Institute. Translated and reprinted by permission of Oxford University Press on behalf of the
International Life Sciences Institute. Please visit: https://academic.oup.com/nutritionreviews/article/73/6/359/1845190.]
Outline the function of the stomach in food digestion.
State a mechanism by which the stomach destroys pathogens.
There are times when pathogenic bacteria infect the stomach, causing ulcers.
State a pathogenic bacterium that can cause stomach ulcers.
There are times when pathogenic bacteria infect the stomach, causing ulcers.
Explain how proton pump inhibitors (PPIs) reduce conditions that favour ulcer formation.
Samples from cardiac muscle were taken during autopsies from individuals who had coronary heart disease (CHD) and a control group. The histogram shows the relationship between the quantity of cardiac muscle cells and their diameter in the left ventricle in the two groups.
Distinguish between the distribution of cardiac muscle cell diameters in the CHD and control groups.
Describe how the structure of cardiac muscle cells allows them to transmit impulses.
Explain the reason for the delay between contractions of the atria and of the ventricles.
The diagram demonstrates the action of steroid and peptide hormones in a section of cell and adjacent capillary.
On the diagram, label a
(i) second messenger.
(ii) gene regulatory protein.
Outline one characteristic of steroid hormones that allows them to readily diffuse through cell membranes
Compare and contrast the mechanisms of action of peptide and steroid hormones.
The use of human growth hormone (HGH) to enhance athletic performance is now banned from most major sporting events including the Olympics. To investigate the effect of HGH on athletic performance, doctors in the US looked at changes in body composition and strength in a group of athletes taking the drug. This was compared with a control group of similar athletes who had never taken the drug.
[Source: From Annals of Internal Medicine, H Liu and D M Bravata, Systematic Review: The Effects of Growth Hormone on
Athletic Performance, 148., 10, 747–758. Copyright © 2008 American College of Physicians. All Rights Reserved.
Reprinted with the permission of American College of Physicians, Inc.]
Deduce from the results of the study whether HGH improves strength.
Suggest one reason that it is difficult to detect illegal use of HGH to enhance athletic performance.
HGH is a peptide hormone. Describe the mode of action of peptide hormones on target cells.
In control subjects, blood potassium levels are maintained, through homeostasis,between 3.5 and 4.5 mmol litre–1. In patients with anorexia, blood potassium canfall below this level. This is known as hypokalemia. In patients with kidney failure, levels can rise above this range, causing hyperkalemia. The traces show the electrocardiograms (ECGs) of a patient with hypokalemia, a normal subject and a patient with hyperkalemia.
Distinguish between the ECG trace of the patient with hypokalemia and the patient with hyperkalemia.
Outline the events that occur within the heart that correspond to the QRS complex.
Severe hypokalemia can lead to ventricular fibrillation. Describe the medical response to ventricular fibrillation.
Sometimes hyperkalemia occurs as a body tries to respond to low blood pH. State the normal range of blood pH in the human body.
Explain how low blood pH causes hyperventilation (rapid breathing).
Most stomach ulcers are caused by a bacterium that lives under the mucus lining of the stomach wall.
This organism causes the production of reactive compounds which result in oxidation. This makes the ulcer progress and, consequently, healing is more difficult. A study was carried out to compare the effect of the drug nizatidine (N) alone or combined with the antioxidants vitamin E and thioctic acid.
[Source: Effect of Helicobacter Pylori Eradication Therapy and some Antioxidants on Ulcer Healing Rates
in Patients with Helicobacter pylori-associated Duodenal Ulcer, Ahmed M Ali, 2013, http://www.rroij.com/
open-access/effect-of-helicobacter-pylori-eradication-therapy-and-some-antioxidants-on-ulcer-healingrates-
in-patients-with-helicobacter-pylor-.php?aid=34774, licensed under a
Creative Commons Attribution 4.0 International License]
State the name of the bacterium that can cause stomach ulcers.
Compare and contrast the effect of adding antioxidants to nizatidine on the ulcer healing rate.
Components of gastric juice have been thought to aggravate the development of ulcers. Outline the role of nerves in the secretion of gastric juices.
Gastric juice production can be inhibited by the hormone secretin which is a polypeptide. Outline the mechanism by which a peptide hormone carries out its function.
The electron micrograph shows a section through an alveolus showing blood in a capillary.
[Source: © International Baccalaureate Organization 2019]
Identify the cells found at X and Y.
X:
Y:
Explain, with the aid of an annotated diagram, how physical exercise affects the affinity of hemoglobin for oxygen.
The mean systolic blood pressure and body mass index (BMI) of many individuals were measured. The results are displayed in the box plot.
[Reprinted from Obesity Research & Clinical Practice, 9(2), Noritaka Kawada, Kaori Nakanishi, Tohru Ohama, Makoto Nishida, Keiko Yamauchi-Takihara and Toshiki Moriyama, 'Gender differences in the relationship between blood pressure and body mass index during adolescence', pp. 141–151, Copyright (2015), with permission from Elsevier. https://www.sciencedirect.com/journal/obesity-research-and-clinical-practice]
Compare and contrast the relationship between BMI and systolic blood pressure in males and females.
Outline the relationship between systolic blood pressure and hypertension.
State two effects hypertension can have on the circulatory system.
State how blood pressure and heart rate can be measured.
Thyroxin is a hormone produced in the thyroid gland. State one function of thyroxin.
The action of thyroxin is similar to steroid hormones. Describe the action of steroid hormones.
The World Health Organization recommends that the iodine intake should be supplemented in pregnant women due to their increased requirements. Outline the need for iodine supplementation.
Liver transplantation is a viable treatment option for end-stage liver disease and acute hepatic failure. The graph below shows the main diseases leading to liver transplants, in three age groups.
[Source: European Liver Transplant Registry. http://www.eltr.org/Overall-indication-and-results.html]
One of the functions of the liver is to break down hemoglobin.
Describe the relationship between age and liver transplants due to cancers.
Describe the breakdown of hemoglobin in the liver.
Outline one other function of the liver.
State one material not produced by the human body that is egested from the digestive system.
The diagram shows part of the control of the pituitary gland by the hypothalamus and, at the same time, the control of secretion in the breasts and the ovary by the pituitary gland.
Using the diagram, identify an organ containing an exocrine gland.
Using the diagram, identify a hormone involved in the development of a follicle.
Using the diagram, identify a steroid hormone.
State two effects of prolactin.
List two hormones produced by the posterior pituitary gland.
The X-ray shows the thorax of a patient who has had an artificial pacemaker fitted.
[Source: M S Silvetti and F Drago, Twenty years of paediatric cardiac pacing: 515 pacemakers and 480 leads implanted in 292
patients, Europace, 2006, 8, 7, 530–536, by permission of Oxford University Press]
The micrograph shows cardiac muscle.
[Source: https://commons.wikimedia.org/wiki/File:Musculocardiaco.jpg by Goyitrina,
licensed Creative Commons Attribution-Share Alike 3.0]
State one condition which would require the use of an artificial pacemaker.
Describe briefly how an artificial pacemaker works.
The structure labelled X in the micrograph is a junction between two cardiac muscle cells. Identify the structure labelled X.
Explain how the structure of cardiac muscle cells allows propagation of stimuli through the heart wall.
State one function of the atrioventricular node.
Describe how the structure of cardiac muscle cells allows them to carry out their function.
The micrograph shows a section of cardiac muscle.
[Source: Musculocardiaco by Goyitrina (https://commons.wikimedia.org/wiki/File:Musculocardiaco.jpg)]
Identify the structure labelled X.
Describe the unique properties of cardiac muscle cells.
State an early invention that led to improved knowledge of the heart.
Cells on the surface of intestinal villi have microvilli, which provide a large surface area for absorption. State another structural characteristic of these villus cells that adapts them to the absorption of nutrients.
Explain how the pH of blood is kept constant during exercise.
A good marker of dietary intake of iodine is the urinary iodine level (UI). A study was carried out in the UK to establish urinary iodine levels and milk intake in schoolgirls aged 14–15 years.
Urinary iodine values from 50 to 99 μg dm–3 are considered to be mild iodine deficiency. Deduce the effect of milk intake on the iodine status of schoolgirls in the UK.
Outline the need for iodine in the endocrine system.
Growth hormones are examples of peptide hormones. Explain the mechanism of action of peptide hormones.
Outline the role of the sinoatrial node in the contraction of the heart.
The graph shows the results of a study of the incidence of coronary heart disease (CHD) in different age groups of men participating in a study carried out by the National Heart, Blood and Lung Institute.
Comment on the claim that the bar chart proves that old age causes CHD.
Suggest one factor other than age and hypertension that is correlated with the incidence of CHD.
Hypertension has been suggested as a possible cause of CHD. Explain the possible causes of hypertension.
The hematocrit is the volume percentage fraction of erythrocytes in blood.
From the diagram, deduce the effect of the disease polycythemia on the proportion of erythrocytes in total blood volume.
Suggest how high altitude could lead to polycythemia.
Suggest how changes in hemoglobin could help humans become better adapted to living at high altitude.
Outline the stages involved in the recycling of erythrocytes by the liver.
Water in a calorimeter is heated by burning food in oxygen. The temperature change of the water is used to calculate the energy value of the food. An experiment was set up to calculate the energy value of avocado.
[Source: © International Baccalaureate Organization 2019]
Apart from the water temperature, state two other values to be measured at the start of the experiment.
1.
2.
The energy value calculated for avocado was 750 kJ 100 g–1. The actual energy value of avocado is 840 kJ 100 g–1. Suggest a source of error in the experiment.
Avocados are known to be a good source of dietary fibre and contain all the essential amino acids. State one health benefit of a diet high in fibre.
Avocados are known to be a good source of dietary fibre and contain all the essential amino acids. Distinguish between essential and non-essential amino acids.
The image shows an example of a label showing nutritional information.
State the importance of including vitamins in our diet.
Suggest one limitation of the information about vitamins shown on this label.
Distinguish between gastric juice and pancreatic juice using the table.
Describe the mode of action of steroid hormones.
Many animals, including humans, maintain strongly acidic conditions in part of their digestive systems. Explain two benefits of this to the animal.
Australia is in the Southern Hemisphere so December to February are summer months and June to August are winter months. Data on vitamin D deficiency levels were collected throughout the year for the Australian National Health Measures Survey. This was then used to analyse the seasonal effects of vitamin D deficiency. Vitamin D deficiency levels for those who had their blood samples taken in summer were compared with those who had them taken in winter. The maps show the vitamin D deficiency by state between 2011 and 2012.
[Source: www.abs.gov.au/ausstats/abs@.nsf/Lookup/4364.0.55.006Chapter2002011-12]
Identify which state had the smallest seasonal change in vitamin D levels.
Suggest one reason why people in Victoria show such a large seasonal change in vitamin D levels.
Outline one effect of lack of vitamin D.
Vitamins and minerals are both essential nutrients. Compare and contrast vitamins and dietary minerals.
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.
Explain the process of erythrocyte and hemoglobin breakdown in the liver.
The graph shows the Bohr shift.
[Source: From The New England Journal of Medicine, Connie C.W. Hsia, Respiratory Function of
Hemoglobin, Volume 338(4):239–47. Copyright © 1998, Massachusetts Medical Society. Reprinted with permission
from Massachusetts Medical Society.]
Using the graph, explain the Bohr shift.
State two modes of transport of carbon dioxide in blood.
1.
2.
State the effect of carbon dioxide in blood on the rate of ventilation.
Describe what happens to the hemoglobin from old or damaged red blood cells that are broken down.
State the disease caused by Helicobacter pylori.
Outline how gastric acid is produced in the stomach.
Explain why proton pump inhibitors alleviate the symptoms of H. pylori infections.
The diagram shows the emulsion and absorption of a fat globule in the gut.
The diagram shows the emulsion and absorption of a fat globule in the gut.
State the organ in the digestive system where this process is taking place.
Explain how components of bile are produced by the liver.
Outline a function of fats in the body.
Explain how epithelial cells in the gut are adapted for absorption.
In order to compare the absorption of fat and of glucose in the digestive system, state in the table, using yes or no, whether the processes occur.
The table below summarizes the distribution of the amino acids lysine and tryptophan in four food items.
The table below shows the average content of lysine and tryptophan in diets of the UK and India. The Indian diet is mainly vegetarian.
[Source: reprinted from Protein and amino acid requirements in human nutrition. Copyright (2007).
https://www.who.int/nutrition/publications/nutrientrequirements/WHO_TRS_935/en/]
Distinguish between essential and non-essential amino acids.
Using the data from the tables, suggest a reason for the differences in lysine concentration in the diets from the UK and India.
Explain the consequences of protein deficiency malnutrition.
List two dietary sources of vitamin D.
State one possible cause and one symptom of type II diabetes.
Cause:
Symptom:
Discuss the significance of the oxygen dissociation curves for adult hemoglobin and fetal hemoglobin.
Explain how steroid and peptide hormones exert their effect.
A long term study followed nearly 40 000 apparently healthy young men for coronary heart disease (CHD) from adolescence through adulthood. The results show how the body mass index (BMI) at adolescence and adulthood affect the risk of CHD. The BMIs are divided into five groups (quintiles), Q1 being the lowest BMI and Q5 the highest. A risk factor of 2 or less is desirable.
Using the graph, discuss the hypothesis that a high BMI in adolescence is more dangerous than a high BMI in adulthood.
State one factor, other than BMI, that increases the risk of CHD.
The figure below shows the average death rates from coronary heart disease in the UK.
[Source: Bhatnagar P, Wickramasinghe K, Wilkins E, et al, Trends in the epidemiology
of cardiovascular disease in the UK, Heart 2016; 102: 1945–1952.]
Suggest one reason for the general decrease in the incidence of coronary heart disease.
Outline the use of a defibrillator.
Explain the heart sounds.
The diagram shows the liver and its main blood vessels.
[Source: VectorStock]
Label the hepatic portal vein bringing blood to the liver.
Outline the circulation of blood through liver tissue.
Explain the breakdown of hemoglobin in the liver.
Athletes taking growth hormones show an increase in their sprinting capacity. This is not maintained after discontinuing the drug. Suggest one reason for the disappearance of the effect.
Distinguish between the mode of action of steroid hormones and peptide hormones.
Identify with reasons whether the pituitary gland is an exocrine or endocrine gland.
Explain, using an oxygen dissociation curve, how hemoglobin supplies oxygen to respiring tissues and how the Bohr shift increases the supply.
Jaundice causes a yellow discolouration of the skin, mucous membranes and sclera of the eyes. State the bile pigment causing this discolouration.
Explain how the normal production of bile pigments changes with the development of jaundice.
Distinguish between the structure of liver sinusoids and capillaries.
Blood pressure changes in chimpanzees (Pan troglodytes) fed a salt-supplemented diet during a two-and-a-half-year treatment period were compared to the blood pressure of those fed a normal diet. The graph shows the mean systolic and diastolic blood pressure (± standard deviation) before, during and after the treatment period.
[Source: Republished with permission of American Society for Clinical
Investigation, from The Journal of Clinical Investigation, O’Shaughnessy, K.M. and Karet, F.E., 113, 8, 2004;
permission conveyed through Copyright Clearance Center, Inc.]
Evaluate the effect of salt on blood pressure using the data in the graph.
State the instrument used by doctors to measure blood pressure.
Describe the mechanism by which the heartbeat is initiated.
The graph shows the relationship between the maximum heart rate during exercise and a person’s age.
Outline one method that the researchers could have used to measure heart rate in this study.
Suggest reasons for the change in maximum heart rate with increasing age.
Outline the use of defibrillation to treat life-threatening cardiac conditions.
Describe how the liver regulates nutrient levels.
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.
Discuss high altitude training for athletes.
Explain the role of receptors in mediating the action of both steroid and protein hormones.
The diagram shows the bacterium Helicobacter pylori attacking the gastric mucosa of the stomach.
[Source: Reproduced from Gut, B A Hills, 34, 588–593, 1993 with permission from BMJ Publishing Group Ltd.]
Outline the possible consequences of a Helicobacter pylori infection of the stomach wall.
The bacterium secretes an enzyme that breaks down urea, resulting in an increase in pH. Outline how this would help the bacterium survive in the stomach.
Explain hormonal control of gastric secretion.
Describe a method that could be used to measure the energy content of a sample of food.
The electrocardiogram (ECG) of a normal patient after exercise is shown.
Using the R–R interval in this ECG, calculate the heart beats per minute (bpm) of this patient. Show your working.
Describe the electrical activity that occurs in the heart during the P wave.
Explain why the QRS wave has a larger amplitude than a P wave.
Compare and contrast steroid and peptide hormone action.
Explain how ventilation rate is changed during vigorous physical exercise.
Outline how infection by Vibrio cholerae can lead to dehydration.
Explain how an increase in cell respiration in a tissue causes increased release of oxygen by hemoglobin in the tissue.