Human health and disease

Malaria and Plasmodium life cycle

1. The Plasmodium protozoan undergoes different stages of development in its human and mosquito hosts. Match the event/stage of life cycle with the site at which it occurs.

Event	Site
Initial multiplication of sporozoites in humans	Liver cells
Second stage of asexual reproduction	RBCs
Fertilization of gametocytes	Mosquito gut
Injection of sporozoites into human host	Skin

1. The Plasmodium protozoan undergoes different stages of development in its human and mosquito hosts. Match the event/stage of life cycle with the site at which it occurs.

Event	Site
Initial multiplication of sporozoites in humans	Liver cells
Development of gametocytes	RBCs
Release of hemozoin	Ruptured RBCs
Storage of sporozoites	Mosquito salivary glands

1. A mosquito carrying Plasmodium sporozoites bites a sleeping woman. A few weeks later, she starts to experience a high fever and chills every 3-4 days, followed by a return to normal temperature in between. Which of the following events causes the above described symptoms?
   1. Rupture of RBCs and release of hemozoin
      1. Sporozoites replicate within RBCs, subsequently rupture them, and go on to infect other RBCs. This cyclic release of hemozoin causes the symptoms of recurring fever and chills.
2. A group of scientists are developing a drug to stop the spread of malaria. Specifically, they want to block the infectious form of the Plasmodium parasite, from replicating in human hosts. Where is this drug most likely to be effective against the infectious form?
   1. Mosquito salivary glands
      1. Mature, infectious sporozoites are stored in mosquito salivary glands before entering human bloodstreams through bites. The drug would have maximum efficacy here.
3. Plasmodium protozoans undergo different stages of development in their human and mosquito hosts. Which of the following occurs in the mosquito host?
   1. Migration of sporozoites from gut to salivary glands
      1. Mature sporozoites escape from the gut and move into the salivary glands of the mosquito.
4. When a mosquito bites an infected human, it takes up malarial Plasmodium parasites from the bloodstream. These parasites then undergo development into infectious forms, and are stored within the mosquito until it bites another human. In which part of the mosquito are the infectious forms stored?
   1. Salivary glands Mature, infectious sporozoites are stored in mosquito salivary glands before they are injected into human bloodstreams through bites.
5. The life cycle of a Plasmodium protozoan requires two hosts – human and mosquito. The latter begins when a mosquito bites an infected human, and ends when it later bites a different, healthy human. Which of the following events occurs during the mosquito host phase?
   1. Sexual reproduction of parasites
      1. Gametocytes mate in the mosquito gut and undergo development into further stages.

Active and passive immunity:

1. Passive immunity provides quick and short-lived protection against infectious agents, as seen in the image below. Which of the following would result in antibody levels that resemble this curve?

1. Snake anti-venom
   1. Anti-venom contains pre-made antibodies against snake toxins. It provides immediate and passive immunity which resembles this curve.
2. Colostrum
   1. Colostrum is the antibody-rich fluid initially secreted by lactating mothers. Readymade antibodies provide quick and short-lived passive immunity resembling the curve.

1. Active immunity provides slow, but long-lasting and sometimes permanent protection against infectious agents, as depicted in the image below. Which of the following would result in antibody levels that resemble this curve?
   1. Bacterial infections will induce antibody production by the immune system. This is an example of active immunity and will resemble the curve.
   2. Viral infections will induce antibody production by the immune system. This is an example of active immunity and will resemble the curve.

1. Which of the following options provide active immunity against an infectious microbe?
   1. Exposure to living microbes
      1. Living microbes will induce the immune system to produce antibodies against them. This is a form of active immunity.
   2. Exposure to weakened microbes
      1. Weakened or inactivated microbes (as seen in vaccines) induce the immune system to produce antibodies against them. This is a form of active immunity.
2. Which of the following would provide active immunity against chickenpox?
   1. Prior exposure to chickenpox
      1. Prior exposure provides active immunity by creating a ‘memory‘ of the virus and producing antibodies against it on re-exposure.
3. Traveler’s often have to get vaccinated against Hepatitis A, a viral disease common in some parts of the world. People who are allergic to the vaccine receive injections of a different protective substance just before travel, and additional doses every few months after that. What substance could offer quick, specific and short-lived immunity in place of a vaccine?
   1. Immunoglobulins
      1. Immunoglobulins, or antibodies, provide quick and short-lived passive immunity for travellers who cannot receive active immunity through vaccinations.
4. Animal handlers get rabies vaccinations to protect themselves from potential exposure to the virus through bites or scratches. If an unvaccinated person is bitten by a rabid animal, they will receive the vaccine along with an additional substance. What substance could offer immediate and specific immunity against the rabies virus until the vaccine takes effect?
   1. Immunoglobulins
      1. Immunoglobulins, or antibodies, provide immediate, passive immunity against the rabies virus until the vaccine induces active antibody production.
5. Scientists across the world are working to develop a vaccine against the COVID-19 virus. Several of the vaccines being developed contain portions of a ‘spike’ protein that the virus expresses on its surface. Select the statements that best describe how this vaccine will induce immunity in the human body.
   1. Immune cells in the body will learn to recognise and ‘remember’ the spike protein as a foreign protein.
      1. The vaccine will produce memory B and T cells that will recognise the spike protein as foreign and attack the virus that expresses it.
   1. Immune cells will produce antibodies against the spike protein.
      1. Immune cells will generate specific antibodies against the spike protein of the virus, providing active immunity against infection.
6. Plasma therapy is one of the techniques currently being tested against COVID-19. Patients who have recovered successfully from the disease donate plasma from their blood. This plasma is then used to treat other patients battling COVID-19. Which of the following statements about plasma therapy could explain how it helps fight infection?
   1. It provides antibodies against the virus.
      1. Plasma is the part of blood that contains antibodies. Recovered patients have antibodies against the virus, which are extracted and given to other patients to help fight the disease.
   2. It provides passive immunity against the virus.
      1. Plasma from recovered patients contains antibodies. These antibodies, when given to other patients, provides passive immunity against the virus.

Acquired immunity:

1. During a camping trip, Arun undergoes a long-drawn illness due to a bacterial infection. A few months later, he drinks some contaminated water that contains the same bacteria. This time, however, Arun only experiences mild uneasiness and recovers rapidly. Why is Arun able to fight off the infection better the second time around?
   1. Arun’s immune system recognizes the bacteria and fights them faster.
      1. Arun’s immune system forms a memory of the bacteria during the first infection, which allows it to produce specific antibodies faster during the second.
2. During a field trip, Sahil undergoes a long-drawn illness due to a viral infection. A few months later, he contracts the same infection from a friend. This time, however, Sahil only experiences mild uneasiness and recovers rapidly.Why is Sahil able to fight off the infection better the second time around?
   1. Sahil’s immune system recognizes the virus and fights it faster.
      1. Sahil’s immune system forms a memory of the virus during the first infection, which allows it to produce specific antibodies faster during the second.
3. A schoolchild comes down with chickenpox after an outbreak starts in the neighbourhood. How will the child’s acquired immunity help fight the virus?
   1. Production of chickenpox virus-specific antibodies
      1. Antibodies against the chickenpox virus is an example of acquired immunity producing a pathogen-specific response.
4. A schoolchild comes down with measles after an outbreak starts in the neighbourhood. How will the child’s acquired immunity help fight the virus?
   1. Production of measles-specific antibodies
      1. Antibodies against the measles virus is an example of acquired immunity producing a pathogen-specific response.

1. Which of the following roles do B and T lymphocytes perform during antibody-mediated immune responses?
   1. T lymphocytes assist B lymphocytes with producing antibodies.
      1. B lymphocytes, aided by T lymphocytes, secrete pathogen-specific antibodies during a humoral immune response.
2. A man requires a lung transplant operation. In order to find a donor match, he is asked to undergo tests that check for tissue and blood group compatibility. What would happen in the case of a mismatch?
   1. T lymphocytes will recognize non-self cells and reject the transplant.
      1. T lymphocytes are responsible for cell-mediated immunity, through which non-self cells like mismatched transplants are rejected.
3. What are the roles of B and T lymphocytes during a humoral immune response?
   1. B lymphocytes secrete antibodies against pathogens.
      1. B lymphocytes secrete large quantities of pathogen-specific antibodies during a humoral immune response.
      2. T lymphocytes only assist in antibody production. They do not themselves secrete them.
      3. Only T lymphocytes mediate differentiating between self and non-self cells during cell-mediated immunity, and not humoral immunity.
4. A woman requires a kidney transplant operation. In order to find a donor match, she is asked to undergo tests that check for tissue and blood group compatibility. What would happen in the case of a mismatch?
   1. T lymphocytes will recognize non-self cells and reject the transplant
      1. T lymphocytes are responsible for cell-mediated immunity, through which non-self cells like mismatched transplants are rejected.

Antibodies and acquired immunity:

1. The term ‘humoral’ means ‘of or relating to body fluids’. What role do antibodies play in giving humoral immunity its name?
   1. Antibodies are found in blood.
      1. Humoral immunity is mediated by antibodies, which are found in the plasma component of blood – a bodily fluid.
2. The ability of antibodies to recognize and target particular antigens allows the immune system to fight off specific infections. The image below illustrates the structure of an antibody. Which of the labelled regions makes antibodies pathogen-specific?

1. A represents the antigen-binding region that allows antibodies to recognize and target specific pathogens.
   1. B represents one of the two light chains of the protein. It is not responsible for pathogen-specificity.
   2. C represents the disulphide bonds that hold the peptide chains together. They do not make the antibody pathogen-specific.
   3. D represents one of the two heavy chains of the protein. It is not responsible for pathogen-specificity.

1. Antibodies have antigen-binding sites that let them recognize and target specific pathogens. Scientists can identify cells of interest by using fluorescent antibodies that bind antigens on these cells. The image below illustrates the structure of one such fluorescent antibody. Which of the labelled regions would be responsible for recognizing antigens?
   1. B, represents the antigen-binding region that allows antibodies to identify specific cells or pathogens.
      1. A region does not have any specific function. It does not bind antigens. C represents the disulphide bonds that hold the peptide chains together. They do not help the antibody recognize antigens.
      2. D represents one of the two heavy chains of the protein. Heavy chains do not help the antibody recognize antigens.

1. When a pathogen enters the human body, Z  will help other cells produce antibodies, but will not itself do so. Z also drives other types of immune responses, including cell-mediated immunity (CMI). Identify Z,
   1. T lymphocytes
      1. T lymphocytes aid B lymphocytes in antibody production and mediate CMI.
2. What type of immune responses do molecules like IgA, IgG, IgM etc mediate?
   1. Humoral immunity
      1. IgA, IgG, IgM etc are types of antibodies, which mediate humoral immunity.
3. Joseph, an intern at a lab, studies the chemical composition and structure of an antibody. He tabulates his observations, as seen below.

Detail	Observations
Type of molecule	Nucleic acid
Structure	Four heavy chains
Nature of intramolecular bond	Disulphide bond

1. Joseph’s supervisor goes through his notes and points out several incorrect entries. Which detail did Joseph correctly report?
   1. Nature of bond
      1. The peptide chains in an antibody are held together by disulphide bonds.
2. Ameya, an intern at a lab, studies the chemical composition and structure of an antibody. She tabulates her observations, as seen below.

Detail	Observations
Type of molecule	Carbohydrate
Structure	Two heavy, two light chains
Nature of intramolecular bond	Phosphodiester bond

1. Ameya’s supervisor goes through her notes and points out that several of the entries are incorrect. Which detail did Ameya correctly report?
   1. Structure
      1. Antibodies have two heavy and two light peptide chains, and are therefore denoted symbolically as H2L2.
2. When a pathogen enters the human body for the first time,X will produce antibodies against it. Reinfection by the same pathogen will activate X to produce larger amounts of the same antibodies for a secondary immune response. Identify X
   1. B lymphocytes
      1. B lymphocytes produce antibodies against specific pathogens, both during primary and secondary immune responses.

Vaccination and immunisation:

1. Recombinant DNA technology allows scientists to insert specific DNA sequences into cells or organisms like yeast. This technology has been harnessed for large scale production of vaccines. The COVID-19 outbreak, for example, required pharmaceutical companies to manufacture millions of doses of vaccines against the coronavirus. What kind of DNA sequence will scientists use to generate effective vaccines against the coronavirus?
   1. Sequence coding for part of the virus itself
      1. Recombinant vaccines carry sequences of the pathogenic antigen, so that the recipient’s immune system will learn to recognize and remember it.
2. Recombinant DNA technology allows scientists to insert specific DNA sequences into cells or organisms like yeast. This technology has been harnessed for large scale production of vaccines, including the Human papilloma virus (HPV). What kind of DNA sequence will scientists use to generate effective vaccines against HPV?
   1. Sequence coding for part of the virus itself.
      1. Recombinant vaccines carry sequences of the pathogenic antigen, so that the recipient’s immune system will learn to recognize and remember it.

1. The table below lists the medical details of 3 patients who were exposed to the hepatitis A virus.

Details	X	Y	Z
Duration of symptoms	8 weeks	2 days	6 weeks
Antibody production	Slow	Rapid	Slow
Antibody levels	Low	High	Low

The doctor’s notes indicate that one of the patients had been vaccinated, and showed signs of immunological memory of the virus.

1. Which patient is most likely to have received the hepatitis A vaccine?
   1. Y –
      1. Memory B and T cells recognize previously encountered pathogens and overwhelm them quickly with antibodies Y recovers rapidly.
   2. X
      1. Immunological memory helps the system quickly overwhelm previously encountered pathogens with large amounts of antibodies X  takes the longest to recover.
   3. Z
      1. Immunological memory helps the system quickly overwhelm previously encountered pathogens with large amounts of antibodies Z recovers slowly.
2. The table below lists the medical details of 3 patients who were exposed to the tuberculosis bacterium.

Details	A	B	C
Duration of symptoms	4 months	6 months	1 week
Antibody production	Slow	Slow	Rapid
Antibody levels	Low	Low	High

1. The doctor’s notes indicate that one of the patients had been vaccinated, and showed signs of immunological memory of the virus. Which patient is most likely to have received the BCG vaccine against tuberculosis?
   1. C
      1. Memory B and T cells produced by the BCG vaccine recognize the tuberculosis bacteria and overwhelm them quickly with antibodies C recovers rapidly.
      2. Immunological memory helps the system quickly overwhelm previously encountered pathogens with large amounts of antibodies.. While A and B takes the longest time to recover.
2. During a routine checkup, a doctor administers an injection to his patient. A month later, there is an outbreak of measles, but the doctor reassures the patient that the injection vaccinated them against it. What substance could the doctor have administered to actively immunise the patient against the measles virus?
   1. Inactivated measles virus
      1. The patient’s immune system will produce antibodies against inactivated or weakened forms of the measles virus, thus immunising them.
3. During a routine checkup, Dr.Gupta administers an injection to a patient. A month later, there is an outbreak of rubella, but the doctor reassures the patient that the injection vaccinated them against it. What substance could Dr.Gupta have administered to actively immunise the patient against the rubella virus?
   1. Inactivated rubella virus
      1. The patient’s immune system will produce antibodies against inactivated or weakened forms of the rubella virus, thus immunizing them.
4. Sarah is rushed to the hospital after being bitten by a venomous snake. She is taken to the emergency ward, where the medical staff work quickly to counteract the venom. How should the medical staff treat Sarah?
   1. Inject antibodies against the venom
      1. Passive immunisation with preformed antibodies against the snake venom toxins is the fastest way to treat Sarah.
5. Rohan falls down while playing and cuts his knee on a rusted pipe. He rushes to a nearby clinic for medical attention, where he is asked when he last received a tetanus shot. Rohan, however, cannot remember if he has been vaccinated, or when he last received a shot. What is the doctor likely to do next?
   1. Inject Rohan with tetanus antibodies
      1. The doctor can prevent a serious infection by giving Rohan quick, passive immunisation via preformed tetanus antibodies.

The immune system:

1. Which of the following could be a function of a phagocyte?
   1. Engulfing a foreign pathogen
      1. Phagocytes protect the body by engulfing foreign particles or pathogens once they have bypassed the first line of defense (skin).
      2. Phagocytes act on pathogens once they bypass the physical barriers, such as skin.
2. Which immune response is represented in the diagram above?
   1. Humoral immune response
      1. A humoral immune response results in the production of plasma cells, which produce antibodies.

1. Which of the following is circulated throughout the blood as a result of humoral immunity
   1. Antibodies
      1. Antibodies are produced by specialized B cells in the humoral immune system.
2. How do the innate and adaptive immune systems differ?
   1. The innate immune system is nonspecific while the adaptive immune system uses immunological memory.
      1. The innate immune system is a general defense against all pathogens, and the adaptive immune system learns from past pathogens and engages in pathogen-specific defense.
3. Foot-and-mouth disease virus (FMDV) causes severe disease in pigs, cattle, sheep and goats. High levels of FMDV infection can threaten the livestock industry. Which of the following statements best describes how FMDV reproduces in its livestock host?
   1. It uses the animal’s cellular machinery to reproduce inside the animal.
      1. Viruses require the use of host cell to reproduce.
      2. Viruses use the ribosomes of the host cell to undergo protein synthesis.
      3. Viruses use the host cell’s RNA polymerase during replication
4. Viruses are parasites that use host cells to perform most of the functions of life. Which of the following is NOT provided by the host cell?
   1. Genetic material for transcription
      1. Viruses have their own genetic material, but they cannot carry out most of the functions of living things outside of a host cell.
5. Which of the following are involved only in adaptive immunity?
   1. T cells
      1. Some T cells (helper T) assist B cells and others directly kill infected cells (killer T).
   2. Antibodies
      1. They are specialized Y-shaped proteins that can tag antigens for destruction.
   1. B cells
      1. B cells produce antibodies and aid in immunological memory.
      2. Phagocytes are more heavily involved with innate immune responses.
6. The table below shows the characteristics of four pathogens.

Pathogen	Genetic material	Nucleus?	Outer Covering	Can replicate on its own?
1	DNA	No	Cell wall	Yes
2	DNA	Yes	Cell membrane	Yes
3	DNA	No	Protein capsule	No
4	DNA	Yes	Cell wall	Yes

1. Which pathogen is most likely a virus?
   1. Pathogen 3 has a protein capsule covering and is unable to reproduce on its own.
2. Which of the following is/are involved in non-specific (innate) immunity?
   1. Skin
      1. The skin is the first line of defense against pathogens.
   2. Mucous membranes
      1. Mucous membranes serve as a barrier to pathogens and provide chemical defenses.
   3. Phagocytic cells
      1. Phagocytes engulf pathogens that have already passed the first line of defense. Phagocytes are part of the innate immune system.
3. Which of the following is true of B cells and T cells?
   1. T cells mature in the thymus.
      1. T cells are produced in the bone marrow and mature in the thymus.
4. Which of the following is circulated throughout the blood as a result of humoral immunity?
   1. Antibodies
      1. Antibodies are produced by specialized B cells in the humoral immune system.

1. Which statement is true of the adaptive, but not the innate, immune system?
   1. The receptors are highly specific.
   1. The adaptive immune system relies on antigen-specific receptors to produce a highly focused immune response.
      1. Both the innate and adaptive immune systems fight against viruses and bacteria.
      2. Both the innate and adaptive immune systems rely on the coordination of many cells to fight pathogens.
      3. Both the innate and adaptive immune systems use lymphocytes, though not necessarily the same kind.

Allergies:

1. Which of the following statements about allergic reactions is true?
   1. Allergic reactions are caused by normally harmless substances.
      1. Allergic reactions occur when the body overreacts to substances that are normally in the environment, like dust, pollen or certain foods.
   2. Allergic reactions occur when the immune system attacks healthy body cells.
      1. The immune system attacks healthy body or ‘self’ cells in autoimmune disorders, not in allergies.
   3. Allergic reactions involve antibody production.
      1. The immune system overreacts to certain substances, causing a rise in, Ig E
2. When Ayan eats fish, he develops an itchy, swollen tongue and has difficulty swallowing. This does not happen when he eats crab. His doctor prescribes a blood test to check for allergies. What would the results of the blood test show?
   1. High levels of IgE in response to fish
      1. An itchy, swollen tongue and difficulty swallowing are symptoms of an allergic reaction. This would trigger the production of IgE showing high levels in a blood test.
   2. Low levels of IgE in response to crab
      1. Allergens trigger the production of IgE by the immune system. Since Ayan does not show any allergic response to crab, the corresponding IgE levels would be low.
3. The table below lists how Sheetal reacts when exposed to four different objects.

Object	Reaction
Old food	Nausea, vomiting
Metal earrings	Redness, itchiness
Old pillows	Sneezing, red and watering eyes
Chocolate	Blurred vision, excessive thirst

1. Which objects are allergens for Sheetal?
   1. Metal earrings
      1. Nickel, which is commonly used to make metal jewellery, can be an allergen. Itchy, red skin at the place of contact is a sign of an allergic reaction.
   2. Old pillows
      1. Old pillows can contain dust mites, which are allergens for some people. Sneezing and watering, red eyes are symptoms of allergies.
2. In some people, peanuts can cause a severe, potentially life-threatening allergic reaction, known as anaphylaxis. Symptoms include swelling of the throat and tongue, difficulty breathing, and loss of consciousness. Emergency treatment of anaphylaxis involves the injection of certain substances that reduce the allergic response. Which of the following substances are likely to be used for treating anaphylaxis?
   1. Antihistamine blocks the action of histamine, which is released by mast cells in response to an allergen.
   2. Adrenaline, or epinephrine, relaxes muscles and constricts blood vessels. This opens up the airways of the patient and lets them breathe normally again.
3. Blood tests can be used to determine the cause of allergies. After exposing the patient to different substances, their blood is drawn and tested. The image below gives the test results of patient X. Which of the substances are allergens for patient X?

1. The immune system overreacts to allergens by producing antibodies against them. Since substance  B and C induces high levels of IgE, it is an allergen.
2. The table below lists how Sheetal reacts after performing four different activities.

Object	Reaction
Gardening	Wheezing, shortness of breath
Running up stairs	Shortness of breath, fatigue
Eating potatoes	Bloating, gas
Applying hair dye	Itchiness, rashes

1. Which activity causes symptoms of allergies in Sheetal?
   1. Gardening can expose Sheetal to pollen, a common allergen. Wheezing and shortness of breath after this activity indicates an allergic reaction.
   2. Cosmetics like hair dyes can contain chemicals that cause allergies. Itchiness and rashes after contact with dye indicate an allergic reaction.
2. In some people, peanuts can cause a severe, potentially life-threatening allergic reaction, known as anaphylaxis. Symptoms include swelling of the throat and tongue, difficulty breathing, and loss of consciousness. Emergency treatment of anaphylaxis involves the injection of certain substances that reduce the allergic response. Which of the following substances are likely to be used for treating anaphylaxis?
   1. Antihistamine blocks the action of histamine, which is released by mast cells in response to an allergen.
      1. Adrenaline, or epinephrine, relaxes muscles and constricts blood vessels. This opens up the airways of the patient and lets them breathe normally again.

HIV and AIDS:

1. A doctor checks these reports and recommends an HIV test to one of the patients. Which patient is likely to be HIV-positive?
   1. B
      1. HIV replicates inside The cells and macrophages, leading to a progressive decline in their numbers and lowered immunity.

1. A patient is referred to an immunologist because of a history of recurring ailments. The patient’s symptoms include fever, frequent bacterial and viral infections, and weight loss. The immunologist suspects an HIV infection, and orders a blood test. What result would confirm that the patient is HIV-positive?
   1. Low T lymphocyte levels
      1. HIV replicates inside macrophages and T helper cells. T cell count drops over time, and causes reduced immunity in the infected person.
2. Once a cell is infected by HIV, it turns into a factory that produces new viruses. These viruses then go on to infect more cells, and so on until the infection is widespread. What components will the host cell need to produce to replicate HIV?
   1. Viral RNA
      1. The integrated viral DNA will produce viral RNA that can form the genetic material of new viruses.
   2. Viral proteins
      1. The integrated virus will instruct the host cell to produce viral proteins, which can form the envelopes of new viruses.
3. After the virus has successfully entered the host cell, it sets about replicating. Before this process can begin, however, the virus needs to be embedded in the cell’s nuclear machinery. Identify the two events that allow the integration of the virus into the host cell.
   1. Viral DNA is produced using reverse transcriptase
      1. HIV and other retroviruses get their names from the process of reverse transcription, which produces DNA from their RNA genomes.
   2. Viral DNA is integrated into the host cell’s DNA.
      1. Viral DNA is integrated into the host cell DNA, allowing viral genes to be read and translated into proteins.
4. The human immunodeficiency virus (HIV) has structures called glycoproteins embedded in its outer protein envelope (see image below). These glycoproteins enable the virus to bind and fuse with the membrane of a target cell. Following this, the virus injects a substance into the cell, thus infecting it. What does the virus inject into its target cell?
   1. RNA
      1. Retroviruses like HIV inject their genetic material, RNA, into target cells to infect them.
5. HIV and other retroviruses need to first integrate into host cell DNA before they can replicate. Some treatments for HIV target this step by blocking an enzyme called reverse transcriptase. Which of the following events would be inhibited by this treatment?
   1. Production of viral DNA
6. The image below represents the structure of a human immunodeficiency virus (HIV).

1. Each of the labelled structures play a specific role in viral function. For example, the glycoproteins embedded in the envelope allow the virus to bind to the surface of target cells. Which of the following statements about the other labelled structures are true?
   1. The genetic material is injected into the target cell
      1. Retroviruses like HIV inject their genetic material, RNA, into target cells to infect them.
2. Once HIV has integrated into a host cell, it takes over the replication machinery and begins to produce copies of itself. Which of the following steps the virus need to carry out in order to replicate?
   1. Production viral RNA
      1. The integrated viral DNA will produce viral RNA that can form the genetic material of new viruses.
   1. Production of viral proteins
      1. The integrated virus will instruct the host cell to produce viral proteins, which can form the envelopes of new viruses.
3. After the virus has successfully entered the host cell, it sets about replicating. Before this process can begin, however, the virus needs to be embedded in the cell’s nuclear machinery. Identify the two events that allow the integration of the virus into the host cell.
   1. Viral DNA is produced using reverse transcriptase
      1. HIV and other retroviruses get their names from the process of reverse transcription, which produces DNA from their RNA genomes.
   2. Viral DNA is integrated into the host cell’s DNA.
      1. Viral DNA is integrated into the host cell DNA, allowing viral genes to be read and translated into proteins.

Cancer – causes and mechanism:

1. Medical tests confirm that a suspected cancer patient has a malignant tumor. The oncologist informs the patient about this finding, and explains what its implications are. From the list below, identify the correct information that the doctor will give the patient.
   1. The tumor will spread.
      1. Malignant tumor cells can slough off and spread to other parts of the body
2. While examining a dog, a vet finds a lump under its skin. He orders tests to identify the nature of the tumor, and carries out periodic examinations of the dog over the next few weeks. Which of the following test results would indicate that the tumor is benign?
   1. The tumor stays confined to its original location.
      1. Benign tumors usually remain in the original location, and do not migrate to other parts of the body.
3. While examining a cat, a vet finds a lump under its skin. She orders tests to identify the nature of the tumor, and carries out periodic examinations of the cat over the next few weeks. Which of the following test results would indicate that the tumor is benign?
   1. The tumor grows slowly.
      1. Benign tumor cells grow slowly relative to malignant tumor cells.
   2. The tumor does not invade nearby tissues.
      1. Benign tumors are generally non invasive, and cause little damage to their surroundings

1. The human papillomavirus (HPV) is one of the major causes of cervical cancer. Pap smears are recommended for women above the age of 212121, in order to detect pre-cancerous changes in cervical cells, Vaccinating against HPV at a young age can help prevent this cancer from developing in later stages of life. How does HPV cause cancer in humans?
   1. It carries viral oncogenes.
      1. Viruses can disrupt DNA in human cells, and insert their own oncogenes into the system, causing uncontrolled cell multiplication.
2. Large, long-lived mammals like whales and elephants are relatively resistant to developing cancer. Scientists are studying their cellular properties, including contact inhibition, to try to uncover the mechanisms behind their long lives. Why would contact inhibition help prevent cancer?
   1. It controls cell growth and proliferation.
      1. Contact inhibition ensures that cells stop growing when they come into contact with each other.
3. Naked mole rats are famous for their resistance to cancer. Scientists think that this might be due to the expression of genes that increase sensitivity of cells to contact inhibition. Why would hypersensitivity of contact inhibition cause resistance to cancer?
   1. Cells will only multiply in a controlled manner.
      1. Contact inhibition ensures that cells stop growing when they come into contact with each other. So, naked mole rats are unlikely to develop tumors.

1. HER2 is a gene that codes for a cell-membrane receptor. Normally, it is involved in functions such as cell growth, differentiation, and repair. Under abnormal conditions, this gene can cause uncontrolled proliferation of cells, and is associated with aggressive forms of breast cancer. What term can be used to describe genes like HER2?
   1. Proto-oncogene
      1. Proto-oncogenes are normally functioning genes that can become mutated or overactive, leading to cancer formation.
2. A breast cancer patient finds out that new tumors have been detected in her bones and liver. How did the cancer cells metastasize from the breast tissue to other regions?
   1. They entered the bloodstream and reach other organs.
      1. A few neoplastic cells in the breast slough off from the primary tumor and travel to other organs through the bloodstream.

1. Hepatitis B virus (HBV) and hepatitis C virus (HCV) can increase the risk of liver cancer in infected individuals. Immunization against these viruses can thus provide multiple health benefits. How do HBV and HCV infections increase the risk of cancer?
   1. They introduce viral oncogenes to the host.
      1. Viruses can disrupt DNA in human cells, and insert their own oncogenes into the system, causing uncontrolled cell multiplication.
2. The table below lists 4 groups of people who were surveyed as part of a health study.

A	B	C	D
Chain smokers	Nuclear bomb blast survivors	Regular cell phone users	Athletes

1. A – Tobacco is a potent chemical carcinogen that is known to cause lung cancer
   1. B- Nuclear bombs release ionizing radiation that can cause mutations in DNA (physical carcinogens).
2. A national health survey asked people to list activities that they believed to cause cancer. The table below lists 4 of the most common answers.

A	B	C	D
Regular/chain smoking	Eating chocolate/ice cream	Frequent tanning without sunscreen	Heating food with microwave ovens

1. Which of the answers are correct, and actually increase risk of cancer?
   1. A – Tobacco is a potent chemical carcinogen that is known to cause lung cancer.
   2. C – Non-ionizing radiation from the sun, including UV can cause mutation that increase risk of skin .cancer.
2. The KRAS gene is involved in cell signalling pathways that instruct cells to grow. Mutations in this gene are correlated with pancreatic, colorectal and lung cancer. What term can be used to describe genes like KRAS that can become carcinogenic?
   1. Proto-oncogenes are normally functioning genes that can become mutated or overactive, leading to cancer formation.
3. A lung cancer patient finds out that his cancer has metastasized to his brain and liver. How do the cancer cells move from the lungs to other organs?
   1. They enter the bloodstream and reach other organs.
      1. A few neoplastic cells in the lungs slough off from the tumor and travel to other organs through the bloodstream.

1. An oncologist studies a patient’s report and notes that their tumor contains neoplastic cells. He informs the patient about this finding, and proceeds to explain what its implications are. From the list below, identify the correct information that the doctor will give his patient.
   1. The tumor is malignant.
      1. Neoplastic cells proliferate very rapidly, and are found in malignant tumors.
   2. The tumor will damage surrounding tissues.
      1. Neoplastic cells invade surrounding tissues and starve their cells by using up their nutrients and resources.

Mis-used drugs:

1. A scientist is testing the effects of heroin on monkeys. The table below lists the details of drug treatment on 4 different monkeys.

Details	Monkey 1	Monkey 2	Monkey 3	Monkey 4
Number of doses delivered per day	5	3	1	0

1. After a few days, the scientist tests the tolerance levels of each monkey to heroin. She delivers 2 doses of heroin to each monkey and tests their responses. Which of the 4 monkeys will respond to this test?
   1. Monkey 3 and 4
      1. Monkey 3 is used to 1 dose of drug per day, and Monkey 4 not received any heroine thus has relatively low tolerance for the drug. It will respond to the test.
   2. Monkey 1 and 2  will have extremely high tolerance to the drug. It will not respond to lower doses.

Category	Drug	Taken via	effect
Opioid	Morphine, heroine	Snorting/injection	Binds receptors in CNS and GIT; Depressants(slows down body functions)
Cannabinoid	Cannabis, marijuana	Inhalation/oral ingestion	Binds receptor in brain and affects cardiovascular system
Stimulant	Cocaine	Snorting	Stimulates CNS, interferes with dopamine transport; causes euphoria, increased energy, and hallucinations.
	nicotine	Inhalation/Oral ingestion	Stimulates adrenal gland to release adrenaline and noradrenaline; raises blood pressure and heart rate.