Human Health and Diseases ISC Class 12 Biology: Notes

What Human Health and Diseases is about

Weightage: Human Health and Diseases is part of the unit Biology and Human Welfare, which carries 14 of the 70 marks in the ISC Biology Paper 1 (Theory), shared with 1 other chapter. Questions on it can appear in any section of the paper.Source: CISCE ISC Biology syllabus, examination year 2027, distribution of marks

Key concepts

Viral and bacterial diseases

Common cold: Rhinoviruses; infect nose and respiratory passage (not lungs); nasal congestion and discharge, sore throat, hoarseness, cough, headache, tiredness for 3-7 days; spread by droplets from coughs and sneezes or contaminated objects. Dengue: dengue virus (a flavivirus) transmitted by the female Aedes mosquito; high fever, severe headache, pain behind eyes, joint and muscle pain, rash, low platelet count. Chikungunya: chikungunya virus (alphavirus) also spread by Aedes; fever and severe, often prolonged joint pain. Prevention of mosquito-borne diseases: remove stagnant water, mosquito nets and repellents, screens, introduce Gambusia fish in ponds, spray insecticides. Typhoid: Salmonella typhi; spreads through contaminated food and water; enters the small intestine and spreads via blood; sustained high fever (39-40 °C), weakness, stomach pain, constipation, headache, loss of appetite; intestinal perforation in severe cases; confirmed by the Widal test (a famous carrier was 'Typhoid Mary'). Pneumonia: Streptococcus pneumoniae and Haemophilus influenzae; infects the alveoli, which fill with fluid; fever, chills, cough, headache, and in severe cases bluish lips and nails; droplets or sharing utensils. Diphtheria: Corynebacterium diphtheriae; membrane in the throat, fever, difficulty in breathing; DPT vaccine. Plague: Yersinia pestis, spread by the rat flea; high fever, swollen lymph nodes (buboes).

Worked example

A cook who recovered from typhoid years ago is found to be the source of repeated outbreaks in the families she works for. What is such a person called, and how does she spread the disease?

Try it first, then show the solutionSolution

1. She is a healthy carrier: Salmonella typhi persists in her body (as in the famous case of 'Typhoid Mary') without symptoms.
2. The bacteria pass out in her faeces; poor hand hygiene contaminates the food she prepares, and others are infected through the food.

Answer: A carrier; she contaminates food with Salmonella typhi from her faeces

Protozoal, helminth and fungal diseases; Plasmodium life cycle

Amoebiasis (amoebic dysentery): Entamoeba histolytica in the large intestine; constipation, abdominal pain, cramps, stools with mucus and blood; houseflies carry cysts to food; prevent by hygiene. Malaria: Plasmodium (P. vivax, P. malariae, P. falciparum; falciparum malaria is the most serious). Life cycle (graphic outline): an infected female Anopheles bites and injects sporozoites → they reach the liver and multiply → released into blood, they attack RBCs, multiply asexually, and the RBCs rupture, releasing the toxin haemozoin, causing chill and high fever recurring every 3-4 days → some parasites form gametocytes in RBCs → a female Anopheles takes up gametocytes with blood → fertilisation and development in the mosquito's gut (sexual stage) → sporozoites move to the salivary glands → injected into the next human. Humans are the intermediate (secondary) host, the mosquito the definitive (primary) host. Ascariasis: Ascaris lumbricoides (roundworm) in the intestine; eggs passed in faeces contaminate soil, water and vegetables; internal bleeding, muscle pain, fever, anaemia, intestinal blockage. Filariasis (elephantiasis): Wuchereria bancrofti (and W. malayi); transmitted by the female Culex mosquito; adult worms live in lymphatic vessels causing chronic inflammation and swelling of lower limbs and genitals. Ringworm: fungi of the genera Microsporum, Trichophyton and Epidermophyton; dry, scaly, itchy circular lesions on skin, nails and scalp; spread by contact, towels, combs; heat and moisture favour growth.

Worked example

Why does a malaria patient have fever at regular intervals of 3-4 days?

Try it first, then show the solutionSolution

1. Plasmodium multiplies asexually inside RBCs in synchronised cycles.
2. At the end of each cycle many RBCs rupture together, releasing merozoites and the toxin haemozoin, which causes chills and high fever; the cycle takes about 48-72 hours depending on the species.

Answer: Synchronised rupture of RBCs releasing haemozoin

Innate immunity and interferons

Immunity: the ability of the body to fight disease-causing organisms. Innate immunity: non-specific, present at birth, provided by four barriers. (1) Physical barriers: skin (main barrier) and mucus coating of the respiratory, gastrointestinal and urogenital tracts, which traps microbes. (2) Physiological barriers: HCl in the stomach, saliva in the mouth, tears from the eyes (lysozyme), all of which kill or prevent microbes. (3) Cellular barriers: leucocytes such as polymorphonuclear neutrophils (PMNL) and monocytes, natural killer (NK) lymphocytes, and macrophages in tissues, which phagocytose and destroy microbes. (4) Cytokine barriers: virus-infected cells secrete interferons, which protect non-infected cells from further viral infection. Interferons: small proteins (glycoproteins) produced by virus-infected cells (and some leucocytes and fibroblasts); they diffuse to neighbouring cells and make them resistant to viral replication; they also activate NK cells and macrophages and are used in therapy (e.g. some cancers, hepatitis). Production of interferons indicates a viral infection (e.g. dengue).

Worked example

Why are interferons described as a cytokine barrier, and why do they help against viral but not bacterial infections?

Try it first, then show the solutionSolution

1. Interferons are proteins released by virus-infected cells; they act on neighbouring cells as chemical signals (cytokines), making them resistant to viral replication.
2. Bacteria multiply on their own outside host cells and do not use the host's machinery, so the antiviral state induced by interferons does not stop them.

Answer: Signal proteins from infected cells that block viral replication in other cells; bacteria do not depend on that machinery

Acquired immunity, antibodies and lymphoid organs

Acquired immunity: pathogen-specific with memory; the first encounter gives a low-intensity primary response, a later encounter a fast, intense secondary (anamnestic) response. Humoral immunity (antibody-mediated): B lymphocytes produce antibodies into the blood and lymph. Cell-mediated immunity (CMI): T lymphocytes act directly (e.g. graft rejection; helper T cells activate B cells). Antibody structure: Y-shaped molecule of four polypeptide chains: two heavy (H) and two light (L) chains (H₂L₂) joined by disulphide bonds; each arm has a variable region (antigen-binding site) and constant regions; the hinge allows flexibility. Classes: IgG (most abundant in serum; crosses the placenta, giving the foetus passive immunity); IgA (in colostrum, saliva, tears, mucus: mucosal immunity); IgM (largest, a pentamer, first antibody produced in a primary response); IgD (on B-cell surfaces, antigen receptor); IgE (bound to mast cells and basophils; mediates allergy, defence against parasites). Active immunity: the body makes its own antibodies after exposure to the pathogen or a vaccine; slow, long-lasting. Passive immunity: ready-made antibodies given (colostrum IgA, placental IgG, antitoxin injections for tetanus or snake bite); immediate, short-lived. Vaccination and immunisation: vaccines contain inactivated or weakened pathogens or their antigens (or recombinant proteins, e.g. hepatitis B vaccine from yeast); they cause a primary response and memory B and T cells, so a later infection triggers a rapid secondary response. Lymphoid organs: primary: bone marrow (all blood cells, B cell maturation) and thymus (T cell maturation; large at birth, shrinks with age); secondary (where lymphocytes meet antigens and proliferate into effector cells): spleen (filters blood, reservoir of erythrocytes), lymph nodes, tonsils, Peyer's patches of the small intestine, appendix; MALT (mucosa-associated lymphoid tissue, about 50% of lymphoid tissue). Autoimmunity: the immune system attacks self cells (e.g. rheumatoid arthritis). Allergy: exaggerated response to allergens (dust mites, pollen, animal dander); IgE causes mast cells to release histamine and serotonin; symptoms: sneezing, watery eyes, running nose, difficulty in breathing, rashes; treated with antihistamines, adrenaline, steroids.

Worked example

Why does a baby fed with colostrum resist infections better? What kind of immunity is this?

Try it first, then show the solutionSolution

1. Colostrum contains abundant IgA antibodies, which protect the baby's gut and respiratory mucosa.
2. The antibodies are ready-made, so this is passive (naturally acquired) immunity.

Answer: IgA in colostrum; passive immunity

AIDS and retrovirus replication

AIDS (Acquired Immuno Deficiency Syndrome) was first reported in 1981. Causative agent: HIV (Human Immunodeficiency Virus), a retrovirus with an RNA genome and an envelope. Transmission: sexual contact with an infected person; transfusion of contaminated blood and blood products; sharing infected needles (drug users); from infected mother to child through the placenta. Replication in the human cell: HIV enters the body and infects macrophages first; its RNA is copied into viral DNA by reverse transcriptase; the viral DNA is incorporated into the host cell's DNA by integrase; infected cells produce new virus particles, so macrophages act as HIV factories. HIV then enters helper T lymphocytes (T_H), replicates and destroys them; the number of T_H cells falls progressively. Symptoms: fever, diarrhoea, weight loss; the immune deficiency leads to opportunistic infections by Mycobacterium, Toxoplasma, viruses and fungi. The incubation period can be from a few months to many years (5-10 years). Diagnosis: ELISA (enzyme-linked immunosorbent assay). Treatment: anti-retroviral drugs prolong life but do not cure. Prevention: safe blood transfusion, disposable needles and syringes, condoms, free distribution of condoms, controlling drug abuse, regular check-ups for high-risk groups; NACO (National AIDS Control Organisation) and NGOs educate people.

Worked example

Why are antibiotics useless against HIV, and why do anti-retroviral drugs prolong life but not cure AIDS?

Try it first, then show the solutionSolution

1. Antibiotics act on bacterial structures and processes (cell wall, bacterial ribosomes) that a virus does not have.
2. Anti-retroviral drugs block viral enzymes such as reverse transcriptase and slow multiplication, but the viral DNA already integrated into host cells stays there, so the infection cannot be eliminated.

Answer: No bacterial targets in HIV; integrated provirus persists despite anti-retroviral drugs

Cancer

Normal cells show contact inhibition: contact with other cells stops their growth. Cancer cells lose contact inhibition, divide uncontrollably and form masses called tumours. Benign tumours: stay confined to their original location, do not spread, cause little damage (encapsulated). Malignant tumours: a mass of proliferating neoplastic cells that grow rapidly, invade and damage surrounding tissues, starve normal cells of nutrients, and send cells through blood to distant sites where they form new tumours (metastasis), the most feared property. Causes (carcinogens): physical (ionising radiation such as X-rays and gamma rays; non-ionising UV), chemical (tobacco smoke, some dyes and chemicals), biological (oncogenic viruses with viral oncogenes); cellular proto-oncogenes may be activated into oncogenes. Diagnosis: biopsy and histopathology; blood and bone marrow tests for leukaemias; radiography (X-rays), CT and MRI; antibodies against cancer-specific antigens; molecular biology to detect genes for inherited susceptibility. Treatment: surgery, radiotherapy (lethal irradiation of tumour cells, sparing normal tissue as far as possible), chemotherapy (drugs; side effects such as hair loss and anaemia), immunotherapy (biological response modifiers such as α-interferon that activate the immune system to destroy the tumour).

Worked example

Why can a benign tumour usually be cured by surgery, while a malignant tumour often returns after surgery?

Try it first, then show the solutionSolution

1. A benign tumour stays confined to its place of origin, often within a capsule, so removing the mass removes all tumour cells.
2. Malignant cells invade surrounding tissue and may already have spread through blood or lymph (metastasis), so cells left behind or in distant organs form new tumours; radiotherapy, chemotherapy or immunotherapy is added.

Answer: Benign tumours are confined; malignant ones invade and metastasise

Adolescence, drugs, alcohol and smoking

Adolescence: the period (about 12-18 years) between childhood and adulthood, with biological and behavioural changes; a vulnerable phase for experimenting with drugs and alcohol. Drugs: Opioids bind to opioid receptors in the CNS and gastrointestinal tract. Heroin (smack), diacetylmorphine, is a white, odourless, bitter crystalline compound obtained by acetylation of morphine, extracted from the latex of the poppy plant, Papaver somniferum; a depressant that slows body functions; taken by snorting or injection. Cannabinoids interact with cannabinoid receptors in the brain; from the inflorescences, leaves and resin of Cannabis sativa: marijuana, hashish, charas and ganja; taken by inhalation or orally; affect the cardiovascular system. Cocaine (coke, crack), an alkaloid from the coca plant, Erythroxylum coca (South America), interferes with the transport of dopamine; a potent CNS stimulant producing euphoria and energy; excess causes hallucinations. Barbiturates, amphetamines, benzodiazepines and LSD are medicinal drugs (barbiturates are sedatives for insomnia and depression) that are misused. Tobacco: contains nicotine, which stimulates the adrenal gland to release adrenaline and noradrenaline (raising blood pressure and heart rate); smoking is linked to cancers of lung, urinary bladder and throat, bronchitis, emphysema, coronary heart disease, gastric ulcer; it raises carbon monoxide in blood and reduces oxygen carried by haemoglobin. Alcohol: damages the nervous system and liver (cirrhosis); heavy drinking during pregnancy harms the foetus. Reasons for addiction: curiosity, adventure, excitement, experimentation, peer pressure, academic or examination stress, family problems; the drug's euphoric effects and a growing dependence (withdrawal symptoms on stopping). Prevention and control: avoid undue peer pressure, education and counselling, seeking help from parents and peers, looking for danger signs, professional and medical help (de-addiction and rehabilitation centres).

Worked example

Why is cocaine described as a stimulant and heroin as a depressant? Name the source plant of each.

Try it first, then show the solutionSolution

1. Cocaine (from Erythroxylum coca) interferes with the transport of dopamine, increasing its action in the brain: euphoria and increased energy.
2. Heroin (made by acetylating morphine from Papaver somniferum) binds opioid receptors and slows down body functions.

Answer: Cocaine boosts dopamine signalling (stimulant); heroin slows body functions (depressant)

Human Health and Diseases in real life

Each concept, met in an everyday situation. Read the situation, answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Topics in this chapter

• AIDS and Retrovirus Replication
• Immunity, Antibodies and Lymphoid Organs
• Common Diseases in Humans and Malaria

Human Health and Diseases: key facts

Antibody structure

$\text{antibody}=H_2{L}_2\text{(2 heavy + 2 light chains, Y-shaped)}$

Two antigen-binding sites at the arm tips.

Five antibody classes

$IgG,IgA,IgM,IgD,IgE$

IgG crosses placenta; IgA in colostrum; IgM first; IgE allergy.

Retrovirus replication

$\text{viral RNA}\stackrel{\text{reverse transcriptase}}{\to }\text{viral DNA}\stackrel{\text{integrase}}{\to }\text{host genome}\to \text{new viruses}$

Macrophages as HIV factories; T_H cells destroyed.

Plasmodium cycle (outline)

$\text{sporozoites}\to \text{liver}\to \text{RBCs (haemozoin, fever)}\to \text{gametocytes}\to \text{mosquito gut}\to \text{salivary glands}$

Female Anopheles is the vector.

Vectors to remember

$\text{Anopheles: malaria};\text{Aedes: dengue, chikungunya};\text{Culex: filariasis};\text{rat flea: plague}$

Houseflies carry amoebiasis cysts.

Human Health and Diseases: diagrams to practise

Practise each one on paper: draw it from the checklist, then tick off every label.

How the board asks Human Health and Diseases

The question patterns to expect, and the method that works for each.

Tricks to remember Human Health and Diseases

Short memory aids. Say each one aloud once, then use it on a question the same day.

• A-C-C vectors

  Anopheles → malaria; Aedes → dengue and chikungunya; Culex → filariasis.

  Use it when: Vector questions.

• GAMDE

  IgG (placenta), IgA (colostrum), IgM (first), IgD (B-cell receptor), IgE (allergy).

  Use it when: Antibody classes.

• Primary makes, secondary meets

  Bone marrow and thymus make lymphocytes; spleen, nodes, tonsils, Peyer's patches, MALT are where they meet antigens.

  Use it when: Lymphoid organs.

• RT then IN

  Reverse Transcriptase first (RNA → DNA), then INtegrase (DNA into host).

  Use it when: Retrovirus replication.

• Poppy-Opioid, Cannabis-Cannabinoid, Coca-Cocaine

  The drug name echoes the plant.

  Use it when: Drug sources.

Human Health and Diseases: board-level solved questions

Ordered from board level to HOTS. Cover the solution, write your own, then compare step by step.

Case-study practice (Section D style)

Read the situation, then answer every part. In the board paper this is a 5-mark question split into 1 + 1 + 1 + 2 marks.

Where the marks are

How a typical answer is split into step marks. Show every step: a right final answer alone rarely earns full marks.

Where students lose marks in Human Health and Diseases

The slips examiners see most often, and what to write instead.

• ✗Mistake: Generic or misspelt names of pathogens and vectors

  CISCE examiners' comments, 2024: candidates misspelt organism names and ignored binomial nomenclature, wrote 'bacteria' or 'virus' instead of the scientific name, and gave Anopheles, Aedes or just 'mosquito' instead of female Culex for filariasis.

  Wrong working

  Filariasis: worm, spread by mosquito.

  Right working

  Wuchereria bancrofti; bite of female Culex mosquito.

  ✓Do this: Learn genus and species with spelling; name the vector's genus.

  Usually costs: 1 mark each.

• ✗Mistake: Wrong disease, test or enzyme role for AIDS

  CISCE examiners' comments, 2024 and 2025: candidates named dengue or chikungunya for a patient on anti-retroviral drugs, gave Widal test or 'blood test' instead of ELISA, did not state the role of integrase or said it integrates proteins, wrote 'reverse transcription' without naming reverse transcriptase, wrote steps out of sequence, or drew the Plasmodium life cycle instead of the retrovirus.

  Wrong working

  Integrase joins viral proteins; diagnosed by Widal test.

  Right working

  Integrase inserts viral DNA into host DNA; diagnosed by ELISA.

  ✓Do this: Learn the HIV flowchart with both enzyme names in place.

  Usually costs: 1-3 marks.

• ✗Mistake: Listing instead of choosing; naming symptoms instead of the condition

  CISCE examiners' comments, 2024 and 2025: asked which immunoglobulin causes allergy, candidates listed all five; for rashes after hair dye they named a fungal infection or only described the symptoms; and they expanded NACO wrongly.

  Wrong working

  IgG, IgA, IgM, IgD, IgE; 'red itchy rash'.

  Right working

  IgE; allergy. NACO = National AIDS Control Organisation.

  ✓Do this: Give one precise answer to a one-mark question.

  Usually costs: 1 mark.

• ✗Mistake: Plant instead of drug, and tumour features swapped

  CISCE examiners' comments, 2025: shown Cannabis leaves, candidates identified the plant but did not name the drug, or named heroin, cocaine or opium; for tumour types A and B they interchanged the features or called the figures L.S. of a leaf.

  Wrong working

  This is Cannabis.

  Right working

  Cannabinoids such as marijuana, hashish, charas and ganja are obtained from Cannabis sativa.

  ✓Do this: Answer exactly what is asked: the drug.

  Usually costs: 1 mark.

Practice questions on Human Health and Diseases

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

1. Q1 · 1 mark · MCQBoard level

   Widal test is used to confirm:
   (a) malaria
   (b) typhoid
   (c) AIDS
   (d) pneumonia

   Hint

   Salmonella.

   Answer

   (b)

2. Q2 · 1 mark · MCQBoard level

   The toxin released when RBCs rupture in malaria is:
   (a) histamine
   (b) haemozoin
   (c) interferon
   (d) serotonin

   Hint

   Causes chills and fever.

   Answer

   (b)

3. Q3 · 1 mark · Very short answerBoard level

   Name the antibody present in colostrum.

   Hint

   Mucosal.

   Answer

   IgA

4. Q4 · 1 mark · Very short answerBoard level

   Name the fungi that cause ringworm.

   Hint

   Three genera.

   Answer

   Microsporum, Trichophyton and Epidermophyton.

5. Q5 · 2 marks · Short answerHarder board level

   Distinguish between humoral and cell-mediated immunity.

   Hint

   B and T cells.

   Answer

   Humoral: mediated by antibodies made by B lymphocytes, circulating in blood and lymph; acts against extracellular pathogens. Cell-mediated: T lymphocytes act directly, killing infected cells and rejecting grafts.

6. Q6 · 2 marks · Short answerHarder board level

   Why is the thymus large in children and small in adults? What is its function?

   Hint

   T cells.

   Answer

   It is a primary lymphoid organ where immature lymphocytes mature into T lymphocytes. Most T-cell maturation happens in early life, so the thymus is large at birth and shrinks with age.

7. Q7 · 2 marks · Short answerHarder board level

   Explain how vaccination works using the idea of primary and secondary responses.

   Hint

   Memory cells.

   Answer

   A vaccine (weakened, killed pathogen or antigen) causes a primary response and creates memory B and T cells. On real infection these mount a rapid, intense secondary response that destroys the pathogen before disease develops.

8. Q8 · 2 marks · Short answerBoard level

   Give the source and effect of (a) heroin, (b) cocaine.

   Hint

   Poppy, coca.

   Answer

   (a) Acetylation of morphine from latex of Papaver somniferum; a depressant slowing body functions. (b) Erythroxylum coca; interferes with dopamine transport, a CNS stimulant causing euphoria and, in excess, hallucinations.

9. Q9 · 3 marks · Short answerHarder board level

   Explain the role of macrophages and helper T cells in HIV infection.

   Hint

   Factory and target.

   Answer

   HIV first infects macrophages, where reverse transcriptase and integrase allow it to multiply; macrophages continue producing viruses (HIV factories). The viruses then enter helper T cells, replicate and kill them; the fall in T_H cells weakens both humoral and cell-mediated immunity, leading to opportunistic infections.

10. Q10 · 3 marks · Short answerHarder board level

    Give the causes of cancer under physical, chemical and biological agents with one example each.

    Hint

    Carcinogens.

    Answer

    Physical: ionising radiation (X-rays, gamma rays) or UV. Chemical: tobacco smoke chemicals. Biological: oncogenic viruses carrying viral oncogenes (and activation of cellular proto-oncogenes).

11. Q11 · 5 marks · Long answerHarder board level

    (a) Describe ascariasis and amoebiasis: cause, transmission and symptoms. [3]
    (b) Give two measures for preventing such diseases. [2]

    Hint

    Faecal-oral route.

    Answer

    (a) Ascariasis: Ascaris lumbricoides; eggs in faeces contaminate soil, water, vegetables; internal bleeding, muscular pain, fever, anaemia, intestinal blockage. Amoebiasis: Entamoeba histolytica in large intestine; houseflies carry cysts to food; constipation, abdominal pain, cramps, stools with mucus and blood. (b) Personal hygiene (wash hands, clean food and water); proper sanitation and disposal of excreta; control of houseflies.

12. Q12 · 2 marks · Short answerHOTS / competency

    Why can't a single dose of antibody injection give lifelong protection, though vaccination often can?

    Hint

    Memory.

    Answer

    Injected antibodies (passive immunity) are gradually broken down and no memory cells are formed. A vaccine stimulates the body's own B and T cells to form memory cells, which persist for years.

13. Q13 · 2 marks · Short answerHOTS / competency

    An organ transplant patient is given immunosuppressants. Which arm of immunity causes graft rejection, and why are close tissue matches sought?

    Hint

    T cells.

    Answer

    Cell-mediated immunity (T lymphocytes) recognises the graft's 'non-self' antigens and destroys it. Tissue and blood group matching reduces the differences that T cells detect, so rejection is less likely.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1. 1.Causative agent of common cold?Show answer

   Rhinoviruses.

2. 2.Vector of filariasis?Show answer

   Female Culex mosquito.

3. 3.What are interferons?Show answer

   Proteins secreted by virus-infected cells that protect uninfected cells from viral infection.

4. 4.Which antibody crosses the placenta?Show answer

   IgG.

5. 5.Name two primary lymphoid organs.Show answer

   Bone marrow and thymus.

6. 6.Diagnostic test for AIDS?Show answer

   ELISA.

7. 7.What is metastasis?Show answer

   Spread of malignant tumour cells through blood to form new tumours at distant sites.

8. 8.Source of cocaine?Show answer

   Erythroxylum coca.

Quick revision checklist

The night before the exam: can you do each of these without looking?

• ☐Can you name the pathogen (genus and species) and vector of each listed disease?
• ☐Can you draw the Plasmodium life cycle outline?
• ☐Can you list four innate barriers with examples?
• ☐Can you draw an antibody and give the role of each class?
• ☐Can you distinguish active/passive and humoral/cell-mediated immunity?
• ☐Can you draw the retrovirus replication flowchart?
• ☐Can you distinguish benign and malignant tumours and list four treatments?
• ☐Can you give the source and effect of opioids, cannabinoids, cocaine and barbiturates?

Human Health and Diseases: frequently asked questions