What traumatic event does Zitkala-Sa describe at the school?

The forcible cutting of her long hair

Why was the cutting of her hair so humiliating to Zitkala-Sa?

Among her people, shingled hair was worn by cowards and mourners

Name the causative organism and vector of malaria.

Malaria is caused by the protozoan Plasmodium and is transmitted by the female Anopheles mosquito.

Differentiate between innate and acquired immunity.

Innate immunity is non-specific and present from birth, while acquired immunity is pathogen-specific, develops after exposure and shows memory.

What is the structure of an antibody?

An antibody is a Y-shaped protein made of four polypeptide chains: two light and two heavy chains, represented as H2L2.

Differentiate between active and passive immunity.

Active immunity develops when the body produces its own antibodies after exposure to an antigen, while passive immunity is conferred by ready-made antibodies given from outside.

Which cells does HIV primarily attack?

HIV primarily attacks the helper T-lymphocytes (CD4+ T-cells), reducing their number and weakening immunity.

What is the difference between benign and malignant tumours?

Benign tumours remain confined to their original location and do not spread, whereas malignant tumours invade surrounding tissues and undergo metastasis.

What are interferons?

Interferons are cytokines (proteins) secreted by virus-infected cells that protect neighbouring uninfected cells from viral infection.

How does vaccination provide immunity?

Vaccination introduces antigenic proteins or weakened pathogens that generate memory B and T cells, enabling a rapid secondary response upon later infection.

Name the lymphoid organs of the body.

Primary lymphoid organs are the bone marrow and thymus; secondary lymphoid organs include the spleen, lymph nodes, tonsils, Peyer's patches and the appendix.

Name two opioid drugs and their source.

Morphine and heroin (smack) are opioids derived from the latex of the poppy plant Papaver somniferum.

Human Health and Disease

Class 12 Biology · Biology · Chapter 7

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Summary

This chapter examines human health, disease and the body's defence mechanisms. It defines health and discusses common human diseases caused by pathogens, including bacterial (typhoid, pneumonia), viral (common cold), protozoan (malaria caused by Plasmodium, amoebiasis), fungal (ringworm) and helminthic (ascariasis, filariasis) infections, along with their symptoms, life cycles and preventive measures. The immune system is described in detail, distinguishing innate immunity (physical, physiological, cellular and cytokine barriers) from acquired immunity (humoral or antibody-mediated and cell-mediated). The structure of antibodies, types of immunoglobulins, primary and secondary immune responses, active and passive immunity, and the basis of vaccination and immunisation are explained. Allergies, autoimmunity and the role of the lymphoid organs (thymus, bone marrow, spleen, lymph nodes) are covered. AIDS, caused by the Human Immunodeficiency Virus (HIV), its transmission, mode of action on helper T-cells, diagnosis and prevention are detailed. Cancer is explained in terms of cell-cycle deregulation, oncogenes, proto-oncogenes, metastasis, and methods of detection and treatment. The chapter ends with drugs and alcohol abuse, covering opioids, cannabinoids, coca alkaloids, tobacco, their effects, addiction, dependence and the importance of prevention and rehabilitation.

Common diseases and pathogensImmunity: innate and acquiredVaccination and immunisationAIDS and HIVCancerDrugs and alcohol abuse

Key terms

Pathogen

A disease-causing organism such as a bacterium, virus, protozoan, fungus or helminth.

Innate immunity

Non-specific defence present from birth, including physical, physiological, cellular and cytokine barriers.

Acquired immunity

Pathogen-specific immunity characterised by memory, comprising humoral and cell-mediated responses.

Antibody

A Y-shaped protein (immunoglobulin) produced by B-lymphocytes that specifically binds an antigen.

Metastasis

The spread of cancer cells from the primary tumour to distant sites in the body.

Antigen

A foreign molecule that triggers an immune response and binds specifically to antibodies.

Extra questions & answers

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Malaria is caused by the protozoan:

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