Abhranti.ai
Explore
Start free

Human Health and Disease: questions with answers

Class 12 Biology, Chapter 7 (NCERT). 15 questions by concept. Open “Show answer” for the answer and why.

How to teach this chapter · Common misconceptions & worked visual for this chapter

Common bacterial and viral infections

Question 1

Which statement best explains common bacterial and viral infections?

  1. (a)Pathogen, route, target tissue and prevention are different for each infection. Salmonella typhi causes typhoid. Pneumococci can cause pneumonia. Rhinoviruses commonly cause the common cold. Antibiotics do not work against viruses.
  2. (b)Typhoid is caused by a virus
  3. (c)Antibiotics cure the common cold
  4. (d)The process has no biological mechanism and never depends on evidence.
Show answer

(a) Pathogen, route, target tissue and prevention are different for each infection. Salmonella typhi causes typhoid. Pneumococci can cause pneumonia. Rhinoviruses commonly cause the common cold. Antibiotics do not work against viruses.

Pathogen, route, target tissue and prevention distinguish infections: Salmonella typhi causes typhoid, pneumococci may cause pneumonia, and rhinoviruses commonly cause colds; antibiotics do not treat viral replication.

Question 2

A learner claims: Antibiotics cure the common cold. Which correction is best?

  1. (a)Antibiotics cure the common cold
  2. (b)The common cold is viral, so antibacterial drugs do not target its cause.
  3. (c)The claim is correct because all biological systems behave identically.
  4. (d)Typhoid is caused by a virus
Show answer

(b) The common cold is viral, so antibacterial drugs do not target its cause.

The common cold is viral, so antibacterial drugs do not target its cause.

Health, disease and host factors

Question 3

Which statement best explains health, disease and host factors?

  1. (a)Health is a state that keeps changing. It is shaped by a person's genes, infections, nutrition, behaviour, environment and social conditions. Disease means the body is not working normally. It is more than just a visible symptom.
  2. (b)Health means only absence of visible symptoms
  3. (c)The process has no biological mechanism and never depends on evidence.
  4. (d)Every disease is caused by a pathogen
Show answer

(a) Health is a state that keeps changing. It is shaped by a person's genes, infections, nutrition, behaviour, environment and social conditions. Disease means the body is not working normally. It is more than just a visible symptom.

Health is a dynamic state shaped by genetic constitution, infection, nutrition, behaviour, environment and social conditions; disease is a disturbance of normal function rather than merely a visible symptom.

Question 4

A learner claims: Health means only absence of visible symptoms. Which correction is best?

  1. (a)The claim is correct because all biological systems behave identically.
  2. (b)Every disease is caused by a pathogen
  3. (c)Health includes physical, mental and social well-being. Disease can exist even when there are no symptoms yet.
  4. (d)Health means only absence of visible symptoms
Show answer

(c) Health includes physical, mental and social well-being. Disease can exist even when there are no symptoms yet.

Health includes physical, mental and social well-being, and subclinical disease can exist.

Malaria and vector-borne disease

Question 5

Which statement best explains malaria and vector-borne disease?

  1. (a)Malaria is transmitted by male mosquitoes
  2. (b)Plasmodium alternates between humans and female Anopheles mosquitoes. Human liver and red-cell stages cause cyclic fever, while the mosquito is the vector and definitive host for sexual reproduction.
  3. (c)Plasmodium completes its entire life cycle in humans
  4. (d)The process has no biological mechanism and never depends on evidence.
Show answer

(b) Plasmodium alternates between humans and female Anopheles mosquitoes. Human liver and red-cell stages cause cyclic fever, while the mosquito is the vector and definitive host for sexual reproduction.

Plasmodium alternates between humans and female Anopheles mosquitoes. Human liver and red-cell stages cause cyclic fever, while the mosquito is the vector and definitive host for sexual reproduction.

Question 6

A learner claims: Malaria is transmitted by male mosquitoes. Which correction is best?

  1. (a)Plasmodium completes its entire life cycle in humans
  2. (b)Malaria is transmitted by male mosquitoes
  3. (c)Female Anopheles mosquitoes transmit sporozoites that can infect a person, while taking blood meals.
  4. (d)The claim is correct because all biological systems behave identically.
Show answer

(c) Female Anopheles mosquitoes transmit sporozoites that can infect a person, while taking blood meals.

Female Anopheles mosquitoes transmit infective sporozoites while taking blood meals.

Innate immunity and barriers

Question 7

Which statement best explains innate immunity and barriers?

  1. (a)The process has no biological mechanism and never depends on evidence.
  2. (b)Innate immunity acts immediately through physical, physiological, cellular and cytokine barriers such as skin, mucosa, acid, phagocytes and interferons; it lacks antigen-specific memory.
  3. (c)Skin is the only innate barrier
  4. (d)Innate immunity is antigen-specific and improves after each exposure
Show answer

(b) Innate immunity acts immediately through physical, physiological, cellular and cytokine barriers such as skin, mucosa, acid, phagocytes and interferons; it lacks antigen-specific memory.

Innate immunity acts immediately through physical, physiological, cellular and cytokine barriers such as skin, mucosa, acid, phagocytes and interferons; it lacks antigen-specific memory.

Question 8

A learner claims: Innate immunity is antigen-specific and improves after each exposure. Which correction is best?

  1. (a)Innate immunity is antigen-specific and improves after each exposure
  2. (b)Skin is the only innate barrier
  3. (c)Innate defences are broadly acting and do not generate antigen-specific memory.
  4. (d)The claim is correct because all biological systems behave identically.
Show answer

(c) Innate defences are broadly acting and do not generate antigen-specific memory.

Innate defences are broadly acting and do not generate antigen-specific memory.

Acquired humoral and cell-mediated immunity

Question 9

Which statement best explains acquired humoral and cell-mediated immunity?

  1. (a)The process has no biological mechanism and never depends on evidence.
  2. (b)T cells secrete all circulating antibodies
  3. (c)Adaptive immunity is antigen-specific and forms memory. B cells and antibodies handle humoral responses, while T cells coordinate and kill infected or changed cells. Both types arise through clonal selection.
  4. (d)Acquired immunity has no memory
Show answer

(c) Adaptive immunity is antigen-specific and forms memory. B cells and antibodies handle humoral responses, while T cells coordinate and kill infected or changed cells. Both types arise through clonal selection.

Adaptive immunity is antigen-specific and forms memory. B cells and antibodies mediate humoral responses, while T cells coordinate and kill infected or altered cells; both arms arise through clonal selection.

Question 10

A learner claims: T cells secrete all circulating antibodies. Which correction is best?

  1. (a)T cells secrete all circulating antibodies
  2. (b)Acquired immunity has no memory
  3. (c)Plasma cells derived from B lymphocytes secrete antibodies.
  4. (d)The claim is correct because all biological systems behave identically.
Show answer

(c) Plasma cells derived from B lymphocytes secrete antibodies.

Plasma cells derived from B lymphocytes secrete antibodies.

Vaccination and passive immunity

Question 11

Which statement best explains vaccination and passive immunity?

  1. (a)Passive immunity is slow but lifelong
  2. (b)Vaccination safely presents antigen to generate active immunity and memory. Passive immunity transfers ready-made antibodies for immediate short-lived protection and does not itself create memory.
  3. (c)Vaccines provide only ready-made antibodies
  4. (d)The process has no biological mechanism and never depends on evidence.
Show answer

(b) Vaccination safely presents antigen to generate active immunity and memory. Passive immunity transfers ready-made antibodies for immediate short-lived protection and does not itself create memory.

Vaccination safely presents antigen to generate active immunity and memory. Passive immunity transfers ready-made antibodies for immediate short-lived protection and does not itself create memory.

Allergy and autoimmunity

Question 12

Which statement best explains allergy and autoimmunity?

  1. (a)Autoimmunity targets only foreign antigens
  2. (b)Allergy is an exaggerated immune response to normally harmless antigens, often involving IgE and chemical messengers such as histamine. Autoimmunity is the loss of tolerance to self antigens.
  3. (c)The process has no biological mechanism and never depends on evidence.
  4. (d)An allergen is always a disease-causing microbe
Show answer

(b) Allergy is an exaggerated immune response to normally harmless antigens, often involving IgE and chemical messengers such as histamine. Autoimmunity is the loss of tolerance to self antigens.

Allergy is an exaggerated immune response to normally harmless antigens, often involving IgE and mediators such as histamine; autoimmunity is loss of tolerance to self antigens.

HIV infection and AIDS

Question 13

Which statement best explains hiv infection and aids?

  1. (a)HIV infects immune cells including helper T lymphocytes, reverse-transcribes its RNA, and progressively weakens immunity. Transmission requires infected body fluids; casual contact and mosquito bites do not spread HIV.
  2. (b)AIDS is caused directly by mosquitoes
  3. (c)HIV spreads by touch or shared meals
  4. (d)The process has no biological mechanism and never depends on evidence.
Show answer

(a) HIV infects immune cells including helper T lymphocytes, reverse-transcribes its RNA, and progressively weakens immunity. Transmission requires infected body fluids; casual contact and mosquito bites do not spread HIV.

HIV infects immune cells including helper T lymphocytes, reverse-transcribes its RNA, and progressively weakens immunity. Transmission requires infected body fluids; casual contact and mosquito bites do not spread HIV.

Cancer, detection and treatment

Question 14

Which statement best explains cancer, detection and treatment?

  1. (a)Every tumour is malignant and metastatic
  2. (b)Cancer cells obey normal contact inhibition
  3. (c)Cancer involves loss of normal growth control, clonal expansion, invasion and sometimes metastasis. Detection may use imaging, biopsy and molecular markers; treatment can combine surgery, radiotherapy, chemotherapy and immunotherapy.
  4. (d)The process has no biological mechanism and never depends on evidence.
Show answer

(c) Cancer involves loss of normal growth control, clonal expansion, invasion and sometimes metastasis. Detection may use imaging, biopsy and molecular markers; treatment can combine surgery, radiotherapy, chemotherapy and immunotherapy.

Cancer involves loss of normal growth control, clonal expansion, invasion and sometimes metastasis. Detection may use imaging, biopsy and molecular markers; treatment can combine surgery, radiotherapy, chemotherapy and immunotherapy.

Drug and alcohol dependence

Question 15

Which statement best explains drug and alcohol dependence?

  1. (a)Psychoactive substances change how the brain and nerves work. They can cause tolerance, dependence, withdrawal and organ damage. Risk goes down through education, support and treatment, not through shame. Medicines prescribed by a doctor and illegal drug misuse are not the same thing.
  2. (b)More of a drug is always needed because the drug becomes weaker
  3. (c)Addiction is simply a lack of willpower
  4. (d)The process has no biological mechanism and never depends on evidence.
Show answer

(a) Psychoactive substances change how the brain and nerves work. They can cause tolerance, dependence, withdrawal and organ damage. Risk goes down through education, support and treatment, not through shame. Medicines prescribed by a doctor and illegal drug misuse are not the same thing.

Psychoactive substances alter neural function and can cause tolerance, dependence, withdrawal and organ damage. Risk is reduced through education, support and treatment rather than stigma; prescribed medicines and illicit misuse are not equivalent.

Common misconception in Human Health and Disease

Open full misconception guide →

Does receiving antibodies build long-term immune memory?

Wrong

Ready-made antibodies give lasting immunity because the body now has the antibodies it needs.

Why it feels right. I confuse protection by antibodies with the process that creates memory cells.

Right

Passive immunity supplies antibodies. Active immunity activates the recipient's own immune response and can build memory.

Worked example

Passive protection
Antibodies supplied→Rapid protection→Wanes as antibodies clear
Active response
Vaccination→Immune response→Memory supports faster later response
Ready-made antibodies can act quickly and wane. An effective vaccine response can establish immune memory.
  1. A dose of ready-made antibodies can provide protection quickly and then wane as the antibodies are cleared.
  2. After an effective vaccine response, memory cells can support a faster response to a later exposure.