Chapter Exam

Chapter 7: Human Health and Diseases — Online MCQ Test

Q: Typhoid fever in humans is caused by which pathogen?

Answer: B. Salmonella typhi — Typhoid is a bacterial disease caused by Salmonella typhi.

Q: The vector that transmits malaria to humans is:

Answer: A. Female Anopheles mosquito — Malaria is transmitted by the bite of an infected female Anopheles mosquito.

Q: Pneumonia mainly affects which part of the human body?

Answer: B. Alveoli of lungs — Pneumonia infects the alveoli of the lungs, causing them to get filled with fluid.

Q: Which of the following is an example of a physiological barrier of innate immunity?

Answer: B. Acid in the stomach — Stomach acid is a physiological barrier because it prevents microbial growth by creating an acidic environment.

Q: A person receives readymade antibodies against a pathogen. This is an example of:

Answer: B. Passive immunity — Passive immunity occurs when ready-made antibodies are directly given to protect an individual.

Q: In organ transplantation, rejection of a graft is mainly due to:

Answer: B. Cell-mediated immune response of T-lymphocytes — T-lymphocytes are responsible for cell-mediated immunity, which plays a major role in graft rejection.

Q: A mosquito bites a malaria patient and later transmits malaria to another person. Which form of Plasmodium is taken up by the mosquito from the patient?

Answer: B. Gametocytes — The mosquito takes up gametocytes from an infected human; fertilisation and further development occur inside the mosquito.

BIOLOGY · Grade 12 · CBSE(NCERT)

Practice Chapter 7: Human Health and Diseases with a free chapter-wise online MCQ test for CBSE(NCERT) Grade 12 BIOLOGY. This chapter covers: Human Health Immunity Innate Immunity Acquired Immunity Malaria Typhoid Pneumonia Filariasis Cancer HIV AIDS Vaccination Drug Abuse Alcohol Abuse. AI-generated questions from basic to board-exam level, with instant results and explanations.

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Chapter 7: Human Health and Diseases — Important Questions & Answers (FAQ)

Frequently asked questions from CBSE(NCERT) Grade 12 BIOLOGY — Chapter 7: Human Health and Diseases, with answers and explanations. These are sample questions; the exam has its own separate question set.

Which of the following best defines health according to the NCERT context?

A. Absence of any disease only
B. A state of complete physical, mental and social well-being ✓
C. Ability to work continuously without rest
D. Having strong immunity against all pathogens

Answer: B. A state of complete physical, mental and social well-being
Health is not merely the absence of disease; it includes physical, mental and social well-being.

Typhoid fever in humans is caused by which pathogen?

A. Plasmodium vivax
B. Salmonella typhi ✓
C. Streptococcus pneumoniae
D. Wuchereria bancrofti

Answer: B. Salmonella typhi
Typhoid is a bacterial disease caused by Salmonella typhi.

The vector that transmits malaria to humans is:

A. Female Anopheles mosquito ✓
B. Male Anopheles mosquito
C. Female Culex mosquito
D. Aedes mosquito

Answer: A. Female Anopheles mosquito
Malaria is transmitted by the bite of an infected female Anopheles mosquito.

Pneumonia mainly affects which part of the human body?

A. Liver
B. Alveoli of lungs ✓
C. Small intestine
D. Lymph vessels of limbs

Answer: B. Alveoli of lungs
Pneumonia infects the alveoli of the lungs, causing them to get filled with fluid.

Which of the following is an example of a physiological barrier of innate immunity?

A. Skin
B. Acid in the stomach ✓
C. Natural killer cells
D. Interferons

Answer: B. Acid in the stomach
Stomach acid is a physiological barrier because it prevents microbial growth by creating an acidic environment.

A person receives readymade antibodies against a pathogen. This is an example of:

A. Active immunity
B. Passive immunity ✓
C. Cell-mediated immunity
D. Innate immunity only

Answer: B. Passive immunity
Passive immunity occurs when ready-made antibodies are directly given to protect an individual.

In organ transplantation, rejection of a graft is mainly due to:

A. Antibiotic resistance in the graft
B. Cell-mediated immune response of T-lymphocytes ✓
C. Absence of antibodies in blood plasma
D. Excessive production of haemozoin

Answer: B. Cell-mediated immune response of T-lymphocytes
T-lymphocytes are responsible for cell-mediated immunity, which plays a major role in graft rejection.

A mosquito bites a malaria patient and later transmits malaria to another person. Which form of Plasmodium is taken up by the mosquito from the patient?

A. Sporozoites
B. Gametocytes ✓
C. Haemozoin granules
D. Ookinetes

Answer: B. Gametocytes
The mosquito takes up gametocytes from an infected human; fertilisation and further development occur inside the mosquito.

Which combination is correctly matched?

A. Malaria - Wuchereria bancrofti - Female Culex mosquito
B. Filariasis - Wuchereria malayi - Female Culex mosquito ✓
C. Typhoid - Plasmodium falciparum - Contaminated water
D. Pneumonia - Salmonella typhi - Droplet infection

Answer: B. Filariasis - Wuchereria malayi - Female Culex mosquito
Filariasis is caused by filarial worms such as Wuchereria malayi and is transmitted by female Culex mosquitoes.

In HIV infection, why does the number of helper T-lymphocytes progressively decrease?

A. HIV converts helper T-cells into red blood cells
B. HIV-producing macrophages act as virus factories and infect helper T-cells ✓
C. Helper T-cells are destroyed only by antibiotics
D. Helper T-cells stop forming antibodies against malaria

Answer: B. HIV-producing macrophages act as virus factories and infect helper T-cells
HIV first replicates in macrophages, which continue producing viruses that infect and reduce helper T-lymphocyte numbers.

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