CBSE Class 12 Biology 2024-25: Chapter 7 Human Health And Disease Competency-Based Questions with Answers; Download Free PDF

Get ready for your CBSE Class 12 Biology exams with our easy guide on Chapter 7: Human Health And Disease. This chapter is very important, especially with the new exam pattern starting in the 2024-25 school year. The CBSE will include 50% more competency-based questions. These questions ask you to use what you've learned in real-life situations.

In this article, we focus on key questions from Chapter 7: Human Health And Disease. These questions help you think and solve problems. You’ll find different types of questions, such as multiple-choice, true-false, gap-filling, and short-answer questions. Each question has clear answers to help you understand the concepts better.

To help you study, you can download a free PDF that has all the competency-based questions from Chapter 7: Human Health And Disease along with their answer keys.

CBSE 12 Biology Chapter 7 : Human Health And DiseaseCompetency-Based Questions

Q.1 Enzyme-linked immunosorbent assay (ELISA) is used for testing if the patient is suffering from AIDS or not. In this test, the enzyme-linked antibodies bind to __________ in the blood sample and help in their detection. Fill in the blank -

A. HIV DNA
B. HIV RNA
C. HIV antibody or antigen
D. HIV reverse transcriptase

Answer. C. HIV antibody or antigen

Q.2 As a part of increasing immunity against COVID-19, a small part of the virus is administered to people as a vaccine.

Which of the following types of immunity is the above an example of?

A. Naturally acquired active immunity
B. Naturally acquired passive immunity
C. Artificially acquired active immunity
D. Artificially acquired passive immunity

Answer. C. Artificially acquired active immunity

Q.3 Two statements are given below - one labelled Assertion (A) and the other labelled Reason (R).

Assertion (A): Salmonella infects various human organs via the bloodstream.

Reason (R): Only Salmonella spps. can withstand the high pH of the blood.

Which of the following is correct?

A. Both A and R are true, and R is the correct explanation for A.
B. Both A and R are true, but R is not the correct explanation for A.
C. A is true, but R is false.
D. A is false, but R is true.

Answer. C. A is true, but R is false

Q.4 During plasma transfusions from healthy persons, individuals acquire all the components present in the plasma of the healthy person.

Which of the following types of immunity is the above an example of?

A. Naturally-acquired active immunity
B. Artificially-acquired active immunity
C. Naturally-acquired passive immunity
D. Artificially-acquired passive immunity

Answer. D. Artificially-acquired passive immunity

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Q.5 In addition to being a vector, the female Anopheles mosquito also acts as a host for the malarial parasite - Plasmodium.

Choose the option that supports the role of the female Anopheles mosquito as a host.

A. Liver cells serve as the site for the multiplication of Plasmodium.
B. Plasmodium completes part of its lifecycle in the female Anopheles.
C. The female Anopheles mosquito lays eggs in stagnant pools of water.
D. The female Anopheles mosquito transmits Plasmodium to humans by biting.

Answer. B

Q.6 Immuno-suppressants are administered to patients post-organ transplantation and also to those suffering from auto-immune disorders. In which of the following ways are immuno-suppressants helpful?

A. They trigger allergic response.
B. They eliminate unhealthy tissues.
C. They control the cell-mediated response.
D. They differentiate between self and non-self parts of the body.

Answer. C. They control the cell-mediated response.

Q.7 Drug abuse is a common problem faced by countries around the world today due to its impact on the health and well-being of an individual.

(a) How is the cocaine consumed? What impact it has on the body?
(b) Some drugs make an individualsleepy while some other make them hyperenergetic. Using appropriate examples, explain this statement.
(c) Why does a regular drug abuser have withdrawal symptoms when consumption of the drug is suddenly stopped?

Answer. (a) 1 mark each for the following:
- Cocaine is usually consumed by snorting/smoking.
- Both these actions involve the respiratory system and so cocaine consumption can interfere with the regular functioning of the respiratory tract.

(b) 1 marks each for naming the correct drug as an example and 0.5 marks each for the explanation:
- Heroin is a drug that acts as a depressant to the functioning of the nervous system and so it slows down bodily functions and makes an individual sleepy.
- Cocaine is a drug that stimulates the nervous system thereby making an individual feel very energetic.

[Accept any other valid answer]

- Using drugs chronically makes the body used to functioning in the presence of the drug.

- Sudden removal of the drug from the body leads to the body asking for the drug through improper functioning or withdrawal symptoms.

Q.8 Complete DiGeorge Syndrome is when the child is born without the thymus. Which of the following processes is likely to be impaired in such individuals?

A. Red blood cell production
B. Thyroxine production
C. Antibody productionD. Antigen production

Answer. C. Antibody production

Q.9 Antibiotics are most effective against which type of infection?

A. Filaria
B. Ringworm
C. Tuberculosis
D. Rheumatoid arthritis

Answer. C. Tuberculosis

Q.10 Which of these infections is NOT caused by a worm?

A. Filariasis
B. Ringworm
C. Round worm
D. Elephantiasis

Answer. A. Filariasis

Q.11 Mark the following statement as true or false and give a reason for your answer. Immune responses to allergens is an example of passive acquired immunity.

Answer. False
Immune responses to allergens involve the production of specific antibodies leading to allergic reactions and is not the result of receiving pre-formed antibodies. Hence, it is an example of active acquired immunity but not passive acquired immunity.

[No marks to be awarded if the correct justification is not provided.]

Q.12 HIV-infected cells continue to remain alive while the viruses are being replicated inside them and released. Describe THREE ways in which this strategy helps the viral infection process.

Answer. 1 mark each for any THREE of the following:

- Infected cells provide a protected environment where the virus can constantly replicate and assemble new viral particles.

- Infected cells help the viral particles in evading immune detection.

- Some infected cells enter a latent state, allowing the virus to persist without active replication.

- The slow release of viruses from infected cells ensures a continuous supply of virus particles, increasing the chances of infecting neighbouring cells and spreading the infection.

[Accept any other valid answers]

Q.13 Why does a malarial parasite invade red blood cells instead of other cells? Mention any THREE reasons to explain the same.

Answer. [1 mark each for any THREE of the following]

[Accept any other valid answers]

Attacking the red blood cells of the human hosts helps the plasmodium in -

- evade detection by the immune system

- access nutrients and oxygen-carrying haemoglobin

- development of sexual-stage parasites (gametocytes) in red blood cells ensuring that the parasite can continue its life cycle in the mosquito host.

- the periodic release of merozoites leads to synchronized cycles of fever in the host, increasing the likelihood of mosquito feeding during a period when the gametocytes are present, facilitating transmission.

Q.14 Movement of cilia in coordinated waves to sweep mucus and trapped pathogens out of the respiratory tract is an example of passive innate immunity. Mark the above statement as true or false and justify your answer.

Answer. False

An Rh-negative pregnant woman does not produce any antibodies, but receives Rh immunoglobulin containing pre-formed antibodies against Rh-positive blood cells from an external source. This is not an example of active acquired immunity but is an example of passive acquired immunity

Q.15 Name the technique that relies on the difference in response to help an individual fight a disease. Explain the underlying mechanism of the technique.

Answer. False

It is an active physical defense mechanism that helps to prevent the entry and build-up of pathogens in the respiratory system and does not involve any external source of immune components. Thus it is an example of active innate immunity

👉 CBSE Class 12 Study Materials

CBSE Class 12 Syllabus 2024-25	CBSE Class 12 Previous Year Papers
NCERT Books For Class 12 Books	NCERT Class 12 Solutions
CBSE Class 12 Full Study Material	CBSE Class 12 Sample Paper 2024-25