This set of Class 12 Biology Chapter 8 Multiple Choice Questions & Answers (MCQs) focuses on “Human Health – Cell Mediated Immunity”.
1. The full form of CMI is __________
a) cell Medium Immunoglobulin
b) cell-Mediated Immunity
c) cyst Marked Infection
d) cellular Medium Infection
Explanation: The full form of CMI is Cell-Mediated Immunity. The immune system comprises of T- lymphocytes that defend the body against pathogens, cancers and foreign structures like tissue transplants.
2. Which of the following mediate the CMI?
b) Red blood corpuscles
c) White Blood cells
Explanation: T-lymphocytes mediate CMI. T-cells/T-lymphocytes are long-lived small cells which have 100,000 receptor sites on their surface for binding antigens. T-cells themselves do not secrete antibodies but help B-cells to produce them.
3. Which of the following is called as Competent lymphocytes?
c) C- lymphocytes
Explanation: T-lymphocytes are called as Competent lymphocytes. The cells develop antigen specificity through the previous contact. T-lymphocytes respond to specific antigen by forming a clone of cells.
4. Number of lymphocytes present in a healthy human is ___________
a) 1 trillion
b) 1 million
c) 1 billion
d) 10 trillion
Explanation: Number of lymphocytes present in a healthy human is 1 trillion. Unusually high or low lymphocyte counts can be a sign of disease.
5. A person without thymus would not be able to reject a tissue transplant.
Explanation: Thymus is a lobed organ located near the heart and beneath the breast bone. It is the site where T-lymphocytes mature. T-cells are the specialized white blood cells which help to defend the body.
6. What is the life of the effector cells of the immune system?
a) A few weeks
b) A few days
c) A few months
d) A few years
Explanation: The life span of effector cells of the immune system is a few days only. Our body releases two types of cells-effector cells and memory cells, of which, effector cells are short-lived and are responsible for the primary response of our body.
7. Which of the following sets include all the types of T-cells?
a) Killer cells and Helper cells
b) Suppressor and Cytotoxic cells
c) Depressor cells, Helper cells and Memory cells
d) Killer cells, Helper cells, Suppressor cells and Memory cells.
Explanation: T-cells of our immune system gets differentiated into Killer or cytotoxic cells, Helper cells, Suppressor cells and Memory cells. Killer, Helper and Suppressor T-cells are also called as Effector cells.
8. Life span of T-cells __________
a) 4-5 hours
b) 4-5 days
c) 4-5 weeks
d) 4-5 years
Explanation: Life span of T-cells is around 4-5 years. The T-cells produced are relatively long-lived to compensate the less number of T-cells produced by thymus in the later years.
9. B-cells produce antibodies in response to the instruction received from _________
a) Killer T-cells
b) Suppressor T-cells
c) Memory Cells
d) Helper T-cells
Explanation: B-cells produce antibodies in response to the instruction received from Helper T-cells. Along with this, Helper T-cells also attract macrophages to the site of infection.
10. How can Organ transplantation rejection be prevented?
a) Immunosuppressant drugs
b) Depressant drugs
d) New T-cells
Explanation: Our body produces a certain type of antibodies in response to the antigens. When an organ is transplanted, the body recognises the ‘non-self’ cells and starts attacking them. Therefore, Organ Transplantation rejection can be prevented by giving Immunosuppressant drugs so that the immune system gets suppressed and do not attack the ‘non-self’ cells.
11. Which of the following cells of the immune system are responsible for causing pores in the plasma membrane of antigens?
a) Helper T-cells
b) Killer T-cells
c) Suppressor T-cells
d) Memory cells
Explanation: Killer T-cells are responsible for producing pores in the plasma membrane of the antigens. The interaction of Killer T-cells with antigens will produce perforins to kill the infected cells.
12. What does T stand for in T-lymphocytes?
Explanation: The letter T in T-lymphocytes stands for Thymus. The thymus is a primary lymphoid organ which is responsible for differentiating T-lymphocytes into antigen sensitive lymphocytes.
13. Helper T-cells can be distinguished from killer T-cells by the presence of _________
a) CD-2 receptor
b) CD-3 receptor
c) CD-8 receptor
d) CD-4 receptor
Explanation: Helper T-cells can be distinguished from Killer T-cells by the presence of CD-4 receptor. CD-8 receptors are present in both Killer T-cells and Suppressor T-cells.
14. Which of the following cell surfaces do not have Major Histocompatibility complex?
a) Red Blood Corpuscles
b) White Blood Cells
c) Helper T-cells
d) Killer T-cells
Explanation: The cell surface of Red Blood Corpuscle does not have Major Histocompatibility Complex. This complex is responsible for displaying the peptide fragments of antigens to the appropriate T-cells of our immune system.
15. What is meant by Apoptosis?
a) Accidental Cell Death
b) Programmed Cell death
c) Accidental Cell division
d) Programmed Cell division
Explanation: Apoptosis has been derived from an Ancient Greek word meaning “falling off”. In biology, Apoptosis refers to a form of programmed cell death that occurs in multicellular organisms. It is used by the immune system to get rid of the virus-infected cells.
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