Kerala SSLC · Biology · Class 10

Soldiers of Defence: Important Questions with Answers

These are 10 important multiple-choice questions from the Kerala SSLC Biology chapter “Soldiers of Defence” (Kerala SCERT syllabus). Each one shows the correct answer and a short explanation of why it is right. Try answering before you read the answer. ExamSummary has 10 practice questions on this chapter in total.

  1. Q1.Which type of white blood cell is primarily responsible for the production of antibodies?

    • A)Neutrophil
    • B)Lymphocyte
    • C)Monocyte
    • D)Basophil

    Answer: B) Lymphocyte

    Lymphocytes differentiate into plasma cells which secrete antibodies specific to antigens. These antibodies bind to pathogens to neutralize them effectively.

  2. Q2.What is the fundamental principle behind how a vaccine protects the body from disease?

    • A)It kills all existing bacteria immediately
    • B)It introduces weakened pathogens to stimulate memory cells
    • C)It boosts the number of red blood cells
    • D)It permanently alters the DNA of the host

    Answer: B) It introduces weakened pathogens to stimulate memory cells

    Vaccines contain weakened or dead pathogens that stimulate the immune system to create memory cells without causing the actual disease. This ensures a faster response upon future exposure.

  3. Q3.Antigens are foreign substances that trigger an immune response. Where are these molecules typically located?

    • A)Inside the nucleus of healthy cells
    • B)On the surface of pathogens or foreign cells
    • C)Within the cytoplasm of red blood cells
    • D)Only in the bone marrow

    Answer: B) On the surface of pathogens or foreign cells

    Antigens are usually proteins or polysaccharides found on the outer surface of bacteria, viruses, or other foreign bodies. They are recognized by antibodies or lymphocytes as non-self markers.

  4. Q4.Which of the following represents a non-specific defense mechanism in the human body?

    • A)Production of specific antibodies
    • B)Formation of memory cells
    • C)Phagocytosis by neutrophils
    • D)Activation of helper T-cells

    Answer: C) Phagocytosis by neutrophils

    Phagocytosis involves white blood cells engulfing any invading particle indiscriminately. Unlike specific immunity, it does not rely on memory or targeting a particular pathogen.

  5. Q5.Why are individuals generally protected from getting a specific disease like chickenpox a second time?

    • A)The virus becomes inactive in the environment
    • B)Memory lymphocytes remain ready to respond quickly
    • C)The skin produces a permanent chemical shield
    • D)Antibodies last forever in the bloodstream

    Answer: B) Memory lymphocytes remain ready to respond quickly

    After infection, memory lymphocytes persist in the body for years. Upon re-exposure, they trigger a rapid and strong immune response to eliminate the pathogen before symptoms appear.

  6. Q6.An allergic reaction occurs when the immune system overreacts to a substance. What is the underlying cause of this hypersensitivity?

    • A)Lack of white blood cells
    • B)Response to harmless antigens like pollen
    • C)Failure of the spleen to filter blood
    • D)Deficiency of Vitamin C

    Answer: B) Response to harmless antigens like pollen

    Allergies happen when the body mistakenly identifies harmless substances as dangerous antigens. This triggers the release of histamines and other chemicals causing inflammation and symptoms.

  7. Q7.What is the characteristic structural shape of an antibody molecule?

    • A)Linear chain
    • B)Spherical ball
    • C)Y-shaped
    • D)Hexagonal ring

    Answer: C) Y-shaped

    Antibodies have a distinct Y-shape structure which allows them to bind to antigens at the tips of the 'Y'. This shape facilitates the neutralization and clumping of pathogens.

  8. Q8.Which of the following statements best distinguishes active immunity from passive immunity?

    • A)Active immunity is long-lasting while passive is temporary
    • B)Passive immunity is always natural
    • C)Active immunity involves injecting antibodies
    • D)Passive immunity creates memory cells

    Answer: A) Active immunity is long-lasting while passive is temporary

    Active immunity develops when the body produces its own antibodies and memory cells, providing long-term protection. Passive immunity involves receiving pre-made antibodies, offering immediate but short-term protection.

  9. Q9.In the context of immunity, what role does the spleen play?

    • A)Producing insulin
    • B)Filtering blood and housing lymphocytes
    • C)Digesting food particles
    • D)Pumping oxygenated blood

    Answer: B) Filtering blood and housing lymphocytes

    The spleen filters blood to remove old red blood cells and pathogens. It also serves as a site where lymphocytes can multiply and mount immune responses.

  10. Q10.If a patient receives an injection of antivenom after a snake bite, what type of immunity does this provide?

    • A)Natural Active Immunity
    • B)Artificial Passive Immunity
    • C)Natural Passive Immunity
    • D)Innate Non-specific Immunity

    Answer: B) Artificial Passive Immunity

    Antivenom contains pre-formed antibodies injected into the body to neutralize venom immediately. Since the recipient's body did not produce these antibodies, it is classified as artificial passive immunity.

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