Try each question on your own first. Use the Show Answer button only after you have selected your option, then read the explanation and revise the related concept from your chapter notes.
1. Pathogens that cause disease and can be transmitted from an infected person to a healthy one are collectively called:
A. Infectious agents
B. Non-infectious agents
C. Vectors, without further qualification
D. Antigens, without further qualification
Answer: A. Infectious agents
Explanation: Infectious agents such as bacteria, viruses, and protozoans are capable of spreading disease from one host to another.
2. Malaria in humans is caused by a:
A. Protozoan parasite of the genus Plasmodium
B. Bacterium
C. Virus
D. Fungus
Answer: A. Protozoan parasite of the genus Plasmodium
Explanation: Malaria is caused by species of the protozoan parasite Plasmodium, which is transmitted through the bite of an infected mosquito.
3. The vector primarily responsible for transmitting malaria is the:
A. Female Anopheles mosquito
B. Female Aedes mosquito
C. Housefly
D. Male Anopheles mosquito
Answer: A. Female Anopheles mosquito
Explanation: Only the female Anopheles mosquito, which requires blood for egg development, transmits the malarial parasite while feeding.
4. AIDS (Acquired Immunodeficiency Syndrome) is caused by infection with the:
A. Human Immunodeficiency Virus (HIV)
B. Plasmodium parasite
C. Bacterium Mycobacterium tuberculosis
D. Bacterium Salmonella typhi
Answer: A. Human Immunodeficiency Virus (HIV)
Explanation: HIV progressively destroys helper T-lymphocytes, severely weakening the immune system and leading to the syndrome known as AIDS.
5. Antibodies belong to a specific class of proteins known as:
A. Immunoglobulins
B. Enzymes
C. Hormones
D. Antigens
Answer: A. Immunoglobulins
Explanation: Antibodies, or immunoglobulins, are Y-shaped proteins produced by B-cells that specifically recognize and bind to foreign antigens.
6. Innate immunity, which is present in an individual from the time of birth, is also commonly referred to as:
A. Non-specific immunity
B. Acquired immunity
C. Specific immunity
D. Passive immunity, exclusively
Answer: A. Non-specific immunity
Explanation: Innate immunity provides a general, non-specific first line of defence against a wide range of pathogens, without prior exposure being required.
7. Vaccination provides long-term protection mainly by inducing:
A. Active immunity through the formation of memory cells
B. Passive immunity exclusively
C. Only innate immunity
D. No measurable immune response at all
Answer: A. Active immunity through the formation of memory cells
Explanation: Vaccines expose the immune system to a harmless form of an antigen, prompting the body to generate memory cells for a faster future response.
8. Cancer cells differ from normal healthy cells mainly in that they:
A. Divide in an uncontrolled manner, having lost the property of contact inhibition
B. Never undergo cell division
C. Are always benign in nature
D. Are completely unable to spread to other tissues
Answer: A. Divide in an uncontrolled manner, having lost the property of contact inhibition
Explanation: The loss of normal growth-regulating mechanisms, including contact inhibition, allows cancer cells to proliferate uncontrollably.
9. Metastasis refers specifically to the:
A. Spread of cancer cells from their original site to other parts of the body
B. Formation of a strictly benign, localized tumor
C. Normal regulation of the cell division cycle
D. Programmed death of cancer cells
Answer: A. Spread of cancer cells from their original site to other parts of the body
Explanation: Metastasis is the process by which malignant cells break away from a primary tumor and establish secondary growths elsewhere in the body.
10. Drug and alcohol abuse among adolescents can often be effectively addressed through:
A. Proper education, counseling and a supportive family environment
B. Complete social isolation from peers
C. Simply ignoring the underlying problem
D. Punishment alone, without support
Answer: A. Proper education, counseling and a supportive family environment
Explanation: A combination of awareness, open communication, and emotional support has been shown to be more effective than punitive measures alone.
11. Opioid drugs primarily exert their effects by acting on specific receptors present in the:
A. Central nervous system
B. Digestive system
C. Skeletal system
D. Excretory system
Answer: A. Central nervous system
Explanation: Opioids bind to specific receptors in the brain and spinal cord, altering the perception of pain and producing effects such as euphoria.
12. Allergens are substances that:
A. Trigger an exaggerated immune (allergic) response in sensitive individuals
B. Always lead to the development of cancer
C. Generally strengthen an individual's immune system
D. Have no measurable effect on the immune system
Answer: A. Trigger an exaggerated immune (allergic) response in sensitive individuals
Explanation: In sensitive individuals, allergens provoke an excessive immune reaction, often involving the release of histamine and associated symptoms.
This page contains a chapter-wise objective practice set. Try the questions without checking the answer first, then use the explanation to understand the point you missed. The current page contains 12 questions, so you can practise in smaller sets when you are revising.
Quick revision tip
After the practice set, write down the question numbers you missed and revise only those concepts once more. This makes MCQ practice more useful than repeatedly attempting the same questions without reviewing mistakes.
