All Free Biology MCQs with Answers

2451. Which one of the following technique is safest for the detection of cancers?

• A. Magnetic Resonance Imaging (MRI)
• B. Radiography (X-Ray)
• C. Computed tomography (CT)
• D. Histopathological studies

Explanation: The histopathological study is an invasive technique. Radiography and CT involve X-rays which are harmful. In MRI strong magnetic fields and nonionizing radiations are used to detect any physiological changes in the concerned tissue. Hence it is safe for the detection of cancers.

2452. A person suffering from a disease caused by Plasmodium, experiences recurring chill and fever at the time when:

• A. The sporozoites released from RBCs are being rapidly killed and broken down inside spleen
• B. The trophozoites reach maximum growth and give out certain toxins
• C. The parasite after its rapid multiplication inside RBCs ruptures them, releasing the stage to enter fresh RBCs
• D. The microgametocytes and megagametocytes are being destroyed by the WBCs.

Explanation: Plasmodium is a tiny protozoan that is responsible for malaria in humans. In malaria, the patient experiences high fever which periodically rises, and also experiences recurring chills with fever. Such symptoms are seen because when the RBCs carrying Plasmodium (one of the stages in the life cycle of the parasite) ruptures it releases a toxic substance called hemozoin which is chiefly responsible for the chill and high fever recurring every three to four days.

2453. Which one of the following statements is correct?

• A. Benign tumours show the property of metastasis
• B. Heroin accelerates body functions
• C. Malignant tumours may exhibit metastasis
• D. Patients who have undergone surgery are given cannabinoids to relieve pain

Explanation: Tumors are of two types: benign and malignant. Malign or malignant tumors exhibit metastasis. It is the phenomenon in which cancer cells spread to distant sites through body fluids to develop a secondary tumor. Metastasis is a critical factor that makes malignant tumors particularly dangerous and challenging to treat.

2454. Which of the following is a pair of viral diseases?

• A. Common Cold, AIDS
• B. Dysentery, Common Cold
• C. Typhoid, Tuberculosis
• D. Ringworm, AIDS

Explanation: The common cold is a viral disease. It is caused by Rhinoviruses. It causes fever and pain all over the body and affects the nose, throat, and air passages. AIDS(Acquired immunodeficiency syndrome) is a disorder of the cell-mediated immune system of the body. It is caused by HIV (Human immunodeficiency virus). HIV is a retrovirus that attacks helper T cells.

2455. Which one of the following is the correct statement regarding the particular psychotropic drug specified?

• A. Morphine leads to delusions and disturbed emotions.
• B. Barbiturates cause relaxation and temporary euphoria.
• C. Hashish causes after-thought perceptions and hallucinations.
• D. Opium stimulates the nervous system and causes hallucinations.

Explanation: Hashish or charas is a pure resin obtained from female flowers and leaves of selected varieties of Cannabis sativa. It is the most potent hemp product (cannabinoids) and is usually smoked with tobacco. Its use may lead to euphoria, hallucination, drowsiness, and continuous laughing. The hallucinogens act mainly on the CNS and greatly alter one's thoughts, feelings, and perceptions.

2456. Increased asthmatic attacks in certain seasons are related to :

• A. Eating fruits preserved in tin containers
• B. Inhalation of seasonal pollen
• C. low temperature
• D. Hot and humid environment.

Explanation: Increased asthmatic attacks in certain seasons are related to inhalation of seasonal pollen. Pollens are microscopic grains produced by plants in order to reproduce. Pollen allergy is a hypersensitive reaction to pollen. Pollen induced reactions include extrinsic asthma, rhinitis and bronchitis.

2457. If you suspect major deficiency of antibodies in a person, to which of the following would you look for confirmatory evidence?

• A. Serum Globulins
• B. Fibrinogen in the plasma
• C. Haemocytes
• D. Serum Albumins.

Explanation: Serum globulin are globulins occurring in blood serum and containing most of the antibodies of the blood. Serum globulin electrophoresis is a laboratory test that examines specific proteins in the blood called globulins. Globulins are roughly divided into alpha, beta, and gamma globulins. These can be separated and quantitated in the laboratory by electrophoresis and densitometry.

2458. Lysozyme that is present in perspiration, saliva and tears, destroys :

• A. Certain types of bacteria
• B. All viruses
• C. Most Virus Infected Cells
• D. Certain Fungi

Explanation: Lysozyme is an antibacterial enzyme with natural antibiotic properties. Normally excreted in the tears, nasal mucus, milk, and saliva in most animals, lysozyme is part of the body's first natural defense against bacteria and viruses. Lysozyme is an enzyme that degrades the polysaccharide protective coating on the surface of many bacteria and viruses (glycoprotein covering) to allow other enzymes and antibodies to find their appropriate attachment site. Most of the bacteria affected by lysozyme are not pathogenic. Lysozyme serves as a nonspecific innate opsonin by binding to the bacterial surface, reducing the negative charge, and facilitating phagocytosis of the bacterium before opsonins from the acquired immune system arrive at the scene. In other words, lysozyme makes it easier for phagocytic white blood cells to engulf bacteria.

2459. The causative agent of Mad cow disease is a :

• A. Virus
• B. Bacterium
• C. Prion
• D. Worm

Explanation: Mad cow disease is the common term for Bovine spongiform encephalopathy (BSE), a progressive neurological disorder of cattle. It is caused by prions. Symptoms include an excitable or nervous temperament to external stimuli such as touch to the skin. A prion (short for proteinaceous infectious particle) is a unique type of infectious agent, as it is made only of protein. Prions are abnormally structured forms of a host protein, which can convert normal molecules of the protein into abnormal structures.

2460. The bacterium (Clostridium botulinum) that causes botulism is :

• A. An obligate aerobe
• B. A facultative anaerobe
• C. An obligate anaerobe

Explanation: Clostridium is a genus of gram-positive bacteria. They are obligate anaerobes capable of producing endospores.Individual cells are rod-shaped. Foodborne disease caused by C. botulinum is referred to as botulism (a muscle-paralyzing disease). It is caused by the ingestion of a neurotoxin (botulin) produced by the microorganism in the food. Botulin blocks nerve function, leading to respiratory and musculoskeletal paralysis. Symptoms of botulism include weakness, fatigue, and dizziness, followed by blurred vision and progressive difficulty in speaking and swallowing. Weakening of the respiratory muscles is also observed, and death may occur due to respiratory failure.