All Free Biology MCQs with Answers

2481. Which of the following will be curable in next two decades?

• A. Tuberculosis
• B. Cancer
• C. Poliomyelitis
• D. None of these

Explanation: Cancer may be curable in the next two decades. The completion of the human genome is causing profound changes in the thinking and direction of biomedical research. Cancer is caused by the malfunctioning of genes, either through the activation of cancer-causing oncogenes or through the inactivation of tumor suppressor genes. By comparing the active genes in the tumor to those of normal cells, the genes causing the cancer can be determined. Side by side, there is significant progress in the fields of genetic engineering and biotechnology. All these aspects give us hope that cancer may be curable in the next two decades. Tuberculosis is curable by taking antitubercular drugs, and polio may be on the verge of eradication if the pulse polio program succeeds.

2482. Diphtheria is caused by :

• A. Nematodes
• B. Bacteria
• C. Virus
• D. None of these.

Explanation: Diphtheria is caused by Corynebacterium diphtheriae, a type of bacteria that usually affects children up to the age of five. It may start with symptoms such as a sore throat, chills, mild fever, sometimes vomiting, and headache. The throat and/or tonsils may show a gray membrane, which can spread downward and cause hoarseness and difficulty in breathing. The nose may also be affected, giving rise to a blood-tinged nasal discharge from one nostril. If the disease is not treated early and properly, the toxin produced by the bacteria can affect the heart and the nervous system, leading to a fatal outcome. The germs are present in the discharges from the nose and throat of patients, as well as in healthy people who act as carriers. Both patients and carriers can spread the disease through activities like kissing, talking, coughing, and sneezing. The incubation period is typically 2 to 5 days. If there is no isolation hospital in the town, the patient should be kept in a well-ventilated room. The most important preventive measure against this disease is to ensure that all babies are immunized within the first six weeks of birth using the DPT vaccine.

2483. Which of the following diseases is now considered completely eradicated from India?

• A. Small pox
• B. Poliomyelitis
• C. Plague
• D. Kala-azar

Explanation: Smallpox is an acute, highly communicable disease caused by the Variola virus. It has been eradicated worldwide, including in India. This highly infectious disease typically begins with symptoms like high fever, chills, backache, and headache, followed by the appearance of a rash on the third day of illness. The rash initially appears on the face and then spreads to the rest of the body. It begins as small reddish spots that develop into papules. These papules then progress into small vesicles filled with clear fluid, which later evolve into pustules. Eventually, a scab forms and falls off by the third week, leaving deep pits or scars known as pockmarks. The virus is present in the oral and nasal discharges of patients and is expelled during activities like coughing and sneezing, which can infect healthy individuals.

2484. Which of the following symptoms indicate red sickness?

• A. Nausea and Loss of hair
• B. Ulcerated skin, Nausea and Loss of hair
• C. Red and Ulcerated skin
• D. Nausea and Anaemia

Explanation: Pellagra, also known as red sickness, is a vitamin deficiency disease caused by a chronic lack of Vitamin B3 in the diet. It can also be caused by a decreased intake of niacin or tryptophan. The symptoms of pellagra include ulcerated skin, nausea, and hair loss. Possible symptoms include: Nausea and vomiting. Diarrhea. Headache. Fever. Dizziness and disorientation. Weakness and fatigue. Hair loss. Bloody vomit and stools from internal bleeding.

2485. If a person shows production of interferons in his body, the chances are that he has got an infection of :

• A. Tetanus
• B. Malaria
• C. Typhoid .
• D. Measles

Explanation: Interferons are antiviral proteins that increase a cell's resistance to viral attacks. Since measles is a viral disease, the body produces interferons. Measles is an acute infectious eruptive viral disease of childhood caused by the RNA-containing Rubeola virus (Polynosa morbillorum). Typhoid and tetanus are bacterial diseases caused by Salmonella typhi and Clostridium tetani, respectively. Malaria is a protozoan disease caused by Plasmodium species.

2486. Which of the following pair of diseases is caused by virus?

• A. Rabies, Mumps
• B. Cholera, Tuberculosis
• C. Typhoid, Tetanus
• D. AIDS, Syphilis

Explanation: Mumps is an infectious disease that causes fever, difficulty in opening the mouth, and painful swelling of the parotid glands, which lie just below the earlobes. It is caused by a Paramyxovirus, which is present in the saliva of the infected person. Rabies (Hydrophobia) is caused by a virus named the rabies virus. It is introduced into the body through the bite of rabid (mad) dogs. The most important characteristic symptom of this disease is the fear of water.

2487. Antibodies are produced by :

• A. Leucocytes
• B. Monocytes
• C. Lymphocytes
• D. Spleen

Explanation: Lymphocytes secrete antibodies to destroy microbes and their toxins, reject grafts, and kill tumor cells. Antibodies are protein in nature. Monocytes (a type of white blood cell) are phagocytic in nature and engulf bacteria and cellular debris. The spleen is an organ that produces lymphocytes.

2488. The interferons are:

• A. Antigen proteins
• B. Antiviral proteins
• C. Antibiotic proteins
• D. All of these.

Explanation: Interferons are proteins that increase the resistance of a cell to attack by viruses by unmasking genes that synthesize antiviral proteins. In humans, three groups of interferons have been discovered interferons from white blood cells; interferons from connective interferons tissue fibroblasts; and interferons from lymphocytes.

2489. Which of the following is the false statement about antibiotics?

• A. Some persons have allergy from antibiotics
• B. Antibiotics are capable of curing any disease
• C. This term was given by Waksman in 1942
• D. Antibiotics is produced by microorganisms

Explanation: Lymphocytes secrete antibodies to combat microbes and their toxins, reject grafts, and eliminate tumor cells. Antibodies are protein-based in nature. Monocytes, a type of white blood cell, exhibit phagocytic behavior by engulfing bacteria and cellular debris. The spleen is an organ responsible for producing lymphocytes.

2490. Nicotine acts as a stimulant, because it mimics the effect of :

• A. Testosterone
• B. Dopamine
• C. Thyroxine
• D. Acetylcholine

Explanation: Nicotine is the major stimulatory component of tobacco products including cigarettes. Nicotine has a number of effects on the human body similar to acetylcholine. It stimulates the passage of nerve impulses, causes muscles to relax, and causes the release of adrenaline, increasing both blood pressure and heartbeat rate.