All Free Biology MCQs with Answers

2461. HIV which causes AIDS, first starts destroying :

• A. Helper T-Lymphocytes
• B. B-lymphocytes
• C. Leucocytes
• D. None of these

Explanation: AIDS (acquired immunodeficiency syndrome) a syndrome, is caused by the retrovirus HIV (human immunodeficiency virus). The virus Chapter wise NEETAIPMT SOLUTIONS destroys a subgroup of lymphocytes, the helper T cells (or CD4 lymphocytes), resulting in suppression of the body's immune response. HIV is transmitted in blood, semen, and vaginal fluid; the major routes of infection are unprotected vaginal and anal intercourse, intravenous drug abuse, and the administration of contaminated blood and blood products. A combination of antiviral drugs can delay the development of full-blown AIDS for many years, but cannot fully care about the disease.

2462. A person showing unpredictable moods, outbursts of emotion, quarrelsome behaviour and conflicts with others is suffering from :

• A. Addictive Disorders
• B. Schizophrenia
• C. Borderline Personality Disorder (BPD)
• D. Mood Disorders

Explanation: Borderline personality disorder (BPD) is a serious mental illness characterized by pervasive instability in moods, interpersonal relationships, self-image, and behavior. This instability often disrupts family and work life, long-term planning, and the individual's sense of self-identity. Originally thought to be at the "borderline" of psychosis, people with BPD suffer from a disorder of emotion regulation. Schizophrenia is a group of severe mental disorders characterized by disturbances of language and communication; thought disturbances that may involve distortion of reality, misperceptions, delusions, and hallucinations; mood changes, and withdrawn, regressive, or bizarre behavior, lasting longer than six months. A mood disorder is a condition where the prevailing emotional mood is distorted or inappropriate to the circumstances. Addiction is a state of dependence produced by the habitual taking of drugs, alcohol, etc.

2463. Antibodies in our body are complex :

• A. Glycoproteins
• B. Lipoproteins
• C. Steroids
• D. Prostaglandins

Explanation: Antibodies are members of a class of proteins known as immunoglobulins. Immunoglobulins are glycoproteins in the immunoglobulin superfamily. The terms antibody and immunoglobulin are often used interchangeably. They are found in the blood and tissue fluids, as well as many secretions. In structure, they are globulins (in the region of protein electrophoresis). They are synthesized and secreted by plasma cells that are derived from the B cells of the immune system.

2464. Which one of the following depresses brain activity and produces feelings of calmness, relaxation, and drowsiness?

• A. Morphine
• B. Valium
• C. Amphetamines
• D. Hashish

Explanation: Valium is a benzodiazepine (sedative) that gives a feeling of relaxation, calmness, or drowsiness in the body. Morphine is the main opium alkaloid that depresses the respiratory center and contributes to the fall in blood pressure. Amphetamines are synthetic drugs and are stimulant in nature. Hashish is a hallucinogen.

2465. Damage to thymus in a child may lead to :

• A. A reduction in haemoglobin content of blood
• B. A reduction in stem cell production
• C. Loss of antibody mediated immunity
• D. Loss of cell mediated immunity.

Explanation: The thymus is the major gland of our immune system. It is responsible for numerous immune system functions, including the production of T-lymphocytes, a type of white blood cell responsible for cell-mediated immunity. Cell-mediated immunity is a type of defense in which specialized cells carry out protective activities, safeguarding the body against pathogens, including protists and fungi that have entered the host's cells. T-cells and B-cells are the types of lymphocytes that develop from bone marrow cells. Those lymphocytes that migrate to the thymus and differentiate are called T-cells, while those cells that continue to differentiate in the bone marrow are known as B-cells. T-cells are responsible for cell-mediated immunity, whereas B-cells produce antibodies and participate in antibody-mediated immunity.

2466. Which one of the following is not correctly matched?

• A. Glossina Palpalis; Sleeping Sickness
• B. Culex Pipiens; Filariasis
• C. Aedes Aegypti; Dengue Fever
• D. Anopheles Culifacies; Leishmaniasis

Explanation: All the options given are diseases with their associated vectors that transmit the respective diseases. Leishmaniasis, also called kala azar, is caused by Leishmania donovani. It is spread by the sand fly (Phlebotomus) and is characterized by an enlarged spleen and liver, along with high fever. Sleeping sickness is caused by the protozoan Trypanosoma gambiense. Filariasis is caused by the worm Wuchereria bancrofti. Dengue fever is caused by an arbovirus.

2467. Carcinoma refers to :

• A. Malignant tumours of the connective tissue
• B. Malignant tumours of the skin or mucous membrane
• C. Malignant tumours of the colon
• D. Benign tumours of the connective tissue.

Explanation: Carcinoma is a type of cancer that arises in the epithelium, which is the tissue that lines the skin and internal organs of the body. It may occur in any tissue containing epithelial cells. This category includes cervical cancer, breast cancer, skin cancer, stomach cancer, and others.

2468. Christmas disease is another name for :

• A. Haemophilia-B
• B. Hepatitis-B
• C. Down's syndrome
• D. Sleeping sickness.

Explanation: Haemophilia B, a type of haemophilia, is also known as Christmas disease. It is due to a deficiency of a blood coagulation factor known as the Christmas factor (Factor IX). Christmas was the individual (20th century) in whom the factor was first identified. Haemophilia B is a blood disorder that prevents it from clotting.

2469. Salmonella is related with :

• A. Typhoid
• B. Polio
• C. T.B.
• D. Tetanus

Explanation: Typhoid is caused by Salmonella typhi. The organisms responsible for the disease are present in the stool and may also be found in urine. Consequently, they can be carried by water and contaminated food, potentially leading to severe epidemics. Polio is caused by Enterovirus. TB is caused by Mycobacterium tuberculosis. Tetanus is caused by Clostridium tetani.

2470. Which is the most infectious disease?

• A. Hepatitis-B
• B. AIDS
• C. Cough and cold
• D. Malaria

Explanation: Hepatitis-B (serum hepatitis) can occur at any age, and its mode of transmission is through contact with infected blood. Infection is severe, often fatal, and is accompanied by symptoms such as loss of appetite, nausea, pale or whitish stool (due to a lack of bile), and jaundice. Even a very small amount, as little as 0.0002% of hepatitis B infected blood contact, is sufficient to transmit hepatitis B.