Biology (Practice Test)

All these diseases spread through contaminated water or food. While they differ in causative agents (cholera and typhoid are bacterial, polio and hepatitis are viral, amoebiasis is protozoan), they share the water-borne transmission route, making water contamination a key prevention target.

Anaphylactic shock is a severe allergic reaction that causes widespread vasodilation and increased capillary permeability, leading to a rapid and dangerous drop in blood pressure.

Nicotine is a stimulant that affects the nervous system, triggers the release of adrenaline, and can have varying effects on muscle tone, making all listed options correct.

In the liver, alcohol dehydrogenase converts ethyl alcohol into acetaldehyde, which is significantly more toxic and reactive than ethanol itself.

Rh–factor incompatibility leads to anaemic condition in foetus.

Radiations primarily damage cells that are actively dividing (like skin or bone marrow) because they interfere with DNA replication. Neurons are non-dividing cells and are therefore much more resistant to radiation-induced damage.

The DPT vaccine covers Diphtheria, Pertussis (whooping cough), and Tetanus. Since options A and B describe the same set of diseases, option D is the correct choice.

The failure of descending of testes into scrotum is termed as cryptorchidism.

Rabies is the only viral disease in this list, caused by the rabies virus. Tetanus is caused by the bacterium Clostridium tetani, cholera by Vibrio cholerae, and typhoid by Salmonella typhi. All three others are bacterial diseases.

Population size increases through natality (birth rate) and immigration (individuals moving into the population).

Demography is the statistical study of human populations, including size, structure, and distribution.

The Bursa of Fabricius is a specialized lymphoid organ found only in birds, where B-cell maturation occurs.

Macrophages are specialized phagocytic cells that reside in tissues throughout the body to engulf pathogens and debris. Neutrophils and monocytes are primarily found circulating in the blood, though they can migrate to tissues during inflammation.

Vasectomy (in males) and tubectomy (in females) are both surgical procedures designed as permanent methods of sterilization. Therefore, both are correct.

Artificial immunity is acquired through medical intervention, such as vaccination, where the body is exposed to an antigen to stimulate an immune response. Analgesics are pain relievers and penicillin is an antibiotic, neither of which provide immunity.

Natural killer (NK) cells are a type of lymphocyte that play a major role in the host-rejection of both tumours and virally infected cells. They provide an immediate, non-specific immune response.

BCG vaccine provides protection from tuberculosis.

Cyclosporine is a potent immunosuppressive drug widely used in organ transplantation to prevent rejection. Streptomycin and Tetracycline are antibiotics, and Valium is a benzodiazepine.

Mast cells, which are a type of connective tissue cell, are the primary source of histamine in the body. Histamine is released during allergic reactions.

Rheumatic fever is an autoimmune disease resulting from an abnormal immune response to a streptococcal infection. Cholera, Typhoid, and Malaria are infectious diseases caused by pathogens.

Antibiotics are substances that inhibit the growth of or destroy microorganisms, specifically bacteria and fungi. They are ineffective against viruses, which require antivirals.

Both the saphenous vein (from the leg) and the internal mammary artery (from the chest wall) are commonly harvested and used as grafts in coronary artery bypass surgery.

Amniocentesis involves analyzing amniotic fluid to detect chromosomal abnormalities, such as Turner's syndrome and Klinefelter's syndrome, and it can also reveal the sex of the fetus.

Augustus Waller is credited with recording the first human electrocardiogram in 1887. While Einthoven later refined the technology and won a Nobel Prize for it, Waller performed the first recording.

Sir Godfrey Hounsfield is widely recognized for the invention of the CT scanner, for which he shared the Nobel Prize in 1979.

Ultrasound is a versatile diagnostic tool used to visualize soft tissues and organs, including the brain (in infants), gallstones, and liver conditions like cirrhosis.

PET scans use radiotracers that emit positrons. Common isotopes used include Carbon-11, Nitrogen-13, and Oxygen-15, which are all short-lived positron emitters.

Lasers are often referred to as a light knife in surgery because they can cut, cauterize, and vaporize tissue with high precision using focused light energy.

Psilocybin is a naturally occurring psychedelic compound produced by more than 200 species of fungi, commonly known as psilocybin mushrooms.

A CT scan image is composed of a grid of picture elements, known as pixels. The density of these pixels is measured in Hounsfield units.

Neurosis is a class of functional mental disorders involving distress but not delusions or hallucinations, often manifesting as a prolonged emotional reaction to stress or anxiety.

Psychotropic drugs are chemical substances that cross the blood-brain barrier and act primarily upon the central nervous system, where they alter brain function, resulting in changes in perception, mood, consciousness, or behavior.

EEG (electroencephalography) records electrical activity of the brain and is used to diagnose various conditions, including epilepsy, brain tumors, and encephalitis.

 QRS is related to ventricular contraction.

Arunachal Pradesh has the lowest population density in India, according to census data, with approximately 17 persons per square kilometer.