NEET Practice Questions (MCQs) with Answers & Solutions

(a) T-lymphocyte receptors can recognise only antigen that bound to cell membrane protein. These lymphocytes mediate CMI (cell mediated immunity). B-lymphocytes are the major effector molecules of humoral immunity. Erythrocytes are red blood cells. Thrombocytes or platelets secrete factors that are involved in vascular repair.

Widal test is one of the most over utilized diagnostic tests for typhoid fever in developing countries ever since its introduction over 100 years ago. This test demonstrates the presence of somatic (O) and flagellar (H) agglutinins to Salmonella typhi in the patients serum using suspensions of O and H antigens. Antigens of S. paratyphi A and S. paratyphi B are included in most commercial kits.

(b) Serturner, a pharmacist isolated the, active principle of opium in 1806 and named it morphine. Morphine is a phenanthrene opioid receptor agonist, its main effect is binding to and activating the H-opioid receptors in the central nervous system. In clinical setting, morphine exerts its principal pharmacological effect on the central nervous system and gastrointestinal tract. Its primary actions of therapeutic value are analgesic and sedation.

(b) Ringworm refers to fungal infections that are on the surface of the skin. Although the world is full of yeasts, moulds and fungi, only a few cause skin problems. These agents are called the dermatophytes. Some common dermatophytic fungi are Trichophyton rubrum, T. tonsurans, T. interdigitale, T. mentagrophytes, Microsporum, Canis and Epidermophyton floccosum.
 
 

AIDS( Acquired Immuno Deficiency Syndrome) is a viral disease of immune system. It is caused by virus Human patients, the virus home on CD₄ + T-cells (helper T-lymphocytes), infecting and killing them until none are left. Without their crucial immune system cells, the body cannot mount a defence against invading bacteria or viruses. AIDS patient die off infections that a healthy person could fought off.

Allergy is the hypersensitiveness of a person to some foreign substances coming in contact with or entering the body. The common allergens are dust, pollen mould, spores, fabricates, bacteria, etc. During allergic reaction, there is increased release of histamine from mast cells. Use of anti-histamines and steroids give a quick relief from allergy.

Thymus is haemopoietic as well as an endocrine gland. Thymus is the ‘seedbed' of thymic lymphocytes (T-lymphocytes). Certain stem cells, originating in yolk sac and liver in early embryo, but only in bone marrow in late embryo, migrate into the thymus and proliferate to form a large number of lymphocytes. 

Thyroid is an endocrine gland.

Thalamus is the part of forebrain in vertebrate lies above the hypdthalamus.

Tonsil is a mass of lymphoid tissue, several of which are situated at the back of the mouth and throat in higher vertebrates.

(d) Neutrophils and monocytes are phagocytic white blood cells. Monocytes are largest of all leucocytes and generally change into macrophages after entering tissue spaces Neutrophils are most numerous of all leucocytes, and have many lobed nucleus.

Eosinophils are granular white blood cells. Their number increases in people with allergic conditions such as asthma or hay fever. They are non-phagocytic and seem to play part in immune system.

Lymphocytes are non-motile and non-phagocytic in nature. They produce antibodies to destroy microbes. These are found as B and T-lymphocytes. T-lymphocytes either directly attack the antigens or stimulate B-lymphocytes to produce antibodies.

Asthma is a respiratory disorder. It is caused by foreign allergens and dust particles present in the air passing through it, the pollen grains present in air can cause asthmatic attacks in certain seasons.

Histamine is a protein, acting as a vasodilator (widening of blood vessels) in inflammatory and allergic reactions and also increases the permeability of small vessels. It is secreted from the mast cells which widely occur in the areolar connective tissue.
Two other active substances secreted by mast cells are Heparin, a proteoglycan, which prevent coagulation of blood vessels and Serotonin,  a protein, which acts as vasoconstrictor to stop bleeding and to increase blood pressure.