FREE NEET Biology Practice MCQ Test: Human Health And Diseases Exercise 1 Questions Answers With Detailed Explanations [PDF]

Answer: (b)

Both Assertion and Reason are true and Reason is the correct explanation of Assertion.

Antibody mediated immune response occurs due to antibodies produced in the blood. These antibodies are chiefly secreted by B-cells into the body fluids. When an antigen (pathogen) enters the body the B-cells produce antibodies (immunoglobulins) in response to it.

Answer: (b)

Answer: (b)

The statement in option (a) is correct with respect to immunity.

Rest of the statements are incorrect and can be corrected as

• The antibodies against smallpox pathogen are produced by memory cell is B-lymphocytes.
• Antibody is a protein molecule having two light chains and two heavy chains.
• Rejection of kidney graft is the function of T-lymphocytes.

Answer: (b)

Answer: (a)

Statements II and IV show the correct reasons for rheumatoid arthritis. It is an autoimmune disorder. Autoimmunity is an abnormal immune response in which the immune system of the body starts rejecting its own body cells or 'self' cells and molecules. This happens as the body loses its ability to differentiate the pathogen or foreign molecules from self cell and attacks self-cells damaging them.

Answer: (b)

Answer: (b)

Asthma may be attributed to allergic reaction of the mast cells in the lungs. It is an allergic reaction characterised by spasm of bronchi muscles because of the effect of histamine released by mast cells in the lungs.

Answer: (c)

In general, as the concentration of HIV increases the number of helper T cells destroyed increases causing the cell count to fall.

Answer: (c)

Answer: (a)

Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.

Repeated use of drugs, increase the tolerance level of receptors in our body because consumption or use of drugs for a longer period of time increases the number of receptors at neural junction which inturn, increases the tolerance level. Consequently, receptors respond only to higher doses of drugs thereby causing addiction.

Answer: (c)

Reduction of pH of blood will decrease the affinity of hemoglobin with oxygen which in turn causes acidosis.

Answer: (b)

Answer: (c)

Head louse is an obligate ectoparasite of human scalp and as well as laying egg on human hair.

Answer: (d)

Answer: (c)

Answer: (b)

Common Cold, AIDS is a pair of viral diseases. Viruses are a very common type of infectious disease. Viruses are the smallest life-form existing, since they are not even a single cell. It is almost like they are not alive at all. They are small strands of DNA-like cell material. A virus consists mostly of RNA and cannot survive without hostcells.

Answer: (a)

Pneumonia and common cold both are communicable diseases. Pneumonia is an infection that inflames the alveolar air sacs in one or both lungs. The air sacs may fill with fluid or pus (purulent material), causing cough with phlegm or pus, fever, chills, and difficulty breathing. A variety of organisms, including bacteria, viruses and fungi, can cause pneumonia. The most common cause of bacterial pneumonia is Streptococcus pneumoniae.

Common cold, caused by rhinovirus, is a viral infection of upper respiratory tract (nose and throat). A common cold is usually harmless, although it may not feel that way at the time. If it's not a runny nose, sore throat and cough, it's the watery eyes, sneezing and congestion, or maybe all of the above. There's no cure for the common cold. Antibiotics are of no use against cold viruses

Answer: (c)

Answer: (d)

Answer: (b)

Humoral immunity consists of antibodies in the blood and lymph. B-lymphocytes secrete antibodies. Thus, humoral immunity is mediated by B-cells or B-lymphocytes.