NEET Questions

(c): Cancer is caused by cells dividing repeatedly out of control. They cease to respond to the normal signals around them and form unspecialised masses of cells called tumours. Lung cancer usually starts in the epithelium of the bronchioles, so-called bronchial carcinoma. It usually spreads throughout the lungs. It is caused almost exclusively by smoking. Tobacco smoke contains chemicals responsible for lung cancer. The most important of these are polycyclic hydrocarbons which are converted in the body to carcinogens. 
Besides, carbon monoxide combines with haemoglobin and reduces oxygen transport by about 15% in smokers and nicotine increases blood pressure, heart rate and constriciton of blood vessels.

(d) : A major problem in the treatment of bacterial mediated diseases is that many bacteria have been found to show resistance to antibiotics. The emergence of antibiotic-resistant bacteria is closely linked to the extent that antibiotics are used in humans and item of human diet. Resistant strains may appear rapidly or slowly, according to the amount or type of antibiotic used. Bacteria occur in such large number that there is a high chance of mutant individual eventually appearing in the population. As soon as it does, use of the antibiotic to which it is resistant will give it a selective advantage over non-resistant types and it will multiply and eventually become the dominant type.
Antibiotics may also be destroyed by enzymes inside the cells being targetted. A well-known and important example is the group of enzymes known as penicillinases which hydrolyses and destroys penicillins and cephalosporins.

(d) : Diptheria, leprosy and plague are the bacterial diseases of humans. Diptheria is a serious air-borne contagious disease. It is caused by Cornybacterium diphteriae which is Gram-positive bacterium. It is inhaled through droplets and reaches to respiratory tract and infects it. Leprosy or Hansen's disease is a contact disease caused by bacterium Mycobacterium leprae. It degenerates the tissues and deform the body organs. Plague is a disease caused by bacterium Yersinia pestis or Pasteurella pestis.

(b) : Binding of antibodies to the antigens produces a large insoluble complex known as agglutination. It is a specific reaction, i.e., a particular antigen will only clump in the presence of its specific antibody. Each antibody has two antigen binding sites. It combines with two antigens, causing them to aglutinate.

(c): Entamoeba histolytica is a monogenetic parasite, i.e., living in a single host, in the large intestine of humans. It causes amoebiasis or amoebic dysentery.

(d) : Interferon is a group of proteins that increases the resistance of cells to viral infection. Interferon also acts as cytokines and can enhance some immune responses. Three types of interferons have so far been discovered, alpha, beta and gamma, all of which have immune-modulating effects. Interferons are used in the treatment of cancer and autoimmune diseases.

(d) : DPT vaccine is a combined vaccine against diphtheria, whooping cough (pertussis), and tetanus now replaced by the DTaP/IPV/Hib and DTaP/IPV vaccines

(d): Common cold can take place from one person to other as it it a communicable in nature. A healthy person can get infected by being in close vicinity of infected person when he/she sneezes, coughs, as the droplets generted by sneeze and cough contain infecting agents. Typhoid occurs by the intake of contaminated water & food. While ringworm is one of the skin disease which can transfer from one person to other by the use of infected towel & handkerchief. AIDS (Acquired Immuno deficiency) does not occur or transfer by shanking hands.

(a) : AIDS is caused by HIV virus, Gonorrhoea is caused by bacteria Neisseria gonorrhoeae. Diphtheria is caused by bacteria Corynebacterium diphtheria. Ringworm disease is caused by fungus Trichophyton, Epidermophyton and Microsporum, tuberculosis is caused by a bacterium called Mycobacterium tuberculosis.

(a) : Normal cells show the property of contact inhibition, by virtue of which contact with other cells inhibits their uncontrolled growth. Cancer cells appears to have lost this property.

(a): Salmonella typhi (Causal organism of typhoid) is transmitted by faecal oral route and not by a vector. The alpha viruses are transmitted by insect vectors, most commonly by mosquitoes. Plasmodium (malarial parasite) is transmitted by female Anopheles mosquito and Wuchereria bancrofti (filarial worm) is transmitted by female Culex mosquito

(b): DDT (Dichloro diphenyl trichloroethane) is a colourless, crystalline, tasteless and almost odourless organochloride known for its insecticidal properties. DDT is not derived from any plant rather it is prepared by the chemical reactions of some chemical compounds.
Opioids (opiates) are the analgesic drugs that are derived from latex of unripe fruits of poppy plant, Papaver somniferum. Similarly, cocaine and cannabinoids are the drugs derived from Erythroxylon Coca (Coca plant) and Cannabis sativa (Hemp plant) respectively.

(d): Virus-infected cells secrete proteins called interferons which protect non-infected cells from further viral infection.

(d) The Plasmodium infects the phagocytic cells of the body and destroys them. This leads to a rapid decline in the immune response generated against this pathogen.

The drug addict was possibly taking cannabis compounds. The receptors for these are mainly present in brain. These are obtained from dried leaves and flowers of the hemp plants, (cannabis sp.) Regular use causes addiction.