Q. 264.2( 5 Votes )
(a) What is
(a) Mutation breeding is the process by which mutations are induced artificially in plants by changing their base sequences or by using chemicals and radiations and selecting plants with desirable characters. Because of this, new characters are introduced in the plant which were absent in the parent plants.
Mung bean is resistant to yellow Mosaic Virus and Powdery Mildew.
(a) If a patient is advised anti-retroviral drug, he is suffering from AIDS, which is Acquired Immuno Deficiency Syndrome. It is caused by HIV, which is Human Immuno Deficiency Virus.
(b) • The principle of vaccination is based on the ‘memory’ of the immune system.
• In vaccination, weakened or inactivated pathogens are introduced into the body.
• Because of this introduction, antibodies are produced in the body against these antigens which would neutralise the pathogenic agents that attack the person at the time of actual infection later.
• The vaccines also generate memory B and T cells which would recognise the pathogens upon subsequent infection by the pathogens by producing antibodies.
• Normal cells show a property called as Contact Inhibition due to which the normal cells remain in contact with the other cells thereby inhibiting their uncontrolled growth.
• But, this property is lost in cancerous cells.
• Because of the absence of this property, cancerous cells grow rapidly and divide uncontrollably, damaging the surrounding healthy cells as well.
• Cells which are damaged by tumours are carried by blood to different parts of the body and get lodged there starting a new tumour. This property as metastasis.
(d) The physiological barriers that protect the body from such pathogens are acid in the stomach and saliva in the mouth.
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