Describe how do ‘flocs’ and ‘activated sludge’ help in sewage treatment.
Roles of ‘flocs’ and ‘activated sludge’ in sewage treatment are as follows: Flocs These are masses of bacteria held together by slime and fungal filaments to form mesh-like structures. Flocs are used during the secondary sewage treatment in the aeration tank to increase the rate of decomposition. The microbes digest a lot of organic matter, converting it into microbial biomass and releasing a lot of minerals. As a result, BOD of the sewage reduces. As the BOD of waste is reduced to 10-15% of raw sewage, it is passed into settling tanks. In these tanks, flocs are allowed to undergo sedimentation. Activated Sludge The sediment of settling tank is called activated sludge. A part of it is used as inoculum in aeration tanks. The remaining part is passed into a large tank called anaerobic sludge digester. In these tanks, anaerobic microbes are present that digest the organic mass as well as aerobic microbes of activated sludge. The remaining sludge is used as manure or compost.
A number of passengers were severely burnt beyond recognition during a train accident. Name and describe a modern technique that can help hand over the dead to their relatives.
(a) What precaution(s) would you recommend to a patient requiring repeated blood transfusion?
(b) If the advise is not followed by the patient there is an apprehension that the patient might contract a disease that would destroy the immune system of his/her body. Explain with the help of schematic diagram only how the immune system would get affected and destroyed.
During a medical investigation, an infant was found to possess an extra chromosome 21. Decribe the symptoms the child is likely to develop later in the life.
(a) What is inbreeding depression?
(b) Explain the importance of ‘selection’ during inbreeding in cattle.
Explain the role(s) of the following in biotechnology.
(a) Restriction endonuclease
(b) Gel-electrophoresis
(c) Selectable markers in pBR322
(a) List the three states the annuals and biennial angiosperms have to pass through during their life cycle.
(b) List and describe any two vegetative propagules in flowering plants.
