Everything you need to know about biological control. Some of the most frequently asked exam questions are as follows:-
Q.1. What is biological control?
Ans: The use of one organism to control the growth of another organism is a process known as biological control.
Q.2. Give a simple example of biological control that may be of interest to a microbiologist.
Ans: Some insects causing serious diseases of crop plants can be controlled by the use of bacteria that are pathogenic to those insects.
Q.3. Name some bacterial species which can be used as insect larvicides.
Ans: Bacillus larvae, B. propillae and B. thuringiensis.
Q.4. How do the bacilli work as insect pathogens so as to serve as an insect larvicidal.
Ans: The insect pathogenic bacilli function as biological control agents forming crystalline protein during Sporulation referred to as parasporal body which is deposited within the sporangium but outside the spore proper, i.e., on the periphery of spores.
Q.5. Pseudomonas syringe which are leaf inhabiting bacteria bring about the formation of ice crystals on leaves at temperatures higher than that required for frost. Why?
Ans: Pseudomonas syringe produce a protein which causes ice formation.
Q.6. How would you get rid of the frost damage that could be caused by the normal (ice-plus) Pseudomanas syringe?
Ans: By spraying ice-minus strain of P. syringe from which the gene for ice nucleation is deleted. The ice-minus strain brings about the competitive exclusion of ice-plus strain.
Q.7. Which bacterium is used in the recovery of otherwise unprofitable grades of uranium and copper ores?
Ans: Thiobacillus ferroxidans.
Q.8. How is copper recovered using Thiobacillus ferroxidans?
Ans: Solutions containing ferric ion (Fe3+) are passed through deposits of insoluble copper compounds. The copper is oxidized into soluble compounds. The ions m these processes are reduced to Fe2+. The Fe2+ can be oxidized by T. ferroxidans. The soluble copper is then separated from the ore and can be reclaimed.
Q.9. Give steps used in biological oxidation of ores.
Ans: This takes place in the following steps:
(1) Thiobacillus ferroxidans oxidize Fe2+ to Fe3+, which in turn oxidizes Cu+ to Cu2+ and the Cu2+ forms CuSO4.
(2) CuSO4 precipitates as (Cu°), while FeSO4 remains.
(3) In an oxidation pond T. ferroxidans oxidizes FeSO4 to Fe3+ + H2SO4.
Q.10. Give the names of microorganisms that constitute industrial products.
Ans: (i) Yeast cultures for making wines and baker’s yeast. The cells of yeast are harvested by continuous centrifugation and are pressed into familiar yeast cakes.
(ii) Symbiotic nitrogen fixers Rhizobium and Brady rhizobium mixed with peat moss to preserve moisture which helps mix their inoculum with leguminous seeds.
(iii) For many years the insect pathogen Bacillus thuringiensis (Bt) has been used with gardens to control leaf eating insects.
(iv) Bacillus thuringiensis strain israelensis acts against the larvae of mosquitoes. It is widely used by municipal control programmes. Their commercial preparations contain toxic crystals and endospores.
Q.11. How can wastes of landfill sites be used for the production of energy?
Ans: By producing methane.
Q.12. How do antibiotics fed to cattle inhibit derive methane production from the waste excreted by them?
Ans: The antibiotics interfere with the bacterial activity responsible for the production of methane.
Q.13. What is gasohol?
Ans: Gasoline containing ethanol (90% gasoline + 10% ethanol) is available in many parts of USA, is known as gasohol.
Q.14. Name one of the safe landfills that could be used for the production of methane in future.
Ans: At Bhaleswa, in Delhi.
Q.15. What is a landfill?
Ans: The landfill is a site to dump solid waste and is left for decomposition, solid waste containing both organic and inorganic material is deposited and covered with soil to carry on the decomposition.
Q.16. How many landfills were available in Delhi by 1998?
Ans: The three landfills that Delhi had by 1998 are at:
(i) Ghazipur spread over 70 acres,
(ii) Bhaleswa spread over 40 acres and
(iii) Okhla 18 acres.
Q.17. What is a predator?
Ans: The organism which preys upon other smaller organism.
Q.18. Define predation.
Ans: It is based on interaction among organisms in which one is benefited and one is harmed, in which process the smaller organism called prey is ingested by larger organism called a predator.