Class 12th Biology 2016 Set1 Outside Delhi Board Paper Solution
Question 17
How do organic farmers control pests ? Give two examples.
Answer
Organic farmers create a system where the insects are not eradicated, but are kept at manageable levels by a complex system within living and vibrant ecosystem.
Examples are :
(i) The ladybird and dragon flies are useful to get rid of aphids and mosquitoes respectively.
(ii) Bacillus thuringiensis (Bt) are used to control butterfly caterpillars.
Popular Questions of Class 12th biology
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- Q:- Why is reproduction essential for organisms? Answer
- Q:- Write a short note on
(a) Adaptations of desert plants and animals
(b) Adaptations of plants to water scarcity
(c) Behavioural adaptations in animals
(d) Importance of light to plants
(e) Effect of temperature or water scarcity and the adaptations of animals. - Q:- With a neat diagram explain the 7-celled, 8-nucleate nature of the female gametophyte.
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- Q:- What is triple fusion? Where and how does it take place? Name the nuclei involved in triple fusion.
- Q:- With a neat, labelled diagram, describe the parts of a typical angiosperm ovule.
- Q:- Explain the Law of Dominance using a monohybrid cross.
Recently Viewed Questions of Class 12th biology
- Q:- An orchid plant is growing on the branch of mango tree. How do you describe this interaction between the orchid and the mango tree?
- Q:- Identify True/False statements. Correct each false statement to make it true.
(a) Androgens are produced by Sertoli cells. (True/False)
(b) Spermatozoa get nutrition from Sertoli cells. (True/False)
(c) Leydig cells are found in ovary. (True/False)
(d) Leydig cells synthesise androgens. (True/False)
(e) Oogenesis takes place in corpus luteum. (True/False)
(f) Menstrual cycle ceases during pregnancy. (True/False)
(g) Presence or absence of hymen is not a reliable indicator of virginity or sexual experience. (True/False) - Q:- Why is reproduction essential for organisms? Answer
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- Q:- What is self-incompatibility? Why does self-pollination not lead to seed formation in self-incompatible species?
- Q:- Discuss with your teacher and find out how to distinguish between
(a) Plasmid DNA and chromosomal DNA
(b) RNA and DNA
(c) Exonuclease and Endonuclease