Class 12th Biology 2017 Set2 Delhi Board Paper Solution
Why do lepidopterans die when they feed on Bt cotton plant? Explain how does it happen.
Some strains of Bacillus thuringiensis gene called cry gene produce protein that kill certain insects each as Lepidopterons (tobacco budworms, armyworm, bettles and flies). Bacillus thuringiensis forms protein crystal during a particular phase of their growth. These cystals contain a toxin insecticidal protein.The activated toxin binds to the surface of midget epithelial cells and create pores that causes cell swelling and lysis. The toxin is coded by a gene named cry.
Popular Questions of Class 12th biology
- Q:- What is spermatogenesis? Briefly describe the process of spermatogenesis.
- 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.
- Q:- What is DNA fingerprinting? Mention its application.
- Q:- Describe the structure of a seminiferous tubule.
- Q:- What is oogenesis? Give a brief account of oogenesis.
- 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:- Suggest some methods to assist infertile couples to have children.
- Q:- Suggest the aspects of reproductive health which need to be given special attention in the present scenario.
- Q:- Name any five hybrid varieties of crop plants which have been developed in India.
- Q:-
Fill in the blanks:
(a) Humans reproduce __________. (asexually/sexually)
(b) Humans are__________. (oviparous/viviparous/ovoviviparous)
(c) Fertilization is __________ in humans. (external/internal)
(d) Male and female gametes are __________. (diploid/haploid)
(e) Zygote is __________. (diploid/haploid)
(f) The process of release of the ovum from a mature follicle is called__________.
(g) Ovulation is induced by a hormone called the __________.
(h) The fusion of male and female gametes is called _____________.
(i) Fertilisation takes place in _____________.
(j) Zygote divides to form _____________which is implanted in uterus.
(k) The structure which provides vascular connection between fetus and uterus is called ____________. - Q:- Draw a well-labelled diagram of an antibody molecule.
- Q:-
Explain the following terms with example
(a) Co-dominance
(b) Incomplete dominance - Q:- Name the functions of the following.
(a) Corpus luteum
(b) Endometrium
(c) Acrosome
(d) Sperm tail
(e) Fimbriae - Q:- Name the parts of an angiosperm flower in which development of male and female gametophyte take place.
- Q:- In which way have microbes played a major role in controlling diseases caused by harmful bacteria?
- Q:- What are the various public health measures, which you would suggest as safeguard against infectious diseases?