Class 12th Biology 2012 Set1 Delhi Board Paper Solution
Why is Rhizobium categorized as a ‘symbiotic bacterium’ ? How does it act as a biofertiliser ?
Rhizobium, a symbiotic bacteria, which live in the . root nodule of leguminous plants, fixes atmospheric nitrogen into organic forms to be used by plants. It is a biofertilizer as it is a living organism that enriches nutrient content of the plant. Bacterium gets food and shelter from the plant.
Popular Questions of Class 12th biology
- Q:- What is spermatogenesis? Briefly describe the process of spermatogenesis.
- Q:- Why is reproduction essential for organisms? Answer
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(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.
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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:- What are chasmogamous flowers? Can cross-pollination occur in cleistogamous flowers? Give reasons for your answer.
- Q:- Differentiate between the following −
(a) Dominance and Recessive
(b) Homozygous and Heterozygous
(c) Monohybrid and Dihybrid. - Q:- If a population growing exponentially double in size in 3 years, what is the intrinsic rate of increase (r) of the population?
- Q:- Define population and community.
- 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 labeled diagram of a Graafian Follicle?
- Q:- Draw a well-labelled diagram of an antibody molecule.
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