Class 12th Biology 2018 Set1 Delhi Board Paper Solution
You have obtained a high yielding variety of tomato. Name and explain the procedure that ensures retention of the desired characteristics repeatedly in large populations of future generations of the tomato crop.
Plant breeding is the purposeful manipulation of plant species in order to create desired plant types which are better suited for cultivation, give better yields and are disease resistant. Main steps in breeding a new genetic variety of a crop:
(a) Collection of variability
(b) Evaluation and selection of parents
(c) Cross hybridisation among selected parents
(d) Selection and testing of superior recombinants
(e) Testing, release and commercialisation of new cultivars
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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.
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- Q:- Explain the Law of Dominance using a monohybrid cross.
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- 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:- What is parturition? Which hormones are involved in induction of parturition?