What is apomixis? Answer: Apomixis is the phenomenon of production of seeds without fertilization. Question 8. What is microsporogenesis? Answer: The process that leads to the formation of microspores from a pollen mother cell through meiosis is referred to as microsporogenesis. Question 9. What is sporopollenin? Answer: The exine of pollen grain is composed of a highly resistant organic chemical called sporopollenin.
Question Name one plant each where pollination occurs with the help of a Water, b Bats. Answer: Water pollinated: vallisneria and hydrilla. Bat pollinated: Anthocephalous and Bauhinia megalandra. What is polyembryony? Answer: Polyembryony is the phenomenon of formation of more than one embryo during the development of a seed. How many haploid nuclei and haploid cells are present in the female gametophyte of angiosperm?
Answer: 8 — haploid nuclei and 7 — haploid cells. Mention the scientific term for the type of pollination which ensures Genetic recombination.
Answer: Xenogamy or Allogamy. Answer: The second male gamete fuses with the secondary nucleus which is formed by fusion of two polar nuclei to form a triploid primary endosperm [PEN],.
Name the part of plant producing seed and fruit after fertilization. Answer: After fertilization, ovule develops into seed and ovary develops into fruit. What is pericarp? Answer: The wall of fruit developed by the wall of the ovary is called pericarp. What is a false fruit? Give an Example. Answer: A fruit which is formed by any floral parts of the flower other than ovary, eg.
Arrange the following terms in the correct development sequence: pollen grain, sporogenous tissue, microspore tetrad, pollen mother cell, male gametes. What are the parthenocarpic fruits? Answer: The fruits which are formed without fertilization. Example: Seedless fruits like banana. What is double fertilization? Answer: One male gamete fuses with an egg syngamy to form a zygote and a second male gamete fuses with two polar nuclei to form a primary endosperm nucleus triple fusion.
Both these steps together represent double fertilization. What is Apomixis? What is its importance? Answer: The phenomenon of asexual reproduction that mimics sexual reproduction by formation of seed without fertilisation is called apomixis. Importance: Apomixis has the potential to maintain hybrid vigour indefinitely even in those crop plants where vegetative reproduction is not possible. Draw a diagram of pollen grain with germ tube and two male gametes with labelling.
What is self-incompatibility? Why does self-pollination not lead to seed formation in self-incompatible species? Answer: The inability of certain gametes even from genetically similar plant species, to fuse with each other is called self incompatibility. It is because of a continuous dialogue between pollen grain and pistil which is mediated by their chemical components.
What is bagging technique? How is it useful in plant breeding programme? Answer: The process of covering the emasculated flowers or the female flowers after dusting with the desired pollen with bags made of butter paper. Bagging protects the stigmas from further pollination from unwanted pollen.
What is triple fusion? Where and how does it takes place? Name the nuclei involved in triple fusion. Answer: The process of fusion of haploid or diploid nuclei three times is called triple fusion. Why do you think the zygote is dormant for sometime in a fertilized ovule?
Answer: The zygote divides only after a certain amount of endosperm is formed. This is an adaptation to provide assured nutrition to the developing embryo.
Therefore, the zygote is dormant for some time in a fertilized ovule. Differentiate between: a hypocotyl and epicotyl; b coleoptile and coleorrhiza; c integument and testa ; d perisperm and pericarp. Answer: a The portion of embryonal axis above the cotyledon is called epicotyl, while the portion of embryonal axis below the cotyledon is called hypocotyl.
Why is apple called a false fruit? Which parts of the flower forms the fruit? Answer: In apple, thalamus of the flower also contributes in the formation of fruit along with the ovary, hence it is called a false fruit. Thalamus of the flower is mainly involved in the formation of pulp of the apple. What is meant by emasculation?
When and why does a plant breeder employ this technique? Answer: The process of removal of anthers from the flower buds of a bisexual flower, before the anther dehiscense in order to avoid self pollination. Plant breeders employ this technique for artificial hybridization for crop improvement programme. Explain the role of tapetum in the formation of a pollen grain wall.
Answer: Tapetum produce ubisch granules for the formation of exine of pollen grain and also secrete pollenkitt in case of entomophilous pollen grain. It also supplies nutrients for the developing pollengrain. Write the characters of a wind pollinated flower? Answer: Characters of anemophilous flowers :. Distinguish between protandry and protogyny. Answer: a Protandry: Anthers mature earlier than the carpels, e. What are cleistogamous flowers?
Can cross pollination occur in cleistogamous flowers? Give reasons for your answer. Answer: Cleistogamous flowers have exposed anthers and stigma. Cross pollination cannot occur in cleistogamous flowers, as such flowers do not open at all. Mention two strategies evolved to prevent self-pollination in flowers. Answer: 1. Dicliny : It is the condition where one of the two sexes is absent in the flower and the flower becomes a unisexual male or female diclinous.
Such diclinous flowers may be borne either on the same plant or on the two different plants. In such cases, cross pollination, is the rule. In such cases, self pollination is impossible, e. Write the significance of double fertilization. Answer: Importance of double fertilization is the production of seeds from ovules and fruits from ovaries.
Double fertilization also signifies the formation of nutritive tissue endosperm in the seeds. Differentiate Geitonogmy from Xenogamy. Answer: Geitonogamy is the transfer of pollen grains from the anther of a flower to the stigma of another flower of the same plant. Genetically it is similar to autogamy. Xenogamy is the transfer of pollen grains from anther of a flower on one plant to the stigma of a flower on a different plant. Brings genetically different pollen grains to the stigma.
What is xenogamy? Mention its importance. Answer: Xenogamy: Cross pollination which takes place between two flowers borne on two different plants of the same species is called xenogamy. Importance: Characters of the two plants can be combined. What is artificial hybridization? Explain emasculation and bagging techniques used in artificial hybridisation for crop improvement programme.
Answer: It is one of the major approaches of crop improvement programme. It is a crossing experiment to make sure that only the desired pollen grains are used for pollination and the stigma is protected from contamination from unwanted pollen.
This is achieved by emasculation and bagging techniques. Differentiate between non-albuminous and albuminous seeds with examples. Answer: Non albuminous seeds have no residual endosperm as it is completely consumed during embryo development. Albuminous seeds retain a part of endosperm as it is not completely used up during embryo development, e. Differentiate between anemophilous and entomophilus flowers?
Characters of Entamophilous Flowers : In majority of the plants cross pollination takes place through the agency of insects and such flowers are called entomophilous flowers. These show the following characters. Colour: Normally petals of a flower are brightly coloured to attract insects for the purpose to carryout cross pollination.
This is when you start creating a base for yourself and gear up for the final two years after the 10th board exams. Revision, which is an essential aspect to ensure good marks in the exams needs to be precise and cover all the important concepts.
It can be a time taking effort for students to prepare qualitative and concise revision notes that can be used as a reference. As a result, most students end up marking key points in the textbook itself. This not only makes revising a little more confusing and time taking, but the risk of missing out on some key concepts is also high.
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