ZOOLOGY BOTANY CHEMISTRY

Answer :-

Answer :- 1) Vegetative propagation is the only method of reproduction in those plants which have lost their capacity to produce seeds, examples:- Banana, Seedless grapes, Oranges, Rose, Jasmine, Figs, Pineapple, Tulips, Dahlias, Carnation, etc.  2) Plants which produce small quantities of viable seeds. Example :- Cynodon dactylon = Bermuda grass or doob grass are mostly propagated by vegetatively.  3) Plants which have poor seed viability or prolonged seed dormancy reproduce mostly by vegetative methods because these methods are more Rapid, easier and less expensive.  4) The greatest advantage of vegetative propagation is that a plant biotype (original plant) can be retained and multiplied indefinitely without any change or variation. The variation are normally expected if the plants undergo meiosis and Syngamy due to the segregation and recombination of characters.  5) Effects of physicochemical treatments (such as application of some Chemicals and X-rays) and environmental variation

Answer :- Gemmules are dormant structures produced asexually by the formation of specialised exogenous buds, at certain times of the year, in many freshwater sponge species and a few Marine species. To begin, archaeocytes accumulate nutrients by phagocytizing other cells and then cluster together within the sponge. Certain cells surrounding each cluster than secrete a thick, protective covering ; the formed structure is termed gemmule. After gemmule formation, the original sponge disintegrates. In favourable conditions the floating gemmules produce a new sponge. Significance Gemmules are far more resistance to desiccation, freezing and anoxia (lack of oxygen) then the sponges that produce them. Under appropriate environmental conditions, the living cells leave the Gemmule through a narrow escape opening and differentiate to a form functional sponge. 

Answer :- Water is necessary for the transfer of male gametes to reach the female gametes. A large no. of gametes are lost during transport. Hence, they are produced in large numbers. The male gametes are termed antherozoids.

Answer :-  (i) Moss plant requires water for the transfer of antherozoids (male gametes) to the non-motile female gametes. (ii) Spores also require sufficient moisture for germination.

Answer :- (a) Plants that are raised through micropropagation are genetically identical to the original plant from which they are grown. Hence, they are termed as somaclones. (b) Advantages of Micropropagation (i) A large no. of plants can be grown in relatively short time by this method. (i) This method is used to obtain virus free and disease free plants.

Answer :- (a) fruit (b) seeds