Page 1 :
Science, (www.tiwariacademy.com), (Chapter - 12) (Reproduction in Plants), (Class - VII), , Question 6:, Explain the difference between self-pollination and cross-pollination., , €. Answer 6:, , S. No., , Self-Pollination _Cross-Pollination, , Pollen grains are transferred to Pollen grains are transferred to stigma of, , stigma of same flower. different flower., , Pollinating agent is not required. Pollinating agent such as wind, water, insects,, etc. is not required., , Examples: Peanuts, sunflower, etc. Examples: Mango, rose and most of the flowering, plants., , Question 7:, How does the process of fertilisation take place in flowers?, , €. Answer 7:, , Once pollen grain spreads on the stigma, it produces a pollen tube. This, process is called germination of pollen grain. The pollen tube penetrates, the style and reaches the ovary. Male nucleus is transferred through this, , pollen tube. Finally, fusion of male and female nuclei takes place inside the, , Fertilisation in flower, , ovary. This step is called fertilization., , Question 8:, Describe the various ways by which seeds are dispersed., , €. Answer 8:, , Follow, , >, , ing are the various methods of seed dispersal:, Dispersal by Wind: Seeds of some plants are light-weight and some hair-like or wing-like, , structures are present on them. Such seeds float on air and are thus dispersed by wind., Example: Dandelion, maple, drumstick, etc., , Dispersal by Water: Dispersal by water takes place in some aquatic plants and in some which, grow near a water body. Seeds of water lily float and thus dispersed by water. The coconut, seed has a tough fibrous covering which has plenty of air inside. This helps the coconut seeds, in floating on water., , Dispersal by Animals: Some seeds have spine like structures on them. They get stuck to the fur, of animals and thus get spread to different places. Examples; Beggar tick, Xanthium, etc. Some, seeds are swallowed by birds and animals along with fruits. These seeds get dispersed with bird, or animal droppings., , Dispersal by Bursting: Some fruits burst open when they mature. The force of bursting is, enough to spread the seeds. Examples; Ladyfinger, castor, balsam, etc., , Dispersal by Humans: Human beings also help in dispersal of seeds, especially during farming., www.tiwariacademy.com, A Step towards free Education, , Se, , 3