question_answer 22)

  A dicotyledonous plant bears flowers, but never produces fruits and seeds. The most probable cause for the above situation is (a) plant is dioecious and bears only pistillate flowers (b) plant is dioecious and bears both pistillate and staminate flowers (c) plant is monoecious (d) plant is dioecious and bears only staminate flowers

Answer:

                  (d)indioecious plants, the unisexual male flower is staminate, i.e., bearing stamens only, while the female is pistillate or bearing pistils only. For the production of fruits and seeds fertilization must take place, which is possible only in the presence of both male and female flowers. When the plant is dioecious, it will give rise to the following situations (i) If the plant is dioecious and bears only pistillate flowers, fertilization can take place with the help of pollinators. (ii) If the plant is dioecious and bears only staminate flowers, fertilization can't take place, because female gamete is non-motile which can't reach the male gamete in order to fuse with it. When the plant is monoecious i.e., carrying both stamen and pistill together, it may lead to self-fertilization and production of seed.