Pollen tube growth is one of the most fascinating—and essential—phenomena in the life cycle of flowering plants. After a compatible interaction between pollen grains and the stigma surface, the pollen germinates and forms the pollen tube, which grows through the stigma, style, and transmitting tract to deliver the sperm cells to the ovule."
2) Although pollens of many species germinate in simple aqueous media, stigmas do not provide satisfactory sites for the germination of most foreign pollen... Stigmas not only provide the proper conditions for the germination of pollen from their particular species, they actively inhibit the germination of pollen of many unrelated species.
B. Because the environment can not supply for the food and caring of the animal species that is growing larger.
First, weather is the atmospheric condition occurring over a short period of time in a relatively small location. Climate, on the other hand, is the overall environmental condition over extended periods of time. Next, the water cycle is when water from the surface evaporates as water vapor under high temperatures and condenses in the atmosphere under lower temperatures and precipitates back to the surface. In the event that water evaporates more than it condenses then the weather will be warm to hot, the ground will be relatively dry, and drought over extender periods of time may ensue. On the other hand, if water condenses and precipitates more than it evaporates, then there will be a rainy season, and may extremely lead to landslides and floods.
Answer:
rivers because smaller bodies of water always drain into bigger ones
