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.
Answer:
the answer is carbohydrate
<span>The only traits that can be acted upon by natural selection are those that are controlled by ___________________</span>
The correct answer is: A. stimulates secretory activity
Parasympathetic nervous system is a part of the autonomic nervous system (a division of the peripheral nervous system (PNS), so it means it regulates unconscious actions in an organism. Parasympathetic system is known as a system for stimulation of "rest-and-digest", when the body is at rest (differ than sympathetic which is active for fight-or-flight response). Parasympathetic system works usually after the meal and it is involved in the functions such as, secretory activities (salivation, lacrimation ), urination, digestion and defecation..
