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Pollen itself is not the male gamete. [4] It is a gametophyte, something that could be considered an entire organism, which then produces the male gamete.Each pollen grain contains vegetative (non-reproductive) cells (only a single cell in most flowering plants but several in other seed plants) and a generative (reproductive) cell.
Nature versus nurture is a long-standing debate in biology and society about the relative influence on human beings of their genetic inheritance (nature) and the environmental conditions of their development .
Pollination often occurs within a species. When pollination occurs between species, it can produce hybrid offspring in nature and in plant breeding work. In angiosperms, after the pollen grain (gametophyte) has landed on the stigma, it germinates and develops a pollen tube which grows down the style until it reaches an ovary.
The term pollen source is often used in the context of beekeeping and refers to flowering plants as a source of pollen for bees or other insects. Bees collect pollen as a protein source to raise their brood. For the plant, the pollinizer, this can be an important mechanism for sexual reproduction, as the pollinator distributes its
Honey bees, bumblebees, and their relatives do not have a scopa, but the hind leg is modified into a structure called the corbicula (also known as the "pollen basket"). Most bees gather nectar, a concentrated energy source, and pollen, which is high protein food, to nurture their young, and transfer some among the flowers as they are working. [11]
Tapetum is important for the nutrition and development of pollen grains and a source of precursors for the pollen coat. [1] The cells are usually bigger and normally have more than one nucleus per cell. As the sporogenous cells undergo mitosis, the nuclei of tapetal cells also divide.
For example, survivors of sexual abuse found PTSD was influenced considerably by familial nature of support, negative parental reactions were found to intensify PTSD whereas high levels of social support helped diminish psychological fallout and recovery time. Ecological pathways include factors such as a history of abuse, physical and sexual.
Vallisneria spiralis is an example of hydrophily. Female flowers reach the water's surface temporarily to ensure pollination. Hydrophily is a fairly uncommon form of pollination whereby pollen is distributed by the flow of waters, particularly in rivers and streams.