The olfactory epithelium is a specialized epithelial tissue inside the nasal cavity that is involved in smell. In humans, it lies on the roof of the nasal cavity about 7 cm above and behind the nostrils.
Endocytosis. That is the process of the intake of food by creating a vesicle.
Answer:
a. two sperm enter the ovule; one fertilizes the egg, one fuses with 2 polar nuclei
Explanation:
Double fertilization is the characteristic feature of the angiospermic plants. After pollination, pollen grains deposited on the stigma of the pistil or carpel. The pollen grain on the stigma germinates forming a pollen tube. The pollen tube carrying two male gametes grows down through the style of the pistil and enters into the embryosac formed within the ovule and releases two male gametes.
One of the gametes fuses or fertilizes with the egg forming zygote. The other male gamete fuses with the two polar nuclei of the embryo sac. The fertilization between two polar nuclei and one male gamete is called the triple fusion. The triple fusion results in triploid primary endosperm cell (3n).
Thus, in angiosperms, there are two fertilizations called double fertilization resulting in the zygote (2n) and primary endosperm cell (3n).
B. The sun. It is the closest star to Earth. The moon does not heat up the Earth like at all. The distant stars are too far away to have an effect. The hot lava is in the Earth so it doesn't affect the surface.