Answer: food chains or webs
In an ecosystem, energy from the sun is transferred by the way of food chains or webs. A food chain is a linear sequence of organisms through which food and energy is passed as one organism eats the another. A food web is the interconnection or relation of food chains. In a food chain energy is distributed among the trophic levels. Plants are primary producers which traps energy from sun for photosynthesis and belong to first trophic level in the food chain. The energy of sun present in plants is transferred to subsequent higher trophic levels when plants are consumed by other organisms.
Its A. it prevents sperm from reaching the egg and fertilizing it.
The mRNA made from the section of DNA coding for the protein (the gene) exits the nucleus through a nuclear pore after getting modified. It can get modified by getting a poly-A tail and a methylated cap, along with removing the interfering sequences (introns).