During seed production, which part of a flowering plant develops into a seed?

The part of a flowering plant that develops into a seed  is the ovule.

When pollen grains land on the stigma of the correct species, they germinate. A pollen tube grows through the tissues of the flower until it reaches an ovule inside the ovary.

The nucleus of the pollen grain (male gamete) then passes along the pollen tube and joins with the nucleus of the ovule (the female gamete). This process is called fertilization.

After fertilization, the female parts of the flower develop into a fruit. The ovules become seeds and the ovary wall becomes the rest of the fruit. 

2%? i tried finding the exact sorry if it's not 100% correct ; -;

the solute can move "downhill," from regions of higher to lower concentration, relying on the specificity of the protein carrier to pass through the membrane. this process is called passive transport or facilitated diffusion, and does not require energy.