The term referred to the sentence above is : dwarf planet
Tissues form when many similar specializes cells come together.
The level of complexity in organisms from smaller to larger are:
Cells, tissue, organ, organ system, and organism finally.
Cells makes up tissue, tissue makes up organ, organs makes up organ systems, and organ systems makes up an organism.
Therefore, if the same type of cells come together, they'll make up tissue.
I believe it is 'white fur' because living in the Tundra means it is snowing. Snow is white, so basically, the white fur is specifically for the Tundra.
I hope it helps.