Explain 2 reasons why cells need to reproduce

Cells need to reproduce for growth, repair, or replacements. Cells divide whenever a tissue / organ / organism is growing or needs repair.
  Hope this helps :)

c. are smaller than lakes. Ponds and lakes are often indistinguishable, and rules in classifying may differ per region. But ponds are relatively smaller than lakes and more shallow. Lakes are deep  enough that light cannot penetrate the bottom of the water.