Bio Cell Cycle

What do humans, octopuses, and oak trees have in common?

They are all made of cells (about trillions of cells).

What does the Cell Theory state about cell division?

All cells come from pre-existing cells.

Why is cell division necessary for growth?

One cell divides into two, then four, increasing the total number of cells, which allows an organism to grow.

What are the two main reasons cells divide instead of growing indefinitely?

• Increased demand placed on DNA

• Surface area-to-volume ratio limits nutrient and waste exchange

Why does surface area-to-volume ratio limit cell size?

The cell membrane cannot move enough nutrients in or wastes out if the cell gets too large.

Why must cells be replaced?

Cells grow, wear out, or get damaged and must be replaced by forming two new daughter cells.