3.1 Cellular Level of Organization Flashcards
What is the cell theory?
- all organisms are made up of basic living units called cells
- all cells come only from previously existing cells
Why are small cells a great advantage for multicellular organisms?
LARGER CELLS REQUIRE MORE NUTRIENTS AND PRODUCES MORE WASTES THAN A SMALL CELL
nutrients (ie. glucose and oxygen) enter a cell and wastes (ie. carbon dioxide) exit a cell at its surface therefore the amount of SA affects the ability to get material into and out of the cell
What happens when a cell gets larger in volume?
the proportionate amount of SA decreases
ie. cube-shape: volume increases by (h x w x l) while SA increases by (h x w x 6)
What happens to volume and SA when a cell doubles in size?
SA increases fourfold
volume increases eightfold
therefore small cells are likely to have a more adequate SA for exchanging nutrients and wastes
What does cell division restore?
the amount of SA needed for adequate exchange of materials
Why do cells tend to be small and not large?
greater SA:V ratio gets things in and out more efficiently
What shape or feature do cells might have to increase its SA:V ratio?
- surface foldings can increase SA and therefore the ratio
- cells that specialize in absorption have modifications that greatly increase their ratio
- long and thin have greater SA than round and fat
Give an example of a feature of a cell that increases SA:V ratio.
cells that specialize in absorption such as columnar epithelial cells along the surface of the intestinal wall have surface foldings called microvilli that increases SA