3.1 Cellular Level of Organization

Question 1

What is the cell theory?

Answer 1

• all organisms are made up of basic living units called cells
• all cells come only from previously existing cells

Question 2

Why are small cells a great advantage for multicellular organisms?

Answer 2

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

Question 3

What happens when a cell gets larger in volume?

Answer 3

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)

Question 4

What happens to volume and SA when a cell doubles in size?

Answer 4

SA increases fourfold
volume increases eightfold

therefore small cells are likely to have a more adequate SA for exchanging nutrients and wastes

Question 5

What does cell division restore?

Answer 5

the amount of SA needed for adequate exchange of materials

Question 6

Why do cells tend to be small and not large?

Answer 6

greater SA:V ratio gets things in and out more efficiently

Question 7

What shape or feature do cells might have to increase its SA:V ratio?

Answer 7

• 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

Question 8

Give an example of a feature of a cell that increases SA:V ratio.

Answer 8

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