Lab 5.2: Diffusion Through a Membrane Results Starch: Glucose: Iodine Iodine Benedict’s Starch BEFORE Glucose Iodine Glucose Only Heat Iodine Only Benedict’s + Glucose Starch + Iodine AFTER Glucose Only Iodine Heat Benedict’s + Glucose

Inv. 5.2: Diffusion Through a Membrane Question of the Day Question: Explain why farting in an elevator is an example of diffusion. Answer: … … … More than 25 types of elements 2’s Turn In: p. 194 A.Q. 1abc 3ab, 4, 5 Inv. 5.2: Diffusion Through a Membrane

Announcements Lab Quiz Tuesday Biosphere Observations Test Corrections 1/3 of a point back per question Last Day: Wednesday, 11/20

Quiz! Cell Structures & Functions

Unit 4 Vocab

Osmosis: Diffusion of Water Elodea Cells in Water Elodea Cells in Salt Water Membrane-bound sac Important for intracellular digestion, release of waste products Small in animal cells, large in plant cells

Unit 4 Vocab 40. hypertonic- concentration of solutes is high outside of the cell, causing water to leave Animal Cell: Above strength Plant Cell:

Unit 4 Vocab 41. hypotonic- concentration of solutes is low outside of the cell, causing water to enter Animal Cell: Means below strength Plant Cell:

Unit 4 Vocab 39. isotonic- solute concentrations are equal inside and outside of the cell Animal Cell: Same strength Plant Cell:

Why Are Cells So Small? Most cells are between 2µm and 200µm A micrometer is 1 millionth of a meter!

Inv. 5.3: Cell Size & Diffusion

43. surface area- the total area of the outside of an object 44 43. surface area- the total area of the outside of an object 44. volume- the total amount of space inside an object 45. surface area : volume ratio- the amount of surface area per unit volume; helps explain why cells must be small The volume of a cell increases much faster than its surface area! This causes transport of molecules in and out of the cell to be too slow for the cell to survive!

Why Are Cells So Small? Diffusion limits cell size #57. Diffusion limits cell size Larger distance = longer time to get through cell 20 cm cell: months for nutrients to get to the center Volume increase more rapidly than surface area What can’t organisms just be 1 giant cell?

p. 194 A.Q. 1abc, 3ab, 4, 5

p. 194 A.Q. 1abc, 3ab, 4, 5 1a. What is a cell? 1a. A cell is the basic unit of life. 1b. What three statements make up the cell theory? 1b. The three statements that make up the cell theory are: All living things are made up of cells. Cells are the basic unit of structure and function in living things. New cells are produced from existing cells.

p. 194 A.Q. 1abc, 3ab, 4, 5 1c. How did the invention of the microscope help the development of the cell theory? 1c. The microscope enabled people to see cells and study the parts of cells. This ability enabled scientists to learn that all organisms are composed of cells.

p. 194 A.Q. 1abc, 3ab, 4, 5 3a. What features do all cells have? 3a. All cells have DNA at some time in their lives and all cells are surrounded by a thin, flexible membrane. 3b. What is the main difference between prokaryotes and eukaryotes? 3b. Prokaryotes do not have DNA enclosed in a nucleus. Eukaryotes have DNA enclosed in a nucleus. Prokaryote: Eukaryotes:

p. 194 A.Q. 1abc, 3ab, 4, 5 4. What is the total magnification of a microscope that has an eyepiece magnification of 10x and an objective lens magnification of 50x? 4. The total magnification is 500x. A 10 micrometer cell is viewed through a 10x objective and a 10x eyepiece. How large will the cell appear to the microscope user? 5. The cell will appear to be 1000 micrometers (1 mm).

When Do Cells Divide? Before they become too big to survive #59. Mitosis: What can’t organisms just be 1 giant cell?