Determine which cube size shows the most amount of diffusion using surface area to volume ratio calculations Relate lab data to explain why cells remain small. Safety: Goggles and Gloves Using NaOH –wash immediately with water Always cut away from you when using a knife

Powdered agar + distilled water + phenolphtalein Phenolphtalein is an indicator! It is colorless but Will change color when mixed with a base

Calculate the surface area and volume for the cubes. Calculate the surface area to volume ratio for the cubes.

1. Obtain beaker, knife, spoon, and cardboard tray. 2. Carefully cut a 2cm x 2cm x 2cm and a 4cm x 4cm x 4cm agar cube. 3. Place the 1cm, 2cm and the 4 cm cube into the beaker. 4. Carefully pour enough NaOH to cover cubes. Let stand for 10 minutes. Record start time. 5. Complete questions 8, 2, 3, 4, 5, 6, and 7 on the student data sheet.

Why was phenolthalien used in this lab?

Smallest cube showed 100% diffusion and the Largest had the least. Why?

1. Remove the cubes from the NaOH solution with spoon. Place cubes on your cardboard tray and carefully blot if necessary with paper towel. 2. Cut each block in half and measure the pale yellow area in the center in centimeters. Calculate the volume of this yellow region by multiplying length x width x height. Complete Table Draw diagrams of each cube using graph paper.

1. The agar cubes are models which represent cells. What made each cell different? 2. What living process is being modeled when you line up the cubes in the following order: 1cm, 2cm, 4cm? 3. Which part of the cell cycle would the 1cm cube be associated with? 4. Which size cube would represent a cell after mitosis? 5. What transport process is represented by the pink color found within the cubes?

1. Someone tells you that a human cheek cell is much larger than a human blood cell. Which cell would have the larger surface area to volume ratio? 2. The _________________ of a cell is being affected faster than its ____________________ as the amount of cytoplasm increases within it. 3. As a cell grows in size, what happens to it nutritional needs? What transport process needs to change to accommodate this need? 4. What does a cell do make sure that it does not grow too big? 5. How would an increase in cell size affect the cell’s ability to get nutrients? 6. In the lab, what material represented needed nutrient? 7. A rod shape (rectangular shape) bacterium has the following dimensions: 4mm long, 2mm wide, and 2mm deep. (a) What is its surface area to volume ratio? Show all work.